Mémoire
| Résumé : | Species adapt to warming in the context of climate change in many ways. Variations in body and appendage size to facilitate thermoregulation is among the predicted responses based on Bergmann’s and Allen’s Rules. In this context, we studied the Common Waxbill (Estrilda astrild), a passerine bird native to tropical sub-Saharan Africa. In order to gain a clearer picture of the waxbill’s autoecology, we investigated how morphological traits such as body size and bill size varied with climate and environmental predictors. Fluctuating asymmetry, a signature of developmental instability caused by environmental stress was also investigated. Preserved natural history museum specimens of the waxbill were measured for this study. These measurements were summarised into principal components and then modelled against aspects of climate characterised by temperature, precipitation and solar radiation through generalised additive modelling. Categories of land use and anthropogenic footprint were also included as environmental variables. We found that trends in body and bill size were best explained by warm temperatures, patterns of rainfall and land-use type. We found that body and bill size mainly decreased with increasing temperature and precipitation. Body size also decreased in open vegetation types with direct exposure to sunlight and heat, but increased around cultivated lands. We also detected significant levels of fluctuating asymmetry in the tarsii of the waxbill that were best explained by increasing temperatures, suggesting that heat may negatively affect the waxbill. Thus, this study was able to demonstrate the waxbill’s response to various climate and habitat type scenarios. |
