Waders of the Bijagos, Guinea-Bissau: connecting nonbreeding conditions in the tropics with breeding conditions in the arctic

The seasonality of the Earth ensures that in the North large expanses of land become available for use by demanding organisms like birds during the northern summer. Shorebirds are specialized seasonal migrants which capitalize on the temporary summer resources to breed and on the more seasonally stable wetland resources in temperate and tropical zones to survive the rest of the year. By way of the shorebirds feeding on the intertidal mudflats, the Bijagos are connected with both Iceland (by way of whimbrels) and north central Siberia.

Our part of the Waders of the Bijagos MAVA project consist of illuminating the precise character of the connections. The larger question is how conditions in the Bijagos affect the survival and breeding success of the waders of the Bijagos, parameters that will depend as much on the conditions in the Bijagos, as on conditions at the staging sites (e.g. Wadden Sea) and the breeding grounds.

Our approach consists of:

(1) documentation of the precise connections and itineraries of the birds, by ways of tracking, either based on geolocators (ongoing work on whimbrel by the Aveiro/Southern Iceland universities team) and satellite trackers (present effort, with a focus on bar-tailed godwit and whimbrel);

(2) documentation of the ecological conditions, with a focus on food and food intake rates, during the period that the shorebirds remain in the Bijagos (e.g. thesis project Ana Coelho);

(3) a Bijagos wide benthic mapping effort on which to plot the whereabouts of individual tracked birds; and

(4) the search for correlations between conditions experienced by individuals in the Bijagos nonbreeding areas and migration parameters, survival and recruitment.

So far we have been busy analysing the past tracks of bar-tailed godwits previously tagged in the Wadden Sea and wintering in the Bijagos (Piersma et al. unpubl.), worked intensively on the food and feeding of shorebirds during their time in Guinea-Bissau (Coelho and others), and satellite tagged the first whimbrel and bar-tailed godwits, which hopefully will yield the first detailed migration tracks during the 2019 season.