Sedgwick Reserve

30 Jun, 11 PM - 30 Jun, 11 AM

This project will explore the implications of an ontogenetic change in diet on the foraging strategies used by adult and juvenile Southern Pacific rattlesnakes (Crotalus viridis helleri). Ontogeny refers to development, so an ontogenetic shift in diet means that there is a change in diet at some stage in an organisms development to adulthood. Mackessy (1985) showed that in Santa Barbara County adult C. viridis prey on rodents exclusively whereas juvenile include a large proportion of lizards in their diet. To test if prey type and snake size correlates with foraging behaviors, individual snakes will be studied in semi-naturalistic foraging arenas. These arenas, described below, will enable us to manipulate chemosensory prey cues in a controlled environment and study the response of three size classes of C. viridis, neonates, juveniles, and adults. To determine whether or not neonates have an innate preference for lizard prey three groups of snakes determined by their sizes (neonates, juveniles, and adults) will be presented with three different chemosensory prey cues. The cues that will be tested are rodent scent, lizard scent, and a control. In this experiment, snakes will be introduced into an indoor semi-naturalistic arena at U.C. Santa Barbara. The arena is shaped as an equilateral triangle with each side measuring 1.5 m long and 1 m high. Each corner of the arena will be scented with either rodent, lizard, or control cues in the form of bedding from rodent cages, lizard cages, and fresh, clean bedding for the control. At the beginning of each trial, an individual snake will be placed in the center of the arena. The behavior and location of the snake in the arena will then be recorded for three hours with an 8mm video camera. The snake's behaviors and locations will later be quantified to determine if there were differences in the amount of time each snake spent in each corner of the arena and whether these differences correlate to size class. To achieve statistical rigor in this experiment at least 20 snakes in each size class need to be studied in the arena. These groups are based on the size classes of snakes reported in Mackessy (1985). Neonates are defined as 0 to 325mm snout-vent length, juveniles as 326 to 500mm, and adults as 500mm and above. Snakes have been collected from the U.C. Sedgwick Ranch Reserve in the past and I would like to continue using the reserve as a source for study animals. It is difficult to meet the number requirements of this experiment with only one area in which to collect so additionaly locations throughout the county are searched. There are no specific areas on the reserve where searches for rattlesnakes are focussed. All snakes are released at the point of capture immediately after being used in the foraging arenas.

Visit #2201 @Sedgwick Reserve

Approved

Under Project # 1762 | Research

Ontogeny of foraging behavior in the Southern Pacific Rattlesnake

graduate_student - University of California, Santa Barbara

Reservation Members(s)

John LaBonte Jun 30, 2003 - Jun 30, 2004 (367 days)
John LaBonte Jun 30, 2003 - Jun 30, 2004 (367 days)

Reserve Resources(s) | Create Invoice

Day Use Only 2 Jun 30, 2003 - Jun 30, 2004