USGS - science for a changing world

Southeast Ecological Science Center

Our current research direction constitutes a collaboration between USGS and the University of West Florida.

It is focused on the habitat selection and associations of apple snails, snail kites, and limpkins. The logic and details of this collaboration are discussed below.

The Florida Apple Snail Habitat Complex graphic image

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A cooperative study with:

Why the focus on habitat?

There are several reasons why we are directing our current research on habitat.

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First, there has been considerable research already completed on the basic life history and demography of snail kites and apple snails.  Although there are certainly still gaps in our knowledge, we felt that the habitat associations among apple snails, snail kites, and limpkins constitutes a bigger gap in our knowledge.

Habitat is also the aspect of biology for which management is likely to have the most direct impact.  Although understanding vital demographic rates (e.g., survival, reproduction, immigration, and emigration) is essential to understanding population dynamics, it is typically through management of habitat that we have an influence on those vital rates.  For example, it is very difficult to affect the survival of a species such as snail kites directly.  Rather, if we wanted to increase survival, it would most likely be through providing high quality habitat.

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There also exists a number of models related to vegetation communities, hydrology, snail kite population dynamics, etc..  However, most of these models to date act as independent units. It is our hope and intention that our work on the apple snail habitat complex will provide the information necessary to link many of these currently independent models.

Our Objectives:

There are several components of our objectives, which cumulatively will fit together at several scales.  The first relates to apple snails and their environment. At a broad scale, one objective is to determine the association between apple snail densities and particular plant community types (e.g., wet prairie or aquatic slough).

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Within a given pant community type (e.g., wet prairie), we are trying to determine whether apple snail densities are associated with specific plant species or groups (e.g., periphyton). Such plants may be important as a food resource.

Alternatively, there may be particular attributes of the habitat structure that are important. For example, during the reproductive season snails may need emergent vegetation that will support their weight outside of the water, where they lay their eggs.  At all times of the year, apple snails may require plants that will enable them to climb to the water surface to breathe (see apple snail page).

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In addition to the plant attributes themselves, we will also investigate the regime under which they occur, particularly with respect to hydrology. Thus, a substantial part of our effort will be trying to distinguish among the effects of hydrology, plant species, and structure, all of which are correlated among themselves. 

Another aspect of this project will be to simultaneously investigate the habitat selection by snail-eating birds (e.g., Snail Kites and Limpkins). For this aspect of the project, we will focus on foraging habitat characteristics. As with the apple snails, we will examine the plant species, structure, and hydrologic regime of the foraging habitats, but for this phase of the project, the abundance and availability of apple snails become part of the habitat since they are the food for these birds.

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For additional information contact:

Robert E. Bennetts, PhD
National Park Service


Phil Darby, Ph.D.
Department of Biology
University of West Florida
11000 University Parkway
Pensacola, FL  32514-5754



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