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Gopher Tortoise Demographic Responses to a Novel Disturbance Regime
Author(s) -
Howell Hunter J.,
Rothermel Betsie B.,
White K. Nicole,
Searcy Christopher A.
Publication year - 2020
Publication title -
the journal of wildlife management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.94
H-Index - 111
eISSN - 1937-2817
pISSN - 0022-541X
DOI - 10.1002/jwmg.21774
Subject(s) - ruderal species , sandhill , ecology , geography , survivorship curve , habitat , population , biology , demography , sociology
The long‐term viability of gopher tortoise ( Gopherus polyphemus ) populations is jeopardized by increased urbanization and habitat degradation owing to fire suppression. Because the species' remaining natural habitats in the southeastern United States exist within a mosaic of anthropogenic land uses, it is important to understand demographic responses to contrasting land uses and habitat management regimes. We examined differences in demographic parameters among fire‐suppressed sandhill, restored sandhill, and former sandhill (i.e., ruderal) land use‐land cover (LULC) types at Archbold Biological Station in south‐central Florida, USA. Using Program MARK, we estimated population size, and sex‐specific and LULC‐specific survivorship based on 6 years of mark‐recapture data. We also analyzed individual growth trajectories and clutch sizes to determine whether growth rates or reproductive output differed among LULC types. Tortoises in an open, ruderal field occurred at a higher density (7.79/ha) than in adjacent restored (1.43/ha) or fire‐suppressed (0.40/ha) sandhill. Despite this higher density, both adult survivorship and body size were significantly higher in the ruderal field. Furthermore, the larger female body size in the ruderal field likely contributed to increased annual survivorship and slightly larger average clutch sizes. We did not detect offsetting negative demographic effects; in particular, we did not find significant biological or statistical differences in body condition, asymptotic body size, or growth rate among the 3 LULC types. Our results suggest that anthropogenic, grass‐dominated land‐cover types may be important components of the habitat mosaic currently available to this at‐risk species. © 2019 The Wildlife Society.