. The Canadian field-naturalist. Natural history. 2003 Aldridge and Brigham: Greater Sage-Grouse 27 Saskatchewan, but today occupy only about 6000 km2 (Figure 1). The range contraction within Canada is primarily attributed to habitat loss. Population Size and Trends The most cost-effective and time-efficient method to estimate sage-grouse population size and trends is through lek counts. Lek counts involve counting the number of male sage-grouse displaying on a strutting ground during the spring mating season. The maxi- mum number of males observed at each lek is then used as an index of popul
. The Canadian field-naturalist. Natural history. 2003 Aldridge and Brigham: Greater Sage-Grouse 27 Saskatchewan, but today occupy only about 6000 km2 (Figure 1). The range contraction within Canada is primarily attributed to habitat loss. Population Size and Trends The most cost-effective and time-efficient method to estimate sage-grouse population size and trends is through lek counts. Lek counts involve counting the number of male sage-grouse displaying on a strutting ground during the spring mating season. The maxi- mum number of males observed at each lek is then used as an index of population status (Beck and Braun 1980; Emmons and Braun 1984). Lek counts are used as indicators of population trends and to make population estimates for many lekking species, including all monitored sage-grouse populations. Seasonal Lek Attendance Adult males begin returning to leks once the latter are clear of snow. This typically occurs in mid- March in Alberta (Aldridge 2000). Breeding occurs over a one- to two-week period, as indicated by the peak in female attendance at leks: late March to early April in California (Bradbury et al. 1989), mid- April in Colorado (Petersen 1980), early April in Idaho (Autenrieth 1981), mid- to late April in Montana (Wallestad 1975; Jenni and Hartzler 1978), late April in Washington (Schroeder 1997), and in early April in Alberta (Aldridge 2000). The peak in male attendance typically occurs two to three weeks after peak female attendance/breeding at leks (Jenni and Hartzler 1978) (Figure 2). In general, about 50% of male sage-grouse attend leks prior to the peak in female attendance (breeding) (Figure 2). Radiotelemetry studies indicate a later peak in male attendance is due to yearling males first joining the lek two to three weeks after the peak of female atten-. Dav of Peak Urn Mlrndanir Figure 2. Predicted lek attendance by male and female sage-grouse (adapted from Jenni and Hart/ler 1978). In Canada, peak female attendance usual l\ occurs
Size: 2080px × 1202px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectnaturalhistory, booky
