Silent Spring Arrives: The Collapse of Bird Populations in Riverside, California

E. N. Anderson, June 2024


            Silent spring is here. Several mornings this spring I have walked out into my yard and heard nothing. Eventually a mockingbird sings, a dove coos, and slowly a few birds call, but birds are dramatically down in just two years. Rachel Carson’s sad prediction in Silent Spring (1962) has become reality. In 1962, walking out on any California morning was an amazing experience of bird calls and song. It is now almost or totally silent.

            Almost all species are declining in Riverside now. Many species flourished with the spread of agriculture and suburbs, which brought water, fruit trees, sheltered gardens, and other blessings. Unfortunately, they have lately brought more deadly chemicals, supposedly to kill pests but actually killing all living things. Strong rodenticides are wiping out our natural rodent controls, the hawks and owls. Insecticides and other poisons have decimated insect-eating birds. Most seed-eating birds must feed their young on insects at first, so this loss of insects has greatly reduced birds like goldfinches. Herbicides and fires destroy natural habitats. Introduced epidemics, such as the H5N1 bird flu and West Nile virus, have devastated some species. Climate change has brought unprecedented heat and drought. The drought of 2019-22 was particularly serious. Birds have not recovered after two subsequent wet years.

            Natural habitat has largely vanished. Fires and other factors eliminated what little chaparral the area had, and have almost eliminated the coastal sage scrub. It is replaced with nonnative grasses and annuals. The riparian strips are increasingly fragmented, or eliminated outright. Sycamore Canyon Park and Box Springs Mountains Wilderness Park preserve a large amount of excellent habitat. So does the March Base ammunition storage facility and an associated ecological strip east of the facility, but this area is now slated for warehouses.

            It is likely that there will be almost no birds in Riverside in 20 years. Only concerted, dedicated citizen action can save any significant populations. 

            Birds are sharply declining worldwide, with a very conservative estimate of 29% decline over North America since 1970 (Rosenberg et al. 2019), and a more local study showing dramatic declines in the Mohave Desert since early naturalists studied it (Iknayan et al. 2018). Declines in many species in Riverside, California, has been obvious for years. On the other hand, so have some increases. The record deserves some attention.

            This status and distribution account covers the Box Springs Mountains, Sycamore Canyon Park, and immediately adjacent suburbs. The limits are the footslopes of the Box Springs Mountains in Moreno Valley, a couple of miles south of the south boundary of Sycamore Canyon Park, and the Riverside Freeway (Highway 91) between Alessandro and Columbia Avenues.

            This area is about half suburbs, about half open land. The entire Box Springs range, a small hill range rising from 1000’ at base to a bit over 3000’ at the top, is protected, much of it by a wilderness park. Sycamore Canyon Park protects 1500 acres, now surrounded by suburbs, warehouses, and busy streets, making dispersal hard for mammals but not interfering with flying birds. The University of California campus has a large agricultural operations and experiment area, with ponds, and a large and lush botanic garden.

            This is strictly a personal and informal record. I have not dealt with casual records. Most of the eastern warblers have turned up in Riverside at one point, and almost all regular California migrants have occurred, but this list concentrates only on species that are regular and whose population changes, if any, are significant. (I do include a few once-only records too weird or interesting to neglect.) Notably missing are the extremely thorough records for the University of California, Riverside, campus. I have taught there all my adult life, and seen most the bird species that have shown up, but many of them were seen only on campus as strays from far away. I have seen such oddities as Pine Warbler and Ovenbird, but will confine the following account to birds common enough to have a dynamic history of interest to conservationists.

I am grateful to John Green and David Rankin for constant help in all things bird-related. The species order below follows the convenient Sibley guide, 1st edn. 2000, where the scientific names can easily be found.

            I have lived in northeast Riverside or just across the mountains in Moreno Valley since 1966, keeping records of birds observed. I have lived in southern California since 1955, first birding Riverside County in 1956, so have a sense of earlier changes. The bird life has changed dramatically during that time. Many birds have gotten rare, others common. Birds of the old agricultural environment have disappeared. Others, urban in association, have appeared and become established. Some have appeared and then gone.

            The droughts of the 21st century have had major effects. The great drought of 2019-2022 led to several sharp declines, some not evident until the wet year of 2023. This coincided with a huge epidemic of bird flu that caused enormous die-offs in the eastern and central United States; how much the flu had to do with decline in Riverside remains obscure. Very few birds showed up to breed, compared to previous years. The most obvious damage was to the “annual crop” species like goldfinches, which crashed. Longer-lived birds like American Kestrels did better, but most birds showed a sharp decline relative to 2019. Two wet years in a row—2023 and 2024—stabilized many birds, but others, including House Finches, goldfinches, Song Sparrows, and other small common species, continue to be dramatically down relative to 2019.

            Overall, the pattern fits with the models of Victor Cazalis (2022), who has shown on the basis of worldwide studies (largely of tropical forest environments) that the first to go are “habitat-specialist, sensitive, endemic, and threatened” species; these are “losers.” Then “winners” take over: “non-specialist, large-range, human-tolerant, anthropophilic, and non-native” (Cazalis 2022, abstract). Then the winners begin to give way, as disturbance increases, until only the most anthropophilic (human-associated) are left. Species richness of the area can increase at first, then usually decreases, though other patterns exist. In Riverside, long before I came, major predators were gone, and open-country and wetlands birds were decreasing. I have seen the agricultural landscape largely replaced by city, except for the University of California research fields.

The major factor in decline is the loss of brush-loving birds, due to fire and drought and the consequent replacement of native sage scrub and chaparral by weedy annuals. Most of the hills in our area have now become grassfields. This has led to near-disappearance as breeding birds of the Lazuli Bunting and Black-chinned Sparrow, decline in such species as Costa’s Hummingbird, Wrentit and California Thrasher, and lesser declines in birds that can adjust to human-planted shrubbery such as Bewick’s Wrens and Spotted Towhees. On the other hand, the Rufous-crowned Sparrow, which actually prefers a brush-grass mix, stayed almost as common as ever until donkeys became so common that the sparrows cannot nest undisturbed. The Say’s Phoebe has increased along with the open hill grasslands.

            Next most important are suburbanization, eliminating open-country and agricultural species; pesticides, largely by eliminating food; and the general slow decline caused by night lighting, tall buildings, and other factors that endanger migrants. A deadly toll of pervasive poisons, cats, cars, polluted air, and human-vectored epidemics makes suburbs as hostile an environment for birds as all but the harshest deserts.

Disease was certainly a major factor in the early days of the West Nile virus in the 2000s, but populations seem to have stabilized now. Other mysterious declines seem so rapid and large that they are most reasonably explained as the result of disease, but no data exists (see Spotted Dove and Brewer’s Blackbird below).

            One other factor in decline was the Brown-headed Cowbird, which lays its eggs in the nests of smaller species. The young cowbird outcompetes the smaller nestlings, and they usually starve. Small cowbird flocks routinely flew through riparian areas in spring, searching for nests. A female lays many eggs and rarely misses a nest. This led to the decline of several species and the complete extirpation from our area of several, including Willow Flycatcher, Swainson’s Thrush, Warbling Vireo, and Purple Finch. All the small riparian birds have been affected. Eventually the cowbirds too disappeared, partly for lack of victims, but of the birds they parasitized, few have even begun to recover.

            The increases are all due to expansion of suburbs, providing new habitat for birds that like such environments. There is one exception: Say’s Phoebe, formerly rare, has become one of the commonest birds. Burning of the native brush created the short-grass habitat preferred by the phoebe.

            Some interesting contrasts would seem to demand more research. Evergreen forest warblers, formerly abundant migrants, are almost gone, while other warblers continue without so much decline; this certainly has something to do with logging of their nesting areas, but the decline is so great that there must be more to it. The cliff swallow, formerly the commonest swallow, has become one of the rarest. Some flycatchers increase while others die out.

Caused by factors outside our area are the declines in migrants, especially warblers. The reasons for this are multifarious and not always clear. General decline of insect life, as the world gets saturated with pesticides, is probably the major one; it is the insect-eating birds that have declined most. Northerly species may simply be staying farther north (American Robin being a clear case), but the neotropical migrants are simply gone. The declines in some species, such as Townsend’s Warbler and Olive-sided Flycatcher, are horrific throughout their entire range, not just California. Clearcutting of breeding habitat and wintering habitat has been taking place and must be involved. Insecticides on the wintering grounds are also a probable factor.

An extremely disturbing change, since it has strong implications for human health and survival as well as for wildlife, is the collapse of the large-insect-eating guild: Poorwills, Western Kingbirds, Ash-throated Flycatchers, Loggerhead Shrikes, Western Meadowlarks, etc. Another guild collapse, involving far more individuals though without (so far) eliminating whole species, involves the aerial foragers. The Cliff Swallow has declined from thousands to ones and twos in our area. All other aerial foragers have declined sharply.

The major cause of these declines is the collapse of insect populations. It is really rare to see a butterfly (especially anything other than the Cabbage White, Pieris rapae complex) in the Box Springs Mountains, where they used to swarm and occasionally go through migrations or outbreaks of thousands. Grasshoppers are uncommon where they used to swarm. Flies and mosquitoes are no longer the maddening, insufferable problem they were. One indication of the level of decline is the lack of need to clean one’s windshield; once one had to clean one’s windshield every time one filled the gas tank. Now there are rarely any “bug spots.”  Another indication is the lack of fauna at the porch light in the evening. In the 1960s, the amazing quantity and variety of insects attracted to lights was breathtaking—the weirdest forms would turn up. Almost everything in a basic insect guidebook was there to see. Now there is almost nothing. The decline in insects is worldwide (see series of articles in Nature for 11 April 2024). It results from heavy pesticide use, habitat destruction, and climate change.

Obviously, with no insects, insectivorous birds will die out. Currently, only the phoebes, with their almost supernatural ability to see, chase, and capture the tiniest gnats, flourish and thrive. Cassin’s Kingbird hangs on by falling back on berries when necessary; apparently the Western Kingbird does not do that.

Among migrants, we have few shorebirds and no sea ducks, but it is worth noting the horrific decline of these species worldwide. Southern California’s shores and surf are empty.

A happier reason for decline is environmental sanitation. Cleanup of dead animals, closing of garbage dumps, and dramatic reduction in human littering has led to an extreme decline in Turkey Vulture numbers (they no longer breed anywhere near here) and a sharp decline in gulls, Rock Dove (Pigeon), Starling, House Sparrow, Brewer’s Blackbird, and possibly other species in our area.

Another happy effect of change is that the decline of large-scale stock farming has led to a reduction Brown-headed Cowbirds.

Conversely, suburban birds do well. Many are increasing along with suburbs. Black Phoebes, Mockingbirds, Hooded Orioles, and some other species are far commoner than they once were. (Unfortunately, this has apparently peaked; Black Phoebes and Hooded Orioles are down relative to 2019.) Within the last 50 years, Band-tailed Pigeons, Acorn Woodpeckers, and, very recently, Allen’s Hummingbirds and the nonnative Collared Dove and Nutmeg Manakin have colonized the area.

The Habitat

            The area consists of uplands formed of granodiorite (locally grading into tonalite), emplaced around 90-110 million years ago, deep below the earth’s surface. It is cut by many “veins” (dykes and sills) made up of quartz, feldspar, and other minerals that cooled slowly and filled in cracks in the granodiorite. The major ones often show prospectors’ diggings, vain attempts to find gold at the rock contacts. Darker spots indicate lumps of much older schist partially absorbed by the granodiorite under conditions of enormous heat and pressure miles below the earth’s surface.

            The whole area has been uplifted by tectonic action, which still goes on, with small earthquakes being a familiar feature of local life. The area is thus cut by hundreds of faults, large and small. The larger ones define the major slopes, including the spectacular west scarp face of the Box Springs Mountains.

            They also determine the major lines of drainage. Several large permanent springs and a greater number of temporary ones (flowing after heavy rain) provide water. Two Trees Canyon provides the major westward drainage of the Box Springs Mountains, and has a large permanent spring and several small transient ones. The well-named Big Spring also feeds into it. The name “Box Springs” derives from a spring complex at the southwest corner of the range, boxed by the railroad in the 19th century to prevent cattle intrusion; it supports another extensive riparian strip of woodland. Sycamore Canyon, a very large and deep canyon, drains the western part of Moreno Valley, and is thus a large permanent stream. It is joined by many small streams, some permanent, many within the park. South of Sycamore Canyon Park, across Alessandro, the ammunition storage facility of March Base comprised a square mile of fenced land surrounded by open space. This protected grassland supports the only meadowlarks and Western Kingbirds left in our area. An ecological corridor east of it, between Alessandro and Van Buren, includes several stringers of riparian vegetation along transient creeks. This is extremely rich and lush habitat, a lifeline for riparian species. Tragically, the March Base facility was sold by the government to a warehouse construction company, with the result that the wildlife there (which includes jackrabbits and Long-tailed Weasels) is doomed. One hopes the ecological strip can be protected.

            The natural vegetation of the area is now almost entirely eliminated by fire. It was largely coastal sage scrub, dominated on sunny slopes by brittlebush (Encelia farinosa), on shady ones by buckwheats (Eriogonum spp., mostly fasciculatum), black sage (Salvia apiana), white sage (Salvia apiana), and California coast sagebrush (Artemisia californica). Chaparral covered the Box Springs Mountains slopes above 2500’ as well as the more sheltered slopes of Sycamore Canyon. It was basically chamise (Adenostoma fasciculatum) and mountain lilac (Ceanothus crassifolius) with many other species including sumacs, currants, brush cherry (Prunus ilicifolia), and other species. Buckwheats and deerweed (Acmispon glauca) were the main successional plants. A distinctive habitat covered the rolling mesa area of Sycamore Canyon Park: scattered California junipers living in open sage scrub. Wet canyons support a dense riparian flora of California sycamore (Platanus racemosa), willows (largely Pacific Willow, Salix lasiolepis), cottonwood (Populus Fremontii), and rarely other species.

Dry and seasonal canyons and moist spots such as seeps and rockfoot areas were usually dominated by Mexican elderberry (Sambucus mexicana—for now; it gets reclassified every couple of years), whose berries are an essential food for many birds. Sumacs (Malosma laurina, Rhus glabra), penstemon species, monkeyflowers (Diplacus spp.), and other small bushes also occupy these water-concentrating rock formations.

The margins of the riparian strips are marked by dense stands of mulefat (Baccharis pilularis), poison oak (Toxicodendron diversifolium), threeleaf currant (Rhus trilobata), and much less often some other species. In one place in Sycamore Canyon, a salt meadow has developed, bringing saltbushes (Atriplex spp.), saltgrass (Distichlis spicata), and other saline species to the area. The canyon also has rare stands of yerba mansa (Anemopsis californica) and Indian hemp (Apocynum cannibinum), the latter quite likely introduced by Native Californians in pre-settlement times.

            Fire has eliminated or greatly degraded almost all the chaparral and coastal sage scrub, and every year large new areas burn over. Once, the natives regrew, but now introduced weeds choke out the shoots and steadily increasing drought and heat makes renewal impossible. Also, nitrogen from fossil fuel combustion has fertilized the area, benefiting the grasses and mustards and losing the natives their former advantage of being able to thrive on low-N soils. The burned areas have been taken over by various introduced weedy grasses, mustards, and small flowers such as filaree (Erodium, largely cicutarium) and stinknet (a new invader, Oncosiphon pilulifera).

Some native annuals persist, notably fiddlenecks (Amsinckia intermedia) and tarweeds (Deinandra spp.), but drought has reduced most annuals to the vanishing point, though there was a spectacular showing of poppies and Phacelia spp. in 2019. The riparian strips are preserved from most fire by moisture, but invaded by fan palms (Washingtonia filifera and W. robusta), which at least are native to Riverside County (the former) and the wider California floral world (robusta, common not far south of the US border). More serious invaders are castor bean (Ricinus communis, a major pest), giant reed (Arundo donax), and other species. Even California walnut (Juglans californica) occurs in Sycamore Canyon.  Fortunately, most of the riparian areas are still in good shape, unlike the scrublands.

            The suburbs and much of UCR campus are covered by introduced ornamental trees, shrubs, lawns, and flowers, of very wide variety. Many are beneficial to wildlife, producing nector-rich flowers or good fruits, or providing nesting habitat and protective cover. The suburbs thus abound with life—but only the few organisms that can tolerate traffic, dense cat populations, and enormous doses of deadly poisons. Saturating one’s property with many times the legal safe doses of toxic chemicals is a way of life. When buying our current home, we found a shed in the back absolutely filled with deadly poisons for every imaginable organism from mammals to molds. We promptly took all to the county toxic waste disposal, and then tore down the shed and took all its woodwork there too—the whole shed was drenched in poison. The boards showed the characteristic slits that mark injection of “protective” chemicals. We could easily have murdered a large number of people with what was in that shed. This is all too typical of surburban life. It impacts birds largely through eliminating insects and other invertebrates, but rodent poisons also get into the owl and hawk populations, probably causing the recent reduction of barn owls in the city.

Other wildlife

            Coyotes, raccoons, opossums (introduced from the US South in historic times), gray foxes, and smaller fauna abound, all happily entering the suburbs to feed. Striped skunks moved in and completely replaced spotted skunks during the 1970s.

            Two rare mammals of conservation concern occur. The Bryant’s woodrat (or pack rat; Neotoma bryanti) has recently been split from the desert woodrat. It is local to southern California, and has been reduced to rarity by fire, drought, and suburbanization. Formerly abundant in the area, it is now almost gone. The Stephens’ kangaroo rat (Dipodomys stephensi) is a rare, local species of level areas, largely in western Riverside County. It still abounds in the more level parts of Sycamore Canyon Park and the open areas around the March Base ammunition dump (as well as in March Base itself).

            Many lizards and snakes occur, including the rare and declining Orange-throated Whiptail (Aspidoscelis hyperythrus). Vast numbers of insects and other invertebrates, including many native bees, once occurred, but now not only are most insects gone, but many of the survivors are nonnative.


Canada Goose. Common migrant overhead, mostly Nov.-Dec. and Feb. Has become a common breeding bird in Fairmount Park.

Mallard Duck. Occasional flyover. A few nest on ponds not far from mountain foot, e.g. UCR Agricultural Operations reservoirs, occasionally golf courses, and probably the Eastern Municipal Water District waterworks adjacent to Sycamore Canyon Park. More nest in Fairmount Park, where they are heavily mixed with domestic ducks. 

Most duck species are observed in winter on the Agricultural Operations ponds and the golf course ponds. Common ones include Ring-necked Duck, Ruddy Duck, and Hooded Merganser (most years).

Mountain Quail. Very rare wanderer to area. Noted after winter storms in the Box Springs Mountains.

California Quail. Abundant till the droughts of 2001-2, 2006-7, and 2019-22; now much less so, but still common in riparian and chaparral areas. Completely disappeared from lower Two Trees Canyon in 2015, because of a combination of drought and an exceptionally active Cooper’s Hawk nest that raised two young. Recovered substantially after wet years of 2018-19, then decreased again with drought. Survives very locally in suburbs, but does not do well.

Ring-necked Pheasant. Formerly fairly common in the orange groves of the area, rarely appearing around the foot of the Box Springs range. Eliminating the groves has eliminated this bird. It was completely gone before 1990.

Double-crested Cormorant. Erratic but sometimes common migrant; large flocks often fly overhead. As with the other waterbirds, this species is common and regular at Perris Reservoir and the San Jacinto Wildlife Area, and the very commonly used migration routes from these to the coast or over Cajon Pass takes these birds directly over the Box Springs Mountains area. Flocks of water birds, and also migrant hawks, often avoid flying over mountains by flying over Pigeon Pass (on the east side of the Box Springs), or over Box Springs Pass and then over UCR.

White Pelican. Uncommon migrant, but flocks sometimes move northwest from the reservoirs and Salton Sea, flying over Moreno Valley and Pigeon Pass. Much less common than formerly.

Great Blue Heron.  Uncommon migrant and drop-in, usually at ponds, sometimes flying over or in fields. Common at ponds and lakes around Riverside.

Great Egret. Fairly common migrant or year-round visitors at Riverside lakes and ponds.

Snowy Egret and Green Heron show up more rarely.

Black-crowned Night Heron. Migrant. Now very rare, formerly much more common.

Turkey Vulture.  Uncommon migrant. Much less common than formerly. Migrant numbers steadily decline. Used to breed in Riverside area; declined with sanitation, disappearing as breeder with loss of garbage and rapid clean-up of dead animals.

Osprey. Rare migrant.

White-tailed Kite. Rare in the early 20th century, but established in the Santa Ana River bottom. Became steadily commoner, peaking in the 1970s, when it was a common bird. Steady decline since, and now almost completely gone; very rarely seen. The theory in the 1970s was that new suburb construction chased lots of mice out of their holes, and then final suburbanization eliminated open habitat without chasing any more mice.

Bald Eagle.  Rare migrant, mostly February. Winters at Lake Mathews nearby.

Northern Harrier. Rare migrant, very rare wintering bird; formerly common migrant and fairly common winterer. This bird has declined dramatically everywhere in its worldwide range.

Sharp-shinned Hawk. Common, migration and winter.

Cooper’s Hawk   Common resident. Pairs breed every year in Two Trees Canyon, Sycamore Canyon, and the ecological strip south of the latter. Others breed elsewhere in the city. This bird was very rare in the mid-20th century; DDT and probably other factors had almost eliminated it. With banning of DDT, it slowly began to increase, and is now very common here, with consequent devastation of easy-to-catch prey species. Cooper’s Hawks love pigeons, which are big, meaty, fairly easy to catch, and presumably as tasty to hawks as to humans, so where Cooper’s go the pigeons and doves thin out.

Red-shouldered Hawk. Always (since 1950s at least) a substantial and increasing breeding population in Riverside city, until 2023. Only rarely forages outside the suburbs, but has nested near Two Trees Canyon mouth and routinely forages up to the western foot of the mountains. It has spread with suburbs, where it enthusiastically catches rats and other animals. Unfortunately, some decline in 2023 coincided with a savage bird flu epidemic in the US and with the increased use of extremely strong rat poisons. Since the Red-shoulder feeds around houses, it is much more vulnerable than the Redtail, which hunts in open country where poisons are not usually spread. Some recovery in 2024, but still less common than formerly.

Swainson’s Hawk. Very rare migrant, mostly spring. Formerly commoner; appears to be steadily declining as local migrant.

Red-tailed Hawk. Most birds of prey are declining, but the redtail seems to increase slowly but steadily. Hunts for rats and ground squirrels along freeways and seeks out burns to hunt mammals that cannot find much cover. A dramatic situation was created by a major fire in Two Trees Canyon around 1988; the mammals had no cover and up to 8 red-tails hunted constantly over the burn all winter. Ground squirrels never recovered in the area. Breeds wherever there are tall groves. The Two Trees Canyon pair is particularly site-faithful, nesting every year in the central part of the riparian strip. Pairs in Sycamore Canyon and elsewhere are similarly faithful. The mercifully preserved ecological strip south of Sycamore Canyon Park (across Alessandro) has several pairs. The total population of the area is large.

Ferruginous Hawk. Formerly uncommon but regular migrant and rare winter in Pigeon Pass and south from there; now extremely rare. Never seen by me on the Riverside slope of the mountains until an immature appeared in upper Two Trees Canyon in fall 2017 and went on to spend the winter. None seen since.

Golden Eagle   Rare wanderer. Formerly much more common, breeding not far away (in Colton and all the higher mountain ranges) and common in winter. By 1970 it was gone as a breeding bird from most areas, and rare as a winterer. A pair nested on the Box Springs Mountains in 1979 and successfully raised one young, a female. Wind farms in the San Gorgonio Pass have killed many golden eagles, contributing to decline.

American Kestrel. Steady decline, as in most of the US, but not so bad here as in many (or most) areas. Until recently, a fairly common resident. However, following the drought of 2019-22, many pairs failed to breed in 2023. Considerable recovery in 2024.

Merlin. Very rare migrant. (Winters some years at UCR.)

Peregrine Falcon. Has occurred on UCR campus and was briefly regular on tall buildings in downtown Riverside in early 2010s.

Prairie Falcon. Rare migrant; once many migrants on the east side of the Box Springs and in the Pigeon Pass area, including the headwaters of Two Trees Canyon. One spent late fall and early winter in and near southern Sycamore Canyon Park in 2023-4.

Virginia Rail. A marsh formed at the mouth of Two Trees Canyon in a wet spring (1999) and a pair of these rails actually nested there (information from John Green).

American Coot. Common in winter on ponds and lakes throughout Riverside, but not as common as formerly.

Killdeer. Rare migrant and winterer, heard calling overhead on rainy nights. May still breed in UCR Agricultural Operations. Bred until recently in the large protected pond areas of the Eastern Municipal Water District. Steady rapid decrease during my entire time in California, especially with draining of wetlands in the mid-20th century. This formerly extremely abundant bird has shared the fate of many shorebirds. It has decreased at least 95% in our area as winterer.

Solitary Sandpiper.  I try to avoid one-shot sightings, but this one is too weird to miss. One spent several days, Sept. 16-20, 2014, at a transient rainpool left by rains from Hurricane Norbert, at the foot of the Box Springs Mountains, where the railroad blocked a wash channel.

Bonaparte’s Gull. Rare migrant (common where lakes and ponds occur, nearby).

Ring-billed Gull. Abundant in the old days. Steady rapid decline (even more dramatic in Los Angeles) after about 1990. This tracks the rise of recycling and better sanitation and garbage pickup, and probably also the greater charms of Lake Perris luring them away from our (cleaner) area. Closing the landfill north of the Box Springs Mountains greatly reduced gull numbers in our area.

California Gull. As for Ring-billed.

Rock Pigeon (Rock Dove). Extremely common 50 years ago, now almost extirpated from this entire area except for Riverside downtown, because of environmental sanitation and the Cooper’s Hawk population rebound. The very active Cooper’s Hawk nests since 2000 seem to have finally exterminated it from the entire eastern part of our area; Rock Doves occur only casually in the northeast corner of the city. They remain common in downtown Riverside, though Peregrine Falcons occasionally hunt them there.

Band-tailed Pigeon. Uncommon winterer as of 1966. The extreme wet year of 1968-69 drove huge flocks out of the mountains due to heavy snow, and kept them out. Many started breeding in oaks all over southern California, including Riverside suburbs and UCR campus. They stayed, and are still here. Populations rapidly climbed, and one could see flocks of 50 or more in the 1990s. Then Cooper’s Hawk populations recovered, and the band-tails declined in lockstep with the Cooper’s increase. Band-tails are declining in much of their range, so this phenomenon may be widespread. The band-tails and Cooper’s have now apparently reached an accommodation, with band-tails still found in every part of Riverside that has many large live oak trees. Combination of drought and very active Cooper’s hawk breeding in 2013 till present lowered numbers somewhat, and they have stayed down. Now that Rock Doves are essentially gone, the pressure on Band-tails is greater than ever, and they will probably not survive. Band-tails flock to the Box Springs Mountains in large numbers during elderberry season in early summer, with flocks of dozens (formerly) and at least 5-10 (now) often rising from elderberry bushes. The populations in the higher mountain ranges nearby are declining, partly due to poaching (information from Norm Lopez). Sharp decline in 2023-4, possibly due to the bird flu epidemic.

Eurasian Collared Dove. This introduced European bird spread through North America from the 1930s onward, appearing in our area by the early 21st century. Began to show up rarely but regularly by 2010. Now a regular but quite uncommon resident, though it is now common in much of the southwestern US. Our Cooper’s Hawks may be, once again, responsible for keeping it uncommon.

Spotted Dove. Introduced from south China to Los Angeles around 1890-1900, this species spread rapidly and steadily. It was extremely common in Riverside by the 1960s, its loud coo being one of the most characteristic suburban sounds. It suddenly began to decline in the early 1990s and totally disappeared by the early 2000s. It then disappeared from Los Angeles too, and is now extirpated completely from California. Cooper’s Hawk population recovery is almost certainly one part of the story, but the speed and completeness of population collapse, even in Los Angeles where Cooper’s Hawks are rare, implies a disease epidemic of some sort.

Common Ground Dove. Expanded from the deserts into the Riverside area with the expanding orange groves, and contracted as the groves did. Formerly not uncommon around groves, including the lower fringes of the Box Springs range, but gone by about 1980.

Mourning Dove. Much commoner when barley was farmed in Moreno Valley and when north Riverside was mostly orange groves. Part of the reason is probably the recovery of the Cooper’s Hawk population. However, this hardy survivor has adjusted, and remains one of the commonest birds in the area. No recent decline noted.

Parrots. Various escaped cage birds show up now and then. Species seen in the suburbs include Lilac-crowned Parrot, Cockatiel, Budgerigar, and Canary-winged Parakeet. Others will surely appear.

Greater Roadrunner. Formerly commoner, but still fairly common in all more or less wild areas, with about one pair per canyon. Regularly seen in suburbs.

Barn Owl. Remained common till about 2010, after which decline, very notable since 2014. The decline seems to track decline in human-commensal mammals (rats, etc.) due to tough plastic garbage bins and reduction in littering, and probably also to stronger rodenticides; the state has now banned the strongest rodenticide because of devastating effect on wildlife. Still fairly frequent in suburban areas, but sharp decline since 2022-3, probably due at least in part to continuing use of extremely strong rodenticides.

Flammulated Owl. One record near mouth of Two Trees Canyon, Sept. 1992, too unusual to ignore.

Western Screech Owl. Still not uncommon in suburban areas with large oak trees. Rarely observed, because it calls primarily in the wee hours of the late night, but sleepless nights reveal it was and is regular everywhere I have lived in Riverside.

Great Horned Owl. This powerful predator maintains several nesting pairs in the Box Springs Mountains, Sycamore Canyon, UCR campus, and suburbs—it is a common bird for a predator. It is probably a main reason for cat disappearances that get blamed on “coyotes.”  A pair has always lived and nested in Two Trees Canyon. Pairs occur in every major canyon, and in many old and large suburban trees.

Burrowing Owl. Rare migrant. Formerly common breeder in the interior valleys, even in quite urban areas around Riverside. Now eliminated, probably from all of western Riverside County, by suburbanization. I saw it as a breeding bird in Norco, in 1956. It is long gone.

Spotted Owl. One spent the first part of winter in Two Trees Canyon, first noticed 1-26-1988 (but surely there earlier) to 2-28-1988. Frequently photographed.

Long-eared Owl. Rare migrant. Regular, even common (at least formerly), in winter in old orchards in the San Jacinto Wildlife Area, but declining everywhere (as it is throughout North America). Formerly nested in riparian areas of the Inland Empire (Dawson 1923), likely including the Santa Ana River wetlands; nested at Morongo Reserve till fairly recently. Now altogether gone as a breeding bird in southern California.

Lesser Nighthawk. Said to have been common in open valley areas in the old days; now gone as a breeding bird from the Inland Empire. Occasionally seen in migration.

Common (Booming) Nighthawk. Rare wanderer from San Bernardino Mountains, where it breeds (but very much less commonly than formerly). Seen over Moreno Valley and Box Springs range, but not for many years.

Common Poorwill. Rare but regular migrant; slopes of the hills, e.g. in Two Trees Canyon. Much less common than before, when probably summer resident.

Vaux’s Swift. Uncommon spring migrant. Formerly much more common. Usually seen only when heavy cloud cover forces it to fly low. Steady decline over decades, throughout its range.

White-throated Swift. Much less common than formerly. Still fairly common migrant into the 2000s, but now definitely uncommon everywhere. Probably was once a fairly regular breeder in rockier areas. Formerly nested under highway bridges near Box Springs (the springs themselves) and may occasionally still. Rare nester elsewhere.

Black-chinned Hummingbird. This aggressive hummingbird succeeded well until the droughts after 2012. Growth of planted and wild sycamores led to an increase, especially where planted sycamores were near households with hummingbird feeders. Peak around 2011-2012; fewer in 2013; final, total collapse in 2016, when only migrants were observed in the canyon and in most of northeast Riverside. A displaying male in May 2018 indicated there was at least one pair in the lower canyon that year. It has now apparently completely deserted the whole area for breeding. Over the state it has been declining at 1-2% per year (English et al. 2022).

Anna’s Hummingbird. Always common resident. Now commoner than before, spreading with suburbs and feeders. Largest of hummers, it dominates the feeders and also most flowers.

Costa’s Hummingbird. Formerly abundant. Considerably less common now, because fire has turned the flowering bush areas into cheat grass and because drought has reduced the native flowers even more since 2001. Still found, but in steadily shrinking numbers, in the Box Springs wherever there are reliable summer flowers. Costa’s has taken to civilization, but Anna’s and Allen’s beat it out from feeders. It survives especially where humans have created desertlike habitat. Its adaptation to suburbs has led to its meeting the Anna’s and hybridizing; hybrids were apparently extremely rare before 1970 but are not so rare now.

Rufous Hummingbird. Far less common than formerly. Was a very common spring and late summer migrant in the 1960s. Now rare. Still a common summer migrant (July-August) around red flowers in the hills. There is a massive decline rangewide, probably from pesticides etc. on the wintering grounds. Statewide, Rufous/Allen’s hummingbirds declined at 7% per year from 2009 to 2019, indicating a horrific population crash, not fully explained (English et al. 2022).

Allen’s Hummingbird. Dramatic invader. Formerly in southern California (at least south and east of Ventura) confined to Channel Islands and Palos Verdes Peninsula. Spread in recent years, reaching Riverside at some undetermined point possibly in the 1990; first known nesting in 2008. Now common resident of the city, wherever there are many red flowers. Does not occur in wild areas, except briefly as a migrant; strictly a yard and garden bird. Its rapid spread and success in southern California cities, starting from a small population in Palos Verdes Hills (probably augmented from other sources), contrasts dramatically with the decline of most species, and of this species in particular in much of its range.

Calliope Hummingbird. Very rare migrant.

Belted Kingfisher. Uncommon migrant and winter visitor at ponds.

Acorn Woodpecker. Expanding as a suburban bird, as planted oaks grow and flourish. This bird did not occur in the area as a breeder before the late 1960s. There were no oaks here in the old days. By the late 1960s it had colonized areas of the city that had old (human-planted) live oak trees, and it has steadily increased in range and numbers since. Strictly a suburban bird, it almost never appears in the wild areas. Some decline appears to have followed the serious drought of 2020-22; some stabilization since.

Red-breasted Sapsucker. Rare, winter. Rarer than formerly.

Downy Woodpecker. Formerly common in winter, possibly breeding in Santa Ana River bottoms. Now essentially gone, though wanderers may occasionally appear.

Hairy Woodpecker. Rare wanderer. One appeared in fall 2017 and stayed through the winter in Two Trees Canyon.

Nuttall’s Woodpecker. Common resident; no change, perhaps even some increase with growth of trees. A common suburban bird, occurring also in all riparian areas. Readily comes to feeders, thus augmenting its success.

Northern Flicker. Uncommon winter visitor. Formerly common resident, no change noted from 1966 to 2011—but in the spring of 2011 all the flickers in the area, from Two Trees Canyon to the whole of Riverside city, disappeared, apparently simultaneously. They are now uncommon winter visitors. Drought and decline in ant numbers seem likely causes.

Olive-sided Flycatcher. Formerly uncommon migrant. Now very rare. The decline of this bird from one of the commonest in North America 40 years ago to extreme rarity now has been very striking. Factors identified in the literature include changes in forest composition that make its nests more findable to predators, and cultivation on its very limited wintering grounds in South America. There is also the tremendous decline of large insects everywhere, and the abundance of pesticides on the bird’s migration routes as well as its wintering area. Possibly it is given to population fluctuations; it was not scientifically described until 1831, and Audubon considered it extremely rare. Yet in the 20th century it was abundant in evergreen forests throughout North America.

Western Wood Pewee. Formerly very common migrant, now uncommon. Much less common than formerly.

Willow Flycatcher. Uncommon migrant. Formerly an extremely common nesting bird in riparian areas of southern California (Dawson 1923), now completely extirpated except for tiny, local relict populations (not in our area). Cowbirds appear to be the cause, along with destruction of much of the riparian woodlands.

Hammond’s Flycatcher. Rare to uncommon migrant. Empidonax flycatchers are notoriously hard to tell apart. All are seen locally. Pacific-slope is the most common and regular; Hammond’s may be next, or Willow. Definite decline in Empidonax flycatchers of all types in recent decades.

Gray Flycatcher. Rare migrant and very rare winter bird.

Dusky Flycatcher. Rare migrant, much rarer than formerly.

Pacific-slope Flycatcher. Fairly common migrant; has bred in Two Trees Canyon’s densest riparian area. No longer breeds and is much less common than once.

Black Phoebe. Abundant resident. Expanding steadily with suburbanization and sprinklers. Usually stays in the suburbs, but appears anywhere that has any water at all, natural or piped. Population leveled off and has declined recently (since 2020, sharply since 2022).

Say’s Phoebe. Common, winter; breeds in higher dry areas nearby, including the Box Springs Mountains (now from top to bottom). Has actually increased, with conversion of brush to grass over most of the Box Springs Mountains and Sycamore Canyon Park.

This is the only bird that has clearly increased for reasons other than suburbanization. It has taken over the vast areas that were formerly coastal sage scrub but are now weedy grassland. Doubtfully bred in the area as of the 1950s, but now is one of the commonest breeding birds of the open areas, and has even invaded suburbs where there are open patches to forage. Its astonishing ability on the wing, which give it the Indigenous name of “wind’s grandchild” in Arizona, allows it to engage in long chases of even tiny prey. Population has leveled off since 2020.

Ash-throated Flycatcher. Rapidly decreasing migrant, perhaps still rare summer breeder in the hills. Formerly common migrant and breeding bird. Replacement of chaparral and coastal sage scrub with cheat grass has cost it most of its breeding habitat here. However, most of its habitat in the western US and in Mexico is intact, and the key to its decline is the steady decline in large insects. It is one of the fast-disappearing guild of large-insect-eaters.

Cassin’s Kingbird. This is an interesting story. A few years after the Westerns largely disappeared, the Cassin’s began to expand, presumably to fill the niche. They often hunt from the very same trees the Westerns used. Most if not all the expansion is since 2000. Numbers of both kingbirds leveled off around 2011, with the Cassin’s common but no longer increasing, and the Western rare but hopefully stable. Nests abundantly in suburbs and wild riparian woodland. The extreme droughts of 2015-16 and 2020-22 led to abandonment of some of these nesting points, however. Decrease in 2024.

Western Kingbird. Formerly abundant summer breeding bird in all open grassland and field areas. Now almost gone as a breeder, as it is from almost all of southern California. (Statewide, it survives mostly in places with extensive not-very-disturbed grassland.)  Still fairly common migrant. Survives, or did until recently, as breeder in the wilder parts of Moreno Valley badlands and elsewhere—ironically, occupying the newly created grasslands resulting from replacement of chaparral by cheat grass. A couple of pairs survive and reproduce in the March Air Force Base ammunition storage facility south of Alessandro, where the birds are protected by chain-link fencing and razor wire. Successfully bred in the UCR agricultural fields in 2011 and apparently in 2013, and apparently at head of Two Trees Canyon in 2013. Most interestingly, a family appeared and successfully nested in the trees in the open country at the end of Manfield St. in 2015—the same trees being occupied by a family of Cassin’s. In spite of the high drama inevitable in kingbird families, the two families apparently got along well. Unfortunately, the droughts of 2015-16 and 2020-22 reduced the already-small population.

Loggerhead Shrike. Now rare migrant. The last breeding pair I saw in the area lived at the mouth of Two Trees Canyon. It nested every year, and usually raised young; it disappeared in the early 1990s. The young never seemed to establish themselves. This bird is now almost gone from southern California, as from most of its range. One of the more depressing worldwide events of the last 20-30 years has been the decline of many, if not most, shrikes. (Birding in Hong Kong reveals the same decline in the once-abundant Brown Shrikes that we see in Loggerheads here.) Declines of large insects, loss of grassland, and direct poisoning by insecticides, are causes.

Warbling Vireo. Formerly abundant migrant, now uncommon. This bird used to be an abundant breeding species of riparian forests in southern California. Cowbirds and habitat loss have wiped it out. It now appears completely or almost completely extirpated from southern California.

Bell’s Vireo. Formerly common migrant and summer breeding bird (at least nearby); declined due to nest parasitization by cowbirds. With the decline of cowbirds, this vireo expanded again, becoming common in riparian areas nearby, though so far not in the Box Springs Mountains (except as a rare migrant). However, several breed around Box Springs. Breeds abundantly in Sycamore Canyon Park and the riparian areas south of it across Alessandro Blvd. Supposedly saved in the Santa Ana River bottoms due to volunteers and paid staff systematically going through the willow thickets and throwing cowbird eggs out of vireo nests. Alas, higher-nesting vireos like the Warbling Vireo did not benefit from this.

Plumbeous Vireo. Very rare migrant.

Cassin’s Vireo. Uncommon migrant. Formerly much more numerous, though never really common. This bird has suffered extreme declines in the mountains where it breeds, tracking the rapid rise of cowbird numbers there as well as drought and fire.

Western Scrub-Jay. Some reduction from West Nile in 2010, but now about as common as ever. Largely a suburban bird now; natural habitat is so degraded by fires and cheat grass that the birds have taken to the suburbs. Seems to have shared in the widespread and rather mysterious decline of birds in 2023-4.

American Crow. This bird has taken a terrific beating from West Nile virus. The population declined well over 90% in the first 2 years of the virus (by my counts), and declined further since. However, they are rapidly recovering, and are common again, though nothing like their former abundance. There used to be many thousands breeding in the river bottom. Many streamed over to feed at the now-closed garbage dump between Blue Mountain and Pigeon Pass. Successive waves of West Nile keep knocking them back, however, with a serious outbreak in 2014. It might seem hard to be sorry for a bird that eats so many other birds’ eggs and young, but the highly social crow must be seriously and sadly affected by seeing the death of young and of flockmates.

Northern Raven. Very abundant resident. Increasing, as garbage and roadkills get commoner and competition from crows and vultures disappears. Lives mainly in the wildlands, but forages all over the city, seeking anything live or dead that has high nutrient value.

Horned Lark. Formerly common breeder in wide open fields, at least in Moreno Valley; now gone. Migrant in grassfields of Sycamore Canyon and occasionally UCR fields. Still bred in large numbers in the Eastern Municipal Water District lands until the late 20-teens, but this colony abandoned (a few larks in the area in spring 2022 seem not to have stayed). This tracks a general decline of the species in California, where its habitat is now suburbanized, overgrazed, or used by off-road vehicles and the like.

Purple Martin. Formerly very rare migrant. Not seen in recent years. This bird was always rare in southern California. It has declined steadily for the last 50 years, apparently throughout its range. Starlings out-competing martins for nesting holes have had at least something to do with this, but decline of large insects is clearly a more important factor.

Northern Rough-winged Swallow. Common but erratic migrant; some breed in lower parts of the Box Springs area, especially under freeway overpasses near Box Springs itself. Ironically, this once rarest of local swallows is the least affected by decline, though it too is fading slowly.

Violet-green Swallow. Formerly common migrant, but, as for Tree, much less so than once. Visible decline since drought became serious in 2020, and, as with other birds hard hit by drought, not recovering since. Very few in 2024.

Tree Swallow. Common early migrant, but far less common than even two decades ago. Very rarely seen in spring 2024. May still breed locally, but evidence is scarce.

Cliff Swallow. Major decline. Huge population as of 1966, nesting—among other places—under the cornices of the Citrus Experiment Station buildings (now the Business School) and on the agricultural buildings at UCR. The species has declined throughout California, with habitat loss (especially loss of reliable mud supplies for nest-building) and with loss of aerial insects. Some still nest in UCR’s agricultural fields. In 2014, the birds established a flourishing colony under the freeway bridge over University Avenue, showing that no amount of traffic can discourage them; in 2016 a few still nested there, but then no more. A large colony of barn and cliff swallows persisted in the Eastern Municipal Water District waterworks and nearby March Base ammunition storage facility, a large area with much water that is securely protected, until drought (probably) led to decrease, but some rallying by 2024.

This bird occurred in millions in southern California in the 1960s, with up to 100,000 counted at nesting season at San Juan Capistrano Mission. None has nested there for many years now. The bird was once a major part of the local bird fauna, but is now facing extirpation. No other swallow has declined so much, and indeed the numerical decline of this swallow is the greatest of any species except (probably) the Brewer’s Blackbird. The need for quality mud and probably a need for large colonies (for protection and socializing) are factors.

Barn Swallow. Erratically common migrant. A few (formerly many) pairs breed in the Riverside area and erratically forage over wildlands. The last significant colony, in the EMWD grounds and nearby, is greatly reduced. Formerly abundant.

Mountain Chickadee. Formerly casual, usually after winter storms with heavy snow in the mountains. Now a fairly regular winter bird, especially in the UCR botanic garden but sometimes in pines nearer the mountains. Probably tracking the growth of planted conifers.

Oak Titmouse. Formerly at least occasional, in suburbs and canyons, but very susceptible to West Nile, and thus now rare. Probably gone or nearly so, except as a casual visitor.

Bushtit. Still common everywhere that natural brush or extensive planted shrubbery occurs, but much less common after the extreme droughts of the 2000s, and gone from the vast areas of cheat grass where it abounded when those areas were coastal sage scrub. These birds can fluctuate in numbers dramatically from year to year and even from season to season, depending on conditions, making the level of decline hard to estimate, but it is certainly down at least 90% from the 1960s, largely because of loss of habitat to fire and drought. Visible decline throughout our area after the extreme 2021-2 drought.

Red-breasted Nuthatch. Rare wanderer in migration and winter, (but fairly regular winterer in pines on UCR campus). Irruptive, more common some winters.

White-breasted Nuthatch. Occasional wanderer, turning up in suburban areas.

Brown Creeper. Rare migrant or wanderer.

Rock Wren. Formerly abundant on the Box Springs Mtns. and Sycamore Canyon rocky areas, and indeed anywhere with extensive rocky outcrops. Less common after droughts since 2015. Sharp reduction from 2020 on, with drought, burros, and probably other problems.

Canyon Wren. Common in canyons of the Box Springs Mtns. Also in Sycamore Canyon. Declining, however, apparently tracking drought.

House Wren. Common, summer; slightly less so in winter. In spite of its name, it is confined to wild riparian areas in our area, and any wren seen around houses here is almost certain to be a Bewick’s. Much more common as migrant than as breeder. Apparent decline after 2020.

Bewick’s Wren. Common, but gone from pure-grass areas of the hills. Survives wherever some dense brush exists. Formerly abundant in the chaparral and sage scrub, so replacement of these by grass has meant a major population reduction—at least 90%–in the hills. It has, however, successfully colonized suburbia, and remains one of the commonest birds.

 Cactus Wren. Rare wanderer. A pair set up house in a large cactus garden (owned at the time by Jerry Gordon) at the mouth of Two Trees Canyon in the late 1980s and early 90s and bred, and indeed there was some spread, with records all along the west edge of the range, but the birds disappeared in the early 2000s. Otherwise, very rare visitor.

Blue-gray Gnatcatcher. Formerly fairly common winterer and migrant, now much less common. Probably bred locally in the old days.

California Gnatcatcher. The species was first described from “Riverside,” and occurred in our area; its nearest current breeding station is in the Gavilan Hills, if it still survives there. There are a few recent reports from the Box Springs Mountains area. My only observation in this area is of one near the end of Blaine St., Nov. 6, 2020.

Ruby-Crowned Kinglet. Common, winter. Possible decline noted; probably, individuals are staying farther north.

Wrentit. Still common, but drastically reduced by burning of hills and replacement of brush by introduced weedy grasses. Survives only where dense brush exists, but at least stable there, especially in poison oak thickets. Always commonest in riparian brush, which has expanded somewhat, but has lost almost all its habitat on the hills.

Western Bluebird. Common, winter. Formerly, usually did not show up till snow closed off mountain feeding areas. Now it appears early and stays late, and since about 2011 it nests (uncommonly) on and near UCR campus and erratically in Sycamore Canyon Park. A lovely addition to our fauna. Probably could not have nested without the recent decline in starling numbers. In the 1960s and 1970s it was eliminated from much of its lowland habitat through starlings pre-empting the tree holes it needs for nesting. Part of the increase may be due to the bluebirds being forced out of the mountains by drought and fires.

Swainson’s Thrush. Formerly common migrant, now uncommon. Largely (though not totally) eliminated as breeding bird from southern California, by riparian habitat decline and by cowbird parasitization of nests.

Hermit Thrush. Fairly common fall migrant and winterer. Less common than formerly.

American Robin. Still common wintering bird. Much less common in winter than it used to be. Global warming is letting them stay farther north. Breeds in the urban areas, though much less often than formerly. Robins, however, apparently did not breed in the lowlands at all until permanent watering, shade trees, and lawns entered the picture. Apparently wintering birds from the mountains or farther north simply decided to stay around. Numbers nesting in Riverside peaked in the 1980s-90s and have recently declined sharply.

Varied Thrush. Formerly extremely rare winter visitor to area. In the winter of 2014-15, hordes of them descended, with up to a dozen a day seen in the Botanic Gardens and one or two in Two Trees Canyon. This was a winter when several northern and eastern species appeared for the first time or in unusual numbers. No reason is apparent for this phenomenal migration. Since then, it is back to rarity.

California Thrasher. Still fairly common wherever natural brush occurs. Fire and subsequent replacement of brush by weedy grasses has reduced the population probably 90%. However, it has stabilized, remaining very common wherever even small patches of natural brush remain.

Sage Thrasher. Formerly rare to fairly frequent migrant, mostly March and April; now almost gone, due to decline of overall numbers as sagebrush disappears from the Great Basin.

Northern Mockingbird. Abundant resident, commoner than ever. This bird is now purely a human commensal in southern California, and increases with suburbia. Commonly observed in the wilder areas, also, foraging up from suburban nesting grounds, often to eat elderberries in the hills.

European Starling. Not here in the 1950s. Showed up mid-60s and common by late 60s. Kept increasing till peak around 1980s, then slow decline. Environmental sanitation seems to be the cause; the bird forages for insects but eats much human food wastes, and may depend on the latter. Now almost gone from the wilder areas. Pairs persist in Riverside city, commoner in denser suburbs near fast-food outlets.

American Pipit. Winter visitor. Much less common than formerly. Decline tracks loss of open fields. Still erratically common in the open grasslands on the higher parts of the Box Springs range, on UCR campus, and in grasslands of Sycamore Canyon Park.

Cedar Waxwing. Common winterer. Very much less common than before. This bird appears to be declining all over the west.

Phainopepla. Common migrant and occasional summer breeder in canyons and washes with elderberries and/or other small-berried bushes. Even manages to breed in suburban small parks.

Orange-crowned Warbler. Common migrant, rare winter. Less common than formerly, but has declined much less than most warblers.

Nashville Warbler. Fairly common migrant, much less so than formerly.

MacGillivray’s Warbler. Fairly common migrant, much less so than formerly.

Common Yellowthroat. Fairly common migrant, rare winter, occasional local breeder. Unlike other warblers, seems to be holding its own.

American Redstart. Very rare migrant.

Yellow Warbler. Formerly abundant migrant, breeding in riparian habitat. Now much less so, but may be recovering somewhat, though numbers seem erratic. Like the Warbling Vireo, this bird has been almost wiped out of southern California by cowbirds and riparian habitat loss. It was back on UCR campus as an apparently successful breeder in 2011 and since. An impressive population expansion led to its being downright common in summer 2014. Drought has thinned it out since, however. Breeds around Box Springs (the actual spring), and in other riparian areas nearby, but not in the riparian strips in the mountain range. Breeds in Sycamore Canyon Park riparian strips and the ecological strip south of it across Alessandro.

Yellow-rumped Warbler. Common migrant and winterer, but was much commoner once. Steady decline from about 1990, becoming a rapid and serious decline after 2010. The Myrtle type was a regular winterer in past years, but is now very rare.

Black-throated Gray Warbler. Now rare migrant. Very much less common than formerly; well over 90% decline, tracking horrific declines of its numbers in its mountain breeding areas. Drought probably has much to do with this, but perhaps insecticides on the wintering grounds are the real problem. Much of its range in California has burned out and become impossible for breeding purposes.

Townsend’s Warbler. Regular migrant, once seasonally common in Two Trees Canyon and UCR campus. Very much less common than formerly; overall decline over 90%. Formerly fairly common winterer in live oaks and similar trees in the suburbs around the Box Springs range and on UCR campus now much less common. The wintering population here is apparently all from the Queen Charlotte Islands, British Columbia. Much of its forest habitat in California has burned out in the last 10 years, greatly reducing breeding.

Hermit Warbler. Rare migrant, formerly much more numerous though never common. This bird depends on old-growth dense forest for breeding, and has lost most of its habitat to logging and forest fires. It is probably vulnerable on the wintering grounds also.

The Black-throated Gray, Townsend’s, and Hermit Warblers represent some of the most extreme declines of any migrants in our area.

Wilson’s Warbler. Formerly common to abundant migrant, now declined but still fairly common. Still, there seem to be fewer every year.

Yellow-breasted Chat. Summer visitor. Breeds at Box Springs (the actual spring). Has tried breeding elsewhere, and at least formerly was common breeder in the Santa Ana River bottoms. Otherwise uncommon migrant.

Western Tanager. Fairly common migrant. Far less common migrant than formerly. It is not clear why this bird has dramatically declined in the last two or three decades. Much of its California range has burned in the last 10 years, and drought has affected all the range. Large flocks were often seen in spring migration; now seeing even one or two birds is rather unusual. This bird nests in the same areas as the Black-headed Grosbeak, has somewhat similar feeding patterns, and was once at least as common, if not more so. The grosbeak has held its numbers, and is thus now much more common than the tanager. This needs explaining.

Black-headed Grosbeak. Common migrant, only slightly less common than formerly.

Blue Grosbeak. Breeds at least occasionally at Box Springs. Breeds regularly and commonly in Sycamore Canyon and nearby riparian strips. Has bred casually at other springs, but drought has probably ended this. Otherwise, rare migrant. This bird nests only in dense willow thickets near open grasslands. Despite cowbirds and suburbanization, it remains a common breeder in that habitat. Some reduction, presumably due to drought, from 2022; dramatic rebound in 2024.

Lazuli Bunting. Common migrant; formerly bred in the higher Box Springs (probably not every year; largely after fires), but drought has eliminated it in recent years. Breeds in ecological refuge strip and March Base ammunition storage facility south of Alessandro.

Indigo Bunting. Rare migrant; I saw one over several days in May 1994, Two Trees Canyon, and have suspected others in other years. Also Sycamore Canyon Park, April 13, 2021.

Green-tailed Towhee. Rare but regular migrant and winterer. Usually in urban areas, very rare in wild ones.

Spotted Towhee. Eliminated from the high parts of campus and from much of the Box Springs Mountains by post-fire replacement of native brush with introduced weedy annuals, with decline around 90% in such areas. Remains common where there still is brush. Uncommon but widespread in suburbs, wherever there are extensive areas of dense shrubbery.

California Towhee. This indestructible bird is commoner than ever. They even survive in areas where introduced weedy annuals have replaced sage scrub and chaparral, as long as there are any bushes at all. They are always the first birds to come back after fires, sometimes returning to their territories before the ground cools. Extremely abundant in the suburbs; few yards are without their pair. One key to its success was revealed when I watched a pair drive a hungry cat away from their nestling. The weight ratios are comparable to those of a human driving off a tyrannosaur.

Rufous-crowned Sparrow. Better able than other species to accommodate to the vegetation change from sage scrub to grass; still common on the hills. Less so than formerly, but nothing like the declines of the Bewick’s Wren, Wrentit, etc. Harder hit in Sycamore Canyon Park (which is more level and more thoroughly burned) than in the Box Springs Mountains. Unfortunately, overgrazing and general environmental damage by burros has eliminated this otherwise hardy, and very attractive, species from most of the Box Springs Mountains and other burro-infested hills.

Bell’s Sparrow. Greatly reduced in number by replacement of sage scrub by annuals, but they hang on wherever brush continues to exist. Gone from Two Trees Canyon and at least some other areas by 2011, but remains common all along the lower pediments of the Box Springs Mountains and in comparable habitats in Sycamore Canyon Park and south of Alessandro, wherever there are sizable tracts of coastal sage scrub surviving. Sage sparrows may occasionally wander here and should be watched for (the desert race of Bell’s is almost indistinguishable; our common one is the easily distinguished coastal race).

Black-throated Sparrow. Very rare migrant or wanderer.

Black-chinned Sparrow. Common migrant; still breeds in the higher parts of the Box Springs range; numbers steadily and greatly reduced by fires and droughts.

Brewer’s Sparrow. Formerly common migrant, mostly in spring; now greatly diminished in numbers.

Chipping Sparrow. Formerly common migrant and occasional winterer; now almost gone.

Grasshopper Sparrow. Formerly erratically and locally common breeder in Moreno Valley but hard to find; now gone from at least the west and central parts of Moreno Valley, because of urbanization. Spring migrant (and presumably fall migrant, but impossible to find unless singing) in grasslands of Sycamore Canyon Park, so presumably at least occasional in other grasslands.

Savannah Sparrow. Very common migrant, fairly common through the winter, in extensive grasslands and open areas, including all open level areas around the Box Springs Mountains, in Sycamore Canyon Park, on UCR campus, and elsewhere. Some reduction in numbers, but one of the least hard hit of our birds.

Vesper Sparrow. Common migrant in grasslands, such as the outwash area of Two Trees Canyon and the Sycamore Canyon Park grasslands. Regular in winter.

Lark Sparrow. Rare migrant; rarer than in previous decades. Formerly common migrant in Moreno Valley, fairly common winter; now much less common. Common breeder in grasslands in and around March Base ammunition storage facility, and possibly still in or near Sycamore Canyon Park, but requires protected ground areas for nesting.

Golden-crowned Sparrow. Common migrant and occasional winterer wherever there is dense brush. Much more often heard than seen.

White-throated Sparrow. Very rare wanderer, migration and winter.

White-crowned Sparrow. Abundant migrant and winterer (Gambel’s). Dark-lored birds, presumably oriantha, occasionally seen late in spring migration and very rarely in winter. No reduction in numbers noted.

Fox Sparrow. Rare migrant and wintering bird. Remains common in local mountains.

Song Sparrow. Abundant everywhere in dense riparian brush. Also extremely successful in suburbs, where any area with dense shrubbery will have its resident one. Probably has increased with suburbanization. Major decline in 2022-3 probably follows on the 2019-22 drought, but may indicate ravages of bird flu or the like, since two wet years have not reversed this decline.

Lincoln’s Sparrow. Uncommon but regular migrant and winterer wherever there is dense riparian brush.

Dark-eyed Junco. Migration and winter. Much less common than formerly. Almost all are the Oregon subspecies, but Slate-colored and Pink-sided have been seen. Less common in nearby mountains, also.

Western Meadowlark. Formerly extremely abundant winterer and frequent breeder, anywhere that was at all open. Conversion of high Box Springs Mtns to grass has brought a sizable wintering population, but even this population is sharply declining. A few sometimes stay around through the summer and may breed. This bird has crashed all over the west, with population declines of over 99% very widely in California. This decline tracks suburbanization, fencerow-to-fencerow cultivation, heavy pesticide use, conversion of native brush and grassland to weedy nonnatives, and heavy stocking rates of cattle. The only places where meadowlarks nest now are the few places with extensive grassland subject to light grazing, or controlled burning, as in the Santa Rosa Plateau reserve, or in protected areas that are open, like the San Jacinto Wildlife Area. A small population persists in the extremely closely guarded March Base ammunition storage facility.

Brown-headed Cowbird. Fairly common, especially in spring. Much less common than formerly, and declining due to trapping and decline of cattle raising, but still too common for the welfare of riparian birds. Its decline correlates with some rebound of breeding populations of Bell’s Vireo, Yellow-breasted Chat, and goldfinches (but then the goldfinches crashed again with drought).

Red-winged Blackbird. Occasional in migration and summer, where there is water. Once a common migrant, now very rare. (Tricolor and Yellow-headed have been seen in the past, but only as stragglers.)

Brewer’s Blackbird. The most spectacular and mysterious decline in our area. In farming days, this bird occurred in flocks of thousands in the area. Now it is totally gone from northeast Riverside. It has declined all over southern California. My observations suggest that foot pox (avian pox) is one reason; many birds on UCR campus were heavily infected. Cleaner farming is another, urban sanitation another, starling competition probably is another. There are no doubt other problems. The bird has been essentially a human commensal for decades; its natural habitat was probably damp areas near water. It early deserted these for farms, and in its heyday it was largely a farm and ranch bird associated with dairies and other farm environments with much water and food. The last population in northeast Riverside hung on by scavenging in the Stater Brothers parking lot north of campus. It faded out by 2020. The species is still a town bird in Los Angeles.

Great-tailed Grackle. This bird invaded San Bernardino and other California communities, becoming abundant at Glen Helen Park and nearby golf courses. However, it stopped increasing by the late 20th century, and has not become established in our part of Riverside. My only observation is April 25, 2022, over the southern part of Sycamore Canyon Park. More apt to occur at Fairmount Park.

Bullock’s Oriole. Always a fairly common migrant, but much less so than formerly due to loss of nesting habitat in California. However, unlike the smaller riparian birds, it is still seen, due to its being rather large for cowbird parasitism (cowbirds prefer smaller birds, and more open nests) and because this oriole has adapted itself to suburbs. Occasionally still breeds not far from our area in open stands of trees in grassland country. Seems to be declining steadily.

Hooded Oriole. Common summer resident in fan palm trees; an obligatory fan palm nester. Thus, probably not native to the area, appearing only with palm plantings. Dawson (1923) considered it much less common than Bullock’s, a situation now reversed. The Hooded faced a decline when starlings moved into the area and took over the palm trees, but it survived and has rallied considerably, as starling population declines. It is now commoner than ever, expanding with suburbs and growth of taller palms. Hummingbird feeders help this oriole. Unfortunately, the urban areas now trim palms excessively, to their major damage and to the cost of the orioles. Some visible reduction in parts of Riverside in 2024 clearly followed extreme palm pruning.

Scott’s Oriole. Very rare migrant and wintering bird. Extreme droughts in the desert have greatly reduced the population of this species in recent years. One noted near foot of Box Springs Mtns., May 6, 2018.

Purple Finch. Formerly common in migration and winter. I recorded it on almost every morning walk in spring through the 1980s. Now mostly gone, probably largely because of cowbird parasitism on its breeding grounds. Still occurs erratically in winter. Greatly reduced in breeding in the surrounding lower mountains where it once was abundant.

House Finch. Became commoner in early and mid 20th century, due to orchards and suburbanization. Some decline recently, especially since 2011. This is probably because of droughts and the slow decline of home and commercial fruit growing, but also because of an eye disease first noted in 1994 that has now swept the continent, affecting house finches. Sharp reduction in 2023, with stabilization but no increase in 2024, almost certainly due to disease, possibly bird flu.

Pine Siskin. Occasional, winter, often after storms in the mountains and in irruption years.

Lawrence Goldfinch. Formerly uncommon but regular in Riverside, common in parts of Moreno Valley; now rare, as it is in most of southern California. The usual combination of factors that devastate riparian birds—cowbirds and habitat destruction—is presumably the cause. This bird’s entire habitat is being urbanized. With cowbird decline, there was considerable recovery. The birds were abundant in 2010 and 2011. However, they declined after that, almost certainly because of drought, and by 2015-16 were rare again, with continued decrease since.

Lesser Goldfinch. Remained abundant till recently; still common, but sharp decline since the droughts since 2001, especially from 2013 on, with real collapse in 2023. Decline tracks the decline of home fruit growing and of orchards, as well as the droughts. Hard to explain the recent crash without postulating an epidemic, perhaps bird flu, in 2023. Stabilization but no increase in 2024.

American Goldfinch. Like other small riparian birds, extreme decline in southern California. Still fairly common wintering bird through the early 2000s, but became increasingly rare. With decline of cowbirds, this bird appeared to be recovering, but then came drought. Population very low in 2013 and even rarer since. One in south Sycamore Canyon Park on April 27, 2021, is the last I have noted locally.

House Sparrow. Not as common as it used to be. Declining widely. This scavenging human commensal has declined steadily with environmental sanitation, but still succeeds by eating bird seed handouts and what crumbs still fall. More rapid decline in the recent droughts.

Nutmeg Manakin. Invasive; a southeast Asian bird propagated by escapes or releases from cages. Common locally, and rather erratically, in suburbs around UCR.

Pin-tailed Whydah (Vidua macroura). Escaped cage birds wander over southern California, and turn up in suburbs here, notably Andulka Park. They do not seem to have a resident population at present.

Major declines of breeding birds:

Turkey Vulture

American Kestrel

Rock Dove

Mourning Dove

Lesser Nighthawk

White-throated Swift

Costa’s Hummingbird

Ash-throated Flycatcher

Tree Swallow (major decline)

Cliff Swallow (extreme decline)

Scrub Jay

American Crow (extreme decline, then some recovery)

Oak Titmouse


Bewick’s Wren




Blue-gray Gnatcatcher

Yellow Warbler

Lazuli Bunting (possibly all gone)

Spotted Towhee

Bell’s Sparrow

Black-chinned Sparrow

Grasshopper Sparrow

Western Meadowlark (extreme decline relative to 1950s)

Brown-headed Cowbird (extreme decline)

Bullock’s Oriole

Lawrence’s Goldfinch

Lesser Goldfinch

American Goldfinch

Most of the neotropical migrants have suffered declines ranging from minor (e.g. Black-headed Grosbeak) to extreme (Olive-sided Flycatcher), and many wintering birds too, including the Townsend’s Warbler.

Totally extirpated as breeders in the immediate area and more widely:

White-tailed Kite (increased, then declined, now apparently completely gone)

Ring-necked Pheasant

Spotted Dove

Common Ground Dove

Burrowing Owl

Black-chinned Hummingbird

Northern Flicker

Loggerhead Shrike

Warbling Vireo

California Gnatcatcher? (early status uncertain)

Brewer’s Blackbird

Significant increases, all stopped or reversed as of 2024:

Cooper’s Hawk

Band-tailed Pigeon (increased, then declined again, but still commoner than formerly)

Anna’s Hummingbird

Allen’s Hummingbird

Acorn Woodpecker

Cassin’s Kingbird

Black Phoebe (recent decline)

Say’s Phoebe

Northern Mockingbird (steady)

House Finch (recently reversed or stabilized)

Nutmeg Manakin (new, introduced species)


Carson, Rachel. 1962. Silent Spring. Boston: Houghton Mifflin.

Cazalis, Victor. 2022. “Species Richness Response to Human Pressure Hides Important Assemblage Transformations.” Proceedings of the National Academy of Sciences of the United States 119:e2107361119.

Dawson, William Leon. 1923. The Birds of California. San Francisco: South Moulton Company.

English, Simon G., et al. 2022. “Demography of Two Species and One Genus of Hummingbirds with Contrasting Population Trends in California, USA.” Journal of Field Ornithology 92:475-484.

Iknayan, Kelly, and Steven R. Beissinger. 2018. “Collapse of a Desert Bird Community over the Past Century Driven by Climate Change.”  Proceedings of the National Academy of Sciences 115:8597-8602.

Rosenberg, Kenneth V.; Adriaan M. Dokter; Peter J. Blancher; John R. Sauer; Adam C. Smith; Paul A. Smith; Jessica C. Stanton; Arvind Punjabi; Laura Helft; Michael Parr; Peter P. Marra.  2019. “Decline of the North American Avifauna.”  Science 366:120-124.

Sibley, David Allen. 2000. The Sibley Guide to Birds. New York: Knopf.

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