BUSCADOR RECOLECTA

Solar radiation is an important driver of animal coloration, not only because of the effects of coloration on body temperature but also because coloration may protect from the deleterious effects of UV radiation. Indeed, dark coloration may protect from UV, but may increase the risk of overheating. In addition, the effect of coloration on thermoregulation should change with egg size, as smaller eggs have higher surface-volume ratios and greater convective coefficients than larger eggs, so that small eggs can dissipate heat quickly. We tested whether the reflectance of eggshells, egg spottiness and egg size of the ground-nesting Kentish plover Charadrius alexandrinus are affected by maximum ambient temperature and solar radiation at breeding sites. We measured reflectance, both in the UV and human visible spectrum, spottiness and egg size in photographs from a museum collection of plover eggshells. Eggshells of lower reflectance (darker) were found at higher latitudes. However, in southern localities where solar radiation is very high, eggshells are also of dark coloration. Eggshell coloration had no significant relationship with ambient temperature. Spotiness was site-specific. Small eggs tended to be light-coloured. Thermal constraints may drive the observed spatial variation in eggshell coloration, which may be lighter in lower latitudes to diminish the risk of overheating as a result of higher levels of solar radiation. However, in southern localities with very high levels of UV radiation, eggshells are of dark coloration likely to protect embryos from more intense UV radiation. Egg size exhibited variation in relation to coloration, likely through the effect of surface area-to-volume ratios on overheating and cooling rates of eggs. Therefore, differential effects of solar radiation on functions of coloration and size of eggshells may shape latitudinal variations in egg appearance in the Kentish plover., Peer reviewed

Dataset of the characteristics of eggs, nests and nesting substrates of Kentish plover, pied avocet and little tern breeding in southern Spain, as described in Gómez et al. 2018., This dataset contains the information of the article entitled “Individual egg camouflage is influenced by microhabitat selection and use of nest materials in ground-nesting birds” in which we investigated (using avian visual modelling) whether there was an active selection of microhabitats and nest materials in three ground-nesting birds (pied avocet, Kentish plover and little tern) to camouflage their eggs., JG was supported by a FPU predoctoral fellowship (FPU-12/01616) from Ministerio de Educación, Cultura y Deporte, Spain. Our project was funded by grant CGL2011-24230 from Ministerio de Ciencia e Innovación, Spain, with EU-ERDF financial support. JT and MS were funded by a Biotechnology and Biological Sciences Research Council (BBSRC) grant BB/J018309/1 to MS., Peer reviewed