Factors associated with nest survival of Black‐throated Sparrows, desert‐breeding nest‐site generalists

Abstract

Black‐throated Sparrows (Amphispiza bilineata) are common breeding birds throughout the desert regions of North America and can be considered nest‐site generalists. Information about how spatial (e.g., vegetation) and temporal factors influence nest survival of these sparrows is lacking throughout their range. Our objective was to examine the spatial and temporal factors associated with nest survival of Black‐throated Sparrows at the nest and nest‐patch scales in the predator‐rich environment of the northern Chihuahuan Desert of New Mexico. We used a logistic‐exposure model fit within a Bayesian framework to model the daily survival probability of Black‐throated Sparrow nests. Predation was the leading cause of nest failure, accounting for 86% of failed nests. We found evidence of negative associations between nest survival and both vegetative cover above nests and shrub density within 5 m of nests. We found no support for other habitat covariates, but did find strong evidence that daily survival rate was higher earlier in the breeding season and during the egg‐laying stage. A decline in nest survival later in the breeding period may be due to increased predator activity due to warmer ambient temperatures, whereas lower survival during the incubation and nestling stages could be a result of increased activity at nests. A generalist approach to nest‐site selection may be an adaptive response to the presence of a diverse assemblage of nest predators that results in the reduced influence of spatial factors on nest survival for Black‐throated Sparrows.

Compensatory Breeding in Years Following Drought in a Desert-Dwelling Cooperative Breeder

“…In cases of high reproductive effort in response to high predation risk, the number of fledglings produced per breeding attempt is typically low (Mares et al, 2017). Additionally, in arid environments, higher predation rates are often associated with warm, dry weather (McCreedy and van Riper, 2015;Kozma et al, 2017). Our results show that pied babblers produced fewer surviving young during droughts and more surviving young per breeding attempt in breeding seasons following a drought.…”

Breeding productivity, nest-site selection and conservation needs of the endemic Turkestan Ground-jay Podoces panderi

“…It is, therefore, possible that the ground-jays in our study area were using suboptimal nesting substrates. However, the diverse range of predators, with different hunting methods, may confound any one particular nest defence strategy such as maximising nest height (Kozma et al 2017). Interestingly the five species we identified are all new additions to the list of known nest predators of Turkestan Ground-jay, namely martens Martes, polecats Mustela, Caracal Caracal caracal, crows Corvidae, eagles (presumably Aquila) and harriers Circus (Lakhanov 1977).…”

Nest survival of Seaside Sparrows (Ammospiza maritima) in the wake of the Deepwater Horizon oil spill

“…We interpret nest placement in areas of high stem densities in our study as a mechanism to decrease predation risk (see, e.g., [ 73 ]). In contrast, greater vegetation density around nests has sometimes been associated with increased nest predation risk in other sparrow species [ 68 , 74 , 75 ], perhaps because the small mammals implicated as nest predators in those studies used dense vegetation as refugia, or because dense vegetation allowed small mammals easier climbing access to nests. Nest concealment from avian predators (i.e., those hunting from above) does not seem a likely mechanism for nest site selection in our study, as avian nest predators are largely absent from our study area during the nesting season.…”