Captive rearing sage-grouse for augmentation of surrogate wild broods: Evidence for success

Abstract

Both species of North American sage‐grouse (Centrocercus spp.) have experienced declines in distribution and abundance. Translocation of adult birds from a stable population to a small or declining population has been a management tool used by wildlife managers to support population persistence in these areas. Captive rearing chicks and releasing them into wild surrogate broods is an untested alternative to augment declining populations of sage‐grouse. We developed techniques to successfully rear sage‐grouse chicks in captivity, evaluated explanatory variables that could influence hatch and captive‐rearing success, and estimated the survival of domestically hatched (DH) chicks to 28 days of age following introduction to a surrogate wild brood. We collected 304 eggs from radiomarked female greater sage‐grouse (C. urophasianus) during 2004–2007 in 3 study areas in northwestern Colorado. Estimated hatching success of collected eggs was 0.745 (SE = 0.022, 95% CI = 0.700–0.786) and was negatively influenced by the number of days an egg was stored and the percent egg weight loss that occurred during storage and incubation. We monitored 175 DH chicks in captivity for 1–10 days before introduction and adoption into surrogate wild broods. Model‐averaged captive‐rearing success was 0.792 (SE = 0.045, 95% CI = 0.686–0.865) across years, and was positively influenced by initial chick mass at hatch and daily weight gain in captivity but negatively influenced by the number of days the egg was stored and advancing hatch date. We were able to radiomark and monitor 133 DH chicks adopted into surrogate wild broods until 28 days of age. Eighty‐eight percent of DH chicks were successfully adopted within 24 hours. Our overall estimate of DH chick survival to 28 days (0.423; 95% CI = 0.257–0.587) was comparable to published wild‐hatched chick survival. Predation and exposure‐related deaths accounted for 26.3% and 25.6% of the known fates, respectively. Our captive‐rearing protocols and techniques were successful for collecting greater sage‐grouse eggs, hatching and rearing chicks in captivity, and releasing chicks into wild surrogate broods. This success further implies that captive rearing and release can be a potential management strategy to demographically and genetically reinforce or augment small populations of sage‐grouse. © 2015 The Wildlife Society.

Juvenile greater sage‐grouse survival, movements, and recruitment in Colorado

“…We found comparable patterns of survival between wild and domestically hatched juveniles into the fall and through brood break‐up. Our findings further support Thompson et al () who suggested that captive‐rearing techniques could be used to augment demographically challenged sage‐grouse populations (Apa and Wiechman , ), but the technique could be less successful in extreme environments (e.g., Cold Springs Mountain).…”

“…Wildlife managers need a better understanding of age‐specific demographic rates and how they are related to local and regional landscapes in relation to movement patterns, population levels, and habitat use to manage sage‐grouse. We further support recommendations by Thompson et al () that captive‐reared sage‐grouse can recruit to the population and that captive rearing could be used as a potential management strategy for demographically challenged sage‐grouse populations (Apa and Wiechman , ). Although demography research is expensive and logistically challenging, long‐term studies are needed to account for spatial and temporal variability.…”

“…Each year we placed approximately 3 ( = 3.0 ± 0.2, range = 1–8) domestically hatched 1–10‐day‐old ( = 3.9 ± 0.2) chicks into a subset of wild surrogate broods. Domestically hatched chicks were produced in a facility near Craig, Colorado (Thompson et al ). We randomly selected available successful wild females (i.e., with brood) for placement of domestically hatched chicks.…”

“…Thus, research investigating novel captive‐rearing techniques to augment small and declining sage‐grouse and Gunnison sage‐grouse ( C. minimus ; Thompson et al ; Apa and Wiechman , ) populations have been conducted. Specifically, Thompson et al () augmented wild‐reared sage‐grouse broods with domestically hatched chicks that were 1–10 days of age. They reported that chick survival ≤28 days was comparable between wild and domestically hatched chicks.…”

Declining recruitment of Gunnison Sage-Grouse highlights the need to monitor juvenile survival

“…However, there was little evidence for overdispersion in our juvenile survival analysis (ĉ ¼ 1.103). The lack of overdispersion in our juvenile data may in part have been due to brood mixing, which occurs at a relatively high rate within sage-grouse , Dahlgren et al 2010, Thompson et al 2015 and was observed in our study.…”