Romano_et_al

Data on begging behaviour of nestling barn swallow. See README.txt for details

Rainfall, but not temperature, negatively affects the growth of Blue Tit <i>Cyanistes caeruleus</i> nestlings

<p><b>Capsule:</b> Growth trajectories of Blue Tit <i>Cyanistes caeruleus</i> nestlings differed between sexes and were negatively affected by rain but not by temperature during the linear growth phase (LGP).</p> <p><b>Aims:</b> To model the growth trajectories of Blue Tit nestlings and to identify the main ecological factors affecting them.</p> <p><b>Methods:</b> Sixty-five nestling Blue Tits from a population in northern Italy were weighed at regular intervals and sexed using molecular genetic techniques. The LGP period was identified and analysed to test for the influence of age, sex, hatching date, brood size, temperature and rainfall on individual daily growth rates during the LGP.</p> <p><b>Results:</b> Growth curves showed no pre-fledging mass loss. Body mass differed between the sexes, with males being 5% heavier than females at the pre-fledging stage. Daily growth rates during the LGP were higher for males and on non-rainy days, while they were not affected by other factors.</p> <p><b>Conclusion:</b> The higher daily growth rate observed in males during the LGP may determine the extent of sexual size dimorphism at the pre-fledging stage. Susceptibility of growth trajectories to environmental conditions was limited to rainfall and was similar in the two sexes. This contrasts with findings from previous studies, which found sex-biased environmental sensitivity of Blue Tit nestlings.</p

Cloacal microbiota of barn swallows from Northern Italy

<p>Bird gut microbiota shows large variation among geographical populations of the same species – probably because, differently from mammals, gut microbiota of birds is largely affected by extrinsic factors such as diet and environmental conditions. We analysed the cloacal microbiota (CM) of 12 barn swallows (<i>Hirundo rustica</i>) from a colony in Northern Italy by high-throughput DNA sequencing of the 16S rRNA gene. The CMs, dominated by bacteria of the phyla Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes, did not significantly differ between adult females, adult males and fledglings. This first description of barn swallow CM in Italy, together with two previous studies from Europe, suggests that CMs of geographically different barn swallow populations are dominated by bacteria belonging to the same phyla but different genera. The intra-colony similarity of the CMs may be due to the exposure of individuals to the same local environmental conditions while on their breeding grounds.</p

Relationships between sperm area and relative chelae size.

<p>Relative chelae size is expressed as PC2 scores (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0043771#s2" target="_blank">Methods</a>). The regression line is shown.</p

Relationships between sperm longevity and male chelae asymmetry.

<p>Both variables were √ arcsine-transformed and are thus expressed in degrees (°) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0043771#s2" target="_blank">Materials and Methods</a>). The regression line is shown.</p

Stained freshwater crayfish sperm cells released from spermatophores (40× magnification).

<p>a) Phase contrast microscopy: note the radial nuclear arms or spikes spreading out from the sperm cells at activation; b) Fluorescence microscopy: the same sperm cells under fluorescence light with blue excitation filter (<i>λ</i> = 450–480 nm); living sperm with intact cellular membranes are green, while dead sperm are red.</p

Body traits of male and female crayfish used in mating trials in the two years of study.

<p>Body traits of male and female crayfish used in mating trials in the two years of study.</p

Relationships between sperm area and date of insemination.

<p>The regression line is shown.</p

Sex allocation and maternal survival

Sex allocation and maternal surviva

TSR of yearlings in the population in any (<i>t</i>+1)-th study year in relation to adult survival between year <i>t</i> and year <i>t</i>+1.

<p>The analysis was restricted to the years when more than 180 yearlings were sampled (see <i>Statistical analyses</i>).</p