of detections All birds 210 American goldfinch Carduelis tristis 6 American robin Turdus migratorius 1 American tree sparrow Spizella arborea 30 Bewick's wren Thryomanes bewickii 2 Dark-eyed junco Junco hyemalis 1 Eastern meadowlark Sturnella magna 5 European starling Sturnus vulgaris 1 Field sparrow Spizella pusilla 6 Harris's sparrow Zonotrichia querula 4 Horned lark Eremophila alpestris 11 Lapland longspur Calcarius lapponicus 1 Loggerhead shrike Lanius ludovicianus 5 McCown's longspur Calcarius mccownii 1 Northern cardinal Cardinalis cardinalis 2 Rufous-crowned sparrow
Aimophila ruficeps 5 Red-winged blackbird Agelaius phoeniceus 9 Song sparrow Melospiza melodia 6 Spotted towhee Pipilo maculatus 1 Unknown spp.
There were five bird species which were either ubiquitous or seemed to have a random distribution (the Orange-crowned Warbler Vermivora celata, the Rufous-crowned Sparrow Aimophila ruficeps, the Lucifer Hummingbird Calothorax ruficeps, the Magnificent Hummingbird Eugenes fulgens and the Yellow-rumped Warbler).
The remaining species were either ubiquitous (the Ash-throated Flycatcher, the Greenish Elaenia, the Empidonax Flycatcher and the Bewick=s Wren) or less predictable in their distribution due to between-year differences in the same season (the Rufous-crowned Sparrow and the Ladder-backed Woodpecker).
In addition, six species differed in their habitat use between the two autumns and therefore were considered to have unpredictable distributions (the Orange-crowned Warbler, the Black-headed Grosbeak, the Yellow-breasted Chat, the Rufous-crowned Sparrow, the Lucifer Hummingbird, the Magnificent Hummingbird and the Yellow-rumped Warbler).
The Yellow Warbler, the Rufous-crowned Sparrow and the Brown-headed Cowbird had unpredictable distributions.
For species of residents with >10 captures (n = 6), captures of crissal thrashers, cactus wrens, and black-throated sparrows did not differ between arroyos and uplands (P = 0.610, 0.780, and 0.420, respectively), whereas verdins, rufous-crowned sparrows, and canyon towhees were caught more often in arroyos (P = 0.002, <0.001, and <0.001, respectively).
This might explain why some species of residents, such as canyon towhees and rufous-crowned sparrows were never captured in uplands, although they use upland habitats for breeding (Kozma, 1995; Kozma and Mathews, 1997).
California kingsnakes were also the most frequently documented predator of nests of rufous-crowned sparrows
(Aimophila ruficeps) at upland sites in central San Diego County (Morrison and Bolger, 2002).