Assessment of Morphometric Indices Related to Vernal Flight in Migratory Buntings

Migratory songbirds fly over long distances to avoid adverse conditions at their breeding and wintering grounds, and this phenomenon is known as ‘migration’. This migratory phenomenon is highly energy demanding. The present study was aimed to analyze the morphometric analysis of body mass, beak, wings, tail, and tarsus length of two migratory finches i.e., red-headed (RHB) and black-headed buntings (BHB) to investigate whether they showed differences in their morphological attributes. This observational study shows an understanding of the characterization of wing patterns and differences in the length of tarsus, tail, beak, and wings of both species. The size of the beak, tail, and wings of BHB is significantly different when compared to RHB. In addition, body mass was significantly high in BHB than that of RHB during their spring migration (preparatory phase). T

Effects of maternal exposure to a bacterial antigen and altered post-hatching rearing conditions on avian offspring behaviour

The early-life environment plays a crucial role in shaping morphological, physiological, and behavioural traits, with potential long-term consequences for fitness. Indeed, a set of factors experienced by offspring during prenatal and early post-natal development has been recognised to affect behavioural trait expression in later life. Several studies have shown that in birds, nutritional and social rearing conditions and maternal and/or neonatal immunisations may profoundly determine the development and establishment of behaviour in offspring. To our knowledge, no research has examined whether and how the interaction between immune-mediated maternal effects and post-hatching rearing conditions affects offspring behaviour. Here, we studied the effects of maternal exposure to a bacterial antigen and altered brood size on docility, breathing rate, and aggression in the offspring of great tit, Parus major. We used a 2 × 2 design to investigate the interactive effects of maternal immunisation and brood size manipulation on offspring behavioural development. We found no such interactive effect on offspring behaviour, although we observed it regarding to offspring body mass and tarsus length. Maternal immunisation itself did not affect offspring behaviour. However, we demonstrated that the offspring breathing rate and level of aggression were affected by brood size manipulation. Both breathing rate and aggression in offspring reared in enlarged broods were lower than those in offspring reared in non-manipulated broods. Our study did not confirm earlier reports that immune-mediated maternal effects modulate offspring behavioural development, but we showed that brood size during rearing might indeed be a factor that affects offspring behaviour. Significance statement The early environment experienced by offspring constitutes a significant source of developmental plasticity, which may profoundly affect the establishment of their behavioural traits. Food availability, social conditions, and maternal or offspring infection are crucial factors shaping various behavioural traits in birds. However, there remains a lack of studies emphasising the potential interactive effects of early-life conditions on behavioural trait development in natural bird populations. Here, to our knowledge for the first time, we experimentally examined how maternal immunisation and altered post-hatching rearing conditions interact to determine the behaviour of fledged offspring. We found that maternal treatment and brood size manipulation interactively affected offspring body mass and tarsus length, but this interaction had no effect on offspring behaviour. Our findings suggest that different mechanisms may underlie the development of morphological and behavioural traits.

A revision of bird skin preparation aimed at improving the scientific value of ornithological collections

The methods used to preserve bird skins in museums have a potentially crucial impact on the feasibility and use of these specimens as a source of biological knowledge, although this subject is rarely broached. Study skins of birds are usually prepared with folded wings and straight legs to facilitate storage in the collection; yet, this method can hamper the measurement and examination of certain important features such as wing-feather moult. To make consultation easier for ornithologists, alternative preparation methods such as the splitting of wings and tarsi from the rest of the animal have been proposed by curators. Our aim was to study whether or not preparing bird specimens with spread limbs makes consultation simpler. First, we used two different methods to prepare two specimens each of two common European passerine species: (1) ‘traditional’ (folded wings and straight tarsi) and (2) ‘spread’ (limbs spread on one side of the body). Then, we asked 22 experienced ornithologists to identify moult limits and take three biometric measurements (wing chord, length of the third primary feather and tarsus length) from all four specimens. Subsequently, we asked which preparation method they preferred for obtaining data. The ‘spread’ preparation was preferred for moult, third primary feather length and tarsus length, whilst the ‘traditional’ preparation was preferred for wing chord. Data obtained from the folded and spread preparations were very highly repeatable within each method but only moderately to highly repeatable between methods. One of the handicaps with the ‘spread’ preparation is the increase in storage space required, a factor that should be taken into account before it is employed. Nevertheless, this specimen preparation technique can greatly facilitate consultation and therefore improve the scientific value of ornithological collections.

An immune challenge of female great tits decreases offspring survival and has sex-specific effects on offspring body size

Investment in immunity is expected to decrease (costly immunity) or enhance (terminal investment) reproductive performance. Here, we tested the effects of activation of the immune system in female great tits (Parus major) on (1) their reproductive effort and (2) the survival and body condition of their offspring, controlling for chick sex. We injected females tending 3-day-old chicks with sheep red blood cells (SRBC) or saline (control) and recorded their provisioning rates 6 days later, during the expected peak of antibody production. We measured tarsus length and body mass in 11-day-old chicks and monitored changes in brood size. We found that female provisioning rates were unaffected by the SRBC challenge. An analysis without an outlier, however, showed a significant challenge-by-hatch date interaction. This interaction indicated that female provisioning rates decreased with hatch dates in the SRBC but not in the control nests, suggesting a stronger effect in later breeders. Chick body mass was not affected by female immunisation nor by its interaction with chick sex. However, we found a significant challenge-by-sex interaction on offspring tarsus. In SRBC nests, the difference in tarsus length between male and female chicks was lower than in controls, suggesting sex-dependent effects of the challenge on offspring structural growth. Finally, chick mortality was greater in SRBC nests compared with controls, but chick survival probability was not affected by sex. Overall, our results support the costly immunity but not the terminal investment hypothesis in the great tit.

Polygenic basis for adaptive morphological variation in a threatened Aotearoa | New Zealand bird, the hihi ( Notiomystis cincta )

To predict if a threatened species can adapt to changing selective pressures, it is crucial to understand the genetic basis of adaptive traits, especially in species historically affected by severe bottlenecks. We estimated the heritability of three hihi ( Notiomystis cincta ) morphological traits known to be under selection (nestling tarsus length, body mass and head–bill length) using 523 individuals and 39 699 single nucleotide polymorphisms (SNPs) from a 50 K Affymetrix SNP chip. We then examined the genetic architecture of the traits via chromosome partitioning analyses and genome-wide association scans (GWAS). Heritabilities estimated using pedigree relatedness or genomic relatedness were low. For tarsus length, the proportion of genetic variance explained by each chromosome was positively correlated with its size, and more than one chromosome explained significant variation for body mass and head–bill length. Finally, GWAS analyses suggested many loci of small effect contributing to trait variation for all three traits, although one locus (an SNP within an intron of the transcription factor HEY2 ) was tentatively associated with tarsus length. Our findings suggest a polygenic nature for the morphological traits, with many small effect size loci contributing to the majority of the variation, similar to results from many other wild populations. However, the small effective population size, polygenic architecture and already low heritabilities suggest that both the total response and rate of response to selection are likely to be limited in hihi.

Development of nestling blue tits (Cyanistes caeruleus) is affected by experimental addition of aromatic plants

Some passerines incorporate aromatic plants in their nest cups, and several hypotheses have been formulated to explain this behaviour. One of those, the Drug Hypothesis, states that aromatic plants present in nests have positive effects on nestlings’ development through increased immune function. In this study, we aimed to examine if experimental addition of aromatic plants had positive effects on reproductive performance (the number of fledglings produced and nestling survival rate) and nestling development (weight and tarsus length). In addition, we study whether those potential effects were more noticeable in different brood sizes–small and large–through an observational approach. We expect that large broods, due to increased resource competition between nestlings, will benefit more from aromatic plant incorporation, as compared to small broods. Nestlings were significantly heavier in 2015 as compared to 2016 and 2017 and in small broods. No effect of treatment was observed in nestling weight. Although there was no overall effect of treatment on nestling tarsus length, nestlings from aromatic nests had significantly longer tarsi as compared to nestlings from control nests, in large broods.

Ecotypic changes of alpine birds to climate change

In endotherm animals, several traits are related to climate. For example, Bergmann’s rule predicts a decrease in body size within species and across closely related species with increasing temperature, whereas Gloger’s rule states that birds and mammals should be darker in humid and warm environments compared to colder and drier areas. However, it is still not clear whether ecotypic responses to variation in the local environment can also apply to morphological and colouration changes through time in response to climate change. We present a 100-year-long time series on morphological and melanin-based colours of snowfinch (325 Montifringilla, 92 Pyrgilauda and 30 Onychostruthus) museum specimens. Here we show that the tarsus length of the species has decreased and the saturation of the melanin-based colour has increased, which was correlated with the increase of temperature and precipitations. As ecotypic variations are tightly linked to individual behavioural and physiological responses to environmental variations, differently sized and coloured individuals are expected to be differently penalized by global changes. This study opens the pertinent question about whether ecotypic responses can enhance population persistence in the context of global change.

Bergmann’s rule and Allen’s rule in two passerine birds in China

Background Animals that live at higher latitudes/elevations would have a larger body size (Bergmann’s rule) and a smaller appendage size (Allen’s rule) for thermoregulatory reasons. According to the heat conservation hypothesis, large body size and small appendage size help animals retain heat in the cold, while small body size and large appendage size help them dissipate heat in the warm. For animals living in seasonal climates, the need for conserving heat in the winter may tradeoff with the need for dissipating heat in the summer. In this study, we tested Bergmann’s rule and Allen’s rule in two widely-distributed passerine birds, the Oriental Magpie (Pica serica) and the Oriental Tit (Parus minor), across geographic and climatic gradients in China. Methods We measured body size (body mass and wing length) and appendage size (bill length and tarsus length) of 165 Oriental Magpie and 410 Oriental Tit individuals collected from Chinese mainland. We used linear mixed-effect models to assess variation patterns of body size and appendage size along geographic and climatic gradients. Results Oriental Magpies have a larger appendage size and Oriental Tits have a smaller body size in warmer environments. Appendage size in Oriental Magpies and body size in Oriental Tits of both sexes were more closely related to the climates in winter than in summer. Minimum temperature of coldest month is the most important factor related to bill length and tarsus length of male Oriental Magpies, and wing length of male and female Oriental Tits. Bill length and tarsus length in female Oriental Magpies were related to the annual mean temperature and mean temperature of coldest quarter, respectively. Conclusions In this study, Oriental Magpies and Oriental Tits followed Allen’s rule and Bergmann’ rule respectively. Temperatures in the winter, rather than temperatures in the summer, drove morphological measurements in Oriental Magpies and Oriental Tits in Chinese mainland, demonstrating that the morphological measurements reflect selection for heat conservation rather than for heat dissipation.

Fluctuating asymmetry and feather growth bars as biomarkers to assess the habitat quality of shade coffee farming for avian diversity conservation

Shade coffee farming has been promoted as a means of combining sustainable coffee production and biodiversity conservation. Supporting this idea, similar levels of diversity and abundance of birds have been found in shade coffee and natural forests. However, diversity and abundance are not always good indicators of habitat quality because there may be a lag before population effects are observed following habitat conversion. Therefore, other indicators of habitat quality should be tested. In this paper, we investigate the use of two biomarkers: fluctuating asymmetry (FA) of tarsus length and rectrix mass, and feather growth bars (average growth bar width) to characterize the habitat quality of shade coffee and natural forests. We predicted higher FA and narrower feather growth bars in shade coffee forest versus natural forest, indicating higher quality in the latter. We measured and compared FA in tarsus length and rectrix mass and average growth bar width in more than 200 individuals of five bird species. The extent of FA in both tarsus length and rectrix mass was not different between the two forest types in any of the five species. Similarly, we found no difference in feather growth between shade coffee and natural forests for any species. Therefore, we conclude our comparison of biomarkers suggests that shade coffee farms and natural forests provide similar habitat quality for the five species we examined.

Artificial incubation does not affect the post-hatch development, health, or survival of the Lance-tailed Manakin (Chiroxiphia lanceolata), a tropical passerine

Artificial incubation of avian eggs is used in scientific research, conservation, zoo husbandry, and the commercial poultry industry. However, whether artificial incubation negatively impacts post-hatch nestling phenotypes and survival compared to naturally incubated young has not been explicitly tested. Here, we assess whether nestlings artificially incubated as eggs and returned to their natal nest after hatching experienced negative impacts in development, health, and survival. From 2007 to 2017, we measured mass, mass growth rate, tarsus length, tarsus growth rate, external lesions, ejection from the nest, fledging success, and recruitment of Lance-tailed Manakin (Chiroxiphia lanceolata) nestlings from 209 nests where 1 of 2 eggs was artificially incubated, along with 230 unmanipulated nests. We found no statistically significant difference in the development, health, and survival among nestlings artificially incubated as eggs, their naturally incubated nestmates, and nestlings from unmanipulated nests. Our results indicate that artificial incubation can be a safe and effective tool in the study of free-living birds.