The Waterbirds

Migrants and Vagrants

Breeding Birds of Exposition Park

The List Grows

• Checklist of the
  Birds of Exposition Park

Suggested Reading

Ornithologists and avian ecologists are increasingly turning their attention to the birdlife of urban regions. Their scientific investigations are two-pronged: On the one hand evolutionary ecologists are interested in the attributes of species that have become successful in highly modified urban habitats. On the other, considerable interest exists in the rates at which native birds in natural habitats disappear as these habitats are fragmented and diminished by urban development. Interest in these topics is reflected in such recent journal article titles as "Reconstructed dynamics of rapid extinctions of chaparral-requiring birds in urban habitat islands" (Soule et at., 1988), "Urban cemeteries as bird refuges" (Lussenhop, 1977), and "Value of suburban habitats to desert riparian birds" (Rosenberg et al., 1987).

In few areas of the world is so expansive an urban sprawl superimposed upon so diverse an indigenous bird fauna as in the Los Angeles region. More than 445 native species of birds have been recorded within the boundaries of Los Angeles County, and some 90 of these breed regularly in terrestrial habitats of the Los Angeles Basin and surrounding foothills. But relatively few of these species thrive within the urban "habitats" dominated by concrete, asphalt, and normative vegetation. Those that do play an important role in the interplay between human urban culture and the southern California avifauna.

Among the islands of green scattered through the heavily urbanized central part of the Los Angeles Basin is Exposition Park, home for 75 years of the institution we now call the Natural History Museum of Los Angeles County. An open, almost treeless plain prior to development (around 1880) as an agricultural exposition and, ultimately, a sports and museum complex, the park has developed a patchwork flora of trees (eucalyptus, sycamore, live oak, deodar, etc.), geometrically arranged rose bushes, sparse hedges and shrubs, and open lawns.

In much of North America urban wildlife habitat is generally that which remains as urbarn centers are carved out of natural habitats; most of the important plant species are natives though their proportions and densities are highly modified. The plant life of New York's Central Park is a lush amalgam of native species; the park is a well-known birdwatching haven, praised in the writings of John Kieran, Ludlow Griscom, and Roger Tory Peterson, among others. By contrast, the "habitat" in urban Los Angeles is a highly artificial one. The plant species are exotic nonnatives, and the vegetation growth achieves a three-dimensional structure quite different from that of the basin's pristine flora of grassland, oak savanna, riparian woodland corridors, swampy willow bottomlands, and coastal sage scrub. Very few of the trees and shrubs planted in Exposition Park belong to California's native floral roster.

At just over 100 species, plus a handful of established exotics, the birdlife of Exposition Park represents a fascinating mix of adaptable native species, exotic introductions, and transients (some routine, and some well outside the expected range of their species).

 
The Exotics

The exotic, introduced bird species of southern California were described in a previous TERRA article (May/June 1986). Perhaps no immigrant bird has a more solid foothold on urban Los Angeles than the House Sparrow (Passer domesticus). Not surprisingly, Exposition Park House Sparrows are especially partial to outdoor eateries-many a customer of the Natural History Museum's cafeteria has unwittingly lost a french fry or two to these bold interlopers. Recognizing the House Sparrow's fondness for fast food handouts, Curator of Ornithology Ralph Schreiber and the museum's Bird Council conducted banding operations at the museum cafeteria patio in February and November 1987. The bird banding events were intended as demonstrations of the techniques of capturing songbirds in fine "mist nets," taking data on weights, measurements, and molt, and affixing uniquely numbered leg bands provided by the U.S. Fish and Wildlife Service. In addition, a combination of colored leg bands, unique to each of the 27 sparrows captured, allowed recognition of individuals in the "field."

This technique of marking individuals can help answer fundamental demographic questions about lifespan, reproductive output, and ---- bonds, We have banded too few sparrows to yield results in these areas, but have learned a little bit about sparrows' movements between fast food outlets! Male number 1411-44101, bearing a green band on his left leg, was observed feasting at an outdoor eatery on the campus of the University of Southern California on October 2, 1987, eight months after he was banded; he was back at the Natural History Museum ten days later. The male sporting an orange band over the silver numbered band on his right leg (#1411-44116, banded in November 1987) had commuted across Exposition Park to the Science and Industry Museum McDonald's Restaurant three months after he was banded. These movements hardly rival the thousands of miles covered by many migratory species, but at a minimum we have now learned that there is some exchange among the flocks of House Sparrows at Exposition Park's outdoor eateries!

Other familiar exotic bird species in the park and throughout urban Los Angeles include the Rock Dove, Spotted Dove, European Starling, and a variety of parrots and parakeets (again, see TERRA, May/June 1986). Especially frequent in Exposition Park is the Canary-winged Parakeet (Brotogeris versicoloris), a South American native; park visitors are often treated to the sight of small flocks of these parakeets tearing open the green pods of the floss-silk trees (Chorisia) adjacent to the Natural History Museum, extracting the hard seeds from the fluffy "kapok" fibers.

Some "exotics" have obviously recently escaped or been released from captivity, rather than representing established populations, This is certainly true of the occasional Cockatiel or Pin-tailed Whydah seen in the park. But how does one explain the beautiful male Lady Amherst's Pheasant that paraded around the Natural History Museum's north entrance in 1986?

 
The Waterbirds

Many waterbirds, notably the ducks and geese and the shorebirds, are long-distance migrants and therefore likely to overfly urban parks on occasion. Hence we have Exposition Park sightings of such species as Greater White-fronted Goose, Lesser Yellowlegs, Long-billed Dowitcher, and Caspian Tern. I vividly recall a small flock of Cattle Egrets winging over the Los Angeles Memorial Coliseum in the park during the 1985 USC-UCLA football game. But any little patch of water may induce transient waterbirds to linger, and the Rose Garden's central pond and the Natural History Museum's north entrance pools have occasionally filled this role. The Great Blue Heron, Great Egret, Greenbacked Heron, and Black-crowned Night-Heron have all spent time fishing in the park's manicured ponds, and a migrant Belted Kingfisher will sometimes plunge in.

Like most urban parks in the Los Angeles basin, Exposition Park has its share of gulls rummaging through the refuse human visitors leave behind. From November through April California Gulls perform a daily commute from nighttime seashore roosts to urban parks, schoolyards, and landfill sites, and in Exposition Park the odd Mew, Herring, and Ringbilled Gull is seen among them. Surprisingly, the Western Gull, normally a strictly marine species, is now seen regularly as a summertime scavenger in the park.

 
Migrants and Vagrants

To quote Guy McCaskie, mentor of many a California birdwatcher, "Birds have wings ... and they use them!" This little truism was intended to suggest that, at least on a local scale and within reasonable bounds set by a species' life history traits, nearly any species of bird will eventually wander to nearly any locality. The key, of course, is that somebody must be around to record these events. It follows that any well-worked birdwatching site will build up a substantial species list over the years. The ultimate example is certainly Southeast Farallon Island, a chunk of rock less than a sixth of a square mile in area lying some 20 miles off San Francisco's Golden Gate. Daily coverage by the personnel of the Point Reyes Bird Observatory for 20 years has generated a bird list of over 350 species on this windswept, barren islet! The Furnace Creek oasis in Death Valley is a favorite of migrant hunting birdwatchers, and thorough coverage over the years has yielded more than 320 species at this remote desert site.

Clearly, then, even an urban park will ultimately develop a long list of migrants and "vagrants" (a term denoting migrants that have wandered well outside of their "normal" geographical range-not the unfortunate human park-dwellers the term might initially connote). Over half the bird species recorded in Exposition Park simply migrate over the park or make brief stopover visits. The live oaks and sycamores planted in the park will occasionally harbor a nice spring fallout of tanagers, grosbeaks, warblers, and vireos, and in fall the stand of chinese elms at the southwest corner of the Rose Garden is particularly attractive to these same species.

Many species remain in the park through the winter (White-crowned Sparrows, Yellow rumped Warblers, and Cedar Waxwings, among others), or virtually throughout the year (Black Phoebe, Red-tailed Hawk, American Kestrel), but nest elsewhere.

Among the rare migrants to have graced Exposition Park are a handful of eastern North American songbirds that have shown a pattern of vagrancy to the West Coast in late spring or fall: Tennessee Warbler, Chestnut-sided Warbler, Blackpoll Warbler, and Clay-colored Sparrow, for example. Some occurrences have truly defied prediction, most notably the two Least Terns flying over the Natural History Museum one June morning in 1987; the endangered California Least Tern is normally restricted to our beaches and adjacent ocean waters. But we know that transient birds can wander most anywhere; of greater biological interest is the suite of bird species which successfully nest in the urban habitat exemplified by Exposition Park.

The nesting birds of Exposition Park are drawn from a pool of some 90 species that nest in the lowlands and foothills of the Los Angeles basin. We might reasonably predict that species with specialized habitat requirements, such as those of wetlands, forests, or dense low brush, would be absent from the sparsely planted, highly manicured park. Absent, too, would be species whose nesting success is lowered by excessive human disturbance and interference. These logical predictions hold true, and the roster of confirmed nesting species in the park numbers only about a dozen (with a half a dozen other "possibles").

Obviously absent from Exposition Park's breeding avifauna are those species that fail to reach the park in the first place. Some of these absentees are of interest because they thrive in natural and suburban habitats within a few miles of the park. These species include the Plain Titmouse, Bewick's Wren, California Thrasher and Song Sparrow. The familiar Brown (or "California") Towhee has only once reached Exposition Park--a lone juvenile waif perched briefly outside the Natural History Museum Bird and Mammal range on 30 August 1982.

Perhaps the most conspicuous native nesting bird of Exposition Park is a species that has recognized human-built edifices as an excellent substitute for natural cliffs as a nest substrate. These Cliff Swallows build their gourd-shaped mud nest structures over the south entrance to the Natural History Museum each year, apparently having no trouble finding their three major requisite resources-flying insects for food, a sheltered vertical surface for nest attachment, and a source of mud for nest construction. A swallow with quite different nest-site requirements, the tunnel-nesting Northern Roughwinged Swallow, is occasionally seen prospecting nest sites in drain pipes around the Natural History Museum; in what may be the ultimate Los Angeles adaptation, a pair of Rough-wings nests nearby each year under the Santa Monica Freeway at the Normandie Avenue underpass!

One of the most familiar birds of urban areas in the eastern half of North America is the Chimney Swift; as its name suggests, this species has found an appropriate artificial substitute for its natural hollow-tree nest site. (The Chimney Swift's western congener, the Vaux's Swift, still sticks to hollow trees for nesting, in forested areas from central California to southeastern Alaska.) In recent years a few Chimney swifts in California, and Exposition Park has hosted a small but dependable population since 1983; the park has indeed been one of the most reliable sites in western North America for this species.

The other native birds that have been documented as nesting in Exposition Park were all denizens of open brushlands or light woodland in the region's pristine past. These include the Mourning Dove, Black-chinned and Anna's Hummingbirds, Scrub Jay, American Robin, Northern Mockingbird, Brewer's Blackbird, and House Finch. Other species that may nest in the park occasionally include American Crow, Bushtit, and American Goldfinch.

 
The List Grows

While it cannot be seriously argued that the artificial habitats of parks such as Los Angeles' Exposition Park constitute nationally significant wildlife habitat, they nevertheless harbor an astonishing diversity of birds. A large and ever-increasing percentage of Americans live in urban areas; their initial and most frequent encounters with the rich birdlife of North America center around the handful of species that have adapted to urban life. Planners of urban parks would do well to recognize the potential these patches of real estate hold for increasing urban residents' knowledge and appreciation of birds and other wildlife (for an interesting analysis, see Penland, 1987).

And with time, the bird list for Exposition Park will grow. Maybe the next species will be a waif, lost over the urban sprawl, finding the park a welcome respite on some seasonal sojourn. Or perhaps it will prove to be a bird from nearby foothill brushlands or woodlands, a vanguard of its kind at an urban frontier. Maybe it will be sighted on the next Dick Davenport Memorial Bird Walk!

 
Suggested Reading

Lussenhop, John, 1977. Urban cemeteries as bird refuges. Condor 79: 456-461.

Penland, Stephen, 1987. Attitudes of urban residents toward avian species and species' attributes, in Adams, L.W. and D.L. Leedy, Eds. "Integrating man and nature in the metropolitan environment": Proccedings of the National Symposium on Urban Wildlife, Chevy Chase MID, 4-7 November 1986. Columbia, MID: Natl. Inst. for Urban Wildlife.

Rosenberg, Kenneth V., Scott B. Terrill, and Gary H. Rosenberg, 1987. Value of suburban habitats to desert riparian birds. Wilson Bulletin 99 042-654.

Soule, M.E., D.T Bolger, A.C. Alberts, R. Sauvajot, J. Wright, M. Sorice, and S. Hill 1988. Reconstructed dynamics of rapid extinctions of chaparral-requiring birds in urban habitat islands. Conservation Biology 2 (1): 75-92.