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ERIE Research Projects

Spatial dynamics of vernal poool amphibians

Participants:

ERIE Fellow: Mike Habberfield, Department of Geography
Faculty:Chris Larsen, Department of Geography
Research Partners/Collaborators: SUNY College of Environmental Science and Forestry, and the Upper Susquehanna Coalition

Summary:

Mike Habberfield has been working on a collaborative project with researchers at SUNY College of Environmental Science and Forestry. Since spring 2011 he has been conducting field work at ESF's Heiberg research forest where in 2010 dozens of vernal pool wetlands were constructed to investigate various questions regarding vernal pool restoration. Mike’s undertakings include a mark-recapture study and fine-scale tracking of habitat selection by vernal pool amphibians, aimed at understanding the spatial patterns of amphibian use of these landscapes.

Hexagonal array of thirty-nine constructed vernal pools in SUNY-ESF’s Heiberg research forest, central New York. Each hexagon is 9.2 hectares in size and contains a cluster of one, three, or nine pools.

The mark-recapture component seeks to examine movements between pools across multiple years. Wood frogs (Rana sylvatica) are captured at pools during the breeding season and marked for individual identification by subcutaneously injecting small fluorescent tags whose unique codes are read externally. Recaptures of marked animals allow for an individual-level movement history within the vernal pool complex which can inform spatial models of dispersal for this species.

Adult wood frog injected with a uniquely coded tag.

While green frogs (Rana clamitans) are not the target species of the restoration project, and indeed compete with the vernal pool obligate target species such as wood frogs, it is important to understand their use of the pool complex. Green frogs have colonized most pools in the landscape-scale plot but it is unclear if and how they select for terrestrial and aquatic habitat during dispersal. Movement parameters and habitat selection are being measured by tracking movements, using fluorescent powder, following experimental translocations of animals across the landscapes. Translocations are advantageous for investigating dispersal and habitat selection because they allow the researcher to standardize motivations for moving and choose the scale and type of landscape the animals will move across

Green frog with fluorescent dye powder used to track its movements. The powder trail is followed at night by illuminating it with ultraviolet light.

Pools are arranged in clusters of one, three, or nine, and at each density, translocations are implemented at three spatial scales: pool scale (=13 m), intra-cluster scale (=57 m), and inter-cluster scale (=344 m). Preliminary analysis of movement parameters (e.g. step lengths and turning angles) suggest that frogs may move differently when dispersing amongst pools at larger, metapopulation scales versus smaller-scale clusters of pools. Translocation scale may not, however, influence the selected pool’s spatial association with other pools. If scale influences movement parameters but not pool selection, the design of pool networks might benefit from considering species dispersal characteristics for how animals encounter pools, but specific design criteria for increasing or decreasing selection of pools in particular spatial settings may be difficult to obtain. This information can be taken into account when predicting colonization of constructed pool complexes and used to recommend pool spatial arrangements and associations with existing source populations.

Movement parameters such as step length and turn angle are measured from the recorded trail.

In conjunction with data collected by ESF researchers on colonization at the site by vernal pool obligate species (wood frogs and spotted salamanders), we hope to contribute to understanding more fully the overall spatial dynamics of amphibians using vernal pool complexes.

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