TAYLOR, E.N.*; MALAWY, M.; DENARDO, D.F; Arizona State University; Arizona State University; Arizona State University: Effects of food supplementation on the reproductive ecology of female Western Diamond-backed Rattlesnakes (Crotalus atrox)

The physiological processes of desert reptiles may be limited by the availability of food. For example, food availability may influence growth and reproductive output. We have conducted studies showing that adult female Western Diamond-backed Rattlesnakes (Crotalus atrox) in the Sonoran Desert of Arizona grow very little and reproduce infrequently. We hypothesized that the lack of growth and reproduction is due to low food availability. We tested this hypothesis by supplementing the diets of free-ranging snakes and observing the effects on their growth and reproductive output. Radiotelemetered snakes were designated either as �fed� or controls. Fed snakes were offered thawed mice as often as possible from May-October in 2002 and 2003. We examined whether fed snakes differed from control snakes in mass gain, growth, and reproductive output. Fed snakes gained more mass and grew faster than control snakes. This shows that female rattlesnakes are capable of growth as adults when food availability is increased. In the first year of the study, no control snakes reproduced and two fed snakes reproduced. In the second year of the study, one control snake reproduced and five fed snakes reproduced. The control snake that reproduced had two neonates while the fed snakes had a total of 34 neonates, providing evidence that increased food availability leads to increased reproductive output. Our results support the hypothesis that increased food availability leads to increased fecundity and growth rates in a desert reptile.