2009-02-26_REPORT - C1994082 (15)

Home Browse Search

• northwestern Colorado, yet supported 23% of the active leks observed in 2007 (Yost 2007). Within the Yoast survey area, four of the six known lek sites occur on CRP lands. As most grouse observed at leks are males, the peak male counts and overall trend in attendance correlates with the total number of grouse. From 1993 to 2007, the total number of grouse observed during lek counts within the Yoast Mine survey area has ranged from 25 (in 2004) to 92 (in 2000) individuals. However, in 2008, ICF Jones & Stokes biologists recorded only 21 total individuals at the six previously documented sharp-tailed grouse leks within the Yoast Mine survey area (including the Trousdale alternate lek location). Early spring conditions in 2008 were particularly harsh (i.e., substantial snow cover remaining from record precipitation during the winter and inclement weather that continued into June) and may have contributed to the low counts during survey dates in April and early May, but a decline in male attendance at several of the leks (specifically, the Annan's 20-mile 2, Annan's 20-mile 3, and Yoast Mine Road leks) has also been documented in recent years. Despite recent declines and a particularly low count in 2008, an average of 52 sharp-tailed grouse per year has been recorded within the Yoast Mine • survey area between 1993 and 2008. In approximately half of the previous 14 survey years, the Annan's 20-mile 2 lek has hosted higher male attendance than all other leks surveyed (Table 1). Within the past five years however, male numbers have dropped dramatically. Peak male attendance at that lek was fairly consistent from 1993 to 1997 and 2002 to 2003 (ranging from 15 to 20 males each spring) and highest between 1998 and 2001 (at least 35 males present in 1999). Since 2001, gradual declines in attendance have been observed by ICF Jones & Stokes biologists, and a particularly sharp drop was recorded in 2004. For the second consecutive year, no displaying males were present at the Annan's 20-mile 2 lek, as no grouse were observed in 2008 and only two non-displaying males were recorded in 2007. The factors contributing to these declines are unknown. The lek is situated in a moderately dense sagebrush stand, ranging from 10 to 19 inches in height and is within 0.65 mile of the next closest known lek site. Peak male attendance at Annan's 20-mile 1 lek has varied over the years, with high counts of 19 • males and 20 males in 1997 and 2003, respectively. Prior to 2008, the lowest male count at the 2008 Yoast Mine Wildlife Monitoring Page 4