Environmental conditions during early life accelerate the rate of senescence in a short-lived passerine bird

Environmental conditions experienced in early life may shape subsequent phenotypic traits including life history. We investigated how predation risk caused by domestic cats (Felis silvestris catus) and local breeding density affected patterns of reproductive and survival senescence in Barn Swallows (Hirundo rustica) breeding semicolonially in Denmark. We recorded the abundance of cats and the number of breeding pairs at 39 breeding sites during 24 years and related these to age-specific survival rate and reproductive senescence to test predictions of the life history theory of senescence. We found evidence for actuarial senescence for the first time in this species. Survival rate increased until reaching a plateau in midlife and then decreased later. We also found that survival rate was higher for males than females. Local breeding density or predation risk did not affect survival as predicted by theory. Barn Swallows with short lives did not invest more in reproduction in early life, inconsistent with expectations for trade-offs between reproduction and survival as theory suggests. However, we found that the rate of reproductive decline during senescence was steeper for individuals exposed to intense competition, and predation pressure accelerated the rate of reproductive senescence, but only in sites with many breeding pairs. These latter results are in accordance with one of the predictions suggested by the life history theory of aging. These results emphasize the importance of considering intraspecific competition and interspecific interactions such as predation when analyzing reproductive and actuarial senescence

Sexual selection in the Swallow Hirundo rustica - A review

Darwinian theory of sexual selection and its development up to the present state of knowledge are sketched. The most important results of empirical studies on sexual selection in the Swallow Hirundo rustica are reviewed. The Swallow is a socially monogamous, slightly sexually dimorphic avian species. Long tail streamers are considered as sexual ornaments of males. Female preference for long and symmetric male tails has been inferred on both observational and experimental grounds. Experimental elongation of the tail causes short-term benefits and long-term costs in male reproductive performance. Behavioural consequences of sexual selection acting in the Swallow are discussed. An aerodynamic role of male tail streamers is also considered.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę

(Micro)evolutionary changes and the evolutionary potential of bird migration

Seasonal migration is the yearly long-distance movement of individuals between their breeding and wintering grounds. Individuals from nearly every animal group exhibit this behavior, but probably the most iconic migration is carried out by birds, from the classic V-shape formation of geese on migration to the amazing nonstop long-distance flights undertaken by Arctic Terns Sterna paradisaea. In this chapter, we discuss how seasonal migration has shaped the field of evolution. First, this behavior is known to turn on and off quite rapidly, but controversy remains concerning where this behavior first evolved geographically and whether the ancestral state was sedentary or migratory (Fig. 7.1d, e). We review recent work using new analytical techniques to provide insight into this topic. Second, it is widely accepted that there is a large genetic basis to this trait, especially in groups like songbirds that migrate alone and at night precluding any opportunity for learning. Key hypotheses on this topic include shared genetic variation used by different populations to migrate and only few genes being involved in its control. We summarize recent work using new techniques for both phenotype and genotype characterization to evaluate and challenge these hypotheses. Finally, one topic that has received less attention is the role these differences in migratory phenotype could play in the process of speciation. Specifically, many populations breed next to one another but take drastically different routes on migration (Fig. 7.2). This difference could play an important role in reducing gene flow between populations, but our inability to track most birds on migration has so far precluded evaluations of this hypothesis. The advent of new tracking techniques means we can track many more birds with increasing accuracy on migration, and this work has provided important insight into migration's role in speciation that we will review here

Development of the Innate Immune Response in NestlingTree Swallows (Tachycineta bicolor)

The innate immune system provides an immediate, short term, first line of defense from pathogens; its appearance early in development in vertebrates is evidence of its critical importance. Even so, few studies have investigated the development of the immune response as juveniles transition into adults. Ultimately, the ability to respond to pathogens confers fitness benefits in terms of health, survival, and reproductive success, and it follows that functions such as rapid growth cannot be fully met simultaneously since energy is a limiting resource. As a result, defense mechanisms are compromised at an early age due to energy allocation to rapid growth; therefore, immunity should increase as individuals mature. I studied the development of innate immunity in nestling Tree Swallows using microbicidal assays which were conducted in vitro to assess the ability of the immune system to kill E. coli via lysis. This research may provide insight into patterns of disease susceptibility, which in turn influence evolutionary fitness and population dynamics

Does foraging efficiency vary with colony size in the fairy martin Petrochelidon ariel?

Colonial breeding occurs in a wide range of taxa, however the advantages promoting its evolution and maintenance remain poorly understood. In many avian species, breeding colonies vary by several orders of magnitude and one approach to investigating the evolution of coloniality has been to examine how potential costs and benefits vary with colony size. Several hypotheses predict that foraging efficiency may improve with colony size, through benefits associated with social foraging and information exchange. However, it is argued that competition for limited food resources will also increase with colony size, potentially reducing foraging success. Here we use a number of measures (brood feeding rates, chick condition and survival, and adult condition) to estimate foraging efficiency in the fairy martin Petrochelidon ariel, across a range of colony sizes in a single season (17 colonies, size range 28-139 pairs). Brood provisioning rates were collected from multiple colonies simultaneously using an electronic monitoring system, controlling for temporal variation in environmental conditions. Provisioning rate was correlated with nestling condition, though we found no clear relationship between provisioning rate and colony size for either male or female parents. However, chicks were generally in worse condition and broods more likely to fail or experience partial loss in larger colonies. Moreover, the average condition of adults declined with colony size. Overall, these findings suggest that foraging efficiency declines with colony size in fairy martins, supporting the increased competition hypothesis. However, other factors, such as an increased ectoparasitise load in large colonies or change in the composition of phenotypes with colony size may have also contributed to these patterns.

Movement ecology and sex are linked to barn owl microbial community composition.

The behavioural ecology of host species is likely to affect their microbial communities, because host sex, diet, physiology, and movement behaviour could all potentially influence their microbiota. We studied a wild population of barn owls (Tyto alba) and collected data on their microbiota, movement, diet, size, coloration, and reproduction. The composition of bacterial species differed by the sex of the host and female owls had more diverse bacterial communities than their male counterparts. The abundance of two families of bacteria, Actinomycetaceae and Lactobacillaceae, also varied between the sexes, potentially as a result of sex differences in hormones and immunological function, as has previously been found with Lactobacillaceae in the microbiota of mice. Male and female owls did not differ in the prey they brought to the nest, which suggests that dietary differences are unlikely to underlie the differences in their microbiota. The movement behaviour of the owls was associated with the host microbiota in both males and females because owls that moved further from their nest each day had more diverse bacterial communities than owls that stayed closer to their nests. This novel result suggests that the movement ecology of hosts can impact their microbiota, potentially on the basis of their differential encounters with new bacterial species as the hosts move and forage across the landscape. Overall, we found that many aspects of the microbial community are correlated with the behavioural ecology of the host and that data on the microbiota can aid in generating new hypotheses about host behaviour

A case of partial leucism in the American Barn Owl (Tyto furcata) (Temminck, 1827), from Buenos Aires province, Argentina

The diverse colorations of a birds’ plumage are due to either structural colors or pigments that are synthesized in specialized cells or incorporated through the diet. However, plumage color aberrations can occur; several cases of albinism and leucism have been reported for different bird species and some examples correspond to Strigiformes. A specimen of the American barn owl (Tyto furcata) with partial leucism was found in Carhué, Buenos Aires province. The plumage of its facial disc, tail and the ventral region was completely white; furthermore, the neck, and the primary and secondary remiges were pigmented although in a significantly lighter fashion than in normal-phenotype specimens. The rest of the body presented a normal pattern for the species.Fil: Chiale, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; ArgentinaFil: Pagano Luis Gerardo. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina. Grupo Falco; Argentin

Morphological Changes Predict Inter-Seasonal Reproductive Performance In the North American Barn Swallow

Differential allocation between providing costly parental care and self-preservation is a well-known trade off in evolutionary theory. Across a variety of vertebrate taxa, a pattern exists where younger individuals tend to produce less offspring than older individuals after the onset of reproduction. I present data from a three-year study in a population of North American barn swallows Hirundo rustica erythrogaster to determine whether there is a pattern of age-related increases in reproduction and analyze how within-individual (1) site fidelity, (2) social mate, and (3) changes in morphology affect patterns of seasonal reproductive success, defined as the total number of young fledged in a given breeding season. Over the course of this study, I did not detect a clear pattern of increases in reproduction with age. Interestingly, significant changes in morphology between years predicted reproductive performance; females that minimized growth in tail streamers between 2008 and 2009 had greater reproductive performance. Males that became darker had greater reproductive performance only between 2008 and 2009. These relationships were not detected in the years between 2009 and 2010. I did not find that site fidelity or mate familiarity significantly impacted reproductive performance, in contrast to what was concluded in previous work. These analyses of intrinsic, morphological changes within individuals indicate that there are important underlying agerelated mechanisms of reproductive performance