Behavioral Ecology最新文献

Animals that communicate by acoustic signaling share a common acoustic environment. Birds are particularly vocal examples, using a wide repertoire of broadcast signals for mate attraction and territorial defense. However, interference caused by sounds that overlap in frequency and time can disrupt signal detection and reduce reproductive success. Here, we investigated competition avoidance mechanisms used by the bird community inhabiting a primeval lowland temperate forest in Białowieża, Eastern Poland. We recorded the dawn chorus at 84 locations in early and late spring and calculated dissimilarity indices of the broadcast signals to examine how species with greater song similarities use spatial and temporal partitioning to avoid competition for acoustic space throughout the breeding season. The bird community changed its use of acoustic space throughout the day and season. Birds did not use spatial partitioning of signal space when we looked at recording locations over the whole study period, but they did in a seasonal context, with species more acoustically different than expected by chance recorded at the same point in the same part of the season. Our results also indicate that daily temporal niche partitioning may only occur at certain times before sunrise, with no evidence of large-scale temporal partitioning between species vocalizing during the same 1-min recordings in daytime. These results contribute toward our understanding of the evolution of bird communication and highlight the strategies employed by different species to improve their signal transmission.

Individual behavior varies for many reasons, but how early in life are such differences apparent, and are they under selection? We investigated variation in early-life behavior in a wild eastern gray kangaroo (Macropus giganteus) population, and quantified associations of behavior with early survival. Behavior of young was measured while still in the pouch and as subadults, and survival to weaning was monitored. We found consistent variation between offspring of different mothers in levels of activity at the pouch stage, in flight initiation distance (FID) as subadults, and in subadult survival, indicating similarity between siblings. There was no evidence of covariance between the measures of behavior at the pouch young versus subadult stages, nor of covariance of the early-life behavioral traits with subadult survival. However, there was a strong covariance between FIDs of mothers and those of their offspring tested at different times. Further, of the total repeatability of subadult FID (51.5%), more than half could be attributed to differences between offspring of different mothers. Our results indicate that 1) behavioral variation is apparent at a very early stage of development (still in the pouch in the case of this marsupial); 2) between-mother differences can explain much of the repeatability (or "personality") of juvenile behavior; and 3) mothers and offspring exhibit similar behavioral responses to stimuli. However, 4) we found no evidence of selection via covariance between early-life or maternal behavioral traits and juvenile survival in this wild marsupial.

Parents might use signals of need or of quality to decide food provisioning among their offspring, while the use of one or another signal might depend on food availability. Begging success of nestlings of different quality (i.e., body size) would also depend on food availability, and we here explore the effect of experimental food supply in begging success of nestlings and in provisioning of female hoopoes (Upupa epops), a species with extreme hatching asynchrony and nestlings size hierarchy. We video-recorded food allocation of females, begging success of nestlings of different size, and the social context (i.e., the size category of the other nestlings that were begging for food) during periods when experimental food supply was or was not available in the same nests. We found that when experimental food supplementation was present, begging success of the intermediate, but not that of large or small-sized nestlings, increased. The experiment, however, did not affect the feeding preferences of females toward nestlings of different size. Moreover, when small nestlings were the only ones that were begging for food, their begging success decreased in the experimental period, and females used supplemented prey to feed themselves. Those results, on one hand, confirm the importance of food availability for the begging success of nestlings of particular sizes and, on the other, indicate that females prefer to use extra food for their own rather than for the smallest nestlings. We discuss possible mechanisms explaining the detected experimental effects and the adaptive and nonadaptive explanations of mothers ignoring the small nestlings.