Factors Influencing Survival of Black-chinned Hummingbird Nests in Southwest Colorado

We estimated survival of Black-chinned Hummingbird (Archilochus alexandri) nests in southwest Colorado in 1998, 2001, and 2004 by means of models generated in program Mark. The best supported, and parsimonious, model suggested nest age (i.e., time since the nest was initiated) as the most important variable in indicating nest survival; daily survival rates of nests with eggs were lower than those of nests with nestlings. Substrate type was a second covariate that had some support in describing nest survival. Nests in Gambel oak (Quercus gambelii) or narrow-leaf cottonwood (Populus angustifolia) had greater daily survival rates than did those built in other substrates. No other ecological covariates were strongly supported in explaining nest survival. Of the 24 nests studied, 10 were successful, fledging an average of 1.7 (standard error 0.14) chicks.