Towards a Michelin Guide for wading birds: food availability of wetlands in a migration bottleneck in western Greece

Abstract

To fuel their flights, wading birds rely on abundant and high-quality food supply along their migratory route. The time spent in flight in fact represents only a small part of the migration period when compared to the time spent at stopovers. Especially in proximity of major barriers, the conditions at a single site can have a large effect on further travel stages. The Ionian flyway is considered such a migration bottleneck, where flight routes converge along a chain of coastal wetlands.

To gain insight in its function as stopover site for wading birds, the goal of this study was (1) to quantify the refuelling capacity of western Greek wetlands and (2) assess which habitat characteristics are related to high food availability. In a wider framework, both goals support the development of connectivity models that, in addition to spatial characteristics of wetland networks, incorporate the energetic component of migration to evaluate the relative importance of sites.

During autumn (2016) and spring (2017) migration seasons, we sampled benthic macroinvertebrates at 90 locations in four wetlands protected under the European Natura 2000 legislation, i.e. the Kalamas delta and the Amvrakikos, Messolonghi and Gialova lagoons. By using a multilevel core sampling device, we separated prey fractions that are accessible to different wading bird species, depending on their bill length. Invertebrates were identified, weighed and their biomass and nutritional quality (fat and protein content) was determined. Additionally, for each sampling location, information on environmental parameters, wading bird abundance and foraging intensity was collected. We show the first results of the sampling campaigns and discuss the implications for aligning Natura 2000 habitat types with patterns of prey availability and quality.