Evaluating greater sage-grouse brood habitat using human-imprinted chicks

2004 Spring.Includes bibliographic references (pages 76-80).Greater sage-grouse ( Centrocercus urophasianus) populations are experiencing long-term declines throughout their current range. Several researchers have suggested that the quality and availability of brood habitat may be limiting populations through reductions in the recruitment of young. In order to effectively manage brood areas, reliable information is needed on chick resource requirements and the role of various components of the habitat in chick growth, development and survival. Forb abundance has been identified by several studies as an indicator of brood habitat quality, but no studies have quantified the direct effects of forb abundance on sage-grouse chicks. A promising method for conducting such studies involves using human-imprinted sage-grouse chicks in field experiments. In 2002 and 2003, I conducted field experiments in Middle Park and Moffat County, Colorado, respectively. The objectives of these studies were (1) to develop and evaluate methods for acquiring human-imprinted sage-grouse chicks and using them in field experiments; and (2) to quantify the effects of 3 levels of forb abundance (i.e., 20%) in brood habitat on the growth of these chicks. The egg acquisition, incubation, imprinting, and field exposure methods used resulted in human-imprinted sage-grouse chicks that were successfully used in field experiments. These studies showed that using human-imprinted sage-grouse chicks in field experiments is, potentially, a very informative approach to investigating a variety of grouse-habitat relationships. In 2002, there was no evidence that forb abundance in the exposure areas had an effect on the rate of mass gain or feather growth. However, in 2003, the mass gain and feather growth rate of chicks increased with increasing forb abundance. Previous studies have shown a correlation between chick mass and long-term survival. Management actions that increase forb abundance in brood areas with < 20% forb abundance may, therefore, lead to increased chick survival and sage-grouse productivity