Age-specific variation in apparent survival rates of male Lesser Prairie-Chickens

We used mark-recapture methods to estimate age-specific apparent survival rates for male Lesser Prairie-Chickens (Tympanuchus pallidicinctus), a gamebird of conservation concern. A total of 311 male prairie-chickens (135 yearlings, 176 adults) were captured and banded during a 5-year study in southwest Kansas. Time-since-marking models were used to estimate apparent survival after first capture (phi(1)), apparent survival among returning birds (phi(2+)), and probability of capture (p) for yearling and adult prairie-chickens. Apparent survival is the product of true survival and site fidelity, and our model-averaged estimates of this parameter were ranked: yearlings after first capture ((phi) over cap (1)(yr) = 0.60 +/- 0.12) > adults after first capture ((phi) over cap (1)(ad) = 0.44 +/- 0.10) > returning birds ((phi) over cap (2+) = 0.36 +/- 0.10). In contrast, movement data showed that site fidelity to communal display sites (or leks) increased with male age; yearlings returned to leks at lower rates (80%, n = 60) than adults (92%, n = 65). Thus, true survival rates of male Lesser Prairie-Chickens likely decline with increasing age, an unusual pattern found in few species of birds. We hypothesized that declines in survival as males' age may be a feature of promiscuous mating systems where competition for mating opportunities are intense. A review of annual survival rates for holarctic grouse did not support this idea; age-specific declines in male survival were not restricted to lek-mating species, and appear to be a general feature of most grouse populations.