Details - Roadside bird counts on BLM lands in Petroleum and Fergus counties, Montana

Roadside bird counts on BLM lands in Petroleum and Fergus counties, Montana

Title

Roadside bird counts on BLM lands in Petroleum and Fergus counties, Montana

Title Variants

Alternative: Roadside bird counts on Bureau of Land Management lands in Petroleum and Fergus counties, Montana

By

Hendricks, P.

Montana Natural Heritage Program.
United States. Bureau of Land Management.
United States. Bureau of Land Management. Lewistown Field Office.

Type

Book

Material

Published material

Publication info

Helena, Mont, Montana Natural Heritage Program, c2000

Notes

Title from cover.

"March, 2000."

Twenty-three roadside bird transects were run once during late May-early July 1998 or 1999 to document bird presence and relative abundance on and near BLM lands mostly in Petroleum county (20 routes) and adjacent Fergus County (3 routes). Routes tended to be run in morning (n=16), but some (n=7) were run in the afternoon to increase coverage as weather permitted. Each roadside transect consisted of 10 survey stops or point counts (one route consisted of 7 stops), spaced0.5 miles apart. At each stop counts were conducted for 3 min during which all birds detected within a radius of 150m were recorded. Gross vegetative land cover associated with each point was also recorded. Low-stature sagebrush (Artemisia tridentata), often < 0.5 m tall) was classified as the dominant cover type at 173 points (76.2%) of all 23 routes (on only two routes was this dominant at < 5 points). Mixed grassland/cropland/pasture was dominant at 34 points (15.0%) of 14 routes, and ponderosa pine (Pinus ponderosa) savanna was the dominant cover type on 20 points (8.8%) of 5 routes. Each vegetation type was present at additional points to various degrees, and influenced the presence of some bird species at particular counts. Fifty-eight bird species were detected, of which three species occurred on more than half of the point counts: Western Meadowlark (97.4%), Vesper Sparrow (85.9%), Lark Bunting (61.2%). Two species considered sagebrush obligates, Brewer's Sparrow and Sage Thrasher, were detected on 27.3% and < 1.0% of the point counts, respectively. The relatively low abundance of Brewer's Sparrow coupled with the high abundance of Vesper Sparrow and Lark Bunting indicates that low-stature sagebrush cover is often of medium to low density and intermixed with a significant cover of grasses. However, abundance of Brewer's Sparrow was probably underestimated because of the number of point counts conducted in early July, by which time this species was probably less vocal. Sage Thrashers use taller and denser sagebrush, which was relatively rare along the routes, and their very low abundance is a reflection of the scarcity of suitable habitat. Other species often associated with grasslands were detected on relatively few point counts: Upland Sandpiper (9.3%), Long-billed Curlew (< 1.0%), Short-eared Owl (< 1.0%), Sprague's Pipit (< 1.0%), Savannah Sparrow (4.4%), Grasshopper Sparrow (9.7%), Baird's Sparrow (< 1.0%). Brown-headed Cowbird was detected on 13.2% of the point counts, usually in the presence of cattle or pasture. The BLM lands in the survey area are dominated largely by low-stature sagebrush, and provide an opportunity to manage especially for some sagebrush obligate species. Sage Grouse were not detected, but special surveys for this species merit consideration. Grassland species such as the regionally endemic Sprague's Pipit and Baird's Sparrow, of special concern for a number of land management agencies, do not currently occur in the area in significant numbers.