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During a 17-yr telemetry study, we examined the diet and ambush behavior of a population of Crotalus horridus in southeastern Virginia. Forty dietary items were identified from 37 fecal samples. We documented 722 instances of snakes in an ambush posture, 61% of which were in a vertical-tree posture, as if hunting arboreal prey at the base of a tree. The most common prey items were Eastern Gray Squirrels (Sciurus carolinensis), which accounted for 45% of all dietary items and represented an estimated 78% of total biomass consumed by C. horridus. Prey was not consumed in proportion to availability, based on small mammal surveys. Our analysis provides indirect evidence that the vertical-tree foraging behavior is adopted to target arboreal Eastern Gray Squirrels. Further, we provide support for the hypothesis that C. horridus alters ambush behavior to forage selectively for specific prey types.

The Timber Rattlesnake (Crotalus horridus) is beset by a variety of conservation problems, including habitat loss and persecution. Effective management plans require an understanding of rangewide population structure and intraspecific evolutionary subdivisions. Northern and southern populations have been recognized as distinct subspecies, but this classification remains controversial. A proposed alternative arrangement recognizes southern, northern, and western morphotypes. To resolve intraspecific partitions, we examined a 319 base-pair (bp) fragment of mtDNA cytochrome b in 123 specimens of C. horridus. Neighbor-joining and parsimony analyses reveal a shallow gene genealogy (dmax = 0.024) and sharing of haplotypes among putative subspecies. Analysis of molecular variance demonstrates that traditional subspecific divisions explain only 3.5% of variation, whereas the alternative geographic classification (southern, northern, and western regions) explains 18.6% of genetic variation. The superior p...