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- Title
Importance of Habitat Quality and Landscape Connectivity for the Persistence of Endangered Natterjack Toads.
- Authors
STEVENS, VIRGINIE M.; BAGUETTE, MICHEL
- Abstract
The natterjack toad ( ) is endangered in several parts of its distribution, including Belgium, where it occurs mainly in artificial habitats. We parameterized a general model for natterjack population viability analysis (PVA) and tested its sensitivity to changes in the values of basic parameters. Then we assessed the relative efficiency of various conservation measures in 2 situations: a small isolated population and a system of 4 populations connected by rare dispersal movements. We based the population viability analysis on a stage-structured model of natterjack population dynamics. We parameterized the model in the RAMAS GIS platform with vital rates obtained from our own field experience and from published studies. Simulated natterjack populations were highly sensitive to habitat quality (particularly pond drying), to dispersal from surrounding local populations, and to a lesser extent to values of fecundity and survival of terrestrial stages. Population trajectories were nearly insensitive to initial abundances, carrying capacities, and the frequency of extreme climatic conditions. The simulations showed that in habitats with highly ephemeral ponds, where premetamorphosis mortality was high, natterjack populations nearly always had a very high extinction risk. We also illustrated how low dispersal rates (<1 dispersing individual/generation) efficiently rescued declining local populations. Such source-sink dynamics demonstrate that the identification and management of source populations should be a high priority.
- Subjects
NATTERJACK toad; ENDANGERED species; POPULATION viability analysis; SIMULATION methods &; models; PARAMETERS (Statistics); POPULATION dynamics; ANIMAL dispersal; GEOGRAPHIC information systems; ECOLOGICAL carrying capacity; BIOLOGICAL extinction &; the environment
- Publication
Conservation Biology, 2008, Vol 22, Issue 5, p1194
- ISSN
0888-8892
- Publication type
Article
- DOI
10.1111/j.1523-1739.2008.00990.x