bluuebunny/crossref_metadata_2025 huggingface dataset:
Forest‐Dwelling Native Amazonians and the Conservation of Biodiversity: Interests in Common or in Collision?
Authors: Redford Kent H. , Stearman Allyn Maclean
Published: March 2003

Although concern for biodiversity and its conservation originated in the biological sciences, with growing international interest an increasing number of interest groups are claiming standing in discussions of the best ways to conserve biodiversity. One of these groups, formed by various indigenous peoples and their advocates, has repeatedly defended its claim to standing by stating that indigenous peoples are well equipped to conserve biodiversity. These claims have had far‐reaching consequences, as millions of hectares of Amazonian forest have been deeded to indigenous groups, at least partially on the reasoning that such actions would conserve biodiversity. In this paper, we bring to the attention of the community of conservation biologists a group representing 229 native Amazonian groups comprising 1.2 million people in Peru, Bolivia, Ecuador, Brazil, and Colombia. In a document entitled “To the Community of Concerned Environmentalists,” this group of indigenous peoples proposes a broad template for cooperation between conservation biologists and the indigenous peoples of the Amazon Basin. Following reiteration of the statement, we discuss the fact that these two groups define biodiversity and its conservation in different ways, with indigenous peoples focusing more on preservation of general habitat characteristics and exclusion of extensive habitat alteration. We conclude that the interests of conservation biologists may not be completely compatible with the agenda of indigenous peoples and their advocates but that by cooperating valuable time is being bought by both sides.
Modified Cave Entrances: Thermal Effect on Body Mass and Resulting Decline of Endangered Indiana Bats (Myotis sodalis)
Authors: Richter Andreas R. , Humphrey Stephen R. , Cope James B. , Brack Virgil
Published: March 2003

Entrances to many caves occupied by the endangered Indiana bat (Myotis sodalis) have been modified to control human access. We show that modifying cave entrances can degrade the bats’ winter habitat, we demonstrate one mechanism by which this damage occurs, and we document a restoration experiment. We compared a large bar population in an unmodified cave with a small, reduced bat population in a cave with warm winter temperatures resulting from an entrance wall that impeded air exchange. In the modified cave, mean winter temperature at the hibernation site was 5.0° C higher than in the unmodified cave, bats entered hibernation at a 5% higher body mass, bats lost 42% more mass and the frequency distribution of late‐winter mass was truncated, with no bats weighing less than 5.4 g. The results describe unacceptable extremes for hibernation: subfreezing temperatures and warm temperatures causing mass‐loss rates of more than 0.009 g/day. Over a decade following removal of the entrance‐constricting wall, the population increased from 2,000 to 13,000 bats. Previous recommendations, based on common‐sense observation, to open blocked cave entrances are confirmed by this study. The similar case of Coach Cave, Kentucky, offers the potential for recovery of 100,000 Indiana bats.
Effects of Clear‐Cut Harvesting on Boreal Ground‐Beetle Assemblages (Coleoptera: Carabidae) in Western Canada
Authors: Niemelä Jari , Langor David , Spence John R.
Published: March 2003

We compared pitfall catches from four types of mature lodgepole pine—white spruce forest with those from five age classes of young forest regenerating subsequent to clear‐cutting. Ground beetles were most abundant in the youngest sites (1–2 years since cutting) and in the mature stands on moist soil. Species richness was higher in regenerating sites than in mature forest. Cluster analysis grouped the ground‐beetle fauna according to forest age and forest type, suggesting that there is a general pattern of recovery after logging. Responses of common species to forest cutting fell into three groups: (1) forest generalists (2 species) were not dramatically affected, (2) species of open habitat (27 species) appeared and/or increased in abundance, and (3) mature forest species (10 species) disappeared or decreased in abundance. Populations of many mature forest species appear to recover following logging, but several specialists did not recolonize even the oldest regenerating stands. Furthermore, fragmentation and creation of large areas of relatively homogeneous young forest stages through logging may have detrimental long‐term effects even on the more abundant forest generalists. We must better understand subtle variations in habitat in order to maintain invertebrate diversity while harvesting the boreal forest.
A Possible Method for the Rapid Assessment of Biodiversity
Authors: Oliver Ian , Beattie Andrew J.
Published: March 2003

Inventories of vertebrate and flowering plants are frequently used as surrogates for estimates of total biodiversity. This is in part because the inclusion of invertebrates and nonflowering plants is perceived as being too time‐consuming, costly, and difficult because of the shortage of specialists. Estimates of the species richness of field samples of spiders, ants, polychaetes, and mosses made by a biodiversity technician and by specialist taxonomists were compared. The biodiversity technician received a few hours training in the taxonomy of each group and separated specimens into recognizable taxonomic units (RTUs). The specialists sorted to species. For the three animal groups the biodiversity technician recorded 165 taxa and the specialists 147, with the error for the ants and spiders being 13% or less. A small amount of splitting and lumping of species was detected. The concordance of estimates remained very similar when small subsamples were used. The procedure was repeated by 13 undergraduates using a subsample of spiders. Their average error was 14.4%. The greatest similarity in estimates was for the mosses, but with high levels of splitting and lumping this result was entirely fortuitous. The results suggest that RTU estimates made by biodiversity technicians may be sufficiently close to formal taxonomic estimates of species richness to be useful for the rapid assessment of biodiversity. They also show, however, that the procedures outlined here should be used on invertebrate and nonflowering plant groups before they can be confidently included in biodiversity surveys.
An Ecological Evaluation of Proposed New Conservation Areas in Idaho: Evaluating Proposed Idaho National Parks
Authors: Wright R. Gerald , MacCracken James G. , Hall Joel
Published: March 2003

Four areas in the state of Idaho, U.S.A., have been proposed by various interest groups to be designated as national parks. The four areas average 220,000 ha and contain important biological, scenic, recreational, and geological resources. However, the biological resources that would be protected by these proposals have received relatively little consideration. We used the U.S. Fish and Wildlife Service’s Gap Analysis Project databases to evaluate the vegetation types contained in each proposal. The scale of analysis was an ecoregion with the proposals falling within three of six ecoregions that encompass Idaho. Databases included vegetation type, land ownership, and land protection status, which were analyzed using a geographic information system. Vegetation types were used as surrogates for information on the distribution of other biological resources (ie., biodiversity). A conservation strategy was evaluated that would preserve at least 10% of each vegetation type in an ecoregion. Only 15% of the vegetation types in the three ecoregions were protected under this criterion. The four proposals added little to this figure because 67–78% of the vegetation types found in the proposals were already protected elsewhere in each ecoregion. Between 16–30% of the land areas in the proposals provided protection for vegetation types that were previously unprotected. We increased the size of each proposal by including vegetation types in a 15 km zone around each proposal in an attempt to enhance protection. None of the proposals could be feasibly modified to reach the 10% protection goal for all of the vegetation types. However, the protection provided by each proposal could be enhanced to varying degrees with the addition of relatively few hectares to their land area. Although national parks throughout the world play an important role in the conservation of biodiversity, this attribute is often accidental, and as our analysis showed, more attention needs to be devoted to biological data in the selection and design of new parks.
A Test of the Vegetation Mosaic Hypothesis: A Hypothesis to Explain the Decline and Extinction of Australian Mammals
Authors: Short Jeff , Turner Bruce
Published: March 2003

The vegetation mosaic hypothesis suggests that medium‐sized mammals occupying arid and semi‐arid areas of Australia require a habitat that is a fine‐grained mosaic of different vegetation types or seral stages. This mosaic is believed to have been created in the spinifex deserts of central Australia by Aboriginal burning practices. Its loss in the period 1940–1960 is postulated to be a primary reason for both major reductions in range and mainland extinctions of many species of medium‐sized mammals at this time. This study measured the responses of three species of medium‐sized mammals to vegetation patterns within spinifex grasslands that ranged from comparatively uniform to highly diverse. The abundance, condition, and reproductive status of golden bandicoots (Isoodon auratus), northern brush‐tailed possums (Trichosurus vulpecula arnhemensis), and burrowing bettongs (Bettongia lesueur) were assessed within vegetation mosaics of various scales on Barrow Island, off the northwest coast of Australia. Scale of mosaic proved to have no significant effect on the numbers, condition, or reproductive status of any of the three species. Similarly, the creation of fine‐grained mosaics of early seral‐stage vegetation mixed within climax vegetation by extensive oil‐field operations over nearly half the island had no significant effect on the number or condition of animals. Hence, scale of mosaic seems unlikely to be related to the mainland decline or extinction of these species. The pattern of decline and extinction on the mainland but continued survival on offshore islands is more consistent with the presence (mainland) or absence (islands) of introduced predators (foxes and cats) and herbivores (rabbits and stock).
On the Origin of Brucellosis in Bison of Yellowstone National Park: A Review
Authors: Meagher Mary , Meyer Margaret E.
Published: March 2003

Brucellosis caused by Brucella abortus occurs in the free‐ranging bison (Bison bison) of Yellowstone and Wood Buffalo National Parks and in elk (Cervus elaphus) of the Greater Yellowstone Area. As a result of nationwide bovine brucellosis eradication programs, states and provinces proximate to the national parks are considered free of bovine brucellosis. Thus, increased attention has been focused on the wildlife within these areas as potential reservoirs for transmission to cattle. Because the national parks are mandated as natural areas, the question has been raised as to whether Brucella abortus is endogenous or exogenous to bison, particularly for Yellowstone National Park. We synthesized diverse lines of inquiry, including the evolutionary history of both bison and Brucella, wild animals as Brucella hosts, biochemical and genetic information, behavioral characteristics of host and organism, and area history to develop an evaluation of the question for the National Park Service. All lines of inquiry indicated that the organism was introduced to North America with cattle, and that the introduction into the Yellowstone bison probably was directly from cattle shortly before 1917. Fistulous withers of horses was a less likely possibility. Elk on winter feedgrounds south of Yellowstone National Park apparently acquired the disease directly from cattle. Bison presently using Grand Teton National Park probably acquired brucellosis from feedground elk.
Phenotypic Alterations, Evolutionarily Significant Structures, and Rhino Conservation
Authors: Berger Joel , Cunningham Carol
Published: March 2003

To slow the impending loss of wild black (Diceros bicornis) and white (Ceratotherium simum) rhinos, three African countries have resorted to dehorning, a practice designed to remove the incentive for poachers to kill the hornless animals. The efficacy of this controversial conservation action remains unknown, in part because much uncertainty exists about the functional significance of rhino horns. We assessed the current utility of horns in Namibian black rhinos from phenotypically altered and intact populations in the Namib Desert, and we collated data on mortal fighting among horned females living in Etosha National Park. Infant mortality was 100% when dehorned mothers were sympatric with spotted hyenas (Crocuta crocuta). In contrast, infant survival was 100% for both horned mothers living with hyenas and occasional lions (Panthera leo) and 100% for dehorned mothers in the absence of dangerous carnivores. These data suggest that female horns can have direct fitness benefits in terms of calf survival. However, because lethal wounding due to fighting may account for up to 33% of the mortality of horned females, dehorning may improve adult survivorship. Our results (1) suggest that, where the aim of conservation programs is to improve population viability through juvenile recruitment, dehorning is unlikely to be a prudent strategy if practiced in areas with dangerous predators, and (2) illustrate the value of experimental approaches to onerous problems in conservation.
Large Herbivores and the Design of Large‐Scale Nature Reserves in Western Europe
Authors: De Vires Michiel F.
Published: March 2003

Nature conservation in densely populated areas, as in western Europe, faces the continuous loss and fragmentation of suitable habitats for wild species. Current conservation measures have not been successful in countering this threat to biological diversity, so a new concept for nature conservation is required. I propose using the habitat requirements of large herbivores as a key to the design of large‐scale nature reserves. Large herbivores can have a significant influence on vegetation composition and thus act as keystone species. Moreover, they require large tracts of land and can be considered an umbrella species group for the preservation of other plants and animals. I review the present status of nature reserves in the European Union concerning size distribution and the occurrence of large herbivores and their predators. I argue that habitat fragmentation and the increased management costs of maintaining seminatural areas necessitate an enlargement of existing reserves, a process‐oriented management approach, and a minimization of human influence for the long‐term preservation of biological diversity.
Global Patterns of Mammalian Diversity, Endemism, and Endangerment
Authors: Ceballos Gerardo , Brown James H.
Published: March 2003

To assess the conservation status of the world’s land mammals, we compiled data on the number of total species, endemic species, recently extinct species, and currently endangered species for 155 countries. Total species richness was significantly correlated with territorial land area, whereas number of endemic species was only weakly correlated with both area and total number of species. The large amount of variation left unexplained by species‐area regressions reflects the influence of other factors, such as latitude, topographic and habitat heterogeneity, and historical biogeography, on species richness and especially on patterns of endemism. Countries of particular conservation concern, because they have rich mammalian faunas containing many endemic species, are the large islands of Australia, Madagascar, Indonesia, and the Philippines, as well as continental Mexico. Patterns of recent extinctions and the current endangered status of species were difficult to interpret, largely because of inadequate and inconsistent data. The majority of officially listed endangered species are large, well known, and popular mammals, such as primates, ungulates, and carnivores, whereas the majority of species known to have gone recently extinct and likely to be currently threatened are small and inconspicuous, such as rodents and bats. Our work not only illustrates the role of ecological, evolutionary, and biogeographic processes in the origin and maintenance of land mammal diversity, it also presents the information at the level of biogeographic regions and political units where management and policy must be applied in order to slow the loss of this diversity.
Index of Biotic Integrity Based on Fish Assemblages for the Conservation of Streams and Rivers in West‐Central Mexico
Authors: Lyons John , Navarro‐Pérez Sonia , Cochran Philip A. , Santana Eduardo C. , Guzmán‐Arroyo Manuel
Published: March 2003

The rivers and streams of west‐central Mexico are becoming increasingly degraded and warrant expanded conservation efforts. We have developed an index of biotic integrity based on fish assemblage characteristics to aid in the preservation of the biological integrity and biodiversity of these waters. Our version is an adaptation of previous versions of the index of biotic integrity, which have proven effective in environmental assessment and monitoring in the United States and elsewhere. It consists of 10 fish assemblage attributes, termed metrics, that are related to environmental quality, ecosystem integrity, and biodiversity in west‐central Mexican streams and rivers: number of native species, percentage of benthic species, number of water column species, number of sensitive species, percentage of tolerant species, percentage of exotic species, percentage of omnivores, percentage of native livebearing species, relative abundance, and percentage of diseased or deformed. Data on fish communities from 27 sites on streams and small rivers in the vicinity of the Sierra de Manantlán, southwestern Jalisco, and in the upper Río Duero basin, northern Michoacán, were used to develop expectations and scoring criteria for each metric. The index value for a site was the sum of the scores for the 10 metrics. Index values and associated ratings of biotic integrity for the 27 sites corresponded closely with independent ratings based on habitat and water quality. However, additional tests of the index with independent data and refinement of metrics and scoring criteria are clearly warranted. The index shows promise for identifying key watersheds for the protection of intact native biotic communities and individual endangered and threatened species and for the long‐term monitoring and evaluation of biodiversity and ecosystem integrity in the streams and rivers of west‐central Mexico. Our version could serve as a model for the development of similar indices for other regions and other types of aquatic ecosystems in Mesoamerica.
Ecology and Conservation of the Endangered American Burying Beetle (Nicrophorus americanus)
Authors: Lomolino Mark V. , Creighton J. Curtis , Schnell Gary D. , Certain David L.
Published: March 2003

Field studies were conducted on the western population of the endangered American burying beetle (Nicrophorus americanus) in Oklahoma and Arkansas to determine its habitat affinities. A common cause of declining populations is some specialized adaptation that makes it difficult to respond to a rapidly changing habitat. We evaluated the hypothesis that N. americanus is a habitat specialist in its search for food, preferring mature forests with deep, humic soils. This hypothesis was rejected. Based on comparisons of niche breadth among syntopic congeners and niche overlap, N. americanus is relatively generalized in its use of a range of habitats when searching for food. It is likely that the generalist nature and the endangered status of N. americanus both derive from the fact that it is the largest member of its guild. In comparison to smaller species, N. americanus breeds on larger carcasses, which are more unpredictable in space and time. It is likely, therefore, that N. americanus must search over a larger area and greater diversity of habitats than its smaller congeners.
An Integrated Approach to the Ecology and Management of Plant Invasions
Authors: Hobbs Richard J. , Humphries Stella E.
Published: March 2003

Plant invasions are a serious threat to natural and managed ecosystems worldwide. The number of species involved and the extent of existing invasions renders the problem virtually intractable, and it is likely to worsen as more species are introduced to new habitats and more existing invaders move into a phase of rapid spread. We contend that current research and management approaches are inadequate to tackle the problem. The current focus is mostly on the characteristics and control of individual invading species. Much can be gained, however, by considering other important components of the invasion problem. Patterns of weed spread indicate that many species have a long lag phase following introduction before they spread explosively. Early detection and treatment of invasions before explosive spread occurs will prevent many future problems. Similarly, a focus on the invaded ecosystem and its management, rather than on the invader, is likely to be more effective. Identification of the causal factors enhancing ecosystem invasibility should lead to more‐effective integrated control programs. An assessment of the value of particular sites and their degree of disturbance would allow the setting of management priorities for protection and control. Socioeconomic factors frequently play a larger part than ecological factors in plant invasions. Changes in human activities in terms of plant introduction and use, land use, and timing of control measures are all required before the plant invasion problem can be tackled adequately. Dealing with plant invasions is an urgent task that will require difficult decisions about land use and management priorities. These decisions have to be made if we want to conserve biodiversity worldwide.
Terrestrial Buffer Zones and Wetland Conservation: A Case Study of Freshwater Turtles in a Carolina Bay
Authors: Burke Vincent J. , Gibbons J. Whitfield
Published: March 2003

Because freshwater wetlands often support diverse and unique species assemblages, wetland loss is a primary concern in biological conservation. U. S. federal statutes protect many wetlands by deterring development within delineated borders that segregate wetland habitats from upland regions. In addition, some state and local jurisdictions mandate buffer zones that afford varying levels of protection to upland habitats adjacent to wetlands. We used geographic information system analysis to test the adequacy of federal and state wetland protection statutes by determining the degree to which protected acreage encompassed the habitats freshwater turtles needed to complete their life cycles. Two critical life‐cycle stages, nesting and terrestrial hibernation, occurred exclusively beyond wetland boundaries delineated under federal guidelines. The most stringent state buffer zone insulated 44% of nest and hibernation sites. Our data indicate that the freshwater turtles examined in this study required a 275‐m upland buffer zone to protect 100% of the nest and hibernation sites. Insulating 90% of the sites required a 73‐m buffer zone. We suggest that the habitat needs of freshwater turtles demonstrate the dependence of wetland biodiversity on the preservation of adequate amounts of upland habitats adjacent to wetlands.
Ecosystem Management and the Arrogance of Humanism
Authors: Stanley Thomas R.
Published: March 2003

The ecosystem management paradigm has gained wide acceptance among land resource managers. The definition of ecosystem management remains fuzzy, however, and two fundamentally different views of ecosystem management prevail The first view is biocentric and considers human use of resources to be constrained by the primary goal of maintaining ecological integrity. The second view is anthropocentric and retains the importance of human use of resources, but it includes ecological and social considerations. In the 1981 book The Arrogance of Humanism, David Ehrenfeld examines the central tenets and assumptions of humanism. He provides several examples of human activities in which humanist assumptions are manifest and applies end‐product analysis to these to demonstrate the arrogance and failure of humanist assumptions. In this essay, the anthropocentric view of ecosystem management (hereafter just ecosystem management) is discussed in the context of The Arrogance of Humanism, and it is shown that ecosystem management is ultimately humanistic. The underlying assumptions of ecosystem management are also discussed and are examined using end‐product analysis. This analysis suggests that the belief in our ability to meet the assumptions of ecosystem management is unwarranted and that ecosystem management is yet another example of the arrogance of humanism. Solution of our land‐ and resource‐management problems must begin with rejection of humanism's doctrine of final causes.
Predicted Genetic Consequences of Strong Fertility Selection Due to Pollinator Loss in an Isolated Population of Primula sieboldii
Authors: Washitani Izumi
Published: March 2003

Previous studies demonstrated strong fertility selection for a self‐fertile, homostyle morph due to pollinator loss in an isolated population of Primula sieboldii, an endangered heterostylous species. To predict genetic consequences of the selection we developed a deterministic genetic model based on a classical “supergene” model, and we studied the effects of pollinator availability and inbreeding depression on temporal changes of morph frequencies through model simulation. Because of the severe pollinator limitation experienced by the population, fast, irreversible loss of the thrum morph from the population was predicted, even if high inbreeding depression was assumed. To prevent the breakdown of the normal breeding system of the species, morph frequency monitoring for timely active management should be implemented. Active management should include hand pollinations and pollinator therapy—reintroduction and reestablishment of suitable pollinator populations. The method we adopted in this study to parametrize pollinator availability can be used widely in conservation modeling for a range of plant species that have multiple mating types with different degrees of self‐incompatibility.
The Biodiversity Integrity Index: An Illustration Using Ants in Western Australia
Authors: Majer J.D. , Beeston G.
Published: March 2003

Although Western Australia is a relatively unpopulated region, considerable areas of native vegetation have been modified by agricultural clearing, rangeland grazing, urbanization, road construction, and mining. Ant diversity is reduced and community composition changed by each of these land uses. Road construction has the greatest long‐term effect on the alpha diversity of ants, followed by agricultural clearing, mining, urbanization, and rangeland grazing. We present data on the extent of these various land uses in each major Western Australian vegetation association. Then, examples of ant diversity and community composition for each land use are coupled with geographic information system data on the extent of each land use in the various vegetation associations to calculate indices of “biodiversity integrity.” The extent of biodiversity integrity in each region concurs with a subjective opinion of the condition of each unit. Agricultural clearing, followed by rangeland grazing, were found responsible for the greatest loss of ant biodiversity integrity. The findings relate to Australia in general and may serve as a framework for estimating losses of biodiversity integrity in other regions of the world in taxa other than ants.
A Comparison of Richness Hotspots, Rarity Hotspots, and Complementary Areas for Conserving Diversity of British Birds
Authors: Williams Paul , Gibbons David , Margules Chris , Rebelo Anthony , Humphries Chris , Pressey Robert
Published: March 2003

Biodiversity conservation requires efficient methods for choosing priority areas for in situ conservation management. We compared three quantitative methods for choosing 5% (an arbitrary figure) of all the 10 × 10 km grid cells in Britain to represent the diversity of breeding birds: (1) hotspots of richness, which selects the areas richest in species; (2) hotspots of range‐size rarity (narrow endemism), which selects areas richest in those species with the most restricted ranges; and (3) sets of complementary areas, which selects areas with the greatest combined species richness. Our results show that richness hotspots contained the highest number of species‐in‐grid‐cell records (with many representations of the more widespread species), whereas the method of complementary areas obtained the lowest number. However, whereas richness hotspots included representation of 89% of British species of breeding birds, and rarity hotspots included 98%, the areas chosen using complementarity represented all the species, where possible, at least six times over. The method of complementary areas was also well suited to supplementing the existing conservation network. For example, starting with grid cells with over 50% area cover by existing “Sites of Special Scientific Interest,” we searched for a set of areas that could complete the representation of all the most threatened birds in Britain, the Red Data species. The method of complementary areas distinguishes between irreplaceable and flexible areas, which helps planners by providing alternatives for negotiation. This method can also show which particular species justify the choice of each area. Yet the complementary areas method will not be fully able to select the best areas for conservation management until we achieve integration of some of the more important factors affecting viability, threat, and cost.
The Early Development of Forest Fragmentation Effects on Birds
Authors: Hagan John M. , Vander Haegen W. Matthew , McKinley Peter S.
Published: March 2003

The early development of forest fragmentation effects on forest organisms is poorly understood partly because most fragmentation studies have been done in agricultural or suburban landscapes, long after the onset of fragmentation. We develop a temporal model of forest fragmentation effects on densities of forest‐breeding birds and provide data from an active industrial forest landscape to test the model. The model and our empirical data indicate that densities of several forest‐dwelling bird species can increase within a forest stand soon after the onset of fragmentation as a result of displaced individuals packing into remaining habitat. Along with higher densities in the newly formed fragments, pairing success in one species, the Ovenbird (Seiurus aurocapillus), was lower in fragments than nonfragments, possibly due to behavioral dysfunction resulting from high densities. Thus, density was inversely related to productivity. The duration and extent of increased densities following onset of fragmentation depends on many factors, including the sensitivity of a species to edge and area effects, the duration and rate of habitat loss and fragmentation, and the proximity of a forest stand to the disturbance. Incipient forest fragmentation may affect populations differently from later stages of fragmentation when the geometry of the landscape has reached a more stable configuration. Our model and data indicate, for reasons unrelated to traditional edge effects, that large tracts of forest can be important because they are relatively free from the variety of plant and animal population dynamics that might take place near new edges, including the encroachment of individuals displaced by habitat loss.
Conservation of Large, Nomadic Populations of White Ibises (Eudocimus albus) in the United States
Authors: Frederick Peter C. , Bildstein Keith L. , Fleury Bruce , Ogden John
Published: March 2003

We compiled published and unpublished records of large nestings of White Ibises (Eudocimus albus) in the United States between 1930 and 1993. The resulting database provides evidence of at least four major geographic shifts of the breeding population of White Ibises during the period. Banding returns and colony histories demonstrate that the movements were not migratory. The extremely fast growth of most White Ibis breeding colonies indicates that local recruitment could not have fueled the large increases in breeding numbers in colonized areas. Ibises seem to colonize wetland areas that have good feeding resources and to abandon areas that lose the ability to supply this resource. Mechanisms of attraction to new sites and repulsion from degraded ones may work alone or in tandem. Degradation of breeding sites frequently occurs through natural processes, such as hurricanes, stochastic weather patterns, and wetland conditions, and the nomadic behavior of White Ibises appears to be an obligate life‐history feature. Although surveys throughout the range of the U.S. population of White Ibises have never been comprehensive, available records indicate minimum breeding populations of 125,000 pairs in 1933, 170,000 pairs in 1976, and 51,000 pairs in 1991. The U.S. population as a whole appears to be decreasing. White Ibises share a suite of population, social, and movement characteristics with a number of nomadic species. Conservation strategies for these species may differ fundamentally from those targeting more sedentary species. Nomadic species may typically depend on large populations to find food and to stimulate breeding and are therefore likely to decline abruptly and unpredictably as habitat is lost or degraded. Rapid population declines may occur at population levels well above those predicted by genetic and minimum viability models. Because of its nomadic habit, the survival of this species may depend on a regional planning approach. To conserve this species we recommend a continuing commitment to the monitoring, assessment, and preservation of a mosaic of fresh and estuarine wetlands in the southeastern U.S.; the maintenance of natural disturbances needed to produce pulses of food in these wetlands, and the coordination of management efforts throughout the US., as well as between the U.S. and Cuba.
Effects of Slash Pine Silviculture on a Florida Population of Flatwoods Salamander
Authors: Means D. Bruce , Palis John G. , Baggett Mary
Published: March 2003

The largest known breeding migration of the flatwoods salamander (Ambystoma cingulatum) was monitored over a 22‐year period following its discovery in 1970 in Liberty County, Florida (U.S.A.). Nightly migrations of 200–300 adults across a 4.3‐km stretch of paved highway in 1970–1972 had dwindled to less than one individual per night in 1990–1992; the decline apparently was already underway in the 1980s. We discuss possible natural and anthropogenic causes of the decline. The silvicultural practice of converting native longleaf pine savanna to bedded slash pine plantation, implemented on our study site about 1968, may have interfered with migration, successful hatching, larval life, feeding, and finding suitable cover post‐metamorphosis. Longleaf pine‐wiregrass flatwoods inhabited by adults have been drastically reduced and severely degraded throughout the coastal plain and may explain why the species is rare and deserving of threatened status.
Interpretation of Elasticity Matrices as an Aid to the Management of Plant Populations for Conservation
Authors: Silvertown Jonathan , Franco Miguel , Menges Eric
Published: March 2003

Population projection (Lefkovitch) matrices are now a standard method for quantifying and analyzing the demography and population dynamics of plants. Elasticity analysis of such a matrix indicates the relative effect on the population growth rate (λ) of small changes to matrix elements representing different transitions in the life cycle. In a comparison of elasticity matrices for 84 species of plants we show that the relative importance of recruitment from seed (measured by composite elasticity F), stasis (measured by composite elasticity L), and growth (measured by composite elasticity G) varies systematically between the groups semelparous herbs, iteroparous herbs of open habitats, forest herbs, shrubs, and trees. We discuss how this result might be used to construct rules of thumb useful in plant conservation. By looking in detail at how λ covaries with the composite elasticities F, L, and G among 16 populations of the semelparous herb Cirsium vulgare and among 15 populations of the rare iteroparous herb Pedicularis furbishiae, we show that a naive interpretation of elasticities can give a misleading prescription for management. Instead, we show that elasticity analysis supports management prescriptions based upon the successional status of a species or upon its response to disturbance.
A Global Perspective on Large Carnivore Conservation
Authors: Weber William , Rabinowitz Alan
Published: March 2003

The recent reintroduction of the gray wolf (Canis lupus) to Yellowstone signifies a constructive change, but the overall record in the United States on large carnivore conservation remains poor. Many developing countries are determined to do a better job of conserving predators, including their critical habitat and prey populations. We describe current efforts to protect tigers (Panther tigris), jaguars (Panthera onca), and large‐scale forest habitat in Asia, Central America, and Africa. These initiatives take a comprehensive approach that includes biological field research, the identification of local human interests, and a growing recognition of the need for cooperation across political lines. Though often supported by U.S. technical assistance, this international experience could be used better to inform and improve carnivore conservation efforts in North America. Failure to improve our domestic performance or to fully appreciate the contributions of far less developed countries could weaken global efforts to maintain and restore populations of large carnivores.
Conservation Prioritization Using GAP Data
Authors: Kiester A. Ross , Scott J. Michael , Csuti Blair , Noss Reed F. , Butterfield Bart , Sahr Kevin , White Denis
Published: March 2003

Data collected by the Gap Analysis Program in the state of Idaho (U.S.A.) are used to prioritize the selection of locations for conservation action and research. Set coverage and integer programming algorithms provide a sequence of localities that maximize the number of species or vegetation classes represented at each step. Richness maps of vegetation cover class diversity, terrestrial vertebrate species diversity (“hot spot analysis”), endangered, threatened, and candidate species diversity, and unprotected vertebrate species diversity (“gap analysis”), when prioritized, show a rapid accumulation of species as more localities are chosen for terrestrial vertebrates and unprotected vertebrates. Gap analysis identifies four target areas (“gaps”) that include 79 of the 83 vertebrate species not currently protected. Accumulation of vegetation cover classes and endangered, threatened, and candidate species is much slower. Sweep analysis is used to determine how well prioritizing on one component of diversity accumulates other components. Endangered, threatened, and candidate species do not sweep total vertebrates as well as unprotected vertebrates do, but are better than vegetation classes. Total vertebrates sweep endangered, threatened, and candidate species better than unprotected vertebrates do, which in turn are better than vegetation classes. We emphasize that prioritization must be part of conservation efforts at multiple scales and that prioritization points out important localities where more detailed work mast be undertaken.
Relationship of Genetic Variation to Population Size in Wildlife
Authors: Frankham Richard
Published: March 2003

Genetic diversity is one of three levels of biological diversity requiring conservation. Genetic theory predicts that levels of genetic variation should increase with effective population size. Soulé (1976) compiled the first convincing evidence that levels of genetic variation in wildlife were related to population size, but this issue remains controversial. The hypothesis that genetic variation is related to population size leads to the following predictions: (1) genetic variation within species should be related to population size; (2) genetic variation within species should be related to island size; (3) genetic variation should be related to population size within taxonomic groups; (4) widespread species should have more genetic variation than restricted species; (5) genetic variation in animals should be negatively correlated with body size; (6) genetic variation should be negatively correlated with rate of chromosome evolution; (7) genetic variation across species should be related to population size; (8) vertebrates should have less genetic variation than invertebrates or plants; (9) island populations should have less genetic variation than mainland populations; and (10) endangered species should have less genetic variation than nonendangered species. Empirical observations support all these hypotheses. There can be no doubt that genetic variation is related to population size, as Soulé proposed. Small population size reduces the evolutionary potential of wildlife species.
Rule‐Based Models for Evaluating Mechanisms of Distributional Change
Authors: Skelly David K. , Meir Eli
Published: March 2003

Viability models assume that particular mechanisms (e.g., decreased probability of colonization in isolated habitats) drive the pattern of population invasion and extinction. Although authors often provide evidence supporting the inclusion or exclusion of a mechanism, there has been no means of rigorously comparing different factors for a given species. We present a method of evaluating alternative mechanisms of distributional change that relies on two or more surveys of species presence‐absence across a large number of sites, a dataset often available (or at least attainable) for many taxa. The key idea of our approach is to use hypotheses to specify rules for dividing sites into classes. Our model estimates class‐specific probabilities of invasion and extinction and then uses these rates to assign invasions and extinctions to sites in multiple stochastic simulations. The output of the model is a frequency distribution of mistakes generated by comparing predicted distributions with the actual distributions. As a first attempt to apply the approach we modeled invasions and extinctions of 14 amphibian species across 32 ponds in Michigan. We compared hypotheses that amphibian distributions changed as a result of the spatial arrangement of sites, as a result of succession, or randomly. Overall, the spatial approach provided a poor explanation of distributional changes, performing no better than the random model for all species. In contrast, the succession model, based on temporal changes in breeding sites, performed better than the null model for at least three species. These results were surprising as spatial effects are thought to be important to the dynamics of pond‐breeding amphibians. Our results say little about the general importance of fragmentation and other spatial effects, but do suggest that alternative mechanisms of change can be important. Because of their ability to assess the importance of different mechanisms, rule‐based models could provide useful input into the design of biodiversity management strategies.
Acceptance of Scientific Management by Natural Resource Dependent Communities
Authors: Weeks Priscilla , Packard Jane M.
Published: March 2003

We explore the reaction of two resource dependent communities, west Texas ranchers and Gulf Coast oyster fishers, to scientific resource management. We examine the criteria these two social groups use to judge scientific claims, and by extension, scientific resource management. Although scientists rely on factors internal to the scientific enterprise (e.g., methodological rigor), natural resource dependent communities such as ranchers and fishers may rely on factors external to the scientific process. Such factors include the historical relationship the community has had with the managing agency, the extent to which scientific explanations match local experience, the conceptual fit between managers’ and communities’ views of the appropriate relationship between humans and nature, and the resources available to the community to argue against regulation. We conclude that (1) agencies should explore the possibility of including the experiential knowledge of natural resource users where applicable and (2) agencies should recognize that communication skills can be as important as scientific skills in reaching management goals.
Bird Populations in Shade and Sun Coffee Plantations in Central Guatemala
Authors: Greenberg Russell , Bichier Peter , Angon Andrea Cruz , Reitsma Robert
Published: March 2003

We studied the avifauna of sun and shade coffee plantations and associated mid‐elevation habitats during the dry season of 1995. The three plantation types (Inga, Gliricidia, and sun) showed high faunistic similarities with each other and were both distinct and depauperate compared to matorral and forest patch habitats. Of all the coffee plantation habitats, Inga shade had the highest diversity. Species associated with wooded vegetation were more common in shade plantations, particularly in Inga. A second census showed a decline in bird numbers that was more pronounced in sun and Gliricidia than in Inga plantations. Overall, differences between the plantation types were small and all coffee plantations were less diverse than traditional coffee farms previously studied in nearby Chiapas, México. The relatively low bird diversity was probably due to the low stature, low tree species diversity, and heavy pruning of the canopy. These features reflect management practices that are common throughout Latin America. The most common species of birds in all coffee plantation habitats were common second‐growth or edge species; more specialized forest species were almost completely absent from plantations. Furthermore, many common matorral species were rare or absent from coffee plantations, even sun plantations with which matorral shares a similar superficial structure. Coffee plantations probably will only be important for avian diversity if a tall, taxonomically and structurally diverse canopy is maintained. We suggest this is most likely to occur on farms that are managed for a variety of products rather than those designated entirely for the production of coffee.
Predicting Invasions of Woody Plants Introduced into North America
Authors: Reichard Sarah Hayden , Hamilton Clement W.
Published: March 2003

Plant species continue to be introduced in North America for various purposes. If the trend continues, it is probable that some will escape cultivation and become invasive in native ecosystems. We present a retrospective analysis of several structural, life history, and biogeographical attributes of woody plants introduced in North America to determine which traits characterize species that have and have not invaded. Predictive models derived from discriminant analysis correctly classified 86.2% of the species in cross‐validation, whereas those derived from classification and regression trees classified 76% correctly. From these models we created a hierarchical predictive tree that allows the user to divide species into three categories: admit (low risk of invasiveness), deny admission (high risk of invasiveness), or delay admission for further analyses and/or monitor intensively (risk cannot adequately be assessed based on only the included attributes). We recommend that species that are highly invasive elsewhere not be allowed into the U.S. and that a more conservative introduction policy using a hierarchical predictive method be employed.