Female blue tits with brighter yellow chests transfer more carotenoids to their eggs after an immune challenge.

Female ornaments are present in many species, and it is more and more accepted that sexual or social selection may lead to their evolution. By contrast, the information conveyed by female ornaments is less well understood. Here, we investigated the links between female ornaments and maternal effects. In birds, an important maternal effect is the transmission of resources, such as carotenoids, into egg yolk. Carotenoids are pigments with antioxidant and immunomodulatory properties that are crucial for females and developing offspring. In blue tits, we evaluated whether ultraviolet (UV)/blue and yellow feather colouration signals a female's capacity to allocate carotenoids to egg yolk. Because mounting an immune response is costly and trade-offs are more detectable under harsh conditions, we challenged the immune system of females before laying and examined the carotenoid level of their eggs afterward. A positive association between feather carotenoid chroma and egg carotenoid level would be expected if yellow colouration signals basal immunity. Alternatively, if female colouration more generally reflects maternal capacity to invest in reproduction under challenging conditions, then other components of colouration (i.e. yellow brightness and UV/blue colouration) could be linked to maternal capacity to invest in eggs. No association between egg carotenoid levels and UV/blue crown colouration or female yellow chest chroma was found; the latter result suggests that yellow colouration does not signal immune capacity at laying in this species. By contrast, we found that, among females that mounted a detectable response to the vaccine, those with brighter yellow chests transmitted more carotenoids into their eggs. This result suggests yellow brightness signals maternal capacity to invest in reproduction under challenging conditions, and that male blue tits may benefit directly from choosing brighter yellow females.

Noise interfere on feeding behaviour but not on food preference of saffron finches (Sicalis flaveola).

Noise pollution exerts negative well-being effects on animals, especially for captive individuals. A decrease in feeding, reproduction, attention, and an increase in stress are examples of negative effects of noise pollution on animals. Noise pollution can also negatively impact animals' lives by decreasing the efficiency of food choice: attention decrease can cause animals choose the least profitable food, which can affect their fitness. The aims of this study were to analyse the effects of noise on feeding behaviour and food preference of saffron finches. Foraging tests were performed under background sound pressure levels and under a noisy condition. The behaviours exhibited by the birds during the tests were recorded using focal sampling with instantaneous recording of behaviour every 10 s. Results showed that finches consumed more the higher energetic food, and that noise pollution did not impact food consumption by the birds. Noise changed the number of visits on the feeders, and increased the expression of the 'lower the head' and vigilance behaviours during feeding. These findings could be important for wild and captive animals because an increase in vigilance and in changes in foraging behaviour could ultimately impact their fitness. Thus, mitigation measures should be taken in relation to noise impact on wildlife, this is especially the case for captive animals, which have no chance to avoid noisy environments.

Female plumage coloration is sensitive to the cost of reproduction. An experiment in blue tits.

1. A growing number of studies suggest that female ornaments are linked to maternal quality and influence male mate choice. These findings challenge the traditional male-biased view of sexual selection and the hypothesis that female ornaments are the outcome of a genetic correlation with male ornaments. To further test the hypothesis that female traits have a function, it is now essential to investigate their honesty and to determine how signalling and reproduction interact in females. If female traits are honest indicators of quality, then they are likely to have a specific signalling function. 2. We investigated whether carry-over effects of reproduction might ensure the honesty of plumage colour signalling of a bird species with conspicuous UV-blue and yellow coloration, the blue tit Cyanistes caeruleus. Reproductive effort was manipulated by removing clutches, thereby forcing both sexes to reproduce twice and to raise chicks later in the breeding season when food is less abundant. In the year following this manipulation, we investigated the change in plumage in experimental and control males and females. The change was measured in the two putative feather ornaments, the UV-blue cap and the yellow breast, and another feather trait probably less likely to be sexually selected: the wing length. We also tested whether higher-quality females had their coloration less affected by the experiment. 3. We found that control but not manipulated males and females increased their signal towards UV. In addition, in the manipulated group, females that were able to lay more eggs had their UV-blue coloration less affected by the treatment. For yellow coloration, we found that manipulated yearlings but not manipulated adults decreased their yellow chroma in comparison with control. Lastly, our results show that the condition of the manipulated females tended to be positively correlated with yellow chroma. 4. These results show that the trade-offs between reproduction and signalling can ensure the honesty of conspicuous plumage traits in female and male blue tits. In addition, they suggest that female traits have the potential to evolve under sexual selection in this and other bird species.

Scanning the European corn borer (Ostrinia spp.) genome for adaptive divergence between host-affiliated sibling species.

It has recently been shown that the European corn borer, a major pest of maize crops, is actually composed of two genetically differentiated and reproductively isolated taxa, which are found in sympatry over a wide geographical range in Eurasia. Each taxon is adapted to specific host plants: Ostrinia nubilalis feeds mainly on maize, while O. scapulalis feeds mainly on hop or mugwort. Here, we present a genome scan approach as a first step towards an integrated molecular analysis of the adaptive genomic divergence between O. nubilalis and O. scapulalis. We analysed 609 AFLP marker loci in replicate samples of sympatric populations of Ostrinia spp. collected on maize, hop and mugwort, in France. Using two genome scan methods based on the analysis of population differentiation, we found a set of 28 outlier loci that departed from the neutral expectation in one or the other method (of which a subset of 14 loci were common to both methods), which showed a significantly increased differentiation between O. nubilalis and O. scapulalis, when compared to the rest of the genome. A subset of 12 outlier loci were sequenced, of which 7 were successfully re-amplified as target candidate loci. Three of these showed homology with annotated lepidopteran sequences from public nucleotide databases.

Impacts of noise pollution on the agonistic interactions of the saffron finch (Sicalis flaveola Linnaeus, 1766).

Impacts of noise pollution are recognized as a source of stress for animals and as a form of environmental degradation. Behavioural changes associated with noise, such as reduction of reproductive success, reduction in feeding behaviour, increase in vigilance behaviours and inability to detect environment acoustic signals, are observed. The aim of the present study was to evaluate how noise influences aggressive behaviour of the saffron finch (Sicalis flaveola). We conducted tests of territoriality-aggressiveness against conspecifics. Seven individuals were tested, with six tests per individual being conducted in two treatments (traffic pollution and ambient noise), totalling 84 tests. The noise treatment significantly altered the agonistic interactions of the saffron finches, with territorial males exhibiting less aggressive behaviours towards intruders.