Foraging behaviour of wintering shorebirds at Merja Zerga lagoon (Atlantic coast, Morocco)

Abstract

This paper presents the results of a comparative study on the foraging behaviour of 15 species of wintering shorebirds at Merja Zerga lagoon. We video recorded a total of 600 actively foraging birds at the intertidal mudflats of the lagoon during the wintering period. We collected data on capturing rates, foraging method and movement characteristics for each observed individual. Results highlighted that studied shorebird species showed marked differences in their feeding strategies and movements when foraging. Plovers used exclusively a visual-run-stop strategy (superficial pecks), unlike Scolopacidae species that showed a wider range of types of feeding behaviour. Generally, this group favoured a tactile-continuous hunting strategy and it can be divided into two important subgroups. The first, including calidrids and shanks, used a mixed hunting strategy (pecking and probing) and had the highest prey capture rate and the fastest feeding rhythm, whereas the second included larger shorebirds that predominantly used tactile foraging technique with a slower rhythm and straighter trajectory. These differences in foraging behaviour and strategies suggest that shorebird species are able to exploit the intertidal flats and trophic resources of Merja Zerga in different ways, a fact that ensures that this site can host large numbers of birds at the same time, because of a lower level of interspecific competition.

Keywords: benthic prey, comparative study, feeding behaviour, intertidal habitats, waders