Effects of natural gas development on sage grouse (Centrocercus urophasianus) populations.

Authors(s): S. Anderson and A. Lyon

Publication:

Publisher:

Publication Date: 0000-00-00

Type: Annual, Completed Project

Location:

Abstract: The purpose of the project was to study the effects of natural gas and oil development on the lek use, productivity, general movements and habitat use of sage grouse (Centrocercus urophasianus) on the Pinedale Mesa. A total of 80 grouse (60 adult and 20 chicks) were captured and radio-collared off of six leks on the Pinedale Mesa between March-August 1998. Three leks were considered "disturbed" (natural gas development within a two-mile radius of the lek) and three leks were considered "undisturbed" (no natural gas development within a two-mile radius of the lek). The grouse were monitored and located on a weekly basis to determine lek use, nest site, early brood rearing, late brood rearing, summer and winter habitat selection. Vegetative data collected at use and random sites included: sagebrush density, canopy cover and height, grass and residual grass height and cover and forb cover (Daubenmire 1959, Canfield 1941). The vegetation data was collected 1998 and 1999 and is currently being statistically analyzed using two-sample t-tests and tests for homogeneity of variance to assess selection criteria of the seasonal habitats. The sage grouse population on the Pinedale Mesa is considered non-migratory. Weekly locations of radio collared sage grouse were recorded as UTM coordinates using a Garmin GPS unit. Movements were analyzed using Arcview. In 1998 most cocks remained close to the lek of capture through the breeding season. However, six (28.5%) relocated to different lek sites. Of the six male grouse that relocated to other leks, three were originally captured on disturbed leks and three of the grouse were adults. This seems to indicate that there may be some movement between leks during the breeding period. However, no movement between leks was observed in 1999. The majority (68%) of the hens in 1998 remained within a two-mile radius of the lek to nest. Of the hens captured on "undisturbed" leks, eight of nine (89%) hens nested within the two-mile radius of the lek; while 10 of the 19 (47%) hens captured on "disturbed" leks nested within the two-mile radius. One hen moved approximately 60 miles from the lek of capture to nest. 1999 findings exhibit similar movements from lek to nest sites. Fidelity to previous nesting areas is extremely strong. 1999 nests were often located within feet of the previous year's nest. Hens actually exhibited notably high fidelity to year round habitat, returning to the same leks to breed and the same areas to nest and raise broods. Brood rearing hens, broodless hens and cocks selected summering habitat off the Mesa in 1998 and 1999 and most grouse returning to the Mesa to winter. Most winter movements onto the Mesa occurred prior to November 19, 1998. 62% (eight of 13) of our recorded mortalities occurred during this movement (between October 1 and November 19). There was little movement of grouse noted between the November and January location flights. Fall and Winter flights will be carried through February 2000 to document winter fidelity and possible impacts of the increased development on the Mesa.

Keywords: Wyoming Cooperative Fish and Wildlife Research Unit, University of Wyoming, animal, bird, ornithology, breeding, Aves, sage grouse, grouse, Centrocercus uraphasianus, Pinedale, habitat, nest, nesting, population, human activity, oil and gas drilling, radio collar, mortality