Conservation Report: Setting Conservation Priorities for Landbirds in the United States: The Partners in Flight Approach
Year: 2000
Type: article
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 <http://www.cbobirds.org>. 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 Distribution (BD) and Nonbreeding Distribution (ND) parameters in the Partners in Flight species prioritization process Nonbreeding Distribution reflects the proportion of North America or equivalent area that is covered by a species' nonbreeding range. It is scored in the same manner and using the same scale as BD (Table 1). This parameter is based on the smallest nonbreeding range that a species occupies. Therefore, species that move through severe migratory bottlenecks, such as Red Knots (Calidris canutus) staging at Delaware Bay, receive high scores to reflect the risks associated with such concentration. Relative Abundance measures the abundance of a species in appropriate habitat within its range relative to other bird species. Species that are uncommon are assumed to be at greater risk and receive higher RA scores. Scores for RA are determined using one of two methods. Where BBS data are available, RA values are assigned on the basis of the mean number of birds on the 10 BBS routes on which a species is most abundant (Table 2) using an analysis derived from Price et al. (1995). A less-quantitative approach is necessary for species for which BBS data are unavailable or unreliable, including many arctic, boreal, and tropical species whose breeding ranges largely fall outside of the area sampled by the BBS. In these cases, RA scores are assigned on a qualitative scale of abundance (Table 2) on the basis of published notes and expert opinions, as described in earlier versions of the PIF prioritization process (Carter and Barker 1993, Hunter et al. 1993). All departures from BBS-derived criteria and justifications for departures are documented in the database. Criteria used to score the Relative Abundance (RA) parameter in the Partners in Flight species prioritization process Criteria used to score the Relative Abundance (RA) parameter in the Partners in Flight species prioritization process These parameters reflect recent and predicted threats that may put a species at risk of decline or extirpation from an area. TB and TN are scored using a standardized scale for evaluating conditions, including what has happened in the past and what is likely to happen in the future, that affect an area's ability to support healthy populations of a bird (Table 3). These conditions include the amount of suitable habitat, other factors that affect the species' survival or reproductive success, including cowbird parasitism, pesticides, and predation, and the capacity of the species to withstand or recover from negative conditions. Present conditions are based on the percent of conditions that existed around 1945 that still exist today. Future conditions are the percent of current conditions anticipated to exist in subsequent decades. Scoring of Threats Breeding (TB) and Threats Nonbreeding (TN) in the Partners in Flight species prioritization process, based on an evaluation of past, present, and future conditions available to support healthy populations of a given species (see text) Scoring of Threats Breeding (TB) and Threats Nonbreeding (TN) in the Partners in Flight species prioritization process, based on an evaluation of past, present, and future conditions available to support healthy populations of a given species (see text) We illustrate this process for two species that inhabit the Central Shortgrass physiographic area. Much of the shortgrass prairie, the preferred habitat of McCown's Longspur (Calcarius mccownii), has been lost or degraded over the last two centuries (Knopf 1994). Perhaps 51 to 75% of the habitat that existed in 1945 has been lost (with 25 to 49% remaining). Using the 25 to 49% remaining column, McCown's Longspur could only score a 3, 4, or 5 (Table 3). Using similar reasoning, we estimate that loss rates of shortgrass habitat will not exceed 50% in the next few decades, but that not all shortgrass prairie that exists today will exist in the future. Therefore, McCown's Longspur in this physiographic area scores a TB of 4. The Horned Lark (Eremophila alpestris) also occurs in the same shortgrass prairie habitat but would be scored differently. The conversion of shortgrass to agricultural lands has not been as detrimental to Horned Larks as to many other species, so perhaps 100% of past conditions remain for this species, leaving possible scores of 1 to 5. Because future conditions are likely to favor Horned Larks (i.e. no future loss), the species scores a 1 for TB. Although the scoring process for TB is heavily based on amount of habitat, it also may incorporate factors related to the ability of an area to support a species. For example, if we concluded for Horned Larks that new threats (e.g. pesticides, plowing of nests) existed that could limit breeding success to less than 25% of what would occur under current conditions, then Horned Larks would receive a TB score of 5. TN is scored using the same criteria as TB (Table 3). As with Nonbreeding Distribution discussed earlier, TN is named and scored to reflect not only wintering conditions but also threats faced during migration. Species that pass through severe ecological bottlenecks during migration may score higher than they would based on winter conditions alone. Species that reside within an area throughout the year are often assigned the same TB and TN scores, but those that change habitats within that area, or are otherwise more or less vulnerable in winter, could receive different scores for the two parameters. Population trend scores, reflecting the magnitude and direction of population change, are assigned globally as well as locally for each physiographic area. When possible, population trend scores are assigned on the basis of BBS data (Table 4) as analyzed by the BBS laboratory of the United States Geological Survey's Biological Resources Division (J. Sauer pers. comm.). Each PT score is linked with a PTDQ score that assesses the quality of BBS data based on sample size and statistical significance. Criteria for scoring population trend (PT) and population trend data quality (PTDQ). PTDQ depends on number of BBS routes (n) within a physiographic area and the statistical significance of the population trend being different from 0 (P). In addition, a PTDQ symbol of x should be applied whenever PT is based on data other than the BBS (expert opinion, Christmas Bird Count, etc.); the source should be specified in the database Criteria for scoring population trend (PT) and population trend data quality (PTDQ). PTDQ depends on number of BBS routes (n) within a physiographic area and the statistical significance of the population trend being different from 0 (P). In addition, a PTDQ symbol of x should be applied whenever PT is based on data other than the BBS (expert opinion, Christmas Bird Count, etc.); the source should be specified in the database A population trend must meet the thresholds of magnitude and reliability associated with PTDQ scores of A, B, or C to warrant either a very high (4 or 5, declining) or a very low (1, increasing) score (Table 4). Species not meeting these minimum requirements are assigned a PT of 3 (trend unknown) and receive PTDQ scores of D, E, or F. A PTDQ score of D is assigned to species for which a large sample size indicates positive or negative nonsignificant trends of at least 1%. This often applies to birds whose local populations fluctuate greatly from year to year, possibly reflecting fluctuating habitat conditions and/or possibly obscuring long-term trends. Species assigned a PTDQ score of E1 or E2 have insufficient sample sizes. Species not detected on the BBS in the area are given a PTDQ of F and usually are locally rare or difficult to detect. A PT score of 2 reflects two possibilities that are differentiated from each other by the PTDQ score and the magnitude of the trend. A PT of 2 with a PTDQ of A2 or B2 and a trend between ±1% indicates a well-sampled species whose population is essentially stable. A PT of 2 with a PTDQ of C1 or C2 and an increasing trend (at least 1% per year) reflects a species that is probably increasing, but without statistical certainty. In cases where BBS data are unsatisfactory, other population trend data or the opinions of local experts may be substituted with the scoring mimicking the criteria in Table 4. PT scores not derived from the BBS are assigned a PTDQ score of X, and the origin of the information is noted in the database. This variable is intended to evaluate how important a particular physiographic area is to the conservation of a given species. AI scores compare the abundance of a species within a physiographic area relative to other areas throughout its range (Table 5). Because these scores are based on an index of relative abundance, they are not influenced by the size of the geographic unit in question. Data for this criterion are derived from the BBS, when they are adequate. The first step is to identify the physiographic area within the bird's range with the maximum mean number of individuals per BBS route. Mean numbers of birds per route for other physiographic areas are compared with the physiographic area maximum. For cases in which BBS data are not available or seem to be misleading, AI can be assigned on the basis of local review by experts knowledgeable about the distribution and abundance of the species, following as closely as possible the rationale behind the quantitative method. Criteria for scoring Area Importance (AI) in the Partners in Flight species prioritization process Criteria for scoring Area Importance (AI) in the Partners in Flight species prioritization process Although PTDQ is the only supplemental value currently assigned, it may be beneficial to document the quality of information used in developing scores for other variables. In the past, PIF has assigned some data quality scores for TB and TN, but these have been rarely used or have caused confusion. Hunter et al. (1993), following Millsap et al. (1990), described a potentially supplemental score that the amount of that a species is This could in among species that are an amount of from those with similar prioritization scores that may As as scores in a prioritization database may their depends on how they are and applied to conservation In the following we of the species prioritization regarding of scores, and of their current A application is a of the seven parameter scores to conservation This which can range from to is a potentially but only when in the context of its on scores to conservation can be and is perhaps the most of the prioritization process and the numbers it Beissinger et al. a approach that an of priority based on of scores, declining population trend and high threats to PIF bird conservation described a of including the of all scores, as a to priority At present, the seven variables in the prioritization process are in the database. When the database was were to parameters in where one be more important than A particular score may be or by being by a greater than or less than 1 and used to a new We such because the relative of the seven parameters to the vulnerability of a species usually is we that using parameters as factors may in conservation priorities that are to As a first step in priority scores, an AI can be that a species from the of its where conservation efforts would be in a physiographic area should be to species with an AI score of 2 or A of species with an AI score of or 5 in the 3 or 2 in the and 1 in the would on species for which an area has the conservation When BBS data PT scores provide a in that PT is the parameter that is the and of conservation action. with high scores for PT may be more in need of conservation than are birds with low scores. on the basis of TB in breeding habitat and TN in wintering or migration habitat will also conservation actions where they potentially can the most where local PT is In addition, by PTDQ may be because species that receive a high score and a PTDQ that indicates data are those that are most in need of in developing Beissinger et al. the seven scores to a single value because of the for lack of among the parameters. Although scores for some parameters can be to be this not from lack of For example, a species may have a small breeding distribution (high BD but occur in high relative abundance (low RA and its populations may or may not be (high or low The seven parameters in the species prioritization process were because of ability to score independently. in some species among scores to of conservation than lack of Species that score high on parameters, and have high scores, of These species may have a small occur in low relative abundance, threats to breeding and wintering populations, and a significantly declining population trend. species that vulnerability only in one or two of these would have scores, the of which is without of the scores. low and very high scores, have in of some of conservation is warranted. Beissinger et al. a approach that species to thresholds of scores for Population Relative and In their analysis of the breeding bird species of (e.g. high was with the of the seven parameter scores. the same species of conservation concern were by A approach has a in that the may be on parameters for which data are The of used by PIF in its planning process (see below) species priority based on their scores as well as on of scores for the parameters, AI and PT. This is essentially a approach in which a species can the priority by any one of several all species through the prioritization process as high priority are of conservation concern or actions in all and the of to an area's in the for long-term conservation of species, including those that are not currently declining or in that area. species may have relatively high scores, including high or RA, but low to locally derived PT and TB TN for wintering scores. These may be species for which the physiographic area should conservation and for which is warranted. Area also is a of species prioritization efforts in et al. In species that are most in need of conservation actions in a receive high scores for local concern and and global priority high but may score high or low for area on species or species that are of concern is an over many and species which often populations that are locally rare and declining and that may have for long-term conservation of the species. We that the most important application of priority scores to is their in the of Bird Conservation for all of the physiographic areas and/or of the United States. among the breeding avifauna of each physiographic area, a priority species is derived using a of criteria from the prioritization database. A species may be in this if it is in need of conservation has a global or has a large population for which is high local All species in this priority are then each of one or more species. specific conservation or actions may be by of priority scores. for example, are consistently for species in a effort may be required in that used by one or more species with very high scores, high PT and and high AI scores may be in need of or other conservation in habitats for that of many birds with high scores and high AI scores but low PT and TB scores may be at but in need of long-term The will also include quantitative population and habitat for for actions to conservation and an to evaluate the success or of those The of the PIF planning process is to the of conservation to the long-term of populations of landbirds throughout the United with an that efforts may be required in other to provide wintering and migration habitat for many migratory species. PIF prioritization scores have been used to a for the United States (Carter et al. that is based on the of global scores for parameters is because it a global The value of a is to species that may be in need of conservation throughout their range and to in bird conservation. a based on global scores is less for conservation planning at regional or local than are physiographic area scores in which PT, and TB are scored Therefore, we in the of the or any other of species at an geographic as a for conservation Because species prioritization is a critical of the conservation planning process, prioritization scores must reflect the information The current database has been reviewed extensively by and regional as well as by on The AOU Conservation Committee the of the as well as the of the seven used for evaluating vulnerability et al. 2000). regarding several are Because of on the BBS for population data, many species (i.e. some and other or receive an score for population trend 3). Where or data of more trend will greatly the database. In addition, for many species that are in the United States or priority scores is by of abundance, population and beyond those At present, only species are assigned scores in the database. of the species throughout North America only recently have been as species such as and are at the for their high conservation (e.g. are of conservation and such as the may be as a of given to efforts to this in conservation efforts will from as well as of geographic and population As a for conservation the species prioritization process is to identify conservation priorities for the of breeding landbird species in North The database will also in the of conservation for priority landbirds with for such as and other that are in conservation has been in in of bird distribution and population For example, many species with population trends and PTDQ scores are in need of or new As new information available, the of an and prioritization process be To that conservation is based on the available, we the and to in review and of this database. The Partners in Flight species prioritization process from from individuals over the last including many and on scores for physiographic areas throughout the We and Sauer for and Beissinger for and for in and and Beissinger for the accompanying review for the first of the prioritization was by the and of and for the species and winter was from the and with from the Conservation and of through the and We all have been in the
Source: The Auk
Authors: Michael F. Carter, William C. Hunter, David N. Pashley, Kenneth V. Rosenberg
Language: English
Topic: Avian ecology and behavior
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W2051315006