Abstract:

The morphology and parasite burdens of culled free-ranging red jungle fowl (Gallus gallus) from the San Diego Zoo were compared with those of captive roosters used previously in sexual selection experiments, to determine if results obtained with the captive birds were relevant to more natural situations. Zoo roosters had three helminth gut parasites: Ascaridia galli, tapeworms, and Heterakis. Parasite distribution was generally over-dispersed, with most individuals having none or few worms and some having heavy parasite burdens. These levels were comparable to those artificially induced in test roosters. The appearance of the zoo birds was similar to test roosters as well. Higher parasite burdens in the zoo birds was negatively related to hackle feather redness, comb length, and especially testis volume. The latter finding is discussed in light of information about the relationship between testosterone levels, sexual selection, and the immune system. A new analysis of female choice of uninfected controls versus experimentally infected roosters suggests that females prefer a multivariate array of traits perceived as a continuous, rather than categorical, variable.

Document Type: Research article

DOI: 10.1163/156853990X00149

Affiliations: 1: Department of Biology, University of California, Riverside, CA 92521 2: Department of Biology, University of New Mexico, Albuquerque, NM 87131, U.S.A.