Habitat fragmentation effects on annual survival of the federally protected eastern indigo snake

Animal Conservation
By: , and 



The eastern indigo snake (Drymarchon couperi) is a federally listed species, most recently threatened by habitat loss and habitat degradation. In an effort to estimate snake survival, a total of 103 individuals (59 males, 44 females) were followed using radio-tracking from January 1998 to March 2004 in three landscape types that had increasing levels of habitat fragmentation: (1) conservation cores; (2) conservation areas along highways; (3) suburbs. Because of a large number of radio-tracking locations underground for which the state of snakes (i.e. alive or dead) could not be assessed, we employed a multistate approach to model snake apparent survival and encounter probability of live and dead snakes. We predicted that male snakes in suburbs would have the lowest annual survival. We found a transmitter implantation effect on snake encounter probability, as snakes implanted on a given occasion had a lower encounter probability on the next visit compared with snakes not implanted on the previous occasion. Our results indicated that adult eastern indigo snakes have relatively high survival in conservation core areas, but greatly reduced survival in conservation areas along highways and in suburbs. These findings indicate that habitat fragmentation is likely to be the critical factor for species' persistence.
Publication type Article
Publication Subtype Journal Article
Title Habitat fragmentation effects on annual survival of the federally protected eastern indigo snake
Series title Animal Conservation
DOI 10.1111/j.1469-1795.2012.00524.x
Volume 15
Issue 4
Year Published 2012
Language English
Publisher Wiley
Publisher location Hoboken, NJ
Contributing office(s) Patuxent Wildlife Research Center
Description 8 p.
First page 361
Last page 368
Country United States
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