Songbird and habitat assessment in the Columbia Plateau of eastern Oregon and Washington

Bird surveys were conducted at approximately 70 study areas in eastern Oregon and Washington twice annually during 2000-2002. These sites represent a continuum of habitat conditions within Wyoming big sagebrush communities and include sites dominated by exotic annuals, as well as relatively pristine areas with a diverse assemblage of native perennial herbs. Songbird data coupled with information derived from intensive vegetation sampling has resulted in a powerful dataset for addressing habitat associations. In addition baseline survey data was collected at 7 riparian areas under different livestock management regimes. We are preparing several publications and a final report will be available Winter 2003.

Topics being investigated include:

Local and landscape determinants of songbird distribution and abundance in eastern Oregon.

Importance of understory to songbird abundance in sagebrush habitats

Utility of the Greater Sage Grouse as an umbrella species: how songbirds will respond to sage grouse management guidelines

Partners: BLM, USFWS, ODFW, NFWF, The Bullitt Foundation

For more information contact: Aaron Holmes

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Fire induced changes in vegetation and bird populations in xeric sagebrush steppe

A cooperative project involving PRBO, Oregon Department of Fish and Wildlife (ODFW), and the United States Navy began in 1995 on the Naval Weapons Systems Training Facility Boardman (locally known as the Boardman Bombing Range). This 19,000 ha facility represents one of the largest remaining blocks of shrubsteppe habitat within the Umatilla Plateau, Oregon's portion of the Columbia Basin Ecoregion.

Vegetation on the Bombing Range varies from a sandy shrubsteppe community dominated by antelope bitterbrush (Purshia tridentata) at the northern boundary to basin big sagebrush steppe on the loess soils present on the south half of the facility. Extensive perennial grasslands dominated by needle-and-thread (Hesperostipa comata) occur in the central part of the facility, although in much of the remaining area the native grasses have been replaced by cheatgrass (Bromus tectorum).

In August of 1998 a lightening strike started a wildfire that burned approximately 9,700 ha of the Bombing Range, including roughly half the existing sagebrush habitat. Our pre-fire data sets provided a unique opportunity to study the effects of fire through comparisons of pre- and post-fire bird distribution, abundance, and nest success. Therefore, PRBO contracted with ODFW to repeat portions of the original monitoring program during the 2000 and 2001 breeding seasons. Our objectives were to:

1) Evaluate changes in vegetation structure, songbird community composition, and relative abundance of key species on 8 sagebrush study plots;
2) Evaluate changes in the breeding population size and nest success of Loggerhead Shrikes in sagebrush habitats of the Bombing Range;
3) Survey and map locations of Sage Sparrow territories in order to make comparisons with pre-fire distributions and densities; and
4) Provide management recommendations based on our results.

Partners: ODFW, US Navy, BLM.

For more information contact: Aaron Holmes

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Avian Population Studies at NWSTF Boardman, Oregon

In 1995, the Department of the Navy, Point Reyes Bird Observatory, and Oregon Department of Fish and Wildlife implemented a 3-year inventory and monitoring program of the avian communities found on the Naval Weapon Systems Training Facility (NWSTF) Boardman, Oregon. Our primary objectives were to:

1) Provide an accurate and quantifiable inventory of birds in each specific habitat type;
2) Assess specific habitat requirements for successful nesting (habitat-specific productivity) of as many breeding species as possible;
3) Determine relative abundance key species using point count surveys, flush mapping, and adaptive sampling methods;
4) Identify habitat and vegetation conditions associated with the occurrence and abundance of as many species as possible;
5) Evaluate the effects of grazing on bird populations; and
6) Provide management recommendations to protect, enhance, and restore shrubsteppe bird populations.

Demographic information suggests that habitats of NWSTF Boardman may be functioning as population sinks for several open-cup nesting species. Despite their high abundance, Loggerhead Shrike reproductive success was among the lowest ever reported for this species. Other common species Horned Lark, Lark Sparrow, and Western Meadowlark also have low nesting success. Habitats in more pristine condition, such as native bunchgrass and lightly grazed upland sagebrush, appear to support healthy populations of some key species, such as Grasshopper Sparrow and Sage Sparrow respectively. Other species that appear to have productive populations on the NWSTF include Long-eared Owl and Burrowing Owl.

Partners: US Navy, ODFW

For more information contact: Aaron Holmes

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