Search

Determining winter resighting range; median laying dates of lesser black-backed gulls in our study colony; accounting for nests of which the wintering location of two partners were known; mark-recapture survival analysis excluding GPS-tagged birds

In this report, we present the analysis of the different available biodiversity data streams at the EU and national level, both baseline biodiversity data and monitoring data. We assess how these biodiversity data inform and trigger policy action and identify the related challenges the different European countries and relevant EU agencies face and the solutions to overcome them. To do this, we consulted with more than 350 expert stakeholders from policy, research and practice. The assessment identified a fragmented biodiversity data landscape that cannot currently easily answer all relevant policy questions. Quantity and quality of biodiversity baseline datasets differ for the different countries, ranging from non-existent biodiversity monitoring due to capacity issues, to regular monitoring of ecosystem processes and state. By engaging stakeholders and experts in both member states and non-member states and from several EU bodies, we identified key challenges and ways to address these with targeted solutions towards building a joint European Biodiversity Monitoring Network. Solutions include focussing on cooperation and coordination, enhanced data standardisation and sharing, as well as the use of models and new technologies. These solutions can however only be realised with dedicated funding and capacity building, in coordination with all stakeholders in partnership.

Additional file 1. Supplementary Information.

Table S1. for shapefiles used to determine habitat use. Table S2 and Figure S1 for showing the relationship between the total time foraging and habitat use per individual. (PDF 195 kb)

For studies of how birds control their altitude, seabirds are of particular interest because they forage offshore where the visual environment can be simply modelled by a flat world textured by waves then generating only ventral visual cues. This study suggests that optic flow, i.e. the rate at which the sea moves across the eye’s retina, can explain gull’s altitude control over seas. In particular, a new flight model that includes both energy and optical invariants help explain the gulls’ trajectories during offshore takeoff and cruising flight. A linear mixed model applied to 352 flights from 16 individual lesser black backed gulls (Larus fuscus) revealed a statistically significant optic flow set-point of ca 25° s−1. Thereafter, an optic flow-based flight model was applied to 18 offshore takeoff flights from nine individual gulls. By introducing an upper limit in climb rate on the elevation dynamics, coupled with an optic flow set-point, the predicted altitude gives an optimized fit factor value of 63% on average (30–83% in range) with respect to the GPS data. We conclude that the optic flow regulation principle helps gulls to adjust their altitude over sea without having to directly measure their current altitude.

Proportion of land or sea or mixed foraging trips by GPS tracked gulls divided by year (.pdf). An extended version of Fig. 4 a. (PDF 850 kb)

Map of all GPS tracked gullsâ locations (.pdf). (PDF 7882 kb)

Table of lesser black-backed gulls GPS deployments (.doc). GPS deployments on lesser black-backed gulls at Stora KarlsĂś (2011â 2013) with number of foraging trips per individual per year included in analysis. (PDF 125 kb)

Capsule: Lesser Black-backed Gulls Larus fuscus breeding 30 km from the coast in the Netherlands focussed entirely on terrestrial food sources and reached relatively high breeding success. Aim: To gain insight in the foraging ecology, habitat use and breeding performance of inland-breeding Lesser Black-backed Gulls. Methods: We received data from seven birds fitted with global positioning system (GPS) loggers. The colony was frequently visited to collect pellets and boluses and to monitor reproductive success, mortality and growth rate of chicks. Results: The GPS data revealed that mainly terrestrial habitats were used, 98% of these GPS positions were within 25 km of the colony. Refuse dumps were the most preferred sites, but also agricultural fields and freshwater bodies were often visited. Only two of the 710 recorded trips were directed to the North Sea. The pellet and bolus analyses confirmed the GPS data: no marine food remains were found. Breeding success of birds in the enclosure was relatively high, with 90% of eggs hatched and 51% of chicks fledged (1.6 chicks/pair). Conclusions: Relying on terrestrial food is feasible when sources are available in the vicinity of the colony. We conclude that Lesser Black-backed Gulls could theoretically shift towards inland breeding after a fishery discards ban.

Random effect of the tracked gull individuals for model 18 in Table 1 (.pdf). (PDF 134 kb)