Does nest placement affect the fate or productivity of California Gnatcatcher nests?

Authors
Citation
Gt. Braden, Does nest placement affect the fate or productivity of California Gnatcatcher nests?, AUK, 116(4), 1999, pp. 984-993
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences
Journal title
AUK
ISSN journal
0004-8038 → ACNP
Volume
116
Issue
4
Year of publication
1999
Pages
984 - 993
Database
ISI
SICI code
0004-8038(199910)116:4<984:DNPATF>2.0.ZU;2-B
Abstract
I monitored 384 California Gnatcatcher (Polioptila californica) nests at fi ve study areas in western Riverside County, California, from 1992 through 1 995. Overall, 78.9% of the nesting attempts failed (52.9% from nest predati on), and 21.1% fledged young. Vegetation measurements were taken at 207 of 384 nest locations and at 207 randomly selected locations within gnatcatche r territories. Nest placement was not random in that gnatcatchers placed th eir nests in locations with greater cover and height of perennial vegetatio n, increased horizontal structural homogeneity, and increased vertical stru ctural homogeneity relative to random locations. The volume of gnatcatcher nest shrubs was lower than that of random shrubs, and concealment was highe r at nests than at random shrubs. Nevertheless, variables that differed sig nificantly between nests and random locations were not significantly associ ated with nesting success, nest predation, nest abandonment, or productivit y. The use of specific perennial shrub species as nest substrates was not p roportional to the availabilities of the shrub species within the study are as, yet I found no relationship between nesting success and the species of nest shrub. Nesting success appeared to be unrelated to the abundance of pe rennial shrubs at four of five study areas. My results suggest that factors affecting the fate of California Gnatcatcher nests operate at scales large r than the nest site or nest patch.