bluuebunny/crossref_metadata_2025 huggingface dataset:
When Are Peripheral Populations Valuable for Conservation?
Authors: Lesica Peter , Allendorf Fred W.
Published: March 2003

A great deal of effort is spent protecting geographically peripheral populations of widespread species. We consider under what conditions it is appropriate to expend resources to protect these populations. The conservation value of peripheral populations depends upon their genetic divergence from other conspecific populations. Peripheral populations are expected to diverge from central populations as a result of the interwoven effects of isolation, genetic drift, and natural selection. Available empirical evidence suggests that peripheral populations are often genetically and morphologically divergent from central populations. The long‐term conservation of species is likely to depend upon the protection of genetically distinct populations. In addition, peripheral populations are potentially important sites of future speciation events. Under some circumstances, conservation of peripheral populations may be beneficial to the protection of the evolutionary process and the environmental systems that are likely to generate future evolutionary diversity.
Effects of Recent Land‐Use Practices on Soil Nutrients and Succession under Tropical Wet Forest in Costa Rica
Authors: Fernandes David N. , Sanford Robert L.
Published: March 2003

The effects of a variety of agricultural land uses were studied using soil nutrients, forest structure, and species assemblages as indicators. We compared soil properties and successional forests between abandoned cacao (Theobroma cacao) and abandoned palm (Bactris gasipaes) orchards, abandoned pasture, and mature forest. These sites co‐occupy an alluvial terrace soil (Andic Dystropept) at La Selva Biological Station, Costa Rica. The agricultural sites were originally cleared of most or all forest vegetation approximately 30 years ago and went into succession approximately 7 years ago. Forest structure, species composition, soil nitrogen and phosphorus pools, and nitrogen‐mineralization and nitrification rates were measured for each site. The abandoned palm orchard had lower basal area and stem density than other secondary forests of the same age. It also had significantly smaller nitrate (NaOH‐extractable) and organic phosphorus pools and significantly lower net rates of nitrogen‐mineralization and nitrification. It is evident that preserving tree cover does not necessarily maintain soil fertility. We found species richness and diversity in the secondary forests to be positively correlated with basal area at the time of abandonment.
Assessing Conservation Value Using Centers of Population Density
Authors: Winston Matthew R. , Angermeier Paul L.
Published: March 2003

We present an index of centers of density for identifying areas of high conservation value. This index represents the average importance of an area to species occurring there as measured by comparisons of relative densities of each species among areas. We evaluated the index using collections of stream fishes from the Clinch River system above Norris Reservoir in Virginia and Tennessee (U.S.A.). A strong correlation between index values measured at the same sites at different times suggested that the index could be applied to sites without replicated samples in the region and still allow centers of density to be distinguished from noncenters. Species richness showed no relationship to the index, suggesting that conservation priorities based solely on species richness can be inadequate. A species‐accumulation curve based on the index performed nearly as well as one based on an algorithm for identifying the minimum number of sites in which all species in the region are represented. This pattern reflected the tendency of the index to weight regionally rare species more heavily than common species. But sites with high index values were not necessarily those selected by the algorithm because the algorithm used only presence/absence, whereas the index used the additional information present in relative densities. Our index represents an additional tool for identifying “hot spots” of diversity, but conservation of biodiversity over the long term will also require that the ecological integrity of regional landscape be maintained.
Knowledge and Perceptions in Costa Rica Regarding Environment, Population, and Biodiversity Issues
Authors: Holl Karen D. , Daily Gretchen C. , Ehrlich Paul R.
Published: March 2003

Public understanding of general environment‐ and population‐related issues is critical for successful conservation efforts. We interviewed 300 residents of Costa Rica, distributed among three socioeconomic groups, to survey knowledge and perceptions about the environment. We focused on Costa Rica because it is an international model for sustainable development and because of its direct economic interest in biodiversity preservation for ecotourism. Our results indicate that Costa Ricans generally have a limited awareness of environment‐ and population‐related problems. In all socioeconomic groups environmental problems were considered less important than various other problems, but 91% of respondents indicated a willingness to pay more for water or electricity if the extra money were used to protect biodiversity. Residents of San Jose’s lower‐class neighborhoods more strongly perceived the effects of population growth and environmental degradation than did residents of urban, upper‐class, or rural neighborhoods. Of those interviewed, 69% thought the rate of population growth should decrease. Only 52% of those surveyed, however, perceived any link between population size or growth rate and environmental quality; of those, 33% could not describe the link. Our findings and others suggest a number of ways to enhance the effectiveness of environmental education programs worldwide: (1) include information on the relationship between population and environmental quality; (2) explain the socioeconomic implications of environmental degradation; (3) in addition to formal education, utilize the mass media more; (4) tailor messages to local circumstances.
Conservation and Management of a Threatened Madagascar Palm Species, Neodypsis decaryi, Jumelle
Authors: Ratsirarson Joelisoa , Silander John A. , Richard Alison F.
Published: March 2003

The dynamics of a remnant population of the palm Neodypsis decaryi were characterized using a linear, stage‐structured demographic model. This palm is a threatened keystone species restricted to a narrow ecological zone in southeastern Madagascar. The population showed high mortality rates in the early stages of the life cycle, followed by a period of lower adult mortality. Demographic results indicated that the population was either stable or increasing inside the reserve (λm close to 1.0). Sensitivity and elasticity analyses indicated that adult stage classes were the most sensitive to producing changes in population growth rates. Continued biological monitoring is appropriate for the long‐term conservation management of this palm inside the reserve. Outside the protected area the population appears to be declining rapidly, mainly because of anthropogenic effects (especially fire and grazing). If the conservation of Neodypsis decaryi is to be successful in the long term, then conservation methods must be carried out in cooperation with local villagers, and the species should be managed as a renewable resource in situ and ex situ. In situ conservation should include cultivation of this species throughout its natural range and protection of the existing viable natural populations. Alternative conservation management practices, both ecologically and economically sustainable, may be useful to alleviate the human pressures on this renewable resource. If leaves of N. decaryi are to be harvested by local people, we recommend restricting annual harvesting to about 25% of leaves per tree per year. Based on sensitivity analysis, seed collection should be kept well below 95% of the yearly crop if harvesting is not to have a significant impact on population growth rates.
Population Status of the Razorback Sucker in the Middle Green River (U.S.A.)
Authors: Modde Timothy , Burnham Kenneth P. , Wick Edmund J.
Published: March 2003

The razorback sucker, Xyrauchen texanus, in the middle Green River (U.S.A.) has been described as a static population consisting of old individuals that will eventually disappear through attrition. Capture data between 1980 and 1992 indicated a constant length frequency despite a slow but positive growth rate of individual fish. Abundance and survival estimates indicated that the population of razorback sucker in the middle Green River is precariously low but dynamic. Although high variation existed among survival estimates, no significant decrease in the population between 1982 and 1992 could be detected. The low level of recruitment occurring in the razorback sucker population of the middle Green River was related to high‐flow years, indicating that floodplain habitats may be necessary for survival of the species.
Mitochondrial DNA Variability in the Endangered Razorback Sucker (Xyrauchen texanus): Analysis of Hatchery Stocks and Implications for Captive Propagation
Authors: Dowling Thomas E. , Minckley W.L. , Marsh Paul C. , Goldstein Elliott S.
Published: March 2003

The razorback sucker (Xyrauchen texanus) is a large, long‐lived catostomid fish endemic to the Colorado River drainage of western North America, endangered because of recruitment failure. Efforts to preserve the species have emphasized artificial propagation and reintroduction. Given the importance of maintaining genetic diversity in such a program, we examined mitochondrial DNA diversity in a source population (Lake Mohave, Arizona‐Nevada) and three hatchery‐produced year classes (1987, 1989, 1990). The source contained considerable variation, indicated by high haplotype diversity (ĥ = 0.97) and a large number of unique haplotypes (17 in 25 individuals). Diversity also was high in the 1987 (ĥ = 0.89, 6 haplotypes in 10 individuals) and 1989 hatchery‐produced year classes (ĥ = 0.91, 7 in 11), but significantly lower in the 1990 year class (ĥ = 0.71, 4 in 10). Low diversity in the last class was likely because of differences among females in fecundity, viability of progeny, or both. Because natural populations have collapsed throughout the species’ range, we must identify methods that preserve the most diversity. We examined three potential alternatives: standard hatchery propagation, natural spawning in predator‐free environments, and protective custody of larvae collected from the lake with reintroduction after growth to a size likely to survive. The last is the preferred alternative and should be pursued as the most cost‐effective option for preserving genetic diversity in the razorback sucker.
Plant Succession, Landscape Management, and the Ecology of Frugivorous Birds in Abandoned Amazonian Pastures
Authors: Da Silva José Maria Cardoso , Uhl Christopher , Murray Gregory
Published: March 2003

From towers constructed at the interface between second‐growth forest and an active and an abandoned pasture, we observed inter‐habitat movements of fruit‐eating birds in eastern Amazônia. The abandoned pasture was composed of grasses and forbs with a scattering of shrubs and small trees. The active pasture contained a low, uniform bed of grass. A total of 47 frugivorous bird species was recorded in the second‐growth forest. We observed that 18 of these species frequented the adjacent abandoned pasture but only 3 were found in the adjacent active pasture. Fruit‐eating birds flying from second‐growth forest typically spent only a few minutes in the abandoned pasture, and their movements were generally restricted to a pasture belt of 1–80 m along the border with the second‐growth forest. Most inter‐habitat movement occurred during the rainy season, which coincided with a peak in fruit availability in the abandoned pasture. Just three bird species, Ramphocelus carbo, Tachyphonus rufus, and Thraupis episcopus, accounted for an estimated 70% of the total movement of frugivores between the second‐growth forest and the abandoned pasture. All three species spent most of their time in the abandoned pasture foraging on shrubs and trees but exhibited differences in their preference for specific habitat elements and in their seed‐defecation habits. An understanding of bird behaviors in altered landscapes provides important information to planners and policy makers concerned with protecting regional biodiversity and maintaining landscape integrity. This research provides a rationale for placing limits on the size of clearings in the Brazilian Amazon.
Comparison of Abiotic and Structurally Defined Patch Patterns in a Hypothetical Forest Landscape
Authors: Chen Jiquan , Franklin Jerry F. , Lowe J. Stephen
Published: March 2003

An understanding of landscape patterns is now considered essential information in developing programs for biological conservation. We examined the adequacy of conventional approaches to landscape‐pattern characterization by evaluating the spatial patterns in environmental conditions and their ecological implications at the landscape level. Six factors were varied in a hypothetical, managed, old‐growth Douglasfir (Pseudotsuga menziesii [Mirb.] Franko) landscape of 3000 ha in the Pacific Northwest: two variables were associated with biotic processes and four with abiotic processes. The two biotic variables represented the distribution of habitat for edge and interior forest species. The abiotic variables included air temperature at dawn and noon, wind speed, and direct solar radiation. The area of edge influence between forest patches and the clearcut matrix was simulated as a unique landscape element in the spatial analysis. The structurally defined landscape pattern (based on vegetation or soil type) differed clearly from the patterns associated with the six variables, which also differed among themselves. Spatial patterns changed at various temporal scales, substantiating the notion that landscape patterns of abiotic variables are very dynamic. Area of edge influence played an important role in configuring spatial patterns of a landscape, occupied much area in the landscape, and significantly influenced ecosystem structure and function. Simulation results showed that landscape patterns based solely on traditional structural parameters are limited in their usefulness because the ecological landscape is the integration of all variables and the associated movement of energy, materials, and species. This information about landscape patterns delineated by various biotic and abiotic variables is critical in reserve design and monitoring and in managing habitats for target species across landscapes. Efforts to describe the ecological function of an area will have to consider not only structurally‐defined patches but also patterns in abiotic variables that are typically not congruent with structural patches and showing daily and seasonal changes.
Ungulate Traffic Collisions in Europe
Authors: Bruinderink G.W.T.A. Groot , Hazebroek E.
Published: March 2003

The expansion of highways and roads can fragment natural habitats and thus decrease the viability of ungulate subpopulations. It can also increase the number of vehicle collisions with wildlife. Although collisions apparently contribute to only a minor part of the annual mortality for most ungulate populations, they have become a serious road‐safety problem in Europe, the United States, and Japan. To better understand this threat to biodiversity and road safety, we reviewed European and, secondarily, North‐American and Japanese literature on ungulate traffic collisions. In contrast to the results of some long‐term studies, we argue that the relationship suggested between the number of road kills and traffic volume is confounded by population dynamics, changes in traffic volume, and sampling intensity. Although sexes may run distinct seasonal risks of collision, the age and sex composition of road kills reflect population structure in the field. We also argue that observed seasonal and daily patterns in the number of road kills, related to life‐history features of the species involved, should form the template for solutions to the problem. We found no strong evidence of the effects of permanent warning signs, 90° light mirrors, scent, or acoustic fencing on the number of kills per crossing. To reduce the risk of ungulate traffic collisions, we recommend a combination of fencing and wildlife passages for roads and railroads that combine high traffic volume with high speed. For secondary roads we recommend seasonal application of intermittently lighted warning signs, triggered if possible by the ungulates. We emphasize the need for educational programs.
The Human Dimension in Conservation Biology Curricula in Developing Countries
Authors: Saberwal Vasant K. , Kothari Ashish
Published: March 2003

The social sciences and humanities are essentially absent from most conservation biology or wildlife management courses in the developing world. This is a critical shortcoming because of human dependence on natural resources within protected areas and the escalating conflicts between humans and wildlife and between local communities and state agencies over access to resources. We call for increased input from the social sciences and the humanities in conservation biology and wildlife management curricula in the developing world. We suggest some materials and methods that should ideally be a part of such curricula.
Null Models for Assessing Ecosystem Conservation Priorities: Threatened Birds as Titers of Threatened Ecosystems in South America
Authors: Beissinger Steven R. , Steadman Eric C. , Wohlgenant Timothy , Blate Geoffrey , Zack Steve
Published: March 2003

We set ecosystem conservation priorities based on a comparison of observed levels of threat and protection versus expected levels derived from the use of null models. We used differences in the proportion of threatened and nonthreatened bird species among ecosystems to assess levels of threat and differences in the coverage of parks and protected areas relative to land area to assess levels of protection. We applied this approach to terrestrial biomes of continental South America and determined where recommendations for species and ecosystem conservation converge and diverge. We calculated the percentage of range in each biome for 132 bird species threatened by habitat destruction and 288 nonthreatened bird species. Three biomes (evergreen forest, broadleaf forest, and cold desert) were not included because few bird ranges fell primarily within them. Tropical humid forest and mountain biomes supported the greatest levels of avian species diversity. But only subtropical and temperate rainforests and tropical dry forests supported a higher proportion of threatened bird species than expected, making them ecosystem destruction hotspots. Tropical humid forests and tropical and temperate grasslands supported lesser proportions of threatened bird species than expected (i.e., coldspots), whereas mountain and warm deserts supported similar proportions of threatened and nonthreatened bird species (i.e., neutral). These patterns were corroborated by the apportionment of human population densities among biomes. Highest densities (> 25 per km2) occurred in subtropical and temperate rainforests and tropical dry forests, whereas tropical humid forests and warm deserts supported the lowest human densities (< 1 per km2). The largest proportions of protected areas were in tropical humid forest and mountain biomes, which is in accord with the distribution of avian diversity but not with our assessment of habitat destruction. Protected areas were especially underrepresented in tropical dry forests, making them the most threatened biome.
Representativeness and Efficiency of Bird and Insect Conservation in Norwegian Boreal Forest Reserves
Authors: Stokland Jogeir N.
Published: March 2003

I quantified local species richness of birds in different forest types and of beetles in spruce forests at different altitudes. In both cases I quantified timber production as a measure of land acquisition cost and used the ratio between the species richness and timber production as a measure of conservation cost‐efficiency. I found a positive correlation between timber production and local species richness of birds as well as beetles, indicating that the forests most valuable for forestry are also the ones most valuable for biodiversity conservation. I used different selection procedures for combining sites in a reserve network to find the minimum set of sites that included all vulnerable species. The minimum set of sites for birds was 30% spruce forest, 30% pine forest, and 40% broad‐leaved forest (the three main forest types). The minimum set of sites for the beetles was uniformly distributed along the altitudinal gradient. Both minimum sets were most cost‐efficient for species conservation. I suggest that equal coverage of different productivity classes is more efficient for optimizing biodiversity conservation than over‐representing low productivity sites. Less than 1% of Norwegian boreal forests have been protected as nature reserves. The reserve network is fairly representative with respect to altitude, but it is seriously skewed toward low productivity sites. The current network is suboptimal with respect to forest type representativeness, species protection, and cost‐efficiency. This is a result of an inefficient strategy of selecting reserve sites and an unfortunate combination of selection criteria.
Benthic Dispersal of Caribbean Spiny Lobsters among Insular Habitats: Implications for the Conservation of Exploited Marine Species
Authors: Acosta Charles A.
Published: March 2003

Abstract:
Understanding how populations of target species interact with their habitats is necessary for developing an effective conservation strategy. During its complex life history, the Caribbean spiny lobster (  Panulirus argus) uses a variety of benthic marine habitats, but how habitat characteristics affect their dispersal is unclear. To assess how habitat insularity affects the benthic dispersal of spiny lobsters, I compared lobster abundance, size class structure, and migration among insular mangrove and coral reef habitats that were surrounded by bare rubble fields or by seagrass meadows. Lobsters were significantly more abundant on mangrove and coral islands surrounded by seagrass. The size‐class distributions of lobsters in these habitats had higher proportions of juveniles, whereas islands surrounded by sand and rubble had skewed distributions dominated by adult lobsters. Seagrass is known to serve as settlement habitat for larval recruits and is likely associated with the higher abundances of lobsters found in seagrass‐isolated habitats. Immigration and emigration rates were three to four times higher on seagrass‐isolated islands than on rubble‐isolated islands, reflected in the significantly greater number of juveniles moving into and from seagrass‐isolated islands. Rubble fields appeared to function as a barrier to benthic dispersal for all lobsters except adults. Vegetated substrates may function as movement corridors for juvenile lobsters and may facilitate dispersal to areas containing new resources. The effects of insularity on a population may be lessened by the nature of the surrounding habitats if those habitats have important functional roles as larval settlement areas, foraging grounds, or movement corridors. Protection of insular habitats like coral reefs may be ineffective if related habitats like seagrass meadows are left unprotected. Conservation strategies for mobile benthic species need to incorporate the protection of areas with heterogenous habitats that are important to meet the changing habitat requirements in complex life cycles.
Evaluating the Effects of Three Forms of Marine Reserve on Northern Abalone Populations in British Columbia, Canada
Authors: Wallace S. Scott
Published: March 2003

Abstract: Marine reserves have been suggested as tools for assisting the management of fisheries by protecting vulnerable marine species from overexploitation. Although there is a theoretical basis for believing that marine reserves may serve as management tools, there are few marine reserves in the world in which to test their effectiveness. My research evaluated three forms of marine reserve on the south coast of Vancouver Island, British Columbia, Canada. I used northern abalone (Haliotis kamtschatkana), a severely depleted shellfish in this region, as an indicator of the effectiveness of the reserves. Abalone populations in eight sites receiving different degrees of spatial protection were counted and measured in situ during the spring of 1996 and 1997. In all sites with enforced harvest closures, populations of abalone were greater, and one site with nearly 40 years of protection had on average much larger (older) abalone. Reproductive output, as a function of abundance and size, was also greater in the enforced reserve areas. Larval dispersal from reserves, and hence the benefit to exploited areas, was not formally surveyed. Nevertheless, the results of my study, combined with knowledge of present abalone populations, life history, and regional hydrodynamics, suggest that establishment of reserves is justified in the absence of perfect knowledge of larval dispersal.
Conservation Value of Semi‐Natural Pastures in Sweden: Contrasting Botanical and Avian Measures
Authors: Pärt Tomas , Söderström Bo
Published: March 2003

Abstract: Conservation of biodiversity in semi‐natural pastures of Sweden is based mainly on management prescriptions to increase botanical values (i.e., species richness of vascular plants confined to pastures), assuming plants to be good indicators of overall biodiversity. We compared species richness and abundance of 29 species of farmland birds breeding in 88 semi‐natural pastures of different conservation value as evaluated by a nation‐wide inventory of semi‐natural pastures in Sweden. We tested whether there was an association between existing measures of conservation value, based mainly on the species richness and rarity of vascular plants, and three species richness subsets of farmland birds. Species richness of all farmland birds, decreasing farmland birds, and dry pasture birds were not associated with the botanical conservation value of pastures. Pastures surrounded by open farmland contained significantly more farmland bird species and more decreasing farmland species than pastures located at forest‐field edges within the same landscape. In addition, richness of all farmland bird species, decreasing farmland species, and decreasing dry pasture species increased significantly with increasing pasture area and increasing proportion of a short field layer (reflecting grazing intensity). The species richness of decreasing dry‐pasture species of birds was also weakly positively correlated with the proportion of the field layer being artificially fertilized. Our results suggest that there are only weak relationships if any between species richness in birds and vascular plants at the local scale (2–15 ha), so using vascular plants as indicators of overall biodiversity may be unreliable. The present management prescription of intensive grazing to increase overall biodiversity is not supported by the literature on invertebrates, birds, and plants. We suggest that future management of semi‐natural pastures should be revised to include a relaxed grazing intensity, which may increase heterogeneity of field layer height, allowing larger areas to be grazed with a given stock size, and may increase meat and milk production due to a higher quality of grazing.
Effects of Riparian Forest Removal on Fish Assemblages in Southern Appalachian Streams
Authors: Jones E. B. Dale , Helfman Gene S. , Harper Joshua O. , Bolstad Paul V.
Published: March 2003

Abstract: Deforestation of riparian zones is known to influence the numbers and kinds of organisms that inhabit adjoining streams, but little quantitative information is available on how much deforestation must occur before the biota isaffected. We sampled fishes and stream habitats in 12 stream segments downstream from deforested but vegetated riparian patches 0–5.3 km long, all downslope from watersheds with at least 95% forest cover. We found an overall decrease in fish abundance with increasing length of nonforested riparian patch; sculpins, benthic minnows, and darters decreased, and sunfishes and water‐column minnows increased in numbers. Introduced species were more common downstream from longer riparian patches. Habitat diversity decreased and riffles became filled with fine sediments as upstream patch length increased. Length of upstream nonforested patch and substrate particle size were much stronger predictors of fish occurrence than riparian patch width. Faunal characteristics and physical features of the stream changed in direct proportion to the gradient of riparian disturbance, but the abundance of several species underwent pronounced change at particular threshold patch lengths. These results suggest that riparian forest removal leads to shifts in the structure of stream fish assemblages due to (1) decreases in fish species that do not guard hidden eggs or that are dependent on swift, shallow water that flows over relatively sediment‐free substrates, or (2) increases in fishes that guard their young in pebble or pit nests or that live in slower, deeper water. When watershed development is anticipated or planned, limited clearing of riparian trees may cause minor disturbance to the fish assemblage, but streams in even a heavily forested watershed with vegetated riparian buffers cannot tolerate disruption of riparian‐zone trees over much more than 1 km in length. Riparian buffer length and area should be given stronger consideration in stream protection and restoration plans.
A Protocol for Plant Conservation by Translocation in Threatened Lowland Fynbos
Authors: Milton S. J. , Bond W. J. , Du Plessis M. A. , Gibbs D. , Hilton‐Taylor C. , Linder H. P. , Raitt L. , Wood J. , Donaldson J. S.
Published: March 2003

Abstract: A form of lowland, sandplain Fynbos restricted to the Cape Flats near the city of Cape Town is the South African vegetation type most threatened by urban and agricultural development. Cape Flats Fynbos remnants, totaling 4.8 km2, contain 14 plant species endemic to the Cape Flats scattered through four protected areas and 11 unprotected vegetation fragments on public land. Despite their small size and management problems, the remaining protected areas are under pressure from the public and developers to function as “lifeboats,” or places of safety, for attractive indigenous plant species from the unprotected areas destined for development because the popular perception is that any indigenous plant population threatened by habitat destruction should be saved by being transplanted into a protected area. The urgency for dealing with the issue of plant rescue in the Cape Town metropolitan area was the catalyst for a workshop held at the University of Cape Town in 1998 to develop protocols for Fynbos plant species translocations. We report on points raised by managers and academics at the workshop, including the selection of target taxa, individuals, and establishment sites, and methods for introduction, and present case histories illustrating possible solutions to the problems encountered.
Response of Winter Birds to Drought and Short‐Duration Grazing in Southeastern Arizona
Authors: Bock Carl E. , Bock Jane H.
Published: March 2003

Abstract:In a grassland–oak savanna in southeastern Arizona, we compared vegetative ground cover and bird populations between a 29‐year livestock exclosure and an adjacent cattle ranch that was managed according to the principles of holistic resource management, including short‐duration rotational grazing. The study took place in the winter after a 2‐year drought and 1 year after the drought ended and stocking densities were reduced. During the first winter, grasses on the livestock exclosure were taller (4.4 times) and had higher basal area ground cover (2.5 times), canopy cover (2.2 times), and reproductive canopy cover (10 times) than in the grazed area. These differences persisted into the second winter but at lower levels. As a group, 19 species of ground‐foraging, seed‐eating birds (e.g., doves, quail, sparrows, towhees) were 2.7 times more abundant on the exclosure than on adjacent grazed grasslands during the first winter. These same species were 1.7 times more abundant on the exclosure during the second winter and were 2.9 times more abundant on both sites combined after the drought had ended. A second group of 24 avian species with different foraging ecologies (e.g., predators, frugivores, arboreal insectivores) did not differ between treatments or years. High‐density, short‐duration rotational grazing, coupled with a drought, left the land in a substantially denuded condition through two winters and negatively affected a variety of resident and migratory birds dependent on ground cover and seed production for over‐winter survival.
Designing the Masoala National Park in Madagascar Based on Biological and Socioeconomic Data
Authors: Kremen Claire , Razafimahatratra Vincent , Guillery R. Philip , Rakotomalala Jocelyn , Weiss Andrew , Ratsisompatrarivo Jean‐Solo
Published: March 2003

Abstract: Conservation biologists have developed powerful tools for reserve selection and design over the past two decades, yet seldom are protected areas actually designed on scientific grounds. Using fundamental biological and socioeconomic principles of conservation science, we designed a new protected area and its multiple‐use zone on the Masoala Peninsula in the humid forest zone of Madagascar. The explicit design criteria determined the data gathered for the work, which included (1) spatial distribution and quality of habitat, (2) the areas and species at greatest risk, (3) the relationship between environmental gradients and species distributions, (4) current and predicted human settlement and land and resource use, and (5) the economic potential of natural forest management as an alternative to deforestation. We used a geographic information system to integrate these data layers and applied the design criteria to develop a park proposal that balanced human and wildlife needs. The proposal won the approval of local residents, and a national decree in 1997 designated 2100 km2 of rainforest and three satellite marine reserves as the Masoala National Park, with a surrounding multiple‐use zone of approximately 1000 km2. The new park is Madagascar's largest protected area and protects more lowland (<400 m) humid forest habitat than the entire reserve system combined, a significant step forward in conserving a globally important ecoregion. Consideration of local needs and the national economy was a key element in gaining approval for the Masoala Park. Such an approach toward reserve design could be applied elsewhere to improve chances of establishing and maintaining protected areas over the long term.
Experimental Tests of Captive Breeding for Endangered Species
Authors: Bryant Edwin H. , Backus Vickie L. , Clark Michael E. , Reed David H.
Published: March 2003

Abstract: Several captive breeding regimes were compared for their ability to maintain fitness ( larval viability) and genetic variation in small populations of the housefly ( Musca domestica L.). Populations were either maintained at constant sizes of 40, 200, or 2000 individuals or initiated with two pairs of flies and allowed to grow to 40 individuals ( low‐founder‐number populations). Low‐founder‐number populations without migration exhibited low larval viability (22%) after 24 generations, compared to larger populations maintained at either 200 (49%) or 2000 (69%) individuals, and suffered high extinction, with only 44% of the lines surviving 24 generations. Low‐founder‐number populations subjected to two additional founder ( bottleneck) episodes, reducing them to two pairs of flies, suffered little additional loss in fitness or extinction compared to the single‐founder treatments. Migration as low as one individual per generation (2.5% migration) significantly offset both reduced fitness and rate of extinction. Conversely, fitness was not significantly increased for low‐founder‐number populations when founders were selected from the top performing 20% of pairs under full‐sib mating. Populations maintained at 40 individuals were not sustainable, exhibiting low larval viability (35%) and a high extinction rate (40%) over 24 generations, similar to the extinction rates for populations initiated with only four founders. Although none of the populations maintained at 200 individuals went extinct, their fitness was reduced by 20% compared to a large control population maintained at 2000 individuals. Electrophoretic variation was significantly correlated with fitness across treatments, but the correlation of fitness to narrow‐sense heritability of two morphometric traits was not significant.
Effects of Exotic Lonicera and Rhamnus on Songbird Nest Predation
Authors: Schmidt Kenneth A. , Whelan Christopher J.
Published: March 2003

Abstract: Habitat fragmentation and disturbance exacerbate the invasion of exotic plant species that, in turn, may attract nesting songbirds by providing a branch structure suitable for nest sites. We document that American Robin (Turdus migratorius) nests in two exotic plants, Lonicera maackii and Rhamnus cathartica, experienced higher predation than nests built in comparable native shrubs (Crataegus, Viburnum) and native tree species. This was due to a combination of lower nest height, the absence of sharp thorns on the exotic species, and perhaps a branch architecture that facilitated predator movement among the exotic species. In a more subtle interaction, nesting Wood Thrushes (Hylocichla mustelina) experienced apparent competition with robins for nest sites in Lonicera, and this interaction was further aggravated by an increased selectivity for Lonicera by nesting robins, possibly due to their early leaf flush and expansion. By documenting increased nest predation in songbirds nesting in exotic shrubs, our results suggest that restoring native plant communities may benefit the surrounding avian community.
Blue Lists of Threatened Species with Stabilized or Increasing Abundance: a New Instrument for Conservation
Authors: Gigon Andreas , Langenauer Regula , Meier Claude , Nievergelt Bernhard
Published: March 2003

Abstract: To counter the often depressing information contained in Red Lists and similar lists of threatened species, we propose the use of Blue Lists that enumerate those red‐list species experiencing lasting overall stabilization or an increase in abundance in the region considered. Blue lists are (mostly) a subset of the Red Lists. We defined three main categories for blue‐listed species: (1) those whose increases merit delisting from the Red List; (2) those increasing in abundance, but not enough to warrant delisting; and (3) those whose abundance is stable. Remaining categories outside the Blue List include (1) decrease; (2) ( local) extinction; and (3) change in abundance unknown. For practical use, information on conservation or recovery techniques necessary for maintaining or promoting the species could be added to the lists. In a test region of 3431 km2 in northern Switzerland, representative of hilly and densely populated areas in central Europe, we enumerated Blue Lists for 122 species of all the vertebrate classes and 722 vascular plant species, all of which are on the regional Red Lists. Large differences exist between these systematic groups in the proportions of species in the different categories. Overall, Blue Lists comprise approximately one‐third of the red‐listed species considered. For a further 50%, nature conservation techniques for maintenance or promotion are known but have not yet been applied effectively. If all known techniques were applied to a greater extent, the persistent decline of most of the species in the region could be stopped or reversed. We discuss the scientific and psychological weaknesses and strengths of the Blue Lists. They can strengthen public motivation for conservation and advance self‐confidence among conservationists by quantifying and stressing successes in species conservation, by giving this positive information an identity, by showing promising possibilities for action, and by providing a useful public relations tool. The Blue List concept can also be applied to species covered by the U.S. Endangered Species Act and by The Nature Conservancy's ranking system on the global, national, or regional scale.
Mass Differences among Male Mangabey Monkeys Inhabiting Logged and Unlogged Forest Compartments
Authors: Olupot William
Published: March 2003

Abstract: Remedies for reduction in primate numbers following rainforest habitat disturbance must incorporate understanding of how disturbance affects population biology. Between July 1996 and July 1998, I captured 31 adult male grey cheeked mangabeys (  Lophocebus albigena) from groups occupying logged and unlogged forest in Kibale National Park, Uganda. Captured males were weighed, measured, fitted with radiocollars, and radiotracked three to five times a week. Males from groups in the unlogged forest were significantly heavier than males from the logged forest. Males that immigrated into the study groups were significantly lighter than resident males in unlogged forest, but they did not differ in mass from males in logged forest. I tested hypotheses that these differences were due to differences in age, skeletal size, and tissue mass. Results support the hypothesis that differences are due to differences in tissue mass. Results of further tests showed that differences in tissue mass were explained more by differences in habitat type than by rates of male turnover. There was no evidence to suggest that differences in tissue mass were related to differences in costs of travel, crowding, or seasonal variation in habitat quality. My results suggest that selective logging may affect primate biomass, although these changes may or may not be reflected in estimates of primate density.
Relationships among Isolated Wetland Size, Hydroperiod, and Amphibian Species Richness: Implications for Wetland Regulations
Authors: Snodgrass Joel W. , Komoroski Mark J. , Bryan A. Lawrence , Burger Joanna
Published: March 2003

Abstract: Wetland development within the United States is regulated primarily by size. Decisions concerning wetland destruction or conservation are therefore based in part on three inherent assumptions: (1) small wetlands contain water for short portions of the year; (2) small wetlands support few species; and (3) species found in small wetlands are also found in larger wetlands. We tested these assumptions using data on wetland size, relative hydroperiod (drying scores), and relative species richness of amphibians in depression wetlands of the southeastern United States. We found a significant (p = 0.03) but weak (r2 = 0.05) relationship between hydroperiod and wetland size and no relationship (p = 0.48) between amphibian species richness and wetland size. Furthermore, synthetic models of lentic communities predict that short‐hydroperiod wetlands support a unique group of species. Empirical investigations support this prediction. Our results indicate that hydroperiod length should be included as a primary criterion in wetland regulations. We advocate a landscape approach to wetlands regulation, focused in part on conserving a diversity of wetlands that represent the entire hydroperiod gradient.
Managing the Koala Problem: Interdisciplinary Perspectives
Authors: Stratford Elaine , Mazur Nicole , Lunney Daniel , Bennett David
Published: March 2003

Abstract: There is a complex scientific, ethical, and cultural debate in Australia about how best to conserve koalas and their habitat. Despite the diverse array of management and research options promoted by scientists, wildlife agency staff, and koala advocates, there remains a gap in our acknowledgment of the social factors influencing decision making about koala conservation. Koala management research has generated valuable scientific knowledge about koala biology and ecology but has been weak about organizational and policy processes and about the cultures within which we produce, disseminate, and legitimize this kind of knowledge. We suggest that more effective koala conservation will result from making the political and cultural influences on decision making regarding the koala more explicit in research, management, and policy‐making forums. Research must be conducted in the context of the cultural significance of the koala. The koala's survival depends on preserving the valuable lands that these creatures (and many others) inhabit. Ultimately, the koala symbolizes conflicting land‐use values and illustrates the need for greater collaboration, cooperation, and trust among social and natural scientists in the conduct of koala conservation research, management, and policy.
Koala Conservation Policy Process: Appraisal and Recommendations
Authors: Clark Tim W. , Mazur Nicole , Cork Steven J. , Dovers Steve , Harding Ronnie
Published: March 2003

Abstract:Australia's koalas are a global treasure, yet there is growing concern that present policy may not adequately conserve viable, wild populations in abundant habitats. Problems in the content and particularly the process of policy making for koala conservation include integrating reliable knowledge and diverse perspectives. We reviewed the overall decision process involved in developing Koala conservation policy, including the functions of intelligence, promotion, prescription, invocation, application, appraisal, and termination. To date, intelligence ( planning ) has lacked social science data, and promotion (open debate) has been confrontational. Koala policy has been unclear about prescription (setting rules) and lacks specificity about needed standards, penalties for violating standards, and making resources available. Invocation and application (implementation) have been differentially successful. Appraisal has been adversarial and incomplete, and termination of weak practices has been difficult. We suggest implementation of procedural standards such as timeliness, comprehensiveness, and rationality for a better koala decision process. The 1998 National Koala Conservation Strategy and various state policies can be upgraded to meet these standards. Opportunities exist to improve koala management policy in all seven functions. We recommend a three‐part strategy: (1) identify, describe, and appraise successful conservation efforts to find the best practices, (2) disseminate success stories, and (3) open up new opportunities for improvement in all aspects of koala conservation.
State Intervention to Protect Endangered Species: Why History and Bad Luck Matter
Authors: Bulte Erwin H. , Van Kooten G. Cornelis
Published: March 2003

Abstract: Illegal exploitation threatens the survival of many species, and anti‐poaching legislation (“protection on paper”) does not protect species. State enforcement is needed to support and supplement the formal status of endangered species, but state enforcement can be a source of instability leading to the demise of species if ad hoc rules are followed blindly. We demonstrate this with a model of poaching, wildlife, and government wildlife enforcement, but our findings apply more generally. Crucial assumptions of the dynamic model are that both poaching and enforcement effort increase or decrease whenever poaching effort and enforcement are relatively profitable or unprofitable activities, respectively. We found that multiple steady states may characterize the system's equilibrium. Depending on initial populations, the initial extent of state involvement, and random events, animal populations may be severely depleted or unexpectedly built up during transition phases. Our findings highlight the importance of history and luck in protecting endangered species.