A bioenergetics-based model was used to simulate the accumulation of total PCBs and 20 PCB congeners by nestling tree swallows at two contaminated sites on the Upper Hudson River, New York. PCB concentrations in birds were calculated as the sum of inherited residues and those acquired through consumption of contaminated insects. Close agreement between simulations and measured residues in 5-, 1...

Anthropogenic activities often produce pollutants that can affect the physiology, growth and reproductive success of wildlife. Many metals and trace elements play important roles in physiological processes, and exposure to even moderately elevated concentrations of essential and non-essential elements could have subtle effects on physiology, particularly during development. We examined the effe...

Aquatic prey subsidies entering terrestrial habitats are well documented, but little is known about the degree to which these resources provide fitness benefits to riparian consumers. Riparian species take advantage of seasonal pulses of both terrestrial and aquatic prey, although aquatic resources are often overlooked in studies of how diet influences the reproductive ecology of these organism...

Group living can provide individuals with several benefits, including cooperative vigilance and lower predation rates. Individuals in larger groups may be less vulnerable to predation due to dilution effects, efficient detection or greater ability to repel predators. Individuals in smaller groups may consequently employ alternative behavioural tactics to compensate for their greater vulnerabili...

Indirect fitness benefits gained through kin-selected helping are widely invoked to explain the evolution of cooperative breeding behavior in birds. However, the impact of helpers on productivity of helped broods can be difficult to determine if the effects are confounded by territory quality or if the benefit of helpers is apparent only in the long term. In riflemen Acanthisitta chloris, helpi...

Exposure to stressors early in life is associated with faster ageing and reduced longevity. One important mechanism that could underlie these late life effects is increased telomere loss. Telomere length in early post-natal life is an important predictor of subsequent lifespan, but the factors underpinning its variability are poorly understood. Recent human studies have linked stress exposure t...

Parental effort has a direct impact on individual fitness. Theoretical models exploring how parental effort evolves to cope with offspring demand and sexual conflicts may differ in the assumptions they make in respect to the genetic heritability of parental behaviours. Only a few attempts, however, have been made to estimate the heritability of parental behaviours and their possible co-evolutio...

Ambient noise can mask acoustic cues, making their detection and discrimination difficult for receivers. This can result in two types of error: missed detections, when receivers fail to respond to the appropriate cues, and false alarms, when they respond to inappropriate cues. Nestling birds are error-prone, sometimes failing to beg when parents arrive with food (committing missed detections) o...

We consider the quenched and averaged (or annealed) large deviation rate functions Iq and Ia for space-time and (the usual) space-only RWRE on Z. By Jensen’s inequality, Ia ≤ Iq. In the space-time case, when d ≥ 3 + 1, Iq and Ia are known to be equal on an open set containing the typical velocity ξo. When d = 1+1, we prove that Iq and Ia are equal only at ξo. Similarly, when d = 2+1, we show th...

Many birds, including some parrots, may adjust the sex ratio of their offspring in relation to the relative fitness benefits of sons and daughters. We investigated nestling sex ratios in Yellow-naped Amazons (Amazona auropalliata) using a molecular sexing technique that amplifies intronic regions of the CHDW and CHD-Z genes in birds. We examined all nestlings in 37 complete clutches comprising ...