Natural Resources, School of

 

Date of this Version

2011

Citation

Ecology, Conservation, and Management of Grouse, Berkeley and Los Angeles: University of California Press, 2011

Abstract

Chick survival during the first three weeks of life is a critical stage in the demography of Greater Prairie-Chickens (Tympanuchus cupido), but little information is available. Biologists often estimate brood success using periodic flushes of radio-marked females, but it is impossible to determine mortality factors if chicks are not radio-marked. We used sutures to attach 0.5-g transmitters to 1- to 2-day-old chicks in Johnson County, Nebraska, during 2008. Our objectives were to (1) assess causes of mortality of 0- to 21-day-old chicks, (2) estimate daily survival probability for 0- to 21-day-old chicks, and (3) evaluate the effect of applying transmitters with suture attachment to chicks. We monitored a total of 221 prairie chicken chicks from 20 broods. We radio-marked 27 chicks from 10 broods of radio-marked females (one to five chicks per brood). The chicks were located twice per day to ensure that they were within a 10-m radius of the female. Our limited sample showed a weak effect of radio-marking on the survival of prairie chicken chicks (β= –0.54; SE= 0.33). Forty-two (19%; 95% CI: ±5%) of the 221 chicks in our sample survived to day 21, confirming low rates of productivity observed in hunter wing surveys and brood flushes of radio-marked females in a concurrent study. All radio-marked chicks in our sample died (13% exposure; 87% predators) before 21 days of age. Survival of chicks increased with age, and survival decreased during periods with high precipitation. Daily and 21-day survival rate estimates for all chicks in our sample were 0.926 (95% CI: 0.915–0.937) and 0.193 (95% CI; 0.155–0.255), respectively. Predation appeared to be the most critical factor for chick survival, so management of landscapes to reduce risk from predators may have a positive effect on Greater Prairie-Chicken populations.