Assemblages of breeding birds as indicators of grassland condition

Abstract

We developed a measure of biological integrity for grasslands (GI) based on the most influential habitat types in the Prairie Pothole Region of North Dakota. GI is based on proportions of habitat types and the relationships of these habitat types to breeding birds. Habitat types were identified by digital aerial photography, verified on the ground, and quantified using GIS. We then developed an index to GI based on the presence or abundance of breeding bird species. Species abundance data were obtained from 3 min roadside point counts at 889 points in 44, 4050 ha study plots over a 2-year period. Using a modified North American Breeding Bird Survey protocol, species were recorded in each of four quadrants at each point. Fifty species selected for analysis included al1 grassland species that occurred in at least 15 quadrants and al1 other bird species that occurred in at least 1% of quadrants. We constructed preliminary models using data from each of the 2 years, then tested their predictive ability by cross-validation with data from the other year. These cross-validation tests indicated that the index consistently predicted grassland integrity. The final four models (presence and abundance models at 200 and 400 m scales) included only those species that were statistically significant (P 5 0.05) in al1 preliminary models. Finally, we interpreted the components of the indices by examining associations between individual species and habitat types. Logistic regression identified 386 statistically significant relationships between species and habitat types at 200 and 400 m scales. This method, though labor-intensive, successfully uses the presence of grassland-dependent species and absence of species associated with woody vegetation or cropland to provide an index to grassland integrity. Once regional associations of species with habitat types have been identified, such indices can be applied relatively inexpensively to monitor grassland integrity over large geographic areas. Indices like the ones presented here could be applied widely using bird abundance data that are currently being collected

Biotic integrity of the arthropod communities in the natural forests of Azores

“…In terrestrial ecosystems the IBI approach has seldom been tested, although its usefulness is potentially as large as in aquatic ecosystems (Andreasen et al 2001). Bradford et al (1998), O'Connell et al (1998) and Browder et al (2002) followed similar approaches with the objective of reaching an index based on bird communities. For terrestrial arthropods, Majer and Beeston (1996) have tested the approach in Australian ant fauna, although this was on a very broad scale and using a very restricted set of metrics.…”

Sensitivity of breeding birds to the “human footprint” in western Great Lakes forest landscapes

“…Anthropogenic landscape degradation can be inferred by remotely-sensed land cover variables, fragmentation metrics, and other measures of human activity (e.g., road density), similar to the approach of Bryce et al (2002) and Browder et al (2002). We used principal components analysis to reduce a relatively uncorrelated subset of these variables to a single axis of condition scaled from 0 (maximally disturbed) to 10 (minimally disturbed).…”

“…The value of species assemblages as indicators of ecosystem health has been recognized by many other researchers (Karr and Chu 1997, Bradford et al 1998, Canterbury et al 2000, O'Connell et al 2000, Browder et al 2002, Bryce et al 2002, Glennon and Porter 2005, Howe et al 2007a. In this analysis we used all bird species that were adequately abundant and showed consistent responses to environmental disturbance.…”

A farm-scale biodiversity and ecosystem services assessment tool: the healthy farm index

“…Rich et al 2004). Birds stand as an ideal indicator species and are preferable to insects or plants because of their ease of detection, sensitivity to environmental change and broad presence in the environment (Browder et al 2002). In addition, targeting a limited number of relevant indicator species is more suitable to farmer engagement than metrics like species richness.…”