Foraging patch selection by Snail Kites in response to vegetation structure and prey abundance and availability

The role of food abundance and vegetation structure in selection of foraging habitat by the Snail Kite (Rostrhamus sociabilis) was explored. Selection of available foraging patches of either dense or sparse habitat structure within two prairie habitat types used extensively by foraging kites, Eleocharis flats and Panicum flats were examined. Estimated Apple Snail (Pomacea paludosa) densities on our study site ranged from 0.33 to 1.58 per m(2). Vegetation structure (sparse vs. dense) of the habitat type had a greater influence on where prey was captured than did site, the dominant emergent vegetation, or prey abundance. These results are consistent with previous suggestions that dense vegetation may obscure prey and limit or preclude use of densely vegetated habitats by foraging kites. This may be true, even when prey is in relatively high abundance, and may indicate the difference between prey abundance and availability. Most water management recommendations related to the Snail Kite call for prolonged inundation, based on an explicit assumption that this results in increased Apple Snail abundance. Even when directed at a single species such as the Snail Kite, water management may need to be considered in a more holistic framework that considers factors that influence the resulting vegetation communities, rather than just production of Apple Snails.