Literaturdatenbank
Literaturdatenbank |
|
 |
|
Litzgus, J. D. , Long-term study reveals decline in a spotted turtle (clemmys guttata) population in a relatively pristine environment - abstract. Unpublished paper presented at Program and Abstracts of the Tenth Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles.
Added by: Admin (06 Jan 2014 18:22:56 UTC) |
| Resource type: Conference Paper BibTeX citation key: anon2012.14556 View all bibliographic details  |
Categories: General Keywords: Clemmys guttata, Emydidae, Habitat - habitat, Nordamerika - North America, Schildkröten - turtles + tortoises Creators: Litzgus Collection: Program and Abstracts of the Tenth Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles |
Views: 2/448
Views index: 11% Popularity index: 2.75% |
| Abstract |
|
Long-term data are essential for elucidating patterns in population parameters for long-lived species and are invaluable for monitoring species at risk. A Spotted Turtle (Clemmys guttata) metapopulation in central Ontario, Canada, has been studied using mark-recapture surveys since 1977 (36 years), including two radio telemetry studies (1993-95 and 2005-06). A total of 222 turtles (93 females, 101 males, 25 juveniles, 2 hatchlings, 1 unknown sex) have been marked and 11 turtles are known to have died over the course of the study. The study site is relatively pristine with no roads or human dwellings, although it is surrounded by cottages, camps and boat traffic, and these human impacts have recently increased. Spring survey data indicate an acute reduction in population size between 1999 and 2000. Despite no changes in search effort, the number of turtles captured during spring surveys has declined to approximately half of former numbers (from ~33 to ~17). There has been no apparent recovery as the number of turtles captured during spring surveys has remained consistent and low for the past 10 years. There are at least three possible hypotheses to explain the decline: 1. a localized poaching event; 2. a localized mass mortality event (e.g., during hibernation); or 3. a sudden habitat change that caused dispersal. In support of the poaching hypothesis, turtles that remain are damaged and injured; poachers would likely collect the most attractive animals. In support of the over-winter mortality event hypothesis, the missing turtles historically tended to hibernate in one complex, subjecting them all to the same environmental threat. In support of the sudden habitat change hypothesis, in 2000, beaver occupied and flooded the main deme and the number of turtles captured in that site has declined from ~10 to zero; however, most of these turtles have not been found in other demes suggesting that emigration was not successful. Additional observational evidence in support and evidence to refute each hypothesis will be presented, and the implications for conservation of this federally endangered species will be discussed.
Added by: Admin |