The Greater Sage-grouse: Life History, Distribution, Status and Conservation in Nevada. Governor s Stakeholder Update Meeting January 18 th, 2012

Transcription

1 The Greater Sage-grouse: Life History, Distribution, Status and Conservation in Nevada Governor s Stakeholder Update Meeting January 18 th, 2012

2 The Bird Largest grouse in North America and are dimorphic with males much larger than females ( kg males vs kg females) (Dalke et al. 1963, Eng 1963, beck and Braun 1978, Hupp and Braun 1991). Sagebrush obligate species. Sagebrush is a primary source of food for adults throughout the year (Wallestad et al. 1975); however, forbs and insects are consumed (Knowlton and Thorny 1942, Leach and Hensley 1954, Pyle 1993). Can display migratory movements between seasonal ranges. Populations can be characterized as resident, 2 stage, or 3 stage migratory. Fidelic to certain sites. Fidelity to breeding display sites (leks) has been well documented (Dalke et al. 1963, Wallestad and Schladweiler 1974, Emmons and Braun 1984, Dunn and Braun 1985, Schroeder and Robb 2004) and to their nesting areas with distance between nests in consecutive years averaging 0.7 km (range km) (Fischer et al. 1993, Schroeder and Robb 2004).

3 The Bird (cont.) Females lay clutch sizes that average 7.1 eggs with a range of 6-9 eggs; Likelihood of nesting averages 78.4%; Likelihood of re-nesting averages 30%; Average percent nest success is 52.1% Western portion of species range (after Schroeder et al 1999)

4 The Habitat Sage-grouse are a true landscape scale species requiring vast areas to carry out life history needs. On an annual basis, individuals can occupy areas from km2 (Hagen 1999, Connelly et al. 2000, Hausleitner 2003). Sage-grouse habitat is often partitioned into the following categories: Breeding : lek attendance, nesting and early brood rearing (Connelly et al 2000, Connelly et al 2003); Summer and Late Brood Rearing Habitat: Used during dessication of herbaceous vegetation in the sagebrush uplands (Klebenow and Gray 1968, Savage 1969, Fischer et al 1996) Fall: Transitional period, diet changes to sagebrush Winter: Diet is exclusively sagebrush. Site selection is influenced by snow depth and hardness, topography and vegetation height and cover (Gill 1965, Beck 1977, Connelly 1982, Schoenberg 1982, Robertson 1991, Schroeder et al. 1999).

5 The Lek A traditional display area where two or more male sage-grouse have attended in two or more of the previous five years (Connelly et al. 2003) Occur in relatively open areas on comparatively gentle terrain (Rogers 1964). Nisbet et al. (1983) developed a lek suitability model that included slope (<10%), precipitation (>25cm) and distance to nearest water source (<2km). Leks in Wyoming range in size from 0.25 to 16 ha (Scott 1942) Males display in the early morning and evening hours, traveling up to 2.1 km from the lek to day use areas (Ellis et al. 1987) The period from March through June often represents a period of higher mortality for sage-grouse. In Idaho, 43% of all documented deaths of radio-marked grouse occurred during this time frame (Connelly et al. 2000, Wik 2002).

6 Nesting Habitat Landscapes usually dominated by sagebrush Primarily nest under sagebrush shrubs. In Wyo % of nests were under sagebrush (Patterson 1952, Rothenmaier 1979). In Utah, 70% under big sagebrush, 17% under black sagebrush and 13% under other shrubs (Dahlgren 2006). Canopy cover within vicinity of nest sites varies across the range, but is usually between 15-50%. Sagebrush height at the nest site averaged 46.4 cm (18 in.) in Wyoming (Holloran 1999). Sage-grouse females selected for taller shrubs than surrounding areas. Mean distance of nest sites from lek where female was captured was km in Idaho (Wakkinen et al. 1992, Fischer 1994), 4.0 km in Colorado (Hausleitner 2003), and in southwestern Wyoming, between 75% and 87% of nests were found within 5 km of the lek of capture (Slater 2003).

7 Summer/Late Brood Rearing Habitat Use riparian corridors, wet meadows, irrigated fields and alfalfa pivot edges; Movement to higher elevation sites can occur during this phase; These areas are typically used from July through September; Elevated mortality has been documented during this time frame in Nevada (Blomberg and Sedinger 2010) In Nevada, Savage (1969) found that adult and juvenile sage-goruse used sagebrush adjacent to mesic areas during mid-late summer as loafing sites and for cover. Other studies also suggest this and found that greater shrub cover and height near meadow edges is selected and likely provides greater escape potential from predators (Hausleitner 2003).

8 Winter Habitat These sites are often dominated by big sagebrush species, especially during period of elevated snow depths; Shrub canopy cover on winter ranges varies from 6% to 43% (Schroeder et al. 1999). In Oregon and Montana, researchers found that canopy cover exceeded 20% in winter use sites. (Hanf et al. 1994, Eng and Schladweiler 1972). Wyoming big sagebrush can be particularly important during the winter (Robertson 1991), but use of mountain big sagebrush, black sagebrush and even low sagebrush has been documented. Aspect (south to southwest facing slopes) and use of lower elevation sagebrush habitats help sage-grouse find forage during the winter months.

9 Distribution (Current vs. Historic)

10 Sagebrush distribution Sage-grouse distribution

11 Population Management Units

12 Lek Locations

13 Telemetry Information

14 Core Breeding Density Model (Doherty et al. 2010)

15

16

17

18 Sage-grouse Population Status Surveyed 738 different leks in Nevada of which 405 were active (per definition) in 2011 Observed a total of 7,755 male sage-grouse 2010 Production values = 1.85 chicks per hen and nest success was estimated at 54% Production values = 1.43 chicks per hen and nest success was estimated at 52.4%

19 Average # of Males # of Leks Counted 70.0 Nevada Sage-grouse Trend Lek Counts Average Male Attendance ( ) # of Leks Counted Average Male Attendance Long Term Average Log. (Average Male Attendance)

20 Long term Harvest Statistics 30,000 Nevada Sage-grouse Harvest Information 25,000 20,000 15,000 10,000 5,000 0 Estimated Sage-grouse Harvest Estimated # of Hunters

21 Annual Harvest in Relation to Fall Population Estimates Harvest 5, ,355 6,141 Fall Population Estimate 146, , , , , , , ,120 Percentage 3.6% 2.0% 3.2% 4.6% 4.1% 7.1% 5.2% 3.7%

22 Conservation Measures Since 2001, NDOW involved with >27 sagegrouse specific habitat improvement or restoration projects consisting of; 11 fire restoration projects; 14 brood rearing or nesting habitat projects; 2 habitat protection projects; 2 long term research projects; The total acreage treated = 71,348 acres at a cost of $2.3 million dollars.

23

24

25

26

27