Setting Conservation Priorities for Landbirds in the United States: The Partners in Flight Approach

Abstract

Partners in Flight (PIF) was created in 1990 in response to concern for declining populations of Neotropical migratory songbirds (Robbins et al. 1986, Askins et al. 1990) and in the realization that conservation of these species required efforts beyond the ability of any single organization or agency (Finch and Stangel 1993). In subsequent years, PIF expanded its mandate to include all nongame landbirds and succeeded in raising awareness regarding the status of bird populations, but it had difficulty recommending which specific conservation actions were most warranted. In 1995, PIF began a comprehensive planning effort to conserve nongame landbirds and their habitats throughout the United States. A critical first step in the planning process was to establish clear and consistent priorities among the several hundred landbird species based on their vulnerability and need for conservation action. To this end, PIF developed a species prioritization process for the southeastern United States (Carter and Barker 1993, Hunter et al. 1993) by modifying earlier efforts (Millsap et al. 1990, Master 1991) and later expanded the effort to include all of North America north of Mexico. This prioritization process has been reviewed extensively by local and regional bird experts and most recently by the AOU Conservation Committee (see Beissinger et al. 2000). Here, we describe the species prioritization process and provide the context for its application in conservation. One objective of the PIF process was to develop a system that could be applied consistently to any group of species, in any geographic area, and in any season. Initial development focused on the breeding avifauna of North America north of Mexico, although efforts will be expanded to include breeding birds south of the border and wintering and transient birds. A series of scores is assigned to each species, ranging from 1 (low priority) to 5 (high priority), for seven parameters that reflect different degrees of need for conservation attention. These scores are assigned within physiographic areas, which were modified from Breeding Bird Survey (BBS) physiographic strata (Robbins et al. 1986). The entire matrix of priority scores and accompanying documentation are maintained at the Colorado Bird Observatory . The seven parameters in the prioritization process are based on global and local information. Three of the parameters are strictly global in that a single value is assigned for the entire range of a bird. These are Breeding Distribution (BD), Nonbreeding Distribution (ND), and Relative Abundance (RA). Global values are assigned to three other parameters, Threats to Breeding (TB), Threats to Nonbreeding (TN), and Population Trend (PT), but these may be superseded by values assigned specifically to a physiographic area when appropriate and possible. The last parameter, Area Importance (AI), is always assigned locally for a specific physiographic area. Scores for each of these seven variables are determined independently. Wherever possible, scores are based on quantitative and objective data. For most species, the BBS (Robbins et al. 1986) provides relative abundance and trend data used to assign scores for RA, PT, and AI. Where BBS data are not available, scores may be based on other quantitative data, expert opinions, or may reflect lack of current knowledge. Scores for range size (BD, ND) are based on published maps, and scores for threats are based on expert opinion. In addition, Population Trend Data Quality (PTDQ) assesses BBS sample size and variance to gauge the confidence in data used to assign PT. Generally, species with the widest breeding distributions are the least vulnerable to deleterious environmental changes and catastrophic events. BD is based on the proportion of North America that is covered by a species' breeding range. We have defined North America to include the main body of the continent (excluding Greenland) through Panama and the islands of the Caribbean, comprising an area of 22,059,680 km2(National Geographic Society 1993). A species inhabiting a breeding area that represents 2.5% or less of North America is assigned a BD score of 5 because species with such small ranges could be significantly and negatively affected by a catastrophic event, such as a hurricane (Table 1). At the other extreme, species inhabiting breeding ranges covering 20% or more of North America should be at relatively low risk from stochastic and other negative environmental events and are assigned a score of 1. Species with ranges between 2.5% and 20% were ranked on a graded scale (Table 1). The primary sources of information for bird distribution for BD and ND (see below) were maps from two well-known field guides (National Geographic Society 1987, Howell and Webb 1995). Criteria used to score Breeding Distribution (BD) and Nonbreeding Distribution (ND) parameters in the Partners in Flight species prioritization process Criteria used to score Breeding Distri