Literaturdatenbank
Literaturdatenbank |
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Dodd, C. , Habitat disturbances and florida box turtles: what to do when paradise changes? Unpublished paper presented at 6th World Congress of Herpetology.
Added by: Admin (21 Nov 2009 11:59:51 UTC) |
| Resource type: Conference Paper BibTeX citation key: Dodd2008b View all bibliographic details  |
Categories: General Keywords: Emydidae, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Terrapene, Terrapene carolina Creators: Dodd Collection: 6th World Congress of Herpetology |
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| Abstract |
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Terrapene carolina bauri is a terrestrial, sedentary omnivore with relatively low fecundity and high adult survivorship, delayed sexual maturity, low nest and hatchling survival, and long life span. From 1991-2006, I studied a population of T. c. bauri on Egmont Key in west-central Florida. The island was affected by tropical storms and a large-scale attempt to remove nonindigenous vegetation in 1995-1996. In order to assess the effects of habitat changes on turtles, I estimated survivorship, recruitment into the population, and population growth rates. Adult survival did not vary between sexes or among years, nor did survivorship vary between juveniles and adults. Furthermore, neither adult nor juvenile survival differed significantly from pre- to post-disturbances. However, dispersal rates varied among areas, and pre-disturbance dispersal rates were greater than post-disturbance. Strong recruitment occurred in the years following the disturbances, and population growth rates remained about the same as they were prior to the storms and vegetation changes. These results suggested few long-term demographic effects on the turtle population, at least for 6 years post-disturbances. Instead, box turtles moved to habitats mostly in the center of the island and minimally affected by the disturbances, where they remained. However, major changes occurred in individual growth rates. Adult male growth rates increased by 19% after the disturbances, whereas female growth rates decreased by a similar percentage. Juvenile growth rates briefly increased, but as these animals became subadults their growth slowed post-disturbance, a change more pronounced in females than males. After the disturbances, the onset of male sexual maturity decreased by ca 1 yr (from 10.8 to 9.5 years), female maturity was delayed by 2.5 years (from 8.5 to 11.0 years), and the subadult life stage was extended from 2 to 3.5 years. With resources and habitats similarly available to adults, adult females likely diverted resources from growth to reproduction, whereas males allocated resources to somatic growth. Subadult growth decreased regardless of sex, implying that fewer or lower quality prey were available to small turtles in the years following disturbance. Habitat disturbances affected individual growth rates according to sex and life stage, which in turn affected population structure (particularly sex ratio). Life history traits influence whether populations recover from habitat disturbances, and how long recovery will take. Stage-based effects, such as on individual growth, may help to explain why turtle populations recover slowly following catastrophic disturbance, even when adult survivorship is high.
Added by: Admin |