Nestling Weight and Juvenile Survival in the Blackbird, Turdus merula

Abstract

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Natal territory size, group size, and body mass affect lifetime fitness in the cooperatively breeding Florida Scrub-Jay

“…Jays that achieved 4 postfledging developmental milestones (surviving to day 30, day 90, day 300, and becoming a breeder) were larger as nestlings than jays that failed to achieve these milestones ( Figure 5). This result corroborates evidence from other avian and mammalian species that variation in natal body condition can have far-reaching fitness consequences (Magrath 1991, Hatchwell et al 2004, Hodge 2005, Ridley 2007, Rödel et al 2009, Sparkman et al 2010, Tilgar et al 2010, Brouwer et al 2012.…”

“…Poor-quality natal environments frequently have negative short-term effects on fitness components such as juvenile body condition and juvenile survival (Magrath 1991, van der Jeugd and Larsson 1998, van de Pol et al 2006. In recent years, however, a growing body of literature has indicated that favorable conditions in the natal environment can have significant long-term fitness benefits (Lindström 1999, Cam andAubry 2011).…”

Conflict between biotic and climatic selective pressures acting on an extended phenotype in a subarctic, but not temperate, environment

“…Similarly, nestlings in local subarctic nests grew at a faster rate compared with nestlings in non-local temperate nests, particularly at colder temperatures (figure 3b). Given that nestling growth rate is a positive predictor of future survival in passerine birds [28], investing in thick local nests may provide important longterm advantages for young warblers after leaving the nest. In contrast, biotic selective pressures, in the form of nest In contrast to the subarctic, nest transplants at the temperate site revealed similar patterns of selection acting on nest morphologies.…”

“…For the subarctic site, we predicted that adult incubation behaviours would reflect differences in selective pressures, with less activity and longer incubation bouts associated with higher predation risk [26], and shorter bouts off the nest associated with an increased challenge of cold temperatures [27]. We predicted nestling growth rates (an indicator of nestling quality and future survival [28]) would be fastest in local nests, and that corticosterone levels of both adult females and nestlings would be elevated or atypical in non-local nests compared with local nests [29,30].…”

Parental Body Condition Does Not Correlate With Offspring Sex Ratio in Cory's Shearwaters

“…Mortality may increase during migration to the wintering grounds, when juveniles have to forage by themselves. In fact, body condition at fledging has been shown to affect later survival in several species (Hochachka and Smith 1991, Magrath 1991, Mougin et al 2000 thus differential mortality or fitness gains between sexes could be assessed by differential fledging condition. Differences in mortality or fledging condition between male and female offspring would imply differential costs between sexes.…”