UPDATE March/April200 1 School of Natural Resources and Environment Vol
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UPDATE March/April200 1 School of Natural Resources and Environment Vol. 18 No. 2 THE UNIVERSITY OF MICHIGAN pages 29-60 30 Endangered Species and Peripheral Populations: Cause for Reflection A. Townsend Peterson 32 Special Series: Habitat Conservation Planning Part Ill: Incorporating Adaptive Management and the Precautionary Principle into HCP Design Gregory A. Thomas 41 Endangered Invertebrates: The Case for Greater Attention to Invertebrate Conservation Scott Hoffman Black, Matthew Shepard, and Melody Mackey Allen 50 The Impact of Communication Towers On Neotropical Songbird Populations Joanne M. Lopez 55 Marine Matters Marine Protected Areas: Examples from the San Juan Islands, Washington Terrie Klinger Opinion Endangered Species and Peripheral Populations: Cause for Reflection A. Townsend Peterson Natural History Museum and Biodiversity Research Center, The University of Kansas, Lawrence, Kansas 66045 USA Introduction cupido amaten'), and Florida Scrub-Jay populations of Northern Aplomado Endangered species lists constitute criti- (Aphelocorna coerulescens). These taxa Falcon would be regrettable, they al- cal foci of conservation attention. Spe- are clearly appropriate for inclusion in the naj)shave been marginal, and as such cies on such lists are given special atten- list, given that conservation efforts will likely have a tenuous hold on long-term tion in prioritizations for consenlation either prove successful in the United survival. Worse still. for species such (Peterson et al. 20001, with the Endan- States, or the taxon will be lost to extinc- as the Crested Caracara and the Fer- gered Species Act affording immediate tion. Another 19 of the endangered bird mginous Pygmy-Owl. although U.S. protection to areas known to hold popu- species, while not endemic to the populations are limited in distribution, lations of endangered species. Hence, de- United States, have substantial popu- the species is abundant. and far from cisions regarding "endangered" status of lations in the country that can be an ap- threatened with extinction, just a few species have profound effects on conser- propriate focus of conservation efforts. hundred kilometers south in Mexico. vation action (Tear et al. 1995). Six avian taxa on the list, however, State endangered species lists are Oddly, though. endangered species are represented in the United States only similarly of curious composition. lists seem to be assembled with little at- by peripheral populations when the en- Some states have very clear and tention to the biology of species involved. tire range of the species is considered: straightforward lists: Michigan, for The purpose of this commentary is to point Masked Bobwhite (Colinus virginiancls example. includes Peregrine Falcon . out that many "endangered"species in the ridgwqvi), Audubon's Crested Caracara Bald Eagle (Haliaeetus United States are actually periphel-alpopu- (Polybonuplancusadubonii), Northern lez~cocephalus),and Piping Plover lations when the entire range of the spe- Aplomado Falcon (Falco femoralis (Clzaradriusmelodus). all of which are cies is considered (Godown and Peterson septenfrionalis). Thick-billed parrot represented by breeding populations in 2000). Such populations are often not (Rhynchopsitta pachyrhyncha), Cactus the state, as well as IOrtland's Warbler viable populations to begin with molt and Ferruginous Pygmy-Owl (Glaucidiunz (Dendroica kirtlalzdii), for all intents Gaines 1992). constituting population brasilinn~~incactnru~n), and Wood Stork and purposes endemic to the state as a "sinks," and indeed are often species of (Mycteria americana). Some of these breeding species; 18 other states have little conservation concern in the main species are indeed in global peril of ex- similarly straightforward endangered portion of their geographc distributions. tinction (Masked Bobwhite), and per- species lists. Other states, however, in- Inclusion of these species in status lists haps the attention that they might receive clude species from the federal list that dilutes the effectiveness of endangered in the Unit,& States is worth the effort. are marginal or even accidental in that species legislation and conservation ac- However, others are species that are particular state. For example, the Ohio tion, and changes geographc foci of en- quite common south of the U.S.- list includes Bald Eagle, which is in- dangered species richness (Godown and Mexico border. For example, the Fer- deed a breeding species in the state; Per- Peterson 2000). ruginous Pygmy-Owl is a common egrine Falcon, which is marginal in oc- resident of tropical forests, the Crested currence; and Piping Plover, which is Endangered species lists Caracara is a common resident of open extinct as a breeding species in the state. The U.S. endangered species list includes and disturbed habitats, and the Wood 44 avian taxa (excluding Hawaii). Of Stork is a frequent species of open wet- Discussion these taxa, 19 are endemic or nearly en- lands; all three are found broadly Considering aspects of the theory of demic to the United States, such as the throughout the tropical Americas. population ecology, investing time and California Condor (Gymnogyps These peripheral populations lie at resources in the conservation of periph- cal@omianlrs),Mississippi SandhiU Crane the limits of species' ranges, where they eral populations is a questionable strat- (Grus canadensis pulla), Attwater's are often not viable in the long term. egy. Peripheral populations are well Greater Prairie-chicken (Tvmpanuchus Hence, whereas extinction of the U.S. known to be marginal, and in many 30 Endangered Species UPDATE Vol. 18 No. 2 2001 cases unstable in population dynamics, and the species rapidly disappears from Endangered Species as can be seen in the following hypo- the peripheral area in spite of conserva- UPDATE thetical example. A population grows tion efforts. A forum for information exchange on or declines as the combination of four The point of this commentary is not endangered species issues factors (Figure I), birth (B), death (D), to detract from the important advances March/April2001 Vol. 18 No. 2 immigration (I),and emigration (4.If made in endangered species conserva- M.Elsbeth McPhee ...................Managing Editor individuals did not move among areas, tion in recent decades. Rather, my fo- Chase M.Huntley ................ Publication Editor I and E would be zero, and whether an cus is on how future efforts should con- Jennifer Jacobus MacKay .........Associate Editor area is inhabited or not would depend centrate on taxa in areas in which prob- Stephanie Hitztaler ...............Editorial Assistant Ryan Tefertiller......... .. ....Editorial Assistant simply upon the balance of B and D. abilities of success are high. Under this Kathy Cone............ Subscription Coordinator Hence, in Figure 1, the darkest areas view, peripheral populations appear fre- Leah Thompson ...............Research Coordinator Saul Alarcon .................Web Page Coordinator would have B 2 D, and would be stable quently to represent a losing proposi- Terry L. Root ................ ...... Faculty Advisor or increasing; other areas (light gray tion: populations in these regions will and white) would not be inhabited in fluctuate widely, and are likely to de- Adviso~Board Richard Block the absence of immigration. If indi- cline as source populations are compro- Santa Barbara Zoological Gardens viduals do move among populations mised. The effectiveness of the Endan- Susan Haig Forest and Rangeland Ecosystem sufficiently frequently, areas adjacent gered Species Act would hence be maxi- Science Center, USGS to increasing populations may receive mized by focus on species that have sub Oregon State University Chris Howes n-me immigrants than they send out as stantial portions of their geographic dis- Chicago Zoological Society emigrants (I> E), and a population can tributions within the area of jurisdiction. Norman Myers be maintained as a sink even over long International Consultant in .d Environment and Development periods of time. Hence, peripheral Literature cited Patrick O'Brien populations of species can often prove Godown M.E., Peterson A.T. 2000. Preliminary Chevron Ecological Services distributional analysis of U.S. endangered bird Hal Salwasser not to be viable if adjacent source popu- U.S. Forest Service, species. Biodiversity and Conservation 9: 1313- Boone and Crockett Club lations are removed. 1322. The logical flaw of counting periph- Holt R.D., Gaines M.S. 1992. Analysis of adapta- Instructions for Authors: The Endangered Species eral populations on endangered species tion in heterogeneous landscapes: Implications UPDATE welcomes atricles, editorial comments, for the evolution of fundamental niches. Evo- and announcements related to species protection. lists can thus be appreciated: their conser- For futher information contact the editor. vation has little probability of success. lutionary Ecology 6:433-447. Peterson A.T., Egbert S.L., Sanchez-Cordero V., Subscription Information: The Endangered Peripheral populations are vulnerable to Pnice K.P. 2000. Geographic analysis of con- Species UPDATE is published six times per year by wide fluctuations and instability (Holt and servation priorities using distributional model- the School of Natural Resources and Environment ling and complementarity: Endemic birds and at The University of Michigan. Annual rates are Gains 1992). ,, making " their Ipo~dation I wr- $28 for regular subscriptions,and $23 for students sistence uncertain.