Research Article
Effect of TrappingMethod on Leukocyte Profiles of
Black-Chested Spiny-Tailed Iguanas (Ctenosaura melanosterna ):
Implications for Zoologists in the Field
Andrew K. Davis,1 Leslie E. Ruyle,1, 2 and John C.Maerz3

1Odum School of Ecology, The University of Georgia, Athens, GA 30602, USA
2Applied Biodiversity Science NSF-IGERT Program, Texas A&M University, College Station, TX 77843, USA
3D.B. Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, GA 30602, USA
Correspondence should be addressed to Andrew K. Davis, akdavis@uga.edu
Received 23 June 2011; Accepted 14 July 2011
Academic Editors: A. Ramirez-Bautista and V. Tilgar
Copyright © 2011 Andrew K. Davis et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.

When wild animals are captured for zoological research, researchers must choose a method of capture, and often this can be some
form of passive, baited cage trap, or a direct capture with nets or nooses. If information on basal levels of circulating leukocytes is
a goal, these two methods may provide different information, since recent evidence indicates that animals that enter cage traps
experience stress, and, elevated stress hormones are known to alter leukocyte numbers in circulation by lowering lymphocyte and
raising heterophil numbers. We tested this idea using a study of Black-chested Spiny-tailed iguanas (Ctenosaura melanosterna),
which were captured using cage traps (n = 23) and noose (n = 27). Based on cell counts made from blood smears, iguanas caught
with cage traps had significantly greater relative and absolute numbers of heterophils and higher heterophil-lymphocyte (H-L)
ratios than those captured by noose. Cage-trapped animals also had a nonsignificant reduction in lymphocyte numbers. Similar
trends were observed in animals captured with both methods. These patterns are consistent with the effects of stress hormones on
white blood cell distributions and indicate that caution must be taken in interpreting leukocyte data from studies of wild animals
captured with cage traps.