bluuebunny/crossref_metadata_2025 huggingface dataset:
Endangered Cacti in the Chihuahuan Desert: II. Biogeography and Conservation
Authors: Hernández Héctor M. , Bárcenas Rolando T.
Published: March 2003

The distributions of the majority of the endangered cacti in the Chihuahuan Desert Region are concentrated in the southeastern and eastern segments of the area, where the predominance of narrow endemism is a remarkable phytogeographic phenomenon. We used three criteria—species richness, conservation value, and complementarity—to evaluate 37 cactus‐rich area units in the Chihuahuan Desert. The evaluation of these three quantitative parameters together allowed us to determine that seven of these areas (Huizache, Tolimán, Ciudad Victoria, Metztitlán, Cuatro Ciénegas, Jaumave, and Xichú) should be considered conservation priorities because they hold the most significant assemblage of endangered species, in terms of their numbers and their rarity. Conservation actions in these seven areas would protect 52 (55.9%) of the 93 endangered species studied here, most of which have extremely narrow distributions. Geographically, these critical areas are located in the Queretaroan‐Hidalgoan arid zone (in the States of Querétaro, Hidalgo, and Guanajuato), in the Jaumave Valley (Tamaulipas), and in two disjunct areas (San Luis Potosí and Coahuila) in the interior of the Chihuahuan Desert.
Prioritizing Pacific Salmon Stocks for Conservation
Authors: Allendorf Fred W. , Bayles David , Bottom Daniel L. , Currens Kenneth P. , Frissell Christopher A. , Hankin David , Lichatowich James A. , Nehlsen Willa , Trotter Patrick C. , Williams Thomas H.
Published: March 2003

Over 300 native stocks of Pacific salmon, steelhead, and coastal cutthroat trout (Oncorhynchus spp.) are at risk of extinction in the Pacific Northwest. With only limited resources available for conservation and recovery, prioritization of these stocks may become necessary if meaningful measures are to be implemented. We propose criteria by which prioritization may be guided. First, we rank stocks for risk of extinction, either by population viability analysis or by a set of surrogate measures. Then we rank stocks for biological consequences of extinction, using sets of questions designed to establish the genetic and evolutionary consequences and the ecological consequences if a stock were to become extinct. Together, these rankings allow stocks to be prioritized for a range of possible actions, with those stocks at highest risk and bearing the greatest biological consequences of extinction receiving attention first. Application of the prioritization process to 20 Pacific anadromous salmonid stocks worked as intended, although data limitations are considerable. The process is most likely to work successfully when applied to many stocks on which data exist, when several experts carry out the prioritization, and when the results are peer reviewed.
Geographical Range Size and the Conservation of Mexican Mammals
Authors: Arita Héctor T. , Figueroa Fernanda , Frisch Astrid , Rodríguez Pilar , Santos‐Del‐Prado Karina
Published: March 2003

Range was estimated for the 423 noninsular mammals of Mexico to identify those species with more restricted distributions and to detect priority areas for conservation based on the presence of such species. Thirty‐eight percent of nonvolant mammals and 15.4% of bats are restricted in Mexico to areas of less than 114,000 km2. Restricted species were defined as those occurring in ranges smaller than the median for bats and for nonvolant species. Following this criterion, most nonvolant species with restricted distribution in Mexico are either endemic to the country or are shared with the United States, whereas endemic chiropteran species are few, and most Mexican bats with restricted distribution also occur in South America. Nonvolant mammals with restricted distribution in Mexico tend to be of small body size, herbivore or granivore, and fossorial or semifossorial. Among bats, gleaners are significantly more restricted than aerial insectivores. Species with restricted distribution are inadequately represented in the current official list of endangered species, particularly in the case of nonvolant mammals. Similarly, some areas of Mexico that harbor several species with restricted distribution are not represented in the Mexican system of protected areas. Therefore, rarity, in this case measured by the area of distribution, should be included as an additional criterion for conservation of the Mexican mammal fauna.
Ecological Status of Beaucarnea gracilis, an Endemic Species of the Semiarid Tehuacán Valley, México
Authors: Cardel Yuria , Rico‐Gray Victor , García‐Franco José G. , Thien Leonard B.
Published: March 2003

We present a demographic analysis and suggestions for the conservation of Beaucarnea gracilis, a species endemic to the Tehuacán Valley, Puebla, México. The species is dioecious, it flowers every year, and the breeding system and floral display are typical of a generalist mode of pollination. The density of B. gracilis in the study plot was 16.7 individuals/ha. Distribution of trunk diameter size classes fits a normal distribution (n = 404), but the smaller sizes were not found (<0.7 m). The inflorescences were visited by 46 insect species. Over 2600 seeds are produced per inflorescence; 27–30% are damaged by parasites, and the rest germinate readily (90–100%). Survival of seeds and seedlings is very low. We found 313 seedlings in a 12‐ha area, all (94.24%) of which were at the base of nurse plants; particularly Mimosa luisiana and Castela tortuosa. The ecological status of the population of Beaucarnea gracilis is relatively good for adult individuals. In addition to low recruitment, (whether natural or human influenced), past extraction of seedlings for commerce, grazing by goats, and land clearing for corn cultivation, highway construction, and urbanization, are a real threat to the survival and establishment of seeds and seedlings. Conservation of this slow‐growing, long‐lived species should be promoted because (1) ecologically, it is a feeding center for many insect species, an important host for many Bromeliaceae, and part of the highly rich and endemic flora of Tehuacán and (2) economically, it helps low income people in the area (seedlings raised for commerce). Protection of nurse plants, regulation of grazing by goats, a halt to illegal extraction, and conservation of areas of the Tehuacán valley will help the survival of this species in nature.
Diamondback Terrapin (Malaclemys terrapin) Mortality in Crab Pots
Authors: Roosenburg Willem M. , Cresko William , Modesitte Michael , Robbins Matthew B.
Published: March 2003

The entrapment of diamondback terrapins (  Malaclemys terrapin) in crab pots frequently results in drowning and death of the trapped turtles. We determined the rate of capture, size, sex, and age of terrapins captured, and the potential impact crab pot mortality has on local terrapin populations. We estimated terrapin capture rates of 0.17 terrapins/pot/day in shallow water areas of Chesapeake Bay (Maryland, USA). The sex ratio of terrapins caught in crab pots was 3:2 male biased because female terrapins become too large to enter crab pots by the time they reach 8 years of age. Males, however, remain vulnerable to entrapment throughout their life. Our estimates of capture rates and local population size suggest that 15–78% of a local population may be captured in a single year. As a consequence, crab pots may be the major reason terrapins are extirpated in coastal, shallow water areas with heavy crab pot fisheries. Additionally, the selective removal of males may also contribute to female‐biased sex ratios observed in this diamondback terrapin population. We developed and tested a modified crab pot that increases terrapin survival and does not reduce the number of crabs caught. Our modified crab pot maintained permanent access to air and prevented the drowning of terrapins. Additionally, our modified crab pot caught more crabs than standard commercial crab pots, suggesting that the modified crab pot could be a viable alternative to standard traps that result in terrapin mortality.
Assessing Risks to Biodiversity from Future Landscape Change
Authors: White Denis , Minotti Priscilla G. , Barczak Mary J. , Sifneos Jean C. , Freemark Kathryn E. , Santelmann Mary V. , Steinitz Carl F. , Kiester A. Ross , Preston Eric M.
Published: March 2003

We examined the impacts of possible future land development patterns on the biodiversity of a landscape. Our landscape data included a remote sensing derived map of the current habitat of the study area and six maps of future habitat distributions resulting from different land development scenarios. Our species data included lists of all bird, mammal, reptile, and amphibian species in the study area, their habitat associations, and area requirements for each. We estimated the area requirements using home ranges, sampled population densities, or genetic area requirements that incorporate dispersal distances. Our measures of biodiversity were species richness and habitat abundance. We calculated habitat abundance in two ways. First, we computed the total habitat area for each species in each landscape. Second, we calculated the number of habitat units for each species in each landscape by dividing the size of each habitat patch in the landscape by the area requirement and summing over all patches. Species richness was based on presence of habitat. Species became extinct in the landscape if they had no habitat area or no habitat units, respectively. We then computed ratios of habitat abundance in each future landscape to habitat abundance in the present for each species. We also computed the ratio of future to present species richness. We then calculated summary statistics across all species. Species richness changed little from present to future. There were distinctly greater risks to habitat abundance in landscapes that extrapolated from present trends or zoning patterns, however, as opposed to landscapes in which land development activities followed more constrained patterns. These results were stable when tested using Monte Carlo simulations and sensitivity tests on the area requirements. We conclude that this methodology can begin to discriminate the effects of potential changes in land development on vertebrate biodiversity.
Hotspots of Epiphytic Lichen Diversity in Two Young Managed Forests
Authors: Neitlich Peter N. , McCune Bruce
Published: March 2003

Understanding within‐stand variation in diversity of epiphytes will provide an improved basis for producing timber while conserving biological diversity. Two 80‐ha, 50–year–old managed stands of conifers were surveyed to locate 0.4 ha putative “diversity” plots, the areas appearing most diverse in lichen epiphytes. These plots were generally located in areas made heterogeneous by canopy gaps, wolf trees (trees with large‐diameter lower branches), and old‐growth remnant trees. “Matrix” plots, in contrast, were chosen at random from the remaining, more homogenous forest. Diversity plots hosted from 25% to 40% more epiphytic lichen species than matrix plots in both stands. The strongest within‐stand gradients in species composition were correlated with percentage of plot occupied by gaps and wolf trees. Percentage of the plot in gaps was correlated with species richness (r = 0.79). In the more structurally diverse stand, diversity and abundance of nitrogen‐fixing “cyanolichens” were correlated with percentage of the plot occupied by gaps (0.5 < r < 0.9), and alectorioid lichens were correlated with percentage of the plot occupied by old‐growth remnant trees (0.5 < r < 0.6). In the stand with more homogenous structure, percentage of the plot under gaps was correlated with regionally common species that were otherwise absent or sparse in the matrix. Protecting gaps, hardwoods, wolf trees, and old‐growth remnant trees during thinning or other partial cutting is likely to promote the majority of epiphytic macrolichens in young conifer forests. Because these features are easily recognized on aerial photos and on the ground by land managers, it is practical to manage for forest structures that would promote lichen diversity.
Population Viability Analysis of the Florida Manatee (Trichechus manatus latirostris), 1976–1991
Authors: Marmontel Miriam , Humphrey Stephen R. , O'Shea Thomas J.
Published: March 2003

Recent development of age‐determination techniques for Florida manatees (Trichechus manatus latirostris) has permitted derivation of age‐specific data on reproduction and survival of a sample of 1212 carcasses obtained throughout Florida from 1976–1991. Population viability analysis using these data projects a slightly negative growth rate (−0.003) and an unacceptably low probability of persistence (0.44) over 1000 years. The main factors affecting population projections were adult survival and fecundity. A 10% increase in adult mortality would drive the population to extinction over a 1000‐year time scale, whereas a 10% decrease in adult mortality would allow slow population growth. A 10% decrease in reproduction would also result in extinction. We conclude that management must focus on retaining and improving the conditions under which manatee demography operates. The major identified agent of mortality is boat‐manatee collisions, and rapidly increasing numbers of humans and registered boats portend an increase in manatee mortality. Zoning of manatee‐occupied waters for reductions in boating activity and speed is essential to safeguard the manatee population. If boating regulations being implemented by the state of Florida in each of 13 key coastal counties are completed, enforced, and effective, manatees and human recreation could coexist indefinitely. If regulation is unsuccessful, the Florida manatee population is likely to decline slowly toward extinction.
Sea Otter Mortality Estimated from Carcasses Collected after the Exxon Valdez Oil Spill
Authors: Garshelis David L.
Published: March 2003

Large numbers of sea otters (  Enhydra lutris) died following the 1989 Exxon Valdez oil spill. Two previous studies estimated spill‐related mortality, one from the difference between counts of otters before and after the spill, and the other from the recovery rate of tagged carcasses that had been released at sea. I used a derivative of the second approach, but revised it to account for (1) moribund otters that had hauled out on shore; (2) carcasses that were collected at sea; and (3) differences in search effort in different areas of the spill—considerations that were not addressed previously. The mortality estimation procedure presented here, and applied to Prince William Sound, Alaska, had six input parameters, two with fixed values (the number of spill‐related carcasses collected [391] and the number of otters taken alive that died in captivity [84]) and four that were assigned a range of values (the recovery rate for carcasses on the beach [60–90%], the proportion of recovered carcasses that were onshore [70–95%]), the proportion of offshore deaths recovered onshore (20–50%), and the proportion of moribund otters that hauled out (20–60%). Empirical estimates for these parameters were not available after the spill, but a range of plausible values for each was delimited using other available data. Randomly‐selected combinations of values within these ranges produced mortality estimates for the sound ( x¯= 750, 5–95% quantiles ≈ 600–1000) that were lower than indicated by previous studies. These lower estimates do not diminish the tragic nature of the mortality, but instead highlight the significance of both the process and informational basis in producing estimates of catastrophic loss. Estimates of loss based on faulty or inadequate data may mislead investigations of population recovery and may jeopardize public trust in scientific assessments of future catastrophes.
Near‐Extinction of Porcupines by Mountain Lions and Consequences of Ecosystem Change in the Great Basin Desert
Authors: Sweitzer Richard A. , Jenkins Stephen H. , Berger Joel
Published: March 2003

In North America’s Great Basin Desert changes in plant communities that occurred after the introduction of domestic livestock in the late 1800s resulted in the irruption of mule deer (Ocodoileus hemionus) and expansion of mountain lions (  Felis concolor). We report on a situation in which mountain lion predation caused the near‐extinction of another native species, porcupines (  Erethizon dorsatum). We used demographic information collected over 8 years on an individually identified population and long term climatic data in a stochastic population model to examine the hypothesis that predation and not weather‐induced starvation or random population fluctuations threatened the persistence of a naturally small population of porcupines. Whether drought‐related reductions in mule deer densities induced mountain lions to prey on porcupines is unclear, but our results suggest predation and not climatic conditions caused the decline of a once robust population of over 80 to <5 animals in only 3 years. These data represent an unusual case in which predation by a native predator caused the near‐extinction of a native prey species, suggesting that one unforeseen consequence of ecosystem change in western North America may be the impending loss of small, native vertebrate populations.

Cuasi‐extinción de Puercoespines por Pumas y Consecuencias del Cambio en el Ecosistema del Desierto Great Basin

Los cambios ocurridos en las comunidades vegetales del Desierto Great Basin en Norteamérica después de la introducción de ganado a fines del siglo pasado resultaron en la irrupción del venado bura (Odocoileus hemionus) y en la ezpansión del puma (  Felis concolor). Este trabajo reporta un caso en el que la depredación por pumas casi causó la extinción de otra especie nativa, el puercoespín (  Erethizon dorsatum). Utilizamos información demográfica de una población individual obtenida a lo largo de 8 años así como datos climáticos de varios años en un modelo estocástico de la población para examinar la hipótesis de que la persistencia de poblaciones naturalmente pequeñas de puercoespines estaba amenazada por la depredación y no por hambruna ni por fluctuaciones poblacionales aleatorias. No es claro si la reducción en la densidad de venado bura asociada a períodos de sequía indujo a los pumas a depredar puercoespines, pero nuestros resultados sugieren que la depredación y no las condiciones climáticas, provocó la declinación de una población robusta de mas de 80 animales a menos de 5 en solo tres años. Estos datos representan un caso inusual en el que la depredación por una especie nativa casi causó la extinción de una especie‐presa nativa, lo que sugiere que una consecuencia no prevista de los cambios en los ecosistemas de Norteamérica occidental puede ser la inminente pérdida de poblaciones pequeñas de vertebrados nativos.
Effects of Rock Climbing on Populations of Presettlement Eastern White Cedar (Thuja occidentalis) on Cliffs of the Niagara Escarpment, Canada
Authors: Kelly P. E. , Larson D. W.
Published: March 2003

Cliffs of the Niagara Escarpment support a self‐sustaining presettlement forest of eastern white cedar (  Thuja occidentalis L.) in which some trees are over 1000 years old. Many of the cliffs are also popular locations for recreational rock climbing. Our study employed a stratified random sampling design to assess the impact of rock climbing on populations of cliff‐face and cliff‐edge trees. Tree density and age structure were compared between four climbed and three unclimbed sites in the vicinity of Milton, Ontario. Signs of physical damage were also recorded for the trees sampled at each site. The results showed that living tree density on the cliff face was lower in climbed areas. The age structures of these forests showed that the numbers of older and younger age classes have been reduced on climbed cliff faces compared with unclimbed areas. A high percentage of trees on climbed cliff faces showed evidence of damage by humans. These trends were not as apparent on cliff edges where other disturbances have affected age structure. We recommend that cliff faces be explored for the presence of presettlement forest and that recreation managers of lands with exposed cliff faces incorporate rock climbing considerations into their management plans. Monitoring programs would help track levels of disturbance. Education of the climbing community would be the most effective long‐term solution to limiting disturbance in sensitive areas.
Molecular Genetic Consequences of a Population Bottleneck Associated with Reintroduction of the Mauna Kea Silversword (Arg yroxiphium sandwicense ssp. sandwicense [Asteraceae])
Authors: Robichaux Robert H. , Friar Elizabeth A. , Mount David W.
Published: March 2003

The endangered Mauna Kea silversword (Argyroxiphium sandwicense ssp. sandwicense) has experienced a severe decline in distribution and abundance because of predation by alien ungulates. By the late 1970s only a small remnant natural population persisted on the Mauna Kea volcano on the Island of Hawaii. The Hawaii Department of Land and Natural Resources, Division of Forestry and Wildlife, initiated an outplanting program in the 1970s to promote recovery of A. sandwicense ssp. sandwicense. Intermittent outplanting since 1973 has generated an outplanted population of over 450 plants on Mauna Kea, but the program has unintentionally resulted in a major population bottleneck. All plants in the outplanted population appear to be first‐ or subsequent‐generation offspring of only two maternal founders from the natural population. Genetic variation in the natural and outplanted populations was assessed for 90 random amplified polymorphic DNA loci. Eleven loci were detectably polymorphic in the natural population, whereas only three loci were detectably polymorphic in the outplanted population. Thus, the population bottleneck has been accompanied by a 73% reduction in the level of detectable polymorphism. In addition, for eight loci, the population bottleneck has resulted in the loss of the marker allele in the outplanted population. A management strategy involving manual pollen transfer has recently been implemented to incorporate additional founders from the natural population into the outplanting program. As a supplement to the outplanting program, the strategy also includes a program promoting direct seedling establishment following manual pollen transfer. Incorporating additional founders may serve to overcome the legacy of the population bottleneck, especially if founder representation can be equalized.
Evolutionary Significant Units versus Geopolitical Taxonomy: Molecular Systematics of an Endangered Sea Turtle (genus Chelonia)
Authors: Karl Stephen A. , Bowen Brian W.
Published: March 2003

Abstract: Taxonomic rank is an important criterion in assessing the conservation priority of an endangered organism: the sole member of a distinct family will generally receive a higher priority than a semi‐isolated population in a polytypic species. When cryptic evolutionary partitions are discovered in endangered species, these findings are heralded as a positive step in the conservation process. The opposite action, demoting the taxonomic rank of an endangered organism, can be resisted by the conservation community because it is perceived as detrimental to preservation efforts. We explore the arguments for and against the species status of the endangered black turtle (Chelonia agassizii) and contribute an additional data set based on DNA sequences of single‐copy nuclear loci. These data are concordant with previous mtDNA surveys in indicating no evolutionary distinction between C. agassizii and adjacent green turtle (C. mydas) populations. Although the black turtle is morphologically identifiable at a low level, much of its distinction is based on size and color differences that are highly variable throughout the range of C. mydas. Thus the black turtle would be more accurately classified at the subspecific or population level. There is no strong scientific case available to defend the species status of C. agassizii, and yet that designation has persisted for over a century. We suggest that the maintenance of this name is based on geographical and political considerations, and we propose a pragmatic category for this type of taxonomy: the geopolitical species. Furthermore, we argue against the practice of preserving species status for conservation purposes. There are several good reasons to preserve the black turtle, including morphological diversity and the possibility that it is an incipient evolutionary lineage with novel adaptations; taxonomic rank, however, is not one of them.
On the Decline of the Rusty Blackbird and the Use of Ornithological Literature to Document Long‐Term Population Trends
Authors: Greenberg Russell , Droege Sam
Published: March 2003

Abstract:
Unlike most North American blackbirds, Rusty Blackbirds ( Euphagus carolensis) have shown steep population declines. Declines of approximately 90% are indicated for three recent decades from the Breeding Bird Survey, Christmas Bird Counts, and Quebec Checklist Program. Analyses of abundance classifications in bird distribution books and annotated checklists reveal an overlooked but long‐term decline dating back to at least the early part of this century. Rusty Blackbirds were described as very common to abundant in 56% of the pre‐1920 published accounts, 19% of the 1921–1950 accounts, and only 7% of the post‐1950 accounts. Rusty Blackbirds were described as uncommon in none of the pre‐1950 accounts, 18% of the 1951–1980 accounts, and 43% of the post‐1980 accounts. A similar pattern was found for analyses based on local checklists. Destruction of wooded wetlands on wintering grounds, acid precipitation, and the conversion of boreal forest wetlands could have contributed to these declines. Systematic analysis of regional guides and checklists provides a valuable tool for examining large‐scale and long‐term population changes in birds.
Predicting the Pattern of Decline of African Primate Diversity: an Extinction Debt from Historical Deforestation
Authors: Cowlishaw Guy
Published: March 2003

Abstract: Populations that have survived extensive habitat loss may still face extinction owing to a time lag between initial habitat loss and eventual population collapse. Using island biogeography theory, I investigated the potential existence and magnitude of such “extinction debts” among African forest primates as a result of historical deforestation. Forest primate species exhibited a classic species‐area relationship ( S = cAz) with forest habitat across African countries. I conducted three tests based on the species‐area relationship that indicate extinction debts are likely to exist in African forest primates; in particular, several national extinctions should have already occurred solely as a result of forest loss in the last 50 years (if extinctions occurred simultaneously with habitat loss), but none of these extinctions have yet taken place. I also used the species‐area relationship to predict the number of species that make up the total debt accumulated since deforestation began in these countries. My results suggest that in most countries the debt currently consists of over 30% of the forest primate fauna, which usually constitutes between four and eight species. These figures are likely to be accurate because the same model predicts with a reasonable degree of precision (1) the severity of threat of extinction from deforestation faced by country endemics, (2) the distribution of regional community endemics threatened by deforestation, and (3) the total number of African species threatened by deforestation (according to the 1996 IUCN Red List). My findings indicate that although protected areas are an essential part of conservation, the protection of the remaining forest alone may not be enough to prevent extinctions caused by habitat loss.
Conservation Endocrinology: a Noninvasive Tool to Understand Relationships between Carnivore Colonization and Ecological Carrying Capacity
Authors: Berger Joel , Testa J. Ward , Roffe Tom , Monfort Steven L.
Published: March 2003

Abstract:Reproductive technology, especially the diagnosis of pregnancy by radioimmunoassay of fecal steroid metabolites, is an important component of captive propagation, but its role in our understanding of ecological interactions and in situ biological restoration has been more limited. Where large herbivores have been “released” from predation by the extirpation of carnivores, controversy often exists about possible detrimental effects at the ecosystem level. A related concern is that the reestablishment of large carnivores may decrease the availability of prey populations for human subsistence. We suggest that pregnancy assays can be a valuable tool to help distinguish between the roles of predation versus food‐imposed limitations on population size and their effects on juvenile recruitment in wild species. We explored this issue through analyses of fecal progestagen concentration ( FPC) levels to document pregnancy in moose (Alces alces) in the southern Greater Yellowstone Ecosystem, a site where wolves (Canis lupus) and grizzly bears ( Ursus arctos) are recolonizing former habitats after an absence of more than 60 years. Pregnancy was clearly discernible (mean FPC for pregnant and nonpregnant females, respectively: 10.60 vs. 2.57 μg/g;p <0.0001). Among the potential confounding variables that need to be considered if FPC is applied to ecological and demographic questions are whether baseline values are affected by handling, whether neonate survival has been assessed, and whether sampling efforts are directed at both pregnant and nonpregnant animals. With these issues accounted for, the local moose population experienced juvenile survival rates among the highest in North America. Pregnancy rates, however, dropped from 90% in 1966 to about 75% today, rendering them in the lowest fifteenth percentile among moose populations in North America. Our findings suggest that a relatively low frequency of juvenile moose is not the likely result of predation, and they illustrate how endocrinology can be applied to issues involving reproductive events within an ecological context. They also affirm that noninvasive and generally inexpensive endocrinological procedures will be applicable to understanding interactions between recolonizing predators and prey, an issue that will continue to arise because of global restoration efforts, and to the study of rare ungulates in remote systems where data on reproductive events are difficult to obtain.
Identification of Conservation‐Worthy Areas in Northern Zululand, South Africa
Authors: Maddock Ant , Benn Grant A.
Published: March 2003

Abstract: We used spatial and statistical analyses to identify and prioritize broad areas for conservation attention in the northern Zululand region of KwaZulu‐Natal, South Africa. We attempted to identify conservation‐worthy areas based on species, vegetation types, ecological processes, and threats to biodiversity. Information on species was limited and so could not form the basis of the analysis. Priority vegetation types were identified by degree of endemicity, extent of protection and transformation, and degree of fragmentation. These priority vegetation types and threats to biodiversity were used to define broad linkages between existing protected areas. We set a goal of 10% protection for each vegetation type and 25% for each species. We identified several important (endemic or threatened) animal species and predicted their ranges using a simple model. Species ranges and their hotspots were compared with the distribution of protected areas and the suggested linkages to evaluate increased species representation. Generally, the eastern part of the study area was well protected. Unprotected conservation‐worthy areas under greatest threat lay in the west, and protecting these areas is a priority. Furthermore, several vegetation types were not protected by provincial authorities, a situation that also needs to be addressed. The findings of our study need to be reassessed at a finer land‐parcel scale, and implementation of a range of land‐use options considered.
Changing Species Richness and Composition in Canadian National Parks
Authors: Rivard Donald H. , Poitevin Jean , Plasse Daniel , Carleton Michel , Currie David J.
Published: March 2003

Abstract: Canada's national parks and their surrounding areas differ markedly in size, climate, vegetation, and extent of human development. We tested the extent to which total species richness, native species richness, and the number of extirpations and introductions of terrestrial vertebrates were correlated with each of these factors. To do this, we used surveys of park fauna from the present and from the time of park establishment. Richness, extirpations, and introductions were all strongly related to climate. After we controlled for climate, smaller parks had higher rates of species loss than larger parks. Land‐use patterns (forest cover and fragmentation, roads, etc.) within parks were strongly correlated with land use in the regions surrounding the parks, showing that parks have not been isolated from regional development. Richness and extirpations within parks were generally more strongly related to regional characteristics than to the characteristics of the parks themselves. Species richness and numbers of introduced species were higher in parks found in landscapes with greater fragmentation. Frequencies of extirpations were less clearly related to human‐influenced habitat characteristics. Introductions and extinctions most often involved game species or species directly associated with human activities. There is little evidence of subtle ecological effects being responsible for species loss. Our results suggest that management should focus on direct human interventions, such as hunting, introduction of game species, and habitat fragmentation, in parks and surrounding areas.
Population Size and Reproduction inPhlox pilosa
Authors: Hendrix Stephen D. , Kyhl And John F.
Published: March 2003

Abstract:We analyzed the relationships between population size and reproductive characteristics in the perennial prairie forbPhlox pilosa, an obligate outcrossing butterfly‐pollinated species. We examined 27 populations ranging in size from 9 to over 75,000 flowering ramets in two regions of the state of Iowa (eastcentral and northwest) in 1993 and 1994. We collected flowers from each population and scored them for pollen arrival to stigmas and number of pollen tubes. We collected fruiting ramets from each population at the end of thePhloxgrowing season and scored them for height, biomass, and reproductive variables, including the number of flowers initiated and opened and the number of capsules initiated and matured. In both years, population size was significantly correlated with the number of capsules matured per ramet. Differences between populations in capsule production were set primarily at the pollination stage. In 1993, pollen arrival to stigmas was significantly lower than in 1994 and was correlated with population size in eastcentral Iowa populations, indicating that lower reproduction in small populations that year was at least partially due to inadequate amounts of pollen being moved. In 1993, weather conditions likely depressed pollinator activity, but absolute capsule formation was high because of high flower production per ramet and high population densities. In 1994, when pollen arrival to stigmas was relatively high and unrelated to population size, outcross pollen movement was greater in larger populations. Increased efficacy of outcross pollen movement in 1994 may have resulted from lower flower production and less dense populations forcing greater pollinator movement between ramets or from variation between years in fine‐scale spatial genetic substructuring of populations. Our results indicate that the viability ofPhlox pilosacan be best ensured by protecting and creating populations of at least 1000–2000 flowering ramets.
Life and Death in the Fast Lane: Demographic Consequences of Road Mortality in the Florida Scrub‐Jay
Authors: Mumme Ronald L. , Schoech Stephan J. , Woolfenden Glen E. , Fitzpatrick John W.
Published: March 2003

Abstract:We examined the demographic consequences of road mortality in the cooperatively breeding Florida Scrub‐Jay (Aphelocoma coerulescens), a threatened species restricted to the oak scrub of peninsular Florida. Between May 1986 and July 1995 we monitored the survival and reproductive success of a color‐banded population of jays along a two‐lane highway at Archbold Biological Station. Annual mortality of breeding adults was 0.38 on road territories, significantly higher than the rate of 0.23 for breeders on nonroad territories. High mortality on road territories appeared to be a direct result of automobile traffic per se and not a consequence of road‐induced changes in habitat characteristics. Mortality was especially high for immigrants without previous experience living along the road: in their first two years as breeders on road territories, naive immigrants experienced annual mortality of 0.50 and 0.45. From year 3 onward, however, annual mortality dropped to 0.29, not significantly different from the rate for birds on nonroad territories. This experience‐dependent decline in road mortality could be caused either by surviving jays learning to avoid automobiles or by selective mortality operating through time (demographic heterogeneity). Proximity to the road had no effect on nesting success beyond its indirect effects on breeder experience and group size. Because the mortality of 30‐ to 90‐day‐old fledglings was significantly higher on road territories than on nonroad territories, however, breeder mortality greatly exceeded production of yearlings on road territories. Roadside territories therefore are sinks that can maintain populations of Florida Scrub‐Jays only via immigration. Because Florida Scrub‐Jays do not avoid roadside habitats and may even be attracted to them, road mortality presents a difficult challenge for the management and conservation of this threatened and declining species.
Economic Science, Endangered Species, and Biodiversity Loss
Authors: Bulte Erwin , Van Kooten G. C.
Published: March 2003

Abstract: Although economic analysis can be used to argue for preservation of species and habitats, many natural assets represent inferior investments in society's asset portfolio. We demonstrate this for the case of ancient temperate rainforests and minke whales (  Balaenoptera acutorostrata). For both rainforests and whales, we determined their value for harvest and balanced this against society's valuation of the preserved stock. For the market and nonmarket data available, we then determined how much rainforest and how many minke whales global society should keep in its asset portfolio. Although ecologists increasingly attempt to justify preservation of biological assets on economic grounds, we argue that this might be a dangerous approach to take. Ultimately, it may be necessary to reexamine the ethical foundations for conservation of nature and biodiversity, including the economist's use of utilitarianism. We suggest that the safe minimum standard approach may prove useful in practice.
Effects of Habitat Fragmentation on Bird Species in a Relict Temperate Forest in Semiarid Chile
Authors: Cornelius Cintia , Cofré Hernán , Marquet Pablo A.
Published: March 2003

Abstract:We analyzed the structure and composition of a bird assemblage in a fragmented relict temperate forest located in northcentral Chile ( Fray Jorge National Park). In terms of species composition, the bird assemblage we found in Fray Jorge was more similar to southern temperate forest sites, located more than 1200 km south of Fray Jorge, than to localities found in nearby scrub habitats. The relict character and long‐term isolation of the Fray Jorge forest provides a natural experiment with which to establish the potential long‐term effects of fragmentation and isolation on southern Chilean temperate forests. Between May 1996 and March 1997, we conducted seasonal surveys of birds in six forest fragments, ranging in size from 0.5 to 22.5 ha, at Fray Jorge. The number of bird species at each forest fragment was positively correlated with fragment area during all seasons. The relict forest system had a steeper species‐area slope than that reported for similar temperate‐forest bird assemblages in forest fragments within Chiloé Island and for islands across the Chiloé Archipelago in southern Chile. In this regard, this bird fauna resembled a depauperate oceanic archipelago. This difference in area effects is likely a consequence of the minimization of rescue effects because of the absence of large source forest areas nearby and the long‐term isolation of the system. In addition, the distribution of species among forest fragments in Fray Jorge was not random, showing a nested subset pattern. Thus, some species occur across all fragments, regardless of their area, and therefore are less affected by habitat fragmentation and less prone to local extinction. These results suggest that, for south‐temperate forest birds, large fragments (or reserves) should afford better protection against extinction than small forest patches.
Indicators of Biodiversity for Ecologically Sustainable Forest Management
Authors: Lindenmayer David B. , Margules Chris R. , Botkin Daniel B.
Published: March 2003

Abstract:The conservation of biological diversity has become one of the important goals of managing forests in an ecologically sustainable way. Ecologists and forest resource managers need measures to judge the success or failure of management regimes designed to sustain biological diversity. The relationships between potential indicator species and total biodiversity are not well established. Carefully designed studies are required to test relationships between the presence and abundance of potential indicator species and other taxa and the maintenance of critical ecosystem processes in forests. Other indicators of biological diversity in forests, in addition or as alternatives to indicator species, include what we call structure‐based indicators. These are stand‐level and landscape‐level (spatial) features of forests such as stand structural complexity and plant species composition, connectivity, and heterogeneity. Although the adoption of practices to sustain (or recreate) key characteristics of forest ecosystems appear intuitively sensible and broadly consistent with current knowledge, information is lacking to determine whether such stand‐ and landscape‐level features of forests will serve as successful indices of (and help conserve) biodiversity. Given our limited knowledge of both indicator species and structure‐based indicators, we advocate the following four approaches to enhance biodiversity conservation in forests: (1) establish biodiversity priority areas (e.g., reserves) managed primarily for the conservation of biological diversity; (2) within production forests, apply structure‐based indicators including structural complexity, connectivity, and heterogeneity; (3) using multiple conservation strategies at multiple spatial scales, spread out risk in wood production forests; and (4) adopt an adaptive management approach to test the validity of structure‐based indices of biological diversity by treating management practices as experiments. These approaches would aim to provide new knowledge to managers and improve the effectiveness of current management strategies.
Corridor Length and Patch Colonization by a Butterfly, Junonia coenia
Authors: Haddad Nick
Published: March 2003

Abstract: Corridors have been proposed to reduce isolation and increase population persistence in fragmented landscapes, yet little research has evaluated the types of landscapes in which corridors will be most effective. I tested the hypothesis that corridors increase patch colonization by a butterfly, Junonia coenia, regardless of the butterfly's initial distance from a patch. I chose J. coenia because it has been shown to move between patches preferentially through corridors. Individuals were released 16–192 m away from open experimental patches into adjacent open corridors or forest. Neither corridors nor distance had a significant effect on patch colonization, but there was a significant interaction between the presence or absence of corridors and distance. At small distances (16–64 m), J. coenia was more likely to colonize open patches when released within forest than within open corridors, most likely because J. coenia used corridors as habitat. Nevertheless, patch colonization by butterflies released within forest decreased rapidly as distance from patches increased, as predicted by a null model of random movement. Colonization did not change with distance in the corridor, and at long distances (128–192 m), butterflies released in corridors were twice as likely to colonize open patches as those released in forest. These results suggest that one critical factor, interpatch distance, may determine the relative effectiveness of corridors and other landscape configurations, such as stepping stones, in reducing isolation in fragmented landscapes. When distances between patches are short compared to an animal's movement ability, a stepping stone approach may most effectively promote dispersal. Alternatively, the conservation value of corridors is highest relative to other habitat configurations when longer distances separate patches in fragmented landscapes.
Cougar Dispersal Patterns, Metapopulation Dynamics, and Conservation
Authors: Sweanor Linda L. , Logan Kenneth A. , Hornocker Maurice G.
Published: March 2003

Abstract:We examined cougar (  Puma concolor) dispersal, emigration, and immigration in the San Andres Mountains, New Mexico, from 1985 to 1995 to quantify the effects of dispersal on the local population and surrounding subpopulations. We captured, tagged, and radio‐collared animals to detect the arrival of new immigrants and dispersal characteristics of progeny. We found that cougars in southern New Mexico exhibited a metapopulation structure in which cougar subpopulations were separated by expanses of noncougar habitat and linked by dispersers. Of 43 progeny (n = 20males, 23females) studied after independence, only 13 females exhibited philopatric behavior. Males dispersed significantly farther than females, were more likely to traverse large expanses of noncougar habitat, and were probably most responsible for nuclear gene flow between habitat patches. We estimated that an average of 8.5 progeny (i.e., cougars born in the study area) successfully emigrated from and 4.3 cougars successfully immigrated to the San Andres Mountains each year. Concurrently, an average of 4.1 progeny were recruited into the San Andres cougar population. Protected cougar subpopulations can contribute to metapopulation persistence by supplying immigrants to surrounding subpopulations that are affected by fragmentation or offtake by humans. Cougar population dynamics and dispersal behavior dictate that cougar management and conservation should be considered on a regional scale.
Extinction of a West African Red Colobus Monkey
Authors: Oates John F. , Abedi‐Lartey Michael , McGraw W. Scott , Struhsaker Thomas T. , Whitesides George H.
Published: March 2003

Abstract:We provide the first documented case of the extinction in the twentieth century of a widely recognized primate taxon. During surveys in Ghana and Côte d'Ivoire in 1993–1999, we were unable to find any surviving populations of Miss Waldron's red colobus monkey (  Procolobus badius waldroni), a primate taxon endemic to the forests of this part of West Africa. We conclude that this monkey, which at least one authority considers worthy of species status, is probably extinct. Hunting by humans appears to be the ultimate cause of the extinction. Until our surveys began, little attention had been paid to the plight of this red colobus monkey, despite its listing as endangered by the World Conservation Union. The extinction of other large animals in the Upper Guinea rainforest region is likely to follow soon unless more attention is paid to the full range of endangered forms and more resources are devoted to their rigorous protection.