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Significance of Federal Lands for Endangered Species


by
Bruce A. Stein
The Nature Conservancy
Tom Breden
Association for Biodiversity Information
Richard Warner
The Nature Conservancy
The federal government has overall trust responsibilities for species listed as threatened or endangered under the Endangered Species Act (ESA). The options available for managing and protecting these species, however, are directly related to the ownership of the lands on which the species are found. This article provides information about the presence and numbers of federally listed species on federal lands and the responsibility of federal land managers to care for these species. Our analysis helps evaluate the potential and actual role of federal land-management agencies in the overall protection of threatened and endangered species (Natural Heritage Data Center Network 1993).
Natural Heritage Programs--a partnership between state and federal agencies and The Nature Conservancy--gather and manage a variety of information linking both biological and nonbiological factors of relevance to bio-diversity conservation. Central to this effort is the inventory of all known occurrences for species of conservation concern, including all federally listed endangered or threatened species. An occurrence is defined as an example of a species at a specific location representing a habitat capable of sustaining the survival of that species. What constitutes an occurrence depends on the biology of the particular species, but most often reflects a mappable and geographically distinct population or subpopulation. Pertinent information is documented for each occurrence, such as the biological health and population trends of the occurrence, habitat quality, protection or management status, and land ownership.
Heritage Programs in all 50 states queried their data bases for all documented occurrences of federally listed species in their jurisdiction and reported the class of landowner or type of managing agency. (Note: "Species" under the ESA includes subspecies as well as full species; in the strictest taxonomic sense these collectively would be referred to as "taxa.") Only occurrences observed since 1973 were included in the analysis.
Karner blue butterfly (Lycaeides melissa samuelis), an endangered species found partially on federal lands. Courtesy K. Deitcher©
While the Heritage Programs are the most comprehensive source for such locality information on rare species and reviewed about 350,000 occurrence records for this analysis, this information is incomplete for four reasons: (1) Heritage Programs may not be aware of all occurrences, and indeed, many populations for species of concern may yet be discovered; (2) most programs have a data-entry backlog; (3) not all data centers have completely recorded the land ownerships for all their occurrence records; and (4) species occurrences in lakes and rivers are generally not recorded as under the jurisdiction of a federal agency except where they are entirely included in such areas as national parks or wildlife refuges. On the other hand, in many states more is known about the status of listed species on federal lands than on state or private lands. This imbalance in the available data, largely the result of federally funded inventories on federal lands, will tend to overstate the proportion of a species' range or population on federal lands.

Species on Federal Lands
This analysis includes 344 plant, 254 vertebrate, and 130 invertebrate species found in the 50 United States that as of March 1993 were listed as endangered or threatened under the ESA. About 50% of all federally listed threatened and endangered species occur at least once on federal lands (Fig. 1). The other half of the listed species are found on either state and local public lands, tribal lands, or private lands. About 25% of listed species have more than half of their known occurrences on federal lands and can benefit substantially from federal land-management protection and recovery actions. About 12% of listed species are found almost exclusively on federal lands, with 90%-100% of their known occurrences restricted to lands under federal management.

Fig. 1. Listed species occurring on federal lands.

Number of Listed Species
About 100 species occur on land managed by most major federal agencies (Fig. 2). With nearly 150 species, the U.S. Forest Service (USFS) harbors the largest number of federally listed species of any federal agency. This larger number reflects not only the size and geographic extent of the landholdings, but also the intensive biological surveys that have been conducted on many national forests.

Fig. 2. Listed species occurring by jurisdiction on federal land. USFS--U.S. Forest Service; DoD--Department of Defense; BLM--Bureau of Land Management; NPS--National Park Service; USFWS--U.S. Fish and Wildlife Service.

Occurrences of Listed Species

Of the 24,573 occurrences of federally listed species recorded by the Natural Heritage Network nationwide, 36% are found on federal lands (Fig. 3). The USFS, with 16% of the total, has the largest number of occurrences followed by the Bureau of Land Management (8%) and the Department of Defense (4%). Both the U.S. Fish and Wildlife Service and the National Park Service have 3% of known occurrences on their lands.

Fig. 3. Occurrences of all listed species by land ownership category. See Fig. 2 for definitions of abbreviations.
The average number of occurrences per listed species varies markedly among plants, vertebrates, and invertebrates. There are an average of 34 occurrences per listed species for all species combined, 17 occurrences per plant species, 13 occurrences per invertebrate species, and 67 occurrences per vertebrate species. The broad distribution of some federally listed vertebrates heavily influences these figures, however. Just 12 vertebrate species (e.g., bald eagle) account for 12,121 occurrences, representing 49% of the total for all species. Excluding these 12 vertebrates, the average number of occurrences for vertebrates drops to 20 and the overall average to 17.

Conclusions
This analysis puts in perspective the relevance of federal land management for the protection of federally listed threatened and endangered species. Agencies that manage federal lands have substantial responsibilities and opportunities for protecting listed species, particularly those that are found exclusively, or mostly, on federal lands. An example of a plant entirely restricted to federal lands is Ruth's golden aster (Pityopsis ruthii), and an animal found exclusively on federal lands is the Laysan duck (Anas laysanensis), which lives only on national wildlife refuges.
Federal agencies can also provide substantial, permanent conservation of the listed species that have more than half of all occurrences on their lands. For example, most populations of both the white-haired goldenrod (Solidago albopilosa) and white birds-in-a-nest (Macbridea alba) are on national forest lands.
For many listed species with less than 50% of their occurrences on federal land, federal agencies may still be able to provide important protection and recovery opportunities. For example, the Karner blue butterfly (Lycaeides melissa samuelis), with less than one-quarter of its occurrences on federal lands, still can substantially benefit from federal management actions, such as restoration of the pine and oak savanna habitat on which this butterfly depends.
This study found, however, that fully 50% of federally listed species are not known to occur on federal lands, and that for all listed species, 64% of known occurrences are on nonfederal lands. This strongly points to the need for developing and strengthening federal efforts for protecting these species through cooperative efforts and incentive programs with state and local agencies, private conservation organizations, and private landholders.
For further information:
Bruce A. Stein
The Nature Conservancy
1815 N. Lynn St.
Arlington, VA 22209
References
Natural Heritage Data Center Network. 1993. Perspectives on species imperilment (revised printing). The Nature Conservancy, Arlington, VA. 40 pp.


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