Literaturdatenbank
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Raeder, F. L., & Vogt, R. C. (2003). Non-manipulative procedure to predict podocnemis sextuberculata nest success: it doesn't work! Abstracts ASIH Meeting 2003.
Added by: Admin (14 Aug 2008 20:36:26 UTC) |
| Resource type: Journal Article BibTeX citation key: Raeder2003 View all bibliographic details  |
Categories: General Keywords: Habitat = habitat, Pelomedusidae, Podocnemididae, Podocnemis, Podocnemis expansa, Podocnemis sextuberculata, Podocnemis unifilis, Schildkröten = turtles + tortoises, Südamerika = South America, Zeitigung = incubation Creators: Raeder, Vogt Collection: Abstracts ASIH Meeting 2003 |
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| Abstract |
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In the region where today sits the Mamiraua Sustainable Development Reserve (MSDR), turtles have traditionally been exploited for food and derivates. Increase in local human population and modern fishing methods have led to decline in numbers of three species of Pelomedusidae turtles (Podocnemis sextuberculata, Podocnemis unifilis, and Podocnemis expansa) present in this white-water flooded forest "varzea" environment. To revert this situation, MSDR staff has been working with reserve residents to protect nesting sites used by these turtles from human predation to increase recruitment, enabling turtle populations a better recovery chance. Aiming to improve even more the recruitment rate, we have looked for clues in determining which nests have better chances of survival against natural causes of nest loss, mainly flash floods and animal predation, in order to orient villagers toward simple management procedures that do not depend on complex statistics or equipment. The site chosen was Horizonte Beach, Solimoes River (S 2° 44'33'', W 65° 13'43''). We only used data from P. sextuberculata since the other species nested in too few numbers. At the same day every nest was laid, we registered the distance the female walked from the water to nest site, depth to shallowest egg, and date. All these variables are easily obtained and non-manipulative of eggs, preventing disturbance of microclimate conditions inside nests chamber. Then these were related with nest success (number of eggs hatched/laid) and incubation period. Unfortunately, no significant relation was found, besides a negative relation between "date X incubation period" (P = 0.002) due to warmer sand as river level dropped. The main cause of nest loss was erosion at the highest portion of the beach, but there was no predation whatsoever on nests due to an extremely aggressive colony of Largebilled Terns (Phaetusa simplex) deterring away any animals...or people, that arrived at the beach.
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