Habitat Selection, Movement, and Survival of Hatchling Wood Turtles (Glyptemys insculpta) in an Atypical Habitat
Date
2015-01-30
Authors
Dragon, Jeffrey
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Abstract
Hatchling turtles are the least understood life stage of North American turtles because they are cryptic and difficult to follow in their environment. Although few field studies have been conducted, data suggest that hatchling turtles have higher mortality rates than adults due to their smaller size, more potential predator species, and an increased vulnerability to fluctuating environmental conditions. Therefore, understanding the factors that influence survival in this critical life stage is a crucial step for turtle conservation. The North American wood turtle is considered endangered by the IUCN due to habitat loss, poaching for illegal trade, increased abundance of predators, and climate change. Nevertheless, little is known about the first two months post hatching in this species as few studies have examined hatchling behavior, and only one study has followed hatchling wood turtles from emergence until hibernation. This study site, at the southern end of the range, is unlike typical wood turtle habitat in that it lacks natural sand beaches along the stream; therefore it is probable that hatchling turtles emerge in habitats less conducive to survival. I used paired logistic regression to investigate whether hatchlings were selecting micro habitats during migration and once they reached the stream. I also investigated hatchling movement by looking at weather patterns and comparing the route the hatchling took to reach the stream. A Cox proportional hazards model was used to test a series of hypothesis about survival, and estimate the mortality rate for hatchling wood turtles. I found that hatchlings move in relatively straight directions along the contour of the landscape rather than the shortest path from the nest to the stream, and are more likely to migrate when the weather is overcast or raining, thus preventing desiccation. Once the hatchlings reached the stream they selected micro-habitats that offered lots of cover along the bank of the stream. Survival varied greatly by year, and was influenced by the nest patch the hatchling emerged from. Habitat surrounding the nest patches and at the stream is likely playing a role on survival. The results indicate that the interplay of weather, habitat and behavior all play important roles in the early stage survivorship of wood turtles.
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Keywords
Hatchling, Habitat selection, Wood Turtle, Movement, Survival