reproductive success, family size, home range size, patterns of association with conspecifics, and even parasite load (Boydston and others 2003; Engh and others 2003; Holekamp and others 1996, 1997a).

Most scientists work on animals in the laboratory rather than in the wild precisely to minimize the kind of variation I have described herein. Then why worry about it? My response is that naturally occurring variation is important to those regulating laboratory animal care because this variation suggests that even for a single species there is often likely to be an entire range of conditions under which the species will thrive in the laboratory.

In summary, classical ethology and modern behavioral ecology have taught us that every animal comes into the laboratory with an evolutionary past and a set of traits shaped by natural selection. These include an Umwelt, a normal repertoire of behaviors, and an ability to survive and reproduce under a range of conditions. These traits should factor into our decision making about laboratory animal care guidelines. Given the diversity of conditions under which most species exist in nature, it seems reasonable to expect that a heterogeneous array of husbandry conditions can be utilized in the laboratory without compromising our ability to maintain a homogeneous set of ethical standards for the treatment of these animals.

REFERENCES

Boydston, E.E., Morelli, T.L., Holekamp, K.E. 2001. Sex differences in territorial behavior exhibited by the spotted hyena (Crocuta crocuta). Ethology 107:369-385.

Boydston, E.E., Kapheim, K.M., Szykman, M., Holekamp, K.E. 2003. Individual variation in space utilization by female spotted hyenas (Crocuta crocuta). J Mamm 84:1006-1018.

Bronson, F.H. 1989. Mammalian Reproductive Biology. Chicago: University of Chicago Press.


Cooper, S.M., Holekamp, K.E., Smale, L. 1999. A seasonal feast: Long-term analysis of feeding behavior in the spotted hyaena Crocuta crocuta (Erxleben). Afr J Ecol 37:149-160.


Engh, A.L., Nelson, K.G., Peebles, C.R., Hernandez, A.D., Hubbard, K.K., Holekamp. K.E. 2003. A coprological survey of the parasites of spotted hyaenas (Crocuta crocuta) in the Masai Mara National Reserve, Kenya. J Wildl Dis 39:224-227.


Hofer, H., and East, M.L. 1993a. The commuting system of Serengeti spotted hyaenas: How a predator copes with migratory prey. I. Social organization. Anim Behav 46:547-557.

Hofer, H., and East, M.L. 1993b. The commuting system of Serengeti spotted hyaenas: How a predator copes with migratory prey. II. intrusion pressure and intruders’ space use. Anim Behav 46:559-574.

Hofer, H., and East, M.L. 1993c. The commuting system of Serengeti spotted hyaenas: How a predator copes with migratory prey. III. Attendance and maternal care. Anim Behav 46:575-589.

Hofer, H., and East, M.L. 1995. Population dynamics, population size, and the commuting system of Serengeti spotted hyaenas. In: A.R.E. Sinclair and P. Arcese, eds. Serengeti II: Dynamics, Management, and Conservation of an Ecosystem. Chicago: University of Chicago Press. p. 332-363.



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