Deficiencies in basic ecological information on uncommon and endangered elasmobranch fishes impair the assessment of their ecological role in marine ecosystems. In this study, we examined the feeding ecology (diet composition and trophic level) and trophic relationships of several elasmobranchs species present in the western Mediterranean Sea.

In ground-nesting birds egg colour and appearance may have evolved due to opposite selection pressures. Pigmentation and spottiness make the eggs darker and have been suggested to improve camouflage. However these eggs may reach higher temperatures, which may be lethal for embryos. Some authors suggested that this trade-off may not exist. In this study the occurrence of a trade-off between camouflage and overheating of eggs is tested.

The primary prey of killer whales in the Strait of Gibraltar is the bluefin tuna. All killer whales observed in this area hunt tuna by chasing individual fish until they become exhausted and can be overcome. However, a subset of pods also interact with a dropline tuna fishery which has developed since 1995. Here, authors investigated the social structure within and among social units (pods).

Glucocorticoids play a key role in the stress response in vertebrates. In particular, corticosterone (CORT) is the main glucocorticoid in amphibians, birds, and reptiles.The most common methods for measuring CORT levels are competitive binding immunoassays: RIA and (EIA. Since the 1980's RIA has been broadly used but it requires radioactivity. In the last years, commercial kits of EIA has been developed and permit to measure CORT levels without the use of radioactivity. Here authors use...

Saliva is a secretion rich in epithelial cells and an excellent source of DNA for genetic analysis. Attempts to identify wild vertebrates from noninvasive samples of saliva have been restricted to searching for food remains recently handled by target species. This approach often requires close tracking of animals, which is unfeasible for most species and may explain why saliva is seldom considered in ecological studies. Authors develop a noninvasive method of collection that combines baits...