Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)



Committee Chair(s)

Edmund D Brodie, Jr.


Edmund D Brodie, Jr.


Michael E. Pfrender


Karen H. Beard


S. K. Morgan Ernest


Edward W. Evans


Communication and recognition are closely intertwined and have been well documented in closely related species over the past several decades. These two types of behaviors often will aid in fostering or disrupting coexistence of similar species. Frequently, it is through different diet patterns that similar species will be able to coexist. This study uses data from 1972 through 2006 to demonstrate the diet of Thamnophis sirtalis, T. atratus, T. elegans, and T. couchii throughout their California range of sympatry with Taricha torosa. Additionally, an in depth examination of the diet of T. sirtalis, T. elegans, and T. atratus was conducted at the Santa Lucia Preserve (SLP) in Monterey County California. The results of both data sets indicate that when alone T. sirtalis and T. atratus consume primarily anurans as their main food source. However, when sympatric, T. atratus consumes prey such as earthworms and slugs. Thamnophis sirtalis and T. atratus consume Taricha torosa throughout their California range. The differences of sympatric and allopatric diet of T. sirtalis and T. atratus led to ask the question; are the snakes utilizing different microhabitats? This study demonstrates that T. sirtalis and T. atratus prefer the same habitat when alone. In opposition, when together, T. sirtalis will frequently (21 of 24 individuals) use aggression to manipulate the spatial occupation of T. atratus as well as the position of T. elegans at SLP. This behavior is not consistent throughout T. sirtalis, T. atratus, T. elegans, and T.couchii range in California and appears to be unique to the SLP.