Nesting and Reproductive Activities of Greater Sage-Grouse in a Declining Northern Fringe Population


Cameron L. Aldridge, and R. Mark Brigham


The Condor 103:537-543; 2001


In Canada, Greater Sage-Grouse (Centrocercus urophasianus) are at the northern
edge of their range, occurring only in southeastern Alberta and southwestern Saskatchewan.
The population in Canada has declined by 66% to 92% over the last 30 years. We
used radio-telemetry to follow 20 female Greater Sage-Grouse and monitor productivity in
southeastern Alberta, and to assess habitat use at nesting and brood-rearing locations. All
females attempted to nest. Mean clutch size (7.8 eggs per nest) was at the high end of the
normal range for sage-grouse (typically 6.6–8.2). Nest success (46%) and breeding success
(55%) were within the range found for more southerly populations (15% to 86% and 15%
to 70%, respectively). Thirty-six percent of unsuccessful females attempted to renest. Fledging
success was slightly lower than reported in other studies. Thus, reproductive effort does
not appear to be related to the population decline. However, chick survival to $50 days of
age (mean 5 18%) was only about half of that estimated (35%) for a stable or slightly
declining population, suggesting that chick survival may be the most important factor reducing
overall reproductive success and contributing to the decline of Greater Sage-Grouse
in Canada.