Factors Affecting Nesting Success in Riparian Bird Communities

Abstract

Nest and egg successes are documented for open-nesting bird species in a variety of riparian habitats in central Iowa. In most species, nest success was higher during the nestling period than during the incubation period. Causes of nest failure in order of decreasing importance were: predation by birds, snakes, or small mammals; predation by large mammals; desertion; cowbird parasitism; natural disasters. Relationships between nesting outcome and the following variables are analyzed statistically: adult weight, date, nest height, nest concealment, vegetation form supporting the nest (support life-form), and habitat type. Nest failure resulting from predation by large mammals and parasitism by cowbirds was greater among smaller-sized birds. The percentage of nests successfully fledging young increased with nest height. Losses from natural disasters differed among the support life-forms. Relationships among the factors that may affect nesting outcome are compared statistically to determine possible interactions. Mean body weight, which differed according to nest support life-forms, decreased as the season advanced. Body weight also was inversely related to nest concealment. Concealment differed among nest supports and was greater later in the breeding season. Concealment also was inversely related to nest height. The distribution of nests in the support life-forms changed during the season. Species more generalized in selecting nest substrates had lower nest success. SUCCESS IN RIPARIAN COMMUNITIES 155 NEST SUPPORT LIFE-FORM

Point Counts Underestimate the Importance of Arctic Foxes as Avian Nest Predators: Evidence from Remote Video Cameras in Arctic Alaskan Oil Fields

“…Nest site remains are also frequently used as an indicator of the type of nest predator: disturbed nest remains are often thought to indicate a large mammalian predator, while depredation of a nest left intact is often attributed to birds, snakes, or small mammals (Best and Stauffer, 1980;Wray et al, 1982;Hoover et al, 1995). Our results give little support for these predator identification methods since for the one jaeger and five fox predation events that we recorded, nests remained intact and undisturbed.…”

Biologia reprodutiva de Tyrannus savana (Aves, Tyrannidae) em cerrado do Brasil Central

“…Resultado semelhante foi encontrado para a mesma espécie em áreas alteradas, tanto na fase de incubação (59%), como na fase de ninhegos (41%) (Pimentel 1985). A predação tem sido enfatizada como uma importante força seletiva no processo reprodutivo das aves (Mezquida & Marone 2001) sendo o principal fator de perda de ninhos de muitas espécies, em diferentes hábitats e localizações geográficas (Best & Stauffer 1980, Martin 1993, Mermoz & Reboreda 1998, Aguilar et al 1999, 2000, Mezquida & Marone 2002, Picman et al 2002, Lopes & Marini 2005b, Roper 2005, Pinho et al 2006, Duca 2007, Medeiros & Marini 2007. A taxa de predação de ninhos nos trópicos é alta, em torno de 80 a 90%, mas pode variar entre regiões (Ricklefs 1969, Oniki 1979, Stutchbury & Morton 2001, Roper 2003, sendo em geral maior que a encontrada para esta espécie.…”

Effects of drought and fire on bird communities of the Kofa National Wildlife Refuge, Arizona

“…Given that nests may have lower survival rates later in the breeding season (Grant and others, 2005;Best and Stauffer, 1980), we hypothesized that drought may decrease reproductive output by exposing nesting individuals to higher rates of depredation and parasitism than exist later in the season. We tested this hypothesis with a nesting-delay experiment following the wet winter of 2010.…”