bluuebunny/crossref_metadata_2025 huggingface dataset:
Habitat Use and Movements of Two Ecotypes of Translocated Caribou in Idaho and British Columbia
Authors: Warren C.D. , Peek J.M. , Servheen G.L. , Zager P.
Published: March 2003

Two woodland caribou (Rangifer tarandus caribou) ecotypes, mountain and northern, were translocated to the southern Selkirk Mountains in northern Idaho (U.S.A.) to augment a remnant subpopulation. The translocation resulted in an additional subpopulation that used the general area of the release site. The mountain ecotype stock exhibited patterns of movement and habitat use similar to those of the resident subpopulation. The northern ecotype stock exhibited more variable habitat use, especially in the first year after translocation. Dispersal of the northern stock was not as extensive as that of the mountain stock. Fourteen of 22 caribou from the northern stock and 6 of 18 caribou from the mountain stock died during the 3‐year period after the release. Our results suggest that when donor subpopulations must be used that do not closely compare with resident subpopulations extinct or extant, larger numbers of individuals may be needed to establish a self‐sustaining population.
Mapping Conflicts Between Biodiversity and Human Needs in Langtang National Park, Nepal
Authors: Fox Jefferson , Yonzon Pralad , Podger Nancy
Published: March 2003

We mapped areas of congruence and conflict between the objectives of protecting red pandas (Ailurus fulgens) and meeting the claims and needs of people who live in and around Langtang National Park, Nepal. Semi‐structured interviews were used to solicit information on land‐use practices, and spatial information technology (sketch maps, satellite images, geographical information systems) was used to place these practices in a spatial context and to model the effects of grazing. Spatial information technology was useful for delineating areas where conflicts occur between the objectives of preserving biodiversity and meeting the needs of local residents. Despite the fact that villagers recognize pasture boundaries, rules and regulations govern pasture management, and sanctions are imposed on violators, over 60% of the red panda’s habitat is heavily grazed, and all available land within the study site suitable for grazing is already being used. The study suggests that common property management of natural resources to protect biodiversity (i.e., red pandas) and meet the needs of local people at the same time will be difficult.
Invasibility of Species‐Rich Communities in Riparian Zones
Authors: Planty‐Tabacchi Anne‐Marie , Tabacchi Eric , Naiman Robert J. , Deferrari Collette , Décamps Henri
Published: March 2003

Invasibility of riparian plant communities was estimated by the percentage of alien species found along the Adour River (Southwest France) and along Lockout Creek, McKenzie River, and Willamette River (Central Cascades, Oregon, U.S.A.). At the patch scale, the invasibilities of riparian plant communities were compared between one exceptionally rich site of the Adour River and patches selected in the Hoh and Dungeness watersheds (Olympic Peninsula, Washington, U.S.A.). Alien species represented 24% of 1396 species for the Adour and 30% of 851 species for the McKenzie. They represented 24% of 148 species for the Hoh drainage and 28% of 200 species for the Dungeness drainage. Similar trends were found along the Adour River and along the McKenzie River for changes in total number of species per site and in percentages of alien species per site. These trends may be related to the intermediate disturbance regimes and to the physical structure of the riparian corridors. Climatic and human factors are also involved in these longitudinal changes. Positive linear relationships were found between the total number of species and the percentage of aliens observed in each site. At the patch scale, most of the sampled communities contained alien species. Although mature vegetative patches appeared to be invasible, young communities contained more alien species than older ones. For entire corridors, a positive linear relationship was found between total species richness and percentage of alien species in each patch type for the richest site of the Adour River. This may be partially explained by landscape features considered in a successional context. We suggest the use of empirical rules, and stress the importance of riparian systems for monitoring the conservation of local and regional species pools are suggested.
Genetic Diversity and Population Size in Four Rare Southern Appalachian Plant Species
Authors: Godt Mary Jo W. , Johnson Bart R. , Hamrick J.L.
Published: March 2003

Allozyme diversity was examined in four rare, high‐montane plant species from the Appalachian Mountains of southeastern North America. These species may represent relictual members or descendants of an alpine community that was more widespread during the late Pleistocene. We sampled five populations of Geum radiatum (Rosaceae), Carex misera (Cyperaceae), Trichophorum cespitosum (Cyperaceae), and the four known populations of Calamagrostis cainii (Poaceae). Genetic diversity was low for all species but was typical of that found for plant species with limited ranges. Low genetic diversity may reflect historical events associated with changes in the species’ biogeography. As the Pleistocene climate warmed, suitable habitat decreased in areal extent and became fragmented, probably resulting in smaller, more‐isolated populations. In recent times these species, which co‐occur in fragile rock outcrop habitats, have been adversely affected by human activities. Genetic analyses revealed reduced diversity in populations of decreasing size for three species. Estimates of gene flow were low (Nm < 1.0) in all four species. Positive associations between genetic diversity and population size, evidence of recent population declines, and the low estimates of gene flow suggest that genetic drift may play a prominent role in shaping the present‐day genetic composition of these species. Furthermore, these data suggest that the genetically depauperate populations are unlikely to regain genetic variation without human intervention.
Crafting Effective Solutions to the Large Carnivore Conservation Problem
Authors: Clark Tim W. , Curlee A. Peyton , Reading Richard P.
Published: March 2003

How problems are defined and redefined largely dictates how they will (or if they can) be solved, especially complex problems such as the challenge of conserving large carnivores in North America. We describe a practical and comprehensive method for analyzing problems within specific human and ecological contexts and for inventing, evaluating, and selecting solutions. We conducted a problem definition exercise for the large carnivore conservation problem and arrived at five key variables that must be addressed in order to protect these threatened species: cultural history, valuation, ecology, management systems, and the policy process. Our analysis maps the broad dimensions of the problem and identifies areas to be targeted by any successful solution strategy. The method we present and our proposed initial definition of the carnivore conservation problem can serve as a springboard for further analysis and policy making at specific sites and at appropriate scales for on‐the‐ground solutions to this and other natural resource problems.
Biological, Conservation, and Ethical Implications of Exploiting and Controlling Wolves
Authors: Haber Gordon C.
Published: March 2003

The widespread claim that wolf populations can withstand 25–50% or greater annual reductions without major biological consequences is based primarily on the observation that populations often maintain their size from year to year as harvest or control continues or recover within a few years afterward. This emphasis on numerical status overlooks the likelihood of major, lingering impacts on the size, number, stability, and persistence of family‐group social units, on reproductive, hunting, and territorial behavior, on the role of learning and related traditions, on within‐ and between‐group patterns of genetic variation, and on overall mortality rates. The tendency of biologists and agencies in northern North America to promote wolf harvests that are four to eight times greater than ungulate harvests, in accord with the wolf versus ungulate difference in reproductive rates but contradictory to a broad array of differences in social organization and related behavior, is reason enough to question the logic of this prevailing management view. True sustained‐yield management requires more emphasis on qualitative biological features to determine the extent to which wolves and other species with evolutionary histories as predators rather than as prey should be harvested. Most recent government‐sponsored wolf control programs and proposals, including sterilization, relocation, and “redirected” killing, have been based on questionable claims about ungulate or livestock problems and have not adequately considered potential biological costs (especially to the target wolf populations), benefits, or management alternatives. The high sentience of wolves justifies overlapping biological‐ethical concerns about such programs and especially about the heavy, indiscriminate, deceptively reported public hunting and trapping of wolves that is currently permitted throughout most of Alaska (U.S.A.)—including in national parks—and elsewhere.
A Hierarchical View of Genetic Structure in the Rare Annual Plant Clarkia springvillensis
Authors: McCue Kimberlie A. , Buckler Edward S. , Holtsford Timothy P.
Published: March 2003

Genetic structure at several spatial scales was examined in the rare California annual, Clarkia springvillensis. Using seven isozyme‐encoding loci as genetic markers, we assessed the amount and distribution of genetic variation among three populations and eight subpopulations. Total genetic variation was lower than in species with similar life history traits but equivalent to that of other endemic plants. Spatial autocorrelation showed some evidence for very limited differentiation within subpopulations at a scale of 1–2 m. The subpopulations, separated by tens of meters, were found to be more differentiated from each other (Fsp = 0.084) on average than were populations (F,pt = 0.017). This local genetic differentiation was not correlated with physical distance between subpopulations. The low Fpt estimates suggest that substantial gene flow is occurring among populations. However, the lack of correlation between genetic and geographic distances and the significant differentiation of subpopulations suggest that genetic drift is occurring within populations. Therefore, we believe the apparent homogeneity of populations is due to each population’s gene frequencies’ being an average of several divergent subpopulations. If drift is causing differentiation within populations, it may eventually cause differentiation between populations. The importance of using a hierarchical approach to evaluating genetic structure is clear. Patterns occurring at one spatial scale may not be evident at others. One should not necessarily conclude that gene flow is substantial and that the risk of genetic erosion via drift is negligible just because differentiation between populations is small; the system may not be at equilibrium. This lesson is particularly important when recent changes in climate or land use are apparent.
A Decision‐Support System for Prioritizing Restoration Sites on the Mississippi River Alluvial Plain
Authors: Llewellyn Daniel W. , Shaffer Gary P. , Craig Nancy Jo , Creasman Lisa , Pashley David , Swan Mark , Brown Cindy
Published: March 2003

Conversion of forested wetlands to agricultural use and the resulting fragmentation of the landscape has led to concerns for the functional integrity of the Mississippi River Alluvial Plain ecosystem. We describe an effort spearheaded by The Nature Conservancy to initiate a multi‐decade partnership dedicated to creating and implementing a viable, cooperative, landscape‐level restoration project in the Mississippi River Alluvial Plain. Important phases of the process during the first 5 years were (1) initiation of the development of an extensive network of partners, including state and federal agencies, private land owners, conservation groups, academicians, and other interested citizens; (2) development of a geographic information system (GIS) for the entire extent of the ecosystem; and (3) for one watershed, the Tensas basin in northeastern Louisiana, refinement of a high resolution GIS to generate more detailed land‐use conversion statistics to demonstrate the feasibility of a semi‐objective, landscape‐scale restoration planning procedure, including methodology for prioritization of existing wetland forest patches and areas most suitable for reforestation and connection via corridors.
Regional Biodiversity Planning and Lemur Conservation with GIS in Western Madagascar
Authors: Smith A. P. , Horning N. , Moore D.
Published: March 2003

Primary forest cover in western Madagascar declined from 12.5% in 1950 to 2.8% in 1990. Approximately 23% of remaining forest is located within reserves, but this is no guarantee of protection. Forest cover in the Andranomena Reserve in western Madagascar has been reduced by 44% since 1950. The identification of priority areas for establishment of development projects has been constrained by lack of information on the distribution, abundance, and habitat requirements of threatened species and the size, condition, and threats to survival of forest remnants. We evaluate a rapid fauna survey and habitat modeling procedure specifically designed to generate information for reserve selection and design using Geographical Information Systems (GIS). The study was conducted in the largest remnant (94,000 ha) of primary monsoon rainforest in western Madagascar, using lemurs as an indicator group. Lemur abundance and microhabitat variables were measured at 64 stratified survey sites dispersed throughout the region. These records were incorporated into a GIS with other environmental and landuse data derived from maps and satellite imagery. Statistical procedures were applied to analyze species habitats, predict and map species distributions, and estimate species population sizes throughout the study area. Patterns of slash and burn agriculture and anthropogenic disturbance were also analyzed to identify areas at low risk of cultural disturbance. A map of disturbance risk was overlaid with a map of relative lemur biodiversity to identify conservation priority areas with high biodiversity and low risk of short term disturbance. Lemur diversity was most strongly influenced by habitat clearing and human disturbance (harvesting, stock grazing, and hunting) within 8 km of villages. Lemur diversity was highest in a region of higher elevation and rainfall, distant from villages and roads. The only existing reserve in the study area was located in a region of high disturbance risk. Almost half the reserve has been degraded during the past 45 years. There is considerable scope for re‐allocation of land use within the study area to include a core protected area, a buffer zone with controlled hunting and timber harvesting, and an adjacent ecotourism facility. We found that information generated by a stratified biodiversity and landuse survey at a sampling intensity of less than 0.1% was sufficient to provide an objective foundation for regional biodiversity planning.
Patterns of Rarity in the Birds of the Atlantic Forest of Brazil
Authors: Goerck Jaqueline M.
Published: March 2003

Patterns of rarity in species are generally explained by several factors: evolutionary history, spatial distribution, and genetic structure of each taxon. Human intervention also leads to or increases rarity in species. The discernment of causes of rarity is essential to the understanding of extinction patterns, and thus to devising conservation strategies. I examine patterns of rarity among bird species in the Atlantic forest region in Brazil, one of the most threatened ecosystems in the world. I assigned bird species to one of eight possible categories that differ in degree of vulnerability and that are based on three parameters of rarity: geographic distribution, habitat specificity, and population size. The Atlantic forest avifauna is a highly endangered group; 68% of the species are rare. Patterns of rarity among the birds in the region likely result from their specific ecologies or evolutionary histories. In addition, human alteration of natural habitats and hunting pressures have undoubtedly influenced rarity for a number of species.
Modeling the Persistence of Small Populations of Strongly Interdependent Species: Figs and Fig Wasps
Authors: Anstett Marie‐Charlotte , Hossaert‐McKey Martine , McKey Doyle
Published: March 2003

Conservation problems are usually studied at the population or ecosystem levels. Formulating predictive theory for the domain in between has been difficult. Fig trees and their pollinating wasps, principally tropical groups of organisms, form pairs of obligate mutualists that provide unique opportunities for studying the influence of species interactions on the survival of small populations. Survival of each partner depends on that of the associated species. The pollinator population can be maintained only if figs are produced year‐round. Because fig trees flower synchronously at the individual level, wasps have to locate a new individual host tree at each generation. We describe results of simulation models estimating the minimum number of trees required to maintain a wasp population using two levels of the criteria: (1) different probability of survival (50% and 99%) and (2) different time of survival (5 or 1000 years). We also examined how these different estimates are sensitive to differences in the seasonality of flowering period and in the length of the period of female receptivity in figs. Such estimates can be used to understand the potential effects of the reduction of fig population size via fragmentation. Unlike most studies on the effect of low population size on population viability, our paper focuses on maintenance of a biotic interaction, rather than on single‐species dynamics. The biotic interaction on which we focus is important because figs in many tropical ecosystems may be keystone resources for frugivores that are in turn essential seed dispersal agents for other plants.
The Influence of Model Structure on Conclusions about the Viability and Harvesting of Serengeti Wildebeest
Authors: Pascual Miguel A. , Kareiva Peter , Hilborn Ray
Published: March 2003

We investigate how the viability and harvestability predicted by population models are affected by details of model construction. Based on this analysis we discuss some of the pitfalls associated with the use of classical statistical techniques for resolving the uncertainties associated with modeling population dynamics. The management of the Serengeti wildebeest (Connochaetes taurinus) is used as a case study. We fitted a collection of age‐structured and unstructured models to a common set of available data and compared model predictions in terms of wildebeest viability and harvest. Models that depicted demographic processes in strikingly different ways fitted the data equally well. However, upon further analysis it became clear that models that fit the data equally well could nonetheless have very different management implications. In general, model structure had a much larger effect on viability analysis (e.g., time to collapse) than on optimal harvest analysis (e.g., harvest rate that maximizes harvest). Some modeling decisions, such as including age‐dependent fertility rates, did not affect management predictions, but others had a strong effect (e.g., choice of model structure). Because several suitable models of comparable complexity fitted the data equally well, traditional model selection methods based on the parsimony principle were not practical for judging the value of alternative models. Our results stress the need to implement analytical frameworks for population management that explicitly consider the uncertainty about the behavior of natural systems.
Population Viability Analysis of Spring Chinook Salmon in the South Umpqua River, Oregon
Authors: Ratner Susan , Lande Russell , Roper Brett B.
Published: March 2003

Run sizes of spring chinook salmon in the South Umpqua River in Oregon have declined dramatically since the early part of this century. Habitat degradation is thought to be an important factor contributing to the decline of this stock, and qualitative assessment suggests the stock is at moderate risk of extinction. We use data from this and similar stocks to develop an age‐structured, density‐dependent model of the population dynamics that incorporates both demographic and environmental stochasticity. Under the assumption of no further habitat destruction, the population is predicted to have a greater than 95% probability of persistence for 200 years. However, sensitivity analysis for the density‐dependence estimated from historical run‐return data shows that substantially lower predicted viabilities are also statistically consistent with the data. A model that simulates continued habitat degradation results in almost certain extinction within 100 years.
Plant Reproductive Traits as a Function of Local, Regional, and Global Abundance
Authors: Kunin William E. , Shmida Avi
Published: March 2003

Most ecological generalizations stem from the study of common organisms, but most species are rare. There are a number of reasons to expect that rare and common species may differ consistently in their characteristics, with possible implications for conservation. Past analyses of this issue, however, have generally considered only a single measure of rarity and have not corrected analyses for the lack of independence in the traits of related species. We compared several reproductive characteristics of Mediterranean annual crucifers as a function of their global range, regional abundance, and local population density in Israel, making use of independent contrast methods to correct for the phylogenetic relationships of the species involved. We found plants growing at low local density to be disproportionately likely to be self‐compatible. Petal length and floral depth (sepal length) were correlated with breeding system but showed significant interaction effects between breeding system and abundance. Floral longevity was inversely related to abundance and also showed significant interaction effects between breeding system and abundance. Overall, rare species tended to display more extreme values for floral traits than did common plants with the same breeding systems; they had unusually large and deep flowers if self‐incompatible and unusually small, shallow ones if self‐compatible.
Fitness in the Endangered Gila Topminnow
Authors: Sheffer Ruby J. , Hedrick Philip W. , Minckley W. L. , Velasco Anthony L.
Published: March 2003

The Gila topminnow (Poeciliopsis o. occidentalis) is a small, live‐bearing, endangered fish extant in a maximum of nine locales in four separate watersheds in the United States. To determine if these populations differed in their fitness, we obtained samples from the four watersheds and examined them for four fitness correlates: survival, growth rate, fecundity, and bilateral asymmetry. Earlier research found that one population, Sharp Spring, had higher allozyme heterozygosity than the other three and had higher survival, growth rate, and fecundity and lower bilateral asymmetry than a sample from one of the other populations with no polymorphic allozyme loci, Monkey Spring. We also verified that Sharp Spring fish were polymorphic for the same allozyme loci whereas the Monkey Spring population was not. We did not, however, find positive associations of allozyme heterozygosity with the four fitness correlates for the four samples. Because the earlier study had much lower survival, it is likely that the differences resulted from differential response of the two populations to a stressful laboratory environment. Whether this unknown stress occurs in natural environments or its effect is predictive of other stresses remains unresolved. As a result, we concur with suggestions in the draft recovery plan that topminnows from nearby sources be used for reintroductions and that the Sharp Spring stock not be used outside the upper Santa Cruz River drainage.
Conservation Implications of the Natural Loss of Lineages in Wild Mammals and Birds
Authors: Gompper Matthew E. , Stacey Peter B. , Berger Joel
Published: March 2003

Because populations in zoological parks and nature reserves often are derived from only a few individuals, conservationists have attempted to minimize founder effects by equalizing family group sizes and increasing the reproductive contributions of all individuals. Although such programs reduce potential losses of genetic diversity, information is rarely available about the actual persistence of family groups or genetic lineages in natural populations. In the absence of such data, it can be difficult to weigh the importance of human intervention in the conservation of small populations. Separate long‐term studies of two mammals, the North American bison (Bison bison) and the white‐nosed coati (Nasua narica), and a bird, the Acorn Woodpecker (Melanerpes formicivorus), demonstrate differential extinction of genetic lineages. Irrespective of the mechanisms affecting population structure, which may range from stochastic environmental events to such behavioral phenomena as poor intrasexual competitive abilities, our results show that lineages can be lost at rapid rates from natural populations. A survey of comparable studies from the literature indicates that the loss of matrilines over the course of the study varies from 3% to 87% in wild mammals and from 30% to 80% in birds, with several small mammals losing approximately 20% of matrilines per year of study. These lineage extinctions were not an artifact of the length of the study or the generation time of the species. Such rapid losses of lineages in less than 20‐year periods in natural populations suggest that efforts to maintain maximal genetic diversity within populations may not always reflect processes that occur in the wild. Conservation biologists need to give further thought to the extent to which parity among genetic lines should be a primary goal of management of captive and small wild populations.
Focal Species: A Multi‐Species Umbrella for Nature Conservation
Authors: Lambeck Robert J.
Published: March 2003

To prevent the further loss of species from landscapes used for productive enterprises such as agriculture, forestry, and grazing, it is necessary to determine the composition, quantity, and configuration of landscape elements required to meet the needs of the species present. I present a multi‐species approach for defining the attributes required to meet the needs of the biota in a landscape and the management regimes that should be applied. The approach builds on the concept of umbrella species, whose requirements are believed to encapsulate the needs of other species. It identifies a suite of “focal species,” each of which is used to define different spatial and compositional attributes that must be present in a landscape and their appropriate management regimes. All species considered at risk are grouped according to the processes that threaten their persistence. These threats may include habitat loss, habitat fragmentation, weed invasion, and fire. Within each group, the species most sensitive to the threat is used to define the minimum acceptable level at which that threat can occur. For example, the area requirements of the species most limited by the availability of particular habitats will define the minimum suitable area of those habitat types; the requirements of the most dispersal‐limited species will define the attributes of connecting vegetation; species reliant on critical resources will define essential compositional attributes; and species whose populations are limited by processes such as fire, predation, or weed invasion will define the levels at which these processes must be managed. For each relevant landscape parameter, the species with the most demanding requirements for that parameter is used to define its minimum acceptable value. Because the most demanding species are selected, a landscape designed and managed to meet their needs will encompass the requirements of all other species.
Vascular Plant Diversity as a Surrogate for Bryophyte and Lichen Diversity
Authors: Pharo Emma J. , Beattie Andrew J. , Binns Doug
Published: March 2003

Abstract:An important issue in conservation biology is the extent to which one group of organisms can function as a surrogate for less well‐known groups. We explored the extent to which vascular plant species diversity (both α‐diversity, or species richness, and β‐diversity, or turnover) and the subgroups of understory, overstory, and ferns can act as surrogates for bryophyte and lichen species diversity. We surveyed 35 sites in a range of forest types in the coastal lowlands of eastern Australia. Fern species richness was strongly positively correlated with bryophyte species richness but negatively correlated with lichen species richness. Fern, bryophyte, and lichen species richness all varied significantly with time since fire, vascular plant cover, and topographic position gradients. Of the other vascular plant groups, the only significant correlation was between overstory and bryophyte species richness. We quantified species turnover using modifications of Whittaker’s original measure as well as multivariate techniques. The rate of lichen species turnover was the lowest of all six groups investigated. The other five groups had similar rates of species turnover, although the results were different depending on the emphasis of the measure used. There were significant correlations between the patterns of species turnover of bryophytes and lichens and those of all four vascular plant groups, but none of the correlations was particularly strong. The understory and all vascular plants were the best predictors of the species turnover pattern of bryophytes and lichens, and correlations appeared strongest in wet sclerophyll sites. With respect to management practices, time since the last fire appears to be an important determinant of bryophyte, lichen, and vascular plant diversity, and logging appears to differentially affect the diversity of the different plant categories. A mosaic of logging and fire intervals and intensities appears to be important for maintaining regional diversity.
The Relative Impacts of Nest Predation and Brood Parasitism on Seasonal Fecundity in Songbirds
Authors: Schmidt Kenneth A. , Whelan Christopher J.
Published: March 2003

The impacts of nest predation and brood parasitism on the seasonal fecundity of birds are strongly dependent on the number of nesting attempts, and thus seasonal fecundity is responsive to behavioral traits that increase the number of opportunities to nest. We developed simple models to investigate the relative impacts of nest predation and brood parasitism on seasonal fecundity in songbirds. In particular, we asked to what extent songbirds can ameliorate the negative effects of high nest predation and brood parasitism often typical of fragmented, urbanized, and agricultural landscapes through (1) renesting following predation, (2) abandoning and renesting following parasitism, and (3) double brooding—renesting following a successful brood. Our model assigned probabilities to all possible fates of breeding females and calculated seasonal fecundity by summing up the individual probabilities. We analyzed the model through the use of fecundity isopleths, which allow one to visually determine the impact of predation and parasitism simultaneously over the entire range of probabilities. Our analysis indicates that (1) nest predation has a greater impact on seasonal fecundity over a larger range of parameter space than does parasitism, especially when brood loss due to parasitism is low; (2) songbird populations experiencing nest predation probabilities typical of fragmented landscapes (>0.65) are unlikely to be self‐sustaining; and (3) amelioration of nest predation through frequent renesting or double brooding may be insufficient to establish self‐sustaining populations. These results suggest that predator control should be at least as high a priority as parasitism control, particularly for species that suffer moderate to low brood reduction due to parasitism and that are single‐brooded. Programs aimed solely at managing cowbirds likely will be of limited success.
Biodiversity Conservation in Traditional Coffee Systems of Mexico
Authors: Moguel Patricia , Toledo Victor M.
Published: March 2003

In Mexico, coffee is cultivated on the coastal slopes of the central and southern parts of the country in areas where two or more types of vegetation make contact. Based on management level and vegetational and structural complexity, it is possible to distinguish five main coffee production systems in Mexico: two kinds of traditional shaded agroforests (with native trees), one commercially oriented polyspecific shaded system, and two “modern” systems (shaded and unshaded monocultures). Traditional shaded coffee is cultivated principally by small‐scale, community‐based growers, most of whom belong to some indigenous culture group. Through an exhaustive review of the literature, we found that traditional shaded coffee plantations are important repositories of biological richness for groups such as trees and epiphytes, mammals, birds, reptiles, amphibians, and arthropods. We evaluated the conservation role of these traditional shaded systems by estimating the percentage of the whole coffee area under traditional management, by reviewing the ecological and geographical distribution of coffee areas in Mexico, and by connecting the geographical distribution of these coffee areas with recognized centers of species richness and endemism. The assesment revealed that in Mexico, coffee fields are located in a biogeographically and ecologically strategic elevational belt that is an area of overlap between the tropical and temperate elements and of contact among the four main types of Mexican forests. We also found that between 60% and 70% of these coffee areas are under traditional management and that at least 14 of 155 priority regions selected by experts as having high numbers of species and endemics overlap with or are near traditional coffee‐growing areas.
Current Normative Concepts in Conservation
Authors: Callicott J. Baird , Crowder Larry B. , Mumford Karen
Published: March 2003

A plethora of normative conservation concepts have recently emerged, most of which are ill‐defined: biological diversity, biological integrity, ecological restoration, ecological services, ecological rehabilitation, ecological sustainability, sustainable development, ecosystem health, ecosystem management, adaptive management, and keystone species are salient among them. These normative concepts can be organized and interpreted by reference to two new schools of conservation philosophy, compositionalism and functionalism. The former comprehends nature primarily by means of evolutionary ecology and considers Homo sapiens separate from nature. The latter comprehends nature primarily by means of ecosystem ecology and considers Homo sapiens a part of nature. Biological diversity, biological integrity, and ecological restoration belong primarily in the compositionalist glossary; the rest belong primarily in the functionalist glossary. The former set are more appropriate norms for reserves, the latter for areas that are humanly inhabited and exploited. In contrast to the older schools of conservation philosophy, preservationism and resourcism, compositionalism and functionalism are complementary, not competitive and mutually exclusive. As the historically divergent ecological sciences—evolutionary ecology and ecosystem ecology—are increasingly synthesized, a more unified philosophy of conservation can be envisioned.
Guidelines for Subspecific Substitutions in Wildlife Restoration Projects
Authors: Seddon Philip J. , Soorae Pritpal S.
Published: March 2003

Reintroduction of animals is becoming increasingly popular as a means of restoring populations of threatened species. Sometimes depletion of wild populations leaves only captive populations from which reintroduction projects can obtain founders for releases. The World Conservation Union guidelines on reintroductions recommend that the individuals to be reintroduced should be of the same subspecies as those that were extirpated. In some cases, however, a subspecies may have become extinct in the wild and in captivity. A substitute form may then be chosen for possible release. Such substitutions are actually a form of benign introduction. Considerations include assessment of the value of a substitution project and the selection of a suitable substitute. Species substitutions increase biodiversity, conserve related forms, improve public awareness of conservation issues, educate the public, and may be implemented for aesthetic or economic reasons. Selection of a suitable substitute should focus on extant subspecies and consider genetic relatedness, phenotype, ecological compatibility, and conservation value of potential candidates. An example of a substitution project is the reintroduction of the North African Red‐necked Ostrich ( Struthio camelus camelus) into areas once occupied by the now extinct Arabian Ostrich ( Struthio camelus syriacus). S. c. camelus was chosen as a substitute because of its geographic proximity, phenotypic similarity, and conservation value. The World Conservation Union’s reintroduction guidelines should be consulted before a project is begun.
Evaluating Costs of Conservation
Authors: Main Martin B. , Roka Fritz M. , Noss Reed F.
Published: March 2003

Abstract: The loss and fragmentation of native habitats caused by agricultural development and conversion of agricultural lands into urban sprawl are widely recognized as the most serious modern threats to the conservation of biodiversity. Regulatory mechanisms have been heavily relied upon but largely ineffective at preventing the loss of wildlife habitat and the decline of endangered species, particularly on private lands. Land acquisition and permanent conservation easements may be more reliable conservation tools, but they are often incompatible with the desires of private landowners and rural communities. We describe resource conservation agreements ( RCAs), an incentive‐based alternative that provides private landowners compensation for the agricultural and nonagricultural development potential of their land in exchange for conserving and managing wildlife habitat. We evaluated the public costs of managing 356,038 ha of existing public lands in southwest Florida critical to the survival of the Florida panther (  Puma concolor coryi). We also reviewed the costs of public ownership, permanent conservation easements, and RCAs for approximately 200,000 ha of priority panther habitat under public ownership in southwest Florida. Assuming a 3.65% nominal interest rate and an infinite life of public ownership, we estimated current annualized expenditures for public ownership as U.S. $69/ha/year. In comparison, estimated costs to purchase and manage ($174–297/ha/year) or enter into permanent conservation easements ($116–208/ha/year) on privately owned, priority panther habitat were much greater. The disparity between the costs of public ownership for existing public lands and those estimated for privately owned lands was due to greater agricultural and residential development potential on the privately owned lands. The mean purchase price for the public lands reviewed was $1291/ha, whereas the estimated average value of privately owned priority panther habitat was $4744–7401/ha. The estimated cost of RCA on private lands was $74–82/ha/year. The estimated cost of RCA was roughly equivalent to current expenditures for the public lands we reviewed, 200–400% less expensive than the estimated cost of purchasing privately owned lands and 200–300% less expensive than the estimated cost of permanent conservation easements to conserve privately owned priority panther habitat in southwest Florida.
Dispersal in Spatially Explicit Population Models
Authors: South Andy
Published: March 2003

Abstract: Ruckelshaus et al. (1997) outlined a simulation model of dispersal between patches in a fragmented landscape. They showed that dispersal success—the proportion of dispersers successfully locating a patch—was particularly sensitive to errors in dispersal mortality and concluded that this limits the utility of spatially explicit population models in conservation biology. I contend that, although they explored error propagation in a simple dispersal model, they did not explore how errors are propagated in spatially explicit population models, as no consideration of population processes was included. I developed a simple simulation model to investigate the effect of varying dispersal success on predictions of patch occupancy and population viability, the conventional outputs of spatially explicit population models. The model simulates births and deaths within habitat patches and dispersal as the transfer of individuals between them. Model predictions were sensitive to changes in dispersal success across a restricted range of within‐patch growth rates, which depended on the dispersal initiation mechanism, patch carrying capacities, and number of generations simulated. Predictions of persistence and patch occupancy were generally more sensitive to changes in dispersal success (1) under presaturation rather than saturation dispersal; (2) at lower patch carrying capacities; and (3) over longer time periods. The framework I present provides a means of assessing, quantitatively, the regions of parameter space for which differences in dispersal success are likely to have a large effect on population model outputs. Investigating the effect of the representation of dispersal behavior within the demographic and landscape context provides a more useful assessment of whether our lack of knowledge is likely to cause unacceptable uncertainty in the predictions of spatially explicit population models.
Mitochondrial DNA Phylogeography and the Conservation of Endangered Lesser AntilleanIcterusOrioles
Authors: Lovette Irby J. , Bermingham Eldredge , Ricklefs Robert E.
Published: March 2003

Abstract:Recent natural and anthropogenic disturbances have endangered two of the three oriole species endemic to single islands in the Lesser Antilles. The ongoing eruption of the Soufriere Hills volcano may have doomed the Montserrat Oriole (  Icterus oberi), whereas high levels of nest parasitism by a cowbird threaten the Martinique Oriole (  I. bonana). These orioles and related Antillean and Central American forms have been considered part of theIcterus dominicensissuperspecies complex, but the taxonomic status of the different Antillean island populations has been long debated. To investigate levels of evolutionary differentiation among threatened Lesser Antillean orioles, we analyzed 2507 nucleotides of protein‐coding mitochondrial DNA (mtDNA) sequence from orioles on Martinique, Montserrat, St. Lucia (  I. laudabilis), Puerto Rico (  I. dominicensis dominicensis), Mexico (  I. d. prosthemelas), and threeIcterusoutgroup species. Phylogenetic analyses of the mtDNA data supported the monophyly of Antillean members of theI. dominicensiscomplex and identified a star‐like pattern of relationship among them. Mitochondrial distances between the Antillean populations were large (4.5–5.8% nucleotide divergence) and suggested that the Lesser Antillean orioles have been isolated evolutionarily from one another since the late Pliocene. The oriole taxa on Montserrat, Martinique, and St. Lucia meet species criteria under the phylogenetic species concept and represent evolutionarily significant units. The impending extinction of the phylogenetically unique Montserrat oriole highlights the vulnerability of island endemics to habitat degradation followed by rare and unpredictable natural catastrophes.
Defining Corridor Functions for Endemic Birds in Fragmented South‐Temperate Rainforest
Authors: Sieving Kathryn E. , Willson Mary F. , De Santo Toni L.
Published: March 2003

Abstract: For five species of endemic understory birds (  families Rhinocryptidae, Furnariidae) inhabiting fragmented temperate rainforest in southcentral Chile, we distinguished between vegetated corridors functioning as living space and those potentially suitable for short‐distance movements only. In the first phase of the study, we surveyed 24 forested corridors ≤50 m wide using passive and song‐playback censuses. Corridor width determined species presence or absence, whereas the number of individuals increased with width and understory vegetation density. Birds were infrequently encountered in corridors ≤10 m wide but were always present in corridors 25–50 m wide. Birds present in intermediate‐width (11–24 m) corridors were detected significantly less often during passive than playback census, suggesting that these birds exhibited conspicuous territorial display less frequently than those present in wider corridors, where passive and playback census yielded similar detection rates. Corridors approximately 10–25 m wide, therefore, may be transitional between corridors too narrow for most regular uses and those sufficiently wide for birds to establish territories. Also, bird abundance decreased as the ratio of corridor length to width ( L /  W) increased. Almost no birds were detected in corridors with L / W ≥ 10, suggesting the existence of a threshold value for the influence of L / W on corridor use. In the second phase of the study, taped‐song playback experiments in corridors ≤10 m wide showed that all five species traveled in them for short distances: 52% of respondents moved up to 50 m from forest patches into narrow corridors. Availability of dense understory vegetation was the primary predictor of birds' responses to playback and may determine their willingness to use minimal corridors for short movements. We suggest that corridors for endemic rainforest‐understory birds living in agricultural landscapes of southern Chile can be designed to fulfill distinct functions.
Effects of Subsistence Hunting on Vertebrate Community Structure in Amazonian Forests
Authors: Peres Carlos A.
Published: March 2003

Abstract: Subsistence hunting affects vast tracts of tropical wilderness that otherwise remain structurally unaltered, yet distinguishing hunted from nonhunted tropical forests presents a difficult problem because this diffuse form of resource extraction leaves few visible signs of its occurrence. I used a standardized series of line‐transect censuses conducted over a 10‐year period to examine the effects of subsistence game harvest on the structure of vertebrate communities in 25 Amazonian forest sites subjected to varying levels of hunting pressure. Crude vertebrate biomass, which was highly correlated with hunting pressure, gradually declined from nearly 1200 kg km−2 at nonhunted sites to less than 200 kg km−2 at heavily hunted sites. Hunting had a negative effect on the total biomass and relative abundance of vertebrate species in different size classes at these forest sites, but it did not affect their overall density. In particular, persistent hunting markedly reduced the density of large‐bodied game species (>5 kg), which contributed a large proportion of the overall community biomass at nonhunted sites (65–78%) and lightly hunted sites (55–71%). Nutrient‐rich floodplain forests contained a consistently greater game biomass than nutrient‐poor unflooded forests, once I controlled for the effects of hunting pressure. Conservative estimates of game yields indicate that as many as 23.5 million game vertebrates, equivalent to 89,224 tons of bushmeat with a market value of US$190.7 million, are consumed each year by the rural population of Brazilian Amazonia, which illustrates the enormous socioeconomic value of game resources in the region. My cross‐site comparison documents the staggering effect of subsistence hunters on tropical forest vertebrate communities and highlights the importance of considering forest types and forest productivity in game management programs.