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The probability that obligate interspecific brood parasitism (OP), among altricial birds evolved directly from the normal breeding (no parasitism, NP) mode or indirectly through intraspecific nest parasitism (INP) was examined by using maximum-likelihood and parsimony approaches. We examined the probability of ancestral states at 24 key nodes in order to test our hypotheses. The state of the most basal node in a tree of 565 genera of altricial birds is equivocal; however, the state probability of NP at this node is about 5.5-fold more likely than the state of obligate parasite. A similar trend was observed for basal nodes of most families examined. The INP state was supported only in the Hirundinidae. The high incidence of INP among martins and swallows explains this finding. Contrary to our predictions, even in other groups where there is a high incidence of INP and OP, such as in the tribe Icteri and the Old World finches, the probability of NP being ancestral was very high. We conclude that in all cases but one (Hirundinidae) obligate, and probably facultative, brood parasitism evolved directly from normal breeding mode rather than indirectly through some other form of parasitism. [ABSTRACT FROM AUTHOR] more...

Using modern comparative methods, we found that both time to independence and time with parents were significantly longer in southern hemisphere and tropical birds than in northern hemisphere ones. These differences held even after removing Australian passerines or cooperatively breeding species, and they do not depend on habitat, diet, or migration pattern. In southern hemisphere and tropical regions, both cooperative breeding and non-cooperative parents continue to feed their young for a similar length of time, but cooperative breeders allow them to stay longer in their natal territory after they become nutritionally independent. Nevertheless, the young of non-cooperative species stay longer with their parents than do the young of non-cooperative species in the temperate northern hemisphere. The fact that extended periods of post-fledging parental care are widespread among passerines provides further empirical support for the view that life histories of southern and tropical birds are ‘slow,’ with small clutches, extended parental care, and long lifespan; parents take care of fewer young for longer. These results support recent theoretical models that predict that high adult survival and low turnover of territory owners generally favor natal philopatry. We suggest that the reasons why some species (with or without cooperative breeding) exhibit natal philopatry and others do not lie in the balance between productivity and survival of adults and of retained or dispersing offspring. [ABSTRACT FROM AUTHOR] more...

Few mammalian species produce vocalizations that are as richly structured as bird songs, and this greatly restricts the capacity for information transfer. Syntactically complex mammalian vocalizations have been previously studied only in primates, cetaceans and bats. We provide evidence of complex syntactic vocalizations in a small social mammal: the rock hyrax (Procavia capensis: Hyracoidea). We adopted three algorithms, commonly used in genetic sequence analysis and information theory, to examine the order of syllables in hyrax calls. Syntactic dialects exist, and the syntax of hyrax calls is significantly different between different regions in Israel. Call syntax difference is positively correlated to geographical distance over short distances. No correlation is found over long distances, which may reflect limited dispersal movement. These findings indicate that rich syntactic structure is more common in the vocalizations of mammalian taxa than previously thought and suggest the possibility of vocal production learning in the hyrax. [ABSTRACT FROM AUTHOR] more...

Potential mechanistic mediators of Darwinian fitness, such as stress hormones or sex hormones, have been the focus of many studies. An inverse relationship between fitness and stress or sex hormone concentrations has been widely assumed, although empirical evidence is scarce. Feathers gradually accumulate hormones during their growth and provide a novel way to measure hormone concentrations integrated over time. Using liquid chromatography–tandem mass spectrometry, we measured testosterone, corticosterone and cortisol in the feathers of house sparrows (Passer domesticus) in a wild population which is the subject of a long-term study. Although corticosterone is considered the dominant avian glucocorticoid, we unambiguously identified cortisol in feathers. In addition, we found that feathers grown during the post-nuptial moult in autumn contained testosterone, corticosterone and cortisol levels that were significantly higher in birds that subsequently died over the following winter than in birds that survived. Thus, feather steroids are candidate prospective biomarkers to predict the future survival of individuals in the wild. [ABSTRACT FROM AUTHOR] more...

Previous studies of coastal river otters (Lontra canadensis) in Prince William Sound, Alaska, USA, documented atypical social organization for mammals. Social groups were composed largely of males, but some males remained solitary year-round and most females were asocial. Because, in carnivores, groups are usually composed of highly related individuals but group living also provides advantages unrelated to kinship, we concurrently evaluated the role of relatedness and ecological benefits in sociality among coastal river otters. By using DNA microsatellite analysis and radiotelemetry, we were able to reject the hypothesis that social groups of otters were kin based. In addition, we found no indication of kin avoidance, as would be expected from low dispersal and high local competition. Sociality conferred no reproductive benefits or costs to otters; number of offspring and number of relatives in the population did not differ between social and solitary animals. Solitary males were not older or larger than were social males, and there was no relation between male size and number of offspring, indicating that sexual selection did not mask a potential relation between sociality and reproductive success. Among coastal river otters in this region, sociality could be explained by the benefits obtained from cooperative foraging on high-quality schooling pelagic fishes. Such benefits did not require association with kin, resulting in no selection pressure for kin-based groups. The prediction that the degree of sociality in the population will fluctuate relative to the abundance of schooling pelagic fishes merits further investigation. [ABSTRACT FROM AUTHOR] more...