PARENT SESSION
Contributed Oral Session 70: Avian Ecology: Habitat; Human Impact
Tuesday, August 9, 1:30 PM - 5:00 PM, Meeting Room 524 A, Level 5, Palais des congrès de Montréal
Do increasing human activities affect resource use and spatio-temporal distribution of wintering Brent geese (Branta bernicla)?
Desmonts, Diane*,1, Thomas, De Cornouiller1, Mahéo, Roger2, Fritz, Hervé1, 1 CNRS CEBC, Beauvoir-sur-Niort, France2 ODEM, Vannes, France
ABSTRACT- The Golfe du Morbihan is a major wintering area for Brent geese in France, where they feed primarily on eelgrass beds (Zostera spp). During the last thirty years, goose abundance and distribution seem to have changed dramatically, with a simultaneous change and overall development in human activities (recreational and professional). This led to local tensions between developing human activities and nature conservation organisations, and required some closer investigations on the mechanisms relating geese numbers and distribution and human activities. From 1970 to 2000, different periods have been distinguished based on the history of shellfish farming/harvesting, and additional variables, indicators of human presence and possible disturbance, have been built using a G.I.S. (e.g. distance to the shore, zostera bed fragmentation, etc.). Based on the optimal foraging theory framework and using model selection in mixed-effects models, we analysed the interaction between the areas of zostera beds and the aggregative response of geese, using environmental variables associated with human activities to test for a possible role of the changes in human practices. Resource surface was the key factor explaining the geese distribution, but variables reflecting the increase in human activities had also a significant effect. Although the spatial distribution changed a lot, the overall number of Brent days did not show any particular trend in the last 30 years. These results show the importance of evaluating the extent to which human can modify predator-prey relations, but also point out the need for rigorous analyses of data when taking management and conservation decisions.
Key words: aggregative-response, geese, zostera, disturbance