Using Breeding Land Birds in the Assessment of Western Riparian Systems

Rich, Terrell

In the western United States, riparian ecosystems are among the highest priorities for improved management and restoration. Riparian vegetation has been widely destroyed or seriously degraded by livestock grazing, water diversions, altered flood regimes, and other human activities. Riparian degradation has led to a major federal initiative to assess riparian areas and prioritize them for restoration. Proper Functioning Condition (PFC) assessment has served as the main methodology for assessing riparian health by the United States Bureau of Land Management (BLM), United States Forest Service (USFS), and United States Natural Resources Conservation Service (NRCS). PFC is a quantitative rapid assessment method whose purpose is to assess 'how well the physical processes are functioning' (BLM 1998a:1). Here, I propose a simple method for incorporating in assessment of the breeding land-bird community into the PFC methodology. This would bring PFC assessment closer to an evaluation of biotic integrity. Experts identified 77 species as obligate or dependent breeding riparian land birds in the western United States, and their occurrence serves as the standard to which site data can be compared. The method is illustrated with sample data from the Boise River in southwestern Idaho. The first step was to construct a list of riparian obligate and dependent land-bird species that should occur on the site during the breeding season. Relative abundance data from the Breeding Bird Survey could be used to fine-tune the list of expected obligate and dependent species. The simplest scoring was to calculate the percentage of potential obligate and dependent species that actually occurred on the site (i.e., 44% [n=25] in this example). Knowledge of the ecology of those species actually on the site and those missing should be used along with the score to help determine conservation priority.

Using Breeding Land Birds in the Assessment of Western Riparian Systems

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