Prey-mediated effects of drought on condition and survival of a terrestrial snake

Jinelle H. Sperry, Patrick J. Weatherhead

Research output: Contribution to journalArticlepeer-review


Drought can have severe ecological effects and global climate-change theory predicts that droughts are likely to increase in frequency and severity. Therefore, it is important that we broaden our understanding of how drought affects not only individual species, but also multitrophic interactions. Here we document vegetation and small-mammal abundance and associated patterns of Texas ratsnake (Elaphe ohsoleta) body condition and survival before, during, and after a drought in central Texas, USA. Vegetation (grass and forbs) height and small-mammal capture rates were two times greater in wet years compared to the drought year. The decline of small mammals (the snakes' principal prey) during the drought was associated with a drop in ratsnake body condition, consistent with reduced food intake. During the drought, snake mortality also increased 24%. Although higher snake mortality was attributable to predation and road mortality rather than being a direct result of starvation, an increase in risk-prone behavior by foraging snakes probably increased their exposure to those other mortality factors. Drought conditions lasted only for 21 months, and vegetation, small-mammal abundance, and snake condition had returned to pre-drought levels within a year. Although estimates of snake population size were not available, it is likely that substantially more than a year was required for the population to return to its previous size.

Original languageEnglish (US)
Pages (from-to)2770-2776
Number of pages7
Issue number10
StatePublished - Oct 2008


  • Drought effects on species and their interactions
  • Elaphe obsolcta
  • Multitrophic interactions
  • Predator-prey system
  • Small-mammal abundance
  • Snake
  • Survival

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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