GROWTH AND SURVIVAL OF MOUNTAIN PLOVERS

Growth and survival rates of Mountain Plovers (Charadrius montanus) we re monitored using radiotelemetry from hatching until birds left the b reeding grounds on the Pawnee National Grassland, Weld County, Colorad o. Chick weights increased logarithmically (r = 0.961) and tarsus leng th linearly (r = 0.948) with age. Using the average fledging weight of 69.8 g and an age/weight regression we predicted that the average age at fledging was 36 d. Fourteen Mountain Plover nests each had three e ggs; an average of 2.6 eggs hatched in seven nests, whereas remaining nests were lost to predation, storms, or trampling by a cow. Twenty-fo ur adult Mountain Plovers were monitored for 275 telemetry days with n o mortalities. Twenty flightless chicks had a calculated daily surviva l rate of 0.979 for 233 telemetry-days. Mortalities of flightless chic ks were due to predation or unknown causes. The daily survival rate pr edicted that 1.2 of the 2.6 chicks hatched per nest lived to fly. Eigh t fledged chicks were monitored for 74 telemetry-days, with a daily su rvival rate of 0.974. Mortalities of fledglings were all attributed to predation. The combined survival rates predicted that 0.7 of the 2.6 hatched chicks lived to leave the nesting area. Survival rates of flig htless chicks were similar to those reported 20 yr ago, implying that recent declines in Mountain Plover numbers on the continent are not at tributable to either longer-term declines in nesting productivity or p henomena occurring at non-breeding locales.