Development of a Grassland Integrity Index Based on Breeding Bird Assemblages

Abstract

We utilized landscape and breeding bird assemblage data from three Breeding Bird Survey (BBS) routes sampled from 1965-1995 to develop and test a grassland integrity index (GII) in a mixed-grass prairie area of Oklahoma. The overall study region is extensively fragmented from long-term agricultural activity, and native habitat remnants have been degraded by recent encroachment of woody vegetation, namely eastern red cedar (Juniperus virginiana L.). The 50 individual bird survey points along the BBS routes, known as stops, were used as sample sites. Our process first focused on developing a grassland disturbance index (GDI) as a measure of cumulative landscape disturbances for these sites. The GDI was based on five key landscape variables identified in an earlier species-level study of long-term avian community dynamics: total tree, shrub, and herbaceous vegetation cover indices, overall mean landscape patch size, and grassland patch core size. The GII was then developed based on breeding bird assemblage data. Assemblages were based on commonly used response guilds reflective of five avian life history parameters: foraging mode/location, nesting location, habitat specificity, migratory pattern, and dietary guild. We tested the response of 78 candidate assemblage metrics to the GDI, and eliminated those with no or poor response or with high correlations (redundant), resulting in 13 metrics for use in the final index. Individual metric scores were scaled to fall between 0 and 10, and the cumulative index to range from 0 to 100. Although broader application and refinement are possible, the avian-based GII has an advantage over labor-intensive, habitat-based monitoring in that the GII is derived from readily available long-term BBS data. Therefore, the GII shows promise as an inexpensive tool that could easily be applied over other areas to monitor changes in regional grassland conditions.

Effects of the Conservation Reserve Program on northern bobwhite and grassland birds

“…The Breeding Bird Survey (Sauer et al 2005) is a longrunning program monitoring breeding birds across North American and is commonly used for monitoring and assessing effects of broad-scale management actions and environmental change (e.g., Brennen and Schnell 2005;Coppedge et al 2006;Valiela and Martinetto 2007). We derived estimates about the amount of CRP habitat and other land cover types from the Natural Resources Inventory (Nusser and Goebel 1997;USDA NRCS 2000) which is a periodic survey of the United States' soil, water and land resources.…”

Comprehensive conservation planning and ecological sustainability within the United States National Wildlife Refuge System

“…Meretsky et al (2006) recommend that the refuge system gives serious consideration to multimetric indices, for example of biological or ecological integrity, to assess extant conditions. Other recent and relevant tools include indices of grassland integrity (Coppedge et al 2006) and an ecological integrity index for littoral wetlands (Ortega et al 2004). As individual refuges in the national system implement their current CCPs, FWS will accumulate both quantitative and anecdotal information on various habitat-management and restoration activities.…”

A multispecies dependent double‐observer model: A new method for estimating multispecies abundance

“…Songbirds are becoming increasingly important indicators in diversity monitoring (Iknayan et al., ). Studies have shown that changes in songbird abundance and biodiversity are reliable indicators of impacts resulting from anthropogenic disturbance and land management in numerous ecosystems (e.g., Bradford et al., ; Canterbury, Martin, Petit, Petit, & Bradford, ; Coppedge, Engle, Masters, & Gregory, ; Coppedge, Fuhlendorf, Harrell, & Engle, ; Mac Nally, ; Schulze et al., ). With the reduction in false positives, the MDAM can provide more reliable estimates and rigorous inference about changes in communities than previously available.…”