“…Control males foraged more and engaged in fewer agonistic behaviors but, in this study, the degree to which this affected the ability of males to acquire mates was not significant. If the lower cell numbers reflect an important reduction in immune capacity then males may be making a trade-off during breeding, favoring reproductive effort over survival, as has been proposed for a variety of animals (Boonstra and Boag, 1992;Boonstra et al, 2001b;Bradley, 1987;Deerenberg et al, 1997;Festa-Bianchet, 1989;Gustafsson et al, 1994;Nordling et al, 1998;Sheldon and Verhulst, 1996). The extent to which the low leucocyte counts in breeding male Belding's ground squirrels reflect impaired immune function to the kind of injuries that males face during breeding and how this affects survival or future reproductive success await additional work.…”