IngentaConnect Survival of sharp-tailed grouse Tympanuchus phasianellus chicks a...

Authors: Manzer, Douglas L.; Hannon, Susan J.

Source: Wildlife Biology, Volume 14, Number 1, March 2008 , pp. 16-25(10)

Publisher: Nordic Board for Wildlife Research

Abstract:

We studied survival and probable causes of mortality for plains sharp-tailed grouse Tympanuchus phasianellus jamesi chicks up to 30 days of age, and for hens during the reproductive period in Alberta, Canada, during 1999-2001. We used the Kaplan-Meier function for estimating survival for > 1 radio-marked chick in the same brood and a bootstrapping technique to calculate standard errors while accounting for censored data. Chick survival was 47% over two years (95% CI: 29-64%) with 81% of mortalities occurring during the first 15 days. Predation accounted for 72% of chick mortalities with mammals taking the largest portion. Chick survival was similar when compared between landscapes with < 35% vs ≥ 35% crop and sparsely covered grassland (8 km²). Hen survival was 53% (95% CI: 44-63%) during the reproductive period over three years. Most hen mortalities were from predation (96%), with mammals accounting for the largest portion followed by raptors. Hen survival was similar in landscapes (8 km² with < 35% crop and sparsely covered grasslands compared with those in areas with ≥ 35%. Our study helps clarify values of two critical vital rates, i.e. early chick survival and hen survival over the reproductive period.

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Survival of sharp-tailed grouse Tympanuchus phasianellus chicks and hens in a fragmented prairie landscape