Sex-specific prey partitioning in breeding piscivorous birds examined via a novel, non-invasive approach

Piscivorous birds frequently display sex-specific differences in their hunting and feeding behaviour, which lead to diverging impacts on prey populations. Cormorants (Phalacrocoracidae), for example, were previously studied to examine dietary differences between the sexes and males were found to consume larger fish in coastal areas during autumn and winter. However, information on prey partitioning during breeding and generally on sex-specific foraging in inland waters is missing.
Here, we assess sex-specific prey choice of Great Cormorants (Phalacrocorax carbo) during two subsequent breeding seasons in the Central European Alpine foreland, an area characterized by numerous stagnant and flowing waters in close proximity to each other. We developed a unique, non-invasive approach and applied it to regurgitated pellets: molecular cormorant sexing combined with molecular fish identification and fish-length regression analysis performed on prey hard parts.
Altogether, 364 pellets delivere...