Literaturdatenbank
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Pappas, M. J., Congdon, J. D., & Brecke, B. J. , Orientation of five species of naïve river turtles (graptemys and apalone) dispersing from experimental nests. Paper presented at Turtle Survival Alliance 2006 Annual Meeting.
Added by: Admin (13 Dec 2008 22:23:50 UTC) Last edited by: Beate Pfau (02 Aug 2009 16:36:50 UTC) |
| Resource type: Proceedings Article BibTeX citation key: Pappas2006a View all bibliographic details  |
Categories: General Keywords: Apalone, Apalone mutica, Apalone spinifera, Emydidae, Graptemys, Graptemys geographica, Graptemys ouachitensis, Graptemys pseudogeographica, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Trionychidae, Zeitigung = incubation Creators: Brecke, Congdon, Pappas Collection: Turtle Survival Alliance 2006 Annual Meeting |
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| Abstract |
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Three circular arenas (diameter = 70 - 90 m) were constructed in different areas within natural turtle nesting habitat. Three species of naïve Map turtles (Graptemys geographica, n = 175; Graptemys pseudogeographica, n = 194; and Graptemys ouachitensis, n = 107) and two species of Softshell turtles (Apalone spinifera, n = 117; and Apalone mutica, n = 75) were released in orientation arenas to: 1) test the null hypothesis that the direction of hatchling dispersal from nests is random, 2) test the working geotaxis hypothesis (hatchlings go down hill), 3) compare inter-specific and inter-family patterns of hatchling dispersal at different locations for relationships to environmental cues (horizons, olfaction and humidity). For all releases and under all conditions, hatchling dispersal was not random, or consistent with the “go down hill” rule. There was no evidence of olfaction or humidity cues impacting dispersal patterns of Map turtles. The West Newton Beach arena was close to water and provided an opportunity for olfaction to influence dispersal; however, a sub-group of Softshells treated with Zinc Sulfate in their nares (n = 46), dispersed in the same direction as the untreated groups. There was no evidence of inter-specific differences in hatchling dispersal patterns of Graptemys spp. and Apalone spp., but inter-family dispersal patterns were significantly different. Hatchling Map turtles oriented toward dark or closed horizons and away from open, illuminated horizons (usually, the river proper). In contrast, hatchling Softshell turtles oriented toward more intensely illuminated and open horizions (the Mississippi River in the case of WNB arena) and away from dark or closed horizons. When Softshell hatchlings reached the river edge, they immediately buried in the sand. Hatchling Map turtles move away from the river initially, perhaps because they have not yet developed the motor skills for swimming in the fast current, and also lack the cryptic coloration to avoid the predators of the sandy-shored river.
Added by: Admin Last edited by: Beate Pfau |