Decline and extirpation of an endangered Panamanian stream frog population (Craugastor punctariolus) due to an outbreak of chytridiomycosis

We conducted a mark-recapture study of three subpopulations of Craugastor punctariolus at a mid-elevation site in central Panama between 1999 and 2005. The study spans a period over which the pathogenic fungus Batrachochytrium dendrobatidis (Bd) was absent from the site, invaded the site and decimated all amphibian populations, and now persists. We quantified natural demographic parameters prior to and during an event of mass mortality due to chytridiomycosis caused by Bd. Prior to the event of mass mortality, all three subpopulations of C. punctariolus were large (19-68 animals/200 m), showed a stable age-size distribution, and had high survival. All age-size classes of this species co-occurred on boulder clumps along streams, and adults showed high site fidelity and were likely territorial. Following detection of Bd at this site in late September 2004, four dead C. punctariolus were found infected with Bd and all three subpopulations completely disappeared from this site within 2 months. The association of all age-size classes with microhabitats appropriate for survival and growth of Bd likely contributed to the rapid and severe degree of decline of this species at this site. These data provide insight into the patterns and mechanisms of decline within a species due to Bd.     

Conservation status and limiting factors in the endangered population of Egyptian vulture (Neophron percnopterus) in the Canary Islands

Egyptian vulture populations have decreased sharply in the Western Palearctic; island populations are almost extinct in the Mediterranean and the Macaronesian regions. In the Canary archipelago, the species only survives in the islands of Fuerteventura and Lanzarote. During 1998-2001 we examined population parameters and evaluated some potential limiting factors for this isolated and sedentary population. The total population (breeding and non-breeding birds) was monitored annually. In addition, 26 fledglings and 33 immatures (<6 years old) and adult birds were captured for individual marking with plastic rings. Twenty-three/twenty-four occupied territories were located in the island and the total population estimated at around 130 birds. Breeding success was lower than recorded elsewhere in the species' distribution area: only 0.43 fledglings/pair/year were produced. Adult (>6 years old birds) and immature annual survival rates were similar, around 90%. Adult survival was lower than expected as territorial birds seem more susceptible to poisoning. Immature survival could be favoured by the existence of regular feeding places. Casualties from power lines was the main cause of mortality (12 cases during the study period). Blood sampling revealed high frequencies of lead poisoning: 13.5 and 2.7% of individuals showed sub-clinical and clinical intoxication levels, respectively, probably caused by the ingestion of lead shot. Priority conservation measures should be directed to reduce electrocution risks, illegal poisoning, and lead contamination. Population reinforcement with birds coming from other populations is not recommended as previous information reveals morphological and genetic differentiation of Canarian Egyptian vultures compared with continental populations.     

Current status and conservation of white-headed langur (Trachypithecus leucocephalus) in China

The white-headed langur is classed as a category I species under the Wild Animal Protection Law in China. It is distributed only in Karst hills in four counties (Longzhou, Ningming, Chongzuo and Fusui), in the southern Guangxi province of China. The Mingjiang River and the Zuojiang River form its southern, western and northern boundaries, and the Shiwandashan Mountains restrict its range in the east. Population surveys conducted in the 1980s showed that there were a total of 630 individuals in Guangxi, including 244 in Longzhou and Ningming counties, 117 in six fragments of Chongzuo County and 272 in nine patches of Fusui County. Surveys conducted by our group and Guangxi Forestry Bureau indicated that a total of 580-620 white-headed langurs still live in the above four counties, including 210-240 in Longzhou and Ningming, 90-100 in Chongzuo and 250 in Fusui. According to our statistics, only about 200 km² of habitat remains within the current range of the white-headed langur and this is separated as a total of 16 patches in 13 townships. Shangjin and Xiangshui in Longzhou county and Tingliang and Tuolu in Ningming, form the largest patch of the range, with total area of 68 km², while in Chongzuo and Fusui County, the habitat is heavily fragmented with six patches of 43.5 km² in Chongzuo and nine patches of 88 km² in Fusui. At present, the white-headed langur is still suffering from heavy habitat deterioration and human disturbance such as cultivation, tree-cutting for firewood, and poachings even though the government has made many efforts to protect this endangered species, such as putting it as a category I species for protection and designating the nature reserve and stations.     

Impacts of chronic marine oil pollution and the murre hunt in Newfoundland on thick-billed murre Uria lomvia populations in the eastern Canadian Arctic

We developed a deterministic and stochastic age-based matrix projection population model to assess and quantify the impact of mortality caused by chronic oil pollution and legal hunting on thick-billed murre Uria lomvia populations breeding and wintering in eastern Canada. We calculate the potential population growth rate in the absence of anthropogenic mortality sources using a modeling technique that translates absolute number of birds killed from anthropogenic mortality to potential survival rates in the absence of these anthropogenic impacts. The intrinsic growth rate of the deterministic matrix based on vital rates from Coats Island (λ_d=1.0102), as well as the stochastic growth rate (λ_s=1.0098, 95% C.I. 0.9969-1.0226), matched observed population trends. Hunting mortality reduced population growth rate by 0.020 (0.012-0.039), oiling mortality reduced population growth rate by 0.025 (0.012-0.039). Combined these sources reduced the population growth rate by 0.047 (0.033-0.610). Although thick-billed murre populations are stable or slowly growing in eastern Canada, anthropogenic sources of mortality are reducing the ability of the population to grow, and increase vulnerability in these populations to changes in their environment and other pulse perturbations. Our modeling technique could be used to assess specific anthropogenic impacts on populations where a vital rates and numbers killed are known, but no long-term trend information is available.     

Trade and conservation of Himalayan medicinal plants: Nardostachys grandiflora DC. and Neopicrorhiza scrophulariiflora (Pennell) Hong

There is a large annual international trade in the rhizomes of the alpine Himalayan perennials Nardostachys grandiflora DC. and Neopicrorhiza scrophulariiflora (Pennell) Hong, both species in a monotypic genus. This paper estimates the range of the annual trade levels and discusses the conservation implications. Data was collected through a nation-wide survey in Nepal using standardised open-ended interviews with 223 harvesters, 149 local traders, 90 central wholesalers, 53 regional wholesalers, and 16 processing industries. Data collection allowed cross-checking of findings by comparing an annual supply estimate and an annual consumption estimate. Regarding methodology, it is concluded that using agents’ own-reported values results in reliable volume and value estimates; however, validity should be treated with caution, as there is evidence of systematic bias in price reporting and underestimation of quantities. Trade data is thus evaluated to constitute conservative estimates, with local trader derived data being more valid than wholesaler derived data. Annual trade levels from Nepal are estimated at 100-500 tonnes of N. grandiflora rhizomes and 175-770 tonnes of N. scrophulariiflora rhizomes. In the case year of 1997/1998, the respective global amounts were estimated at 350-400 and 650-1000 tonnes (of which a maximum of 50-300 tonnes are from Picrorhiza kurrooa whose rhizomes are mixed with P. scrophulariiflora and traded under the name kutki) with a total CIF value of USD 2.7-3.6 million. Nepal is the main supplier (82 ± 5% of N. grandiflora and 66 ± 12 of kutki) followed by India (13 ± 5 and 19 ± 12) and Bhutan (5 ± 4 and 14 ± 8). The importance of applying a regional approach to conservation of the species is emphasised, as is the need for improved official trade monitoring by governments.     

Conservation status and causes of decline of musk deer (Moschus spp.) in China

Five species of musk deer (Forest musk deer Moschus berezovskii, Alpine musk deer M. sifanicus, Black musk deer M. fuscus, Himalayan musk deer M. chrysogaster and Siberian musk deer M. moschiferus) occur throughout 17 provinces in China, and all were listed in the second category of the Chinese State Key Protected Wildlife List in 1998. Among these species, the Forest musk deer has the widest distribution, and its population is estimated at about 100,000-200,000 individuals in the wild. Additionally, there are about 100,000 Alpine musk deer and 2000 Siberian musk deer. As for the Black musk deer and Himalayan musk deer, which occur only in parts of Yunnan Province and Tibet, their populations remain unknown but they can be estimated to be rare due to their narrow and limited distribution. Furthermore, there are some 1900 musk deer kept in farms in China. Generally, the musk deer population has been declining due to over-hunting for musk and to loss of habitats. However, the Chinese government is greatly concerned with wildlife protection today. A series of laws and regulations have been launched and many natural reserves and national parks have been established as refuges for this animal, most of which, are within the musk deer's range, and should have positive effects for musk deer conservation.     

Relationship between population size and genetic diversity in endangered populations of the European bullhead (Cottus gobio): implications for conservation

This study investigated the relationship between the current size of endangered bullhead (Cottus gobio) populations and microsatellite genetic variability. Additionally, the microsatellite data were used to evaluate whether a genetic test for population bottlenecks was able to provide evidence of recent severe population declines. Finally, our results were used to develop conservation priorities and measures. Population size appears to be a crucial parameter in determining the amount of genetic diversity that can be preserved in bullheads, since a significant positive correlation was observed between both variables. Furthermore, in some populations we were able to detect genetic signatures of the documented decline in population size. We suggest that the most immediate goal for bullhead conservation should be to increase the size and the range of the populations, and in doing so minimise or even reverse further genetic erosion. Potential management actions like habitat quality improvement, reduction of river fragmentation and supplementation programmes (translocation, supportive breeding) are discussed.     

Distribution and stand characteristics of relict populations of Mexican beech (Fagus grandifolia var. mexicana)

Fagus grandifolia var. mexicana (Mexican beech) is limited to about 10 populations (2-35 ha) in the Sierra Madre Oriental, Mexico. The objectives were to assess the current status and distribution of beech by surveying five sites. Species richness varied between three to 27 tree species in the canopy, and from nine to 29 species in the understorey. Basal area of trees?5 cm dbh varied between 27.87 and 70.98 m² ha⁻¹, and density from 370 to 1290 individual ha⁻¹. Beech represented 22-99.6% of total basal area, and 6.8-83.3% of total density. Beech dominance varied from monodominant to codominance with Carpinus caroliniana, Quercus spp., Liquidambar styraciflua, Magnolia schiedeana, and Podocarpus spp. Beech total population size ranged from 180 to 6300 trees with a total of less than 1300 individuals in four sites. Anthropogenic disturbance remains a major threat to these forests. It is uncertain whether Mexican beech will be able to survive without conservation efforts.     

Population viability of the narrow endemic Helianthemum juliae (CISTACEAE) in relation to climate variability

Narrow endemic plants are highly vulnerable to extinction as a result of human disturbance and climate change. We investigated the factors affecting the population viability of Helianthemum juliae, a perennial plant endemic to the Teide National Park on Tenerife, Canary Islands. One population was demographically monitored from 1992 to 2001 and analysed using matrix projection models to determine finite rates of increase and critical stages in the life cycle. Lambda values varied between 0.697 and 1.740, and were highly positively correlated with annual precipitation, but not with temperature. Survival of adults had the highest elasticity, and summed elasticities of the growth and fecundity transitions correlated positively with lambda and precipitation. Most of the mortality in the population seemed drought-related, and no other threats were identified. Deterministic simulations showed population increase, but introducing environmental stochasticity by modelling variation in precipitation from existing data of the past 85 years revealed high extinction probabilities (0.74-0.83 in the next 100 years). This plant is likely to be at risk under scenarios of global warming. Our simulations suggest that augmenting the population would only delay extinction. A more viable option for long-term conservation seems to be the introduction of populations at more humid locations within the Teide caldera.     

Low levels of genetic variation among southern peripheral populations of the threatened herb, Leontice microrhyncha (Berberidaceae) in Korea

Levels of genetic variation and intrapopulation genetic structures of Leontice microrhyncha S. Moore (Berberidaceae) were assessed for six populations in South Korea, representing the southern most range of a species found in Northeast China and the Korean peninsula. Detected genetic diversity (H_es) was very low (0.024) and F_IS values showed large heterozygote deficiencies. The small percentage of polymorphic loci and numbers of alleles per locus suggest that L. microrhyncha has a history of severe or long-lasting population bottlenecks that have eroded genetic diversity. This study suggests that the Korean population appears to consist of two historically isolated and independently evolving populations. It seems likely that these groups have been isolated and unstable for a significant period of time. However, the effects of recent habitat fragmentation on the historically disjunct and fragmented population system found in L. microrhyncha were not those predicted from the lack of significant relationships between population-level patterns of genetic variation and population sizes. Most non-unique genotypes were shared by most individuals and the lower level of diversity, high levels of inbreeding and population differentiation as well as high rate of seed production indicated that this species is autogamous and self-compatible and probably largely selfing. Therefore, to preserve extant genetic variation, all populations must be protected across the small geographic range of the species to retain both allelic and genotypic diversity.     

Phylogeography and conservation of the populations of Zootoca vivipara carniolica

The lizard Zootoca vivipara has both oviparous and viviparous populations which belong to distinct clades. This study aims to elucidate the geographic distribution, phylogeography and conservation priority of the oviparous subspecies, Zootoca vivipara carniolica, that has recently been identified in Slovenia. We studied seven Slovenian populations, two northeastern Italian populations and five northwestern Italian populations. The seven cytochrome b haplotypes that we identified from the Slovenian and Italian oviparous populations form a monophyletic basal clade. The high homogeneity of the Slovenian and northeastern Italian populations (nucleotide diversity π=0.06%) is a striking contrast with the pattern observed in northwest Italy where each of the five populations studied presents a private haplotype (π=1.03%). The results obtained suggest that all the extant lineages of Z. v. carniolica have originated in an Italian refuge. The reproductive and phylogenetic distinctiveness of Z. v. carniolica clearly justifies conservation of its populations, especially in Italy where the highest genetic diversity and the most ancestral haplotype were observed.     

Evaluation of the extinction risk and of conservation alternatives for a very small insular population: the bearded vulture Gypaetus barbatus in Corsica

The bearded vulture Gypaetus barbatus is a large, long-lived osteophagus vulture whose abundance and breeding range have drastically declined during the last century, making it one of the most endangered European bird species. We evaluated the extinction risk of the bearded vulture population in Corsica (a small, isolated breeding population of 8-10 pairs), one of the last extant populations in Western Europe, and estimated its probability of extinction to be 0.165 over the next 50 years. A sensitivity analysis to assess the influence of uncertain demographic rates showed that it is critical to estimate precisely the values of pre-adult survival. Neither the type nor the parameters of density dependence acting on fecundity and survival rates influenced much the extinction risk of the Corsican population. We evaluated the effect of four realistic conservation actions that could be implemented on the Corsican bearded vulture population and rank them in terms of their respective decrease of the current extinction risk faced by this population. We found that the release of two juveniles every other year for 12 years and the increase of fecundity due to selective food provisioning would reduce by more than one-half the current extinction risk of Corsican bearded vulture population. In contrast, even substantial increases in the carrying capacity through large supplemental feeding produced very modest decreases in the extinction risk, thus calling into question the efficacy of one of the main pan-European conservation strategies for this species. Re-establishing a population network within the Mediterranean could be a potentially better strategy, though its efficacy depends on natal dispersal among populations that is currently unknown.     

Genetic differences between the two remaining wild populations of the endangered Indian rhinoceros (Rhinoceros unicornis)

The management of rare and endangered species in the wild and in captivity requires an understanding of the characterization of the genetic units within each species and their relationships to each other. The Indian rhinoceros (Rhinoceros unicornis) is an endangered species with a current population size of c. 2800 individuals. We analyzed 26 individuals of known origin kept in captivity and 21 wild ranging individuals of the two remnant large wild populations in Assam (India) and Nepal employing mitochondrial and microsatellite markers to determine whether the two geographically isolated populations show distinct patterns of genetic diversity, and whether the genetic diversity of the populations is influenced by past demographic bottlenecks. We identified 10 different mitochondrial D-loop haplotypes, of which 4 were specific to the Assam population (10 sequences examined) and 6 specific to the Nepal population (19 sequences). Similarly, the microsatellite analysis demonstrated a strong genetic differentiation between the Assam and Nepal populations and allowed to assign each individual to its origin with high confidence. Furthermore, our analyses revealed the occurrence of a bottleneck in the Assam population long before the reported bottleneck in 1908, and it revealed that the Nepal population is a recent (probably post-glacial) colonization. In summary, the extent of genetic divergence between the two remnant R. unicornis populations suggests separate conservation programs (even for captive individuals) as long as the persistence of the entire species is not severely threatened. The microsatellite markers can also be used to determine the origin of confiscated material such as horns.     

Conservation of the critically endangered Rumex rothschildianus as implied from AFLP diversity

Rumex rothschildianus (Polygonaceae) is a small dioecious annual endemic to the central coastal plain of Israel. This very rare sorrel is on the verge of global extinction, as its total gene pool consists of two surviving populations only: one small and the other relatively large and flourishing. The other ten populations of this species recorded during the 20th century (all in Israel) are now extinct. Amplified fragment length polymorphism (AFLP) markers were used to evaluate the population genetic structure of the two remaining populations. Genetic diversity in R. rothschildianus was H=0.17 with 48.9% polymorphic loci. Gene flow values suggest that the differentiation between the two populations is moderate (mean F_st=0.09). Considering these genetic data, two conservation management strategies should be applied: (1) Large scale reseeding in a neighbouring nature reserve to maintain the genetic diversity detected in this study. Seeds from diverse sources should be used for repeated reseedings in order to prevent the reintroduced populations from going through a genetic bottleneck or suffering genetic drift. (2) To maintain the genetic diversity in the two remaining wild populations, and to avoid risks such as possible outbreeding depression, only intrapopulation reinforcement should be considered. These populations should be carefully monitored and protected.     

Consequences of the spatial configuration of resources for the distribution and dynamics of the endangered Parnassius apollo butterfly

Based on several years of data from two populations of the endangered Apollo butterfly (Parnassius apollo, L. 1758), we study how the amount and spatial location of patches of larval (host-plant) and adult (nectar plant) resources affects the distribution of females and their larval offspring in the following year. In the coastal population (nectar-plant and host-plant patches spatially segregated), females moved frequently between patches to aggregate on larger host-plant patches close to nectar-plant patches. In the archipelago population (where nectar-plants and host-plants co-occur), the abundance of females increased with higher proximity to other host-plant patches and with more nectar-plants on the patch. Next year’s larval abundance correlated with the abundance of females in the previous season in both populations. A model of the population dynamics in the two populations in relation to the spatial configuration of nectar and host-plant patches showed that the spatial configuration of larval and adult resources had population-dynamical consequences. In many organisms, different life-history stages use different resources. Incorporation of information on the location and abundance of adult resources can provide additional insight for the suitability of a particular landscape in harbouring a population.     

The effects of fire and predators on the long-term persistence of an endangered shrub, Grevillea caleyi

Grevillea caleyi is an endangered plant species with a restricted range lying partly within Ku-ring-gai Chase and Garigal National Parks in NSW, Australia. The principle threatening processes affecting G. caleyi are habitat destruction and adverse fire regimes combined with high levels of seed predation. A stochastic, spatially explicit, individual-based model was constructed to investigate the population dynamics of small populations of the species and to determine the impact of a variety of management strategies. Results of model simulations indicate there is a high risk of population decline and local extinction in remnant sites with small populations under current management regimes. The most effective fire management strategy is to schedule fires that burn 20-100% of sub-populations every 5-15 years, in combination with reduced predation rates. When predation management strategies are employed in conjunction with a structured fire regime, then a 20-30% reduction in predation rates can improve the chance of long-term persistence substantially.     

Genetic diversity and local population structure of fragmented populations of Trillium camschatcense (Trilliaceae)

Trillium camschatcense, a long-lived common woodland herb, has been experiencing intensive habitat fragmentation over the last century in eastern Hokkaido, Japan. We examined the genetic diversity and population genetic structure of 12 fragmented populations with different population sizes using allozyme electrophoresis. The percentage of polymorphic loci and mean number of alleles per locus were positively related to population size, probably due to the stochastic loss of rare alleles (frequency of q<0.1) in small populations. Populations with 350 flowering plants or fewer had lost almost all of their rare alleles. While the heterozygosity and inbreeding coefficient were not related to population size, some small populations showed relatively high inbreeding coefficients. In spite of the low genetic differentiation among overall populations (F_ST=0.130), local population structuring was recognized between the two geographically discontinuous population groups. Within groups, sufficient historical gene flow was inferred, whereas a low dispersal ability of this species and geographical separation could produce apparent differentiation between groups.     

Estimating population size in the subdesert mesite (Monias benschi): new methods and implications for conservation

The subdesert mesite, a terrestrial non-passerine bird endemic to the Mikea Forest of southwest Madagascar, is currently classified as globally threatened (category: Vulnerable). However, accurate assessment of threat in accordance with the IUCN Red List criteria (A, B and C) requires data on effective population size, area of habitat occupied and rate of decline, none of which is available for this species. Here we present the first empirical estimates of its population size using five complementary methods, three incorporating data on territory size and two using data gathered during call-playback surveys conducted throughout its entire global range. Estimates vary from 98,000 to 152,000 individuals, with the most reliable possibly being that generated by distance sampling (115,000). This figure is more than an order of magnitude greater than the only published estimate of <10,000 individuals. By analysing data on forest cover change, we estimate the population of the subdesert mesite to have declined by, at most, 10% in three generations. Although the rate of deforestation in 1994-1999 is double that calculated for 1962-1994, it is deemed unlikely that the population will decline by 20% over the next three generations. As such the species fails to meet criterion A. Although the subdesert mesite's range and area of occupancy are small, they are not fragmented and do not comprise fewer than 10 locations. Consequently, this species does not meet criterion B. Further, the species fails to meet criterion C, for which a maximum of 10,000 mature adults is required. According to IUCN (2000 Red List of Threatened Species) this species should therefore be downlisted in status. We discuss why it still warrants conservation attention and suggest the need for modifications to the criteria thresholds in relation to basic information about the ecology and taxonomic distinctness of species.     

Geographic differentiation of morphological traits and isozymes in the Mediterranean island endemic Anchusa crispa: implications for the conservation of a protected species

Understanding population differentiation and genetic diversity within population is critical to the development of conservation programmes for threatened species. The protected species, Anchusa crispa Viv. occurs on coastal sand dunes in three disjunct geographical groups of populations: two populations on the east coast of Corsica, several populations around a single estuary on the west coast of Corsica and at a number of sites in north-west Sardinia, where two different subspecies occur. In this study we quantify differentiation of reproductive traits and isozymes among regions and populations on Corsica and between subspecies on Sardinia. No isozyme variation was detected within any of the studied populations nor among populations from a given geographic region. Two loci showed geographic differentiation between regions on Corsica. On Sardinia, the two subspecies showed no isozyme differentiation, and, depending on the loci examined, are similar to one or other of the two regions on Corsica. Reproductive traits show significant differentiation between geographic regions on Corsica, but little variation among populations within a region. In populations on the west coast of Corsica, flowers are small and have a stigma situated at the same level as the apex of the anthers whereas on the east coast, flowers are larger and have the stigma below the anthers. On Sardinia, A. crispa subsp. crispa has a floral morphology similar to the Corsican plants, whereas subspecies maritima has larger flowers with the stigma positioned above the anthers (approach-herkogamy). Quantitative variation in floral morphology thus agrees with the separation of two taxonomic entities on Sardinia and geographic variation in reproductive traits and isozymes has important ramifications for the sampling of populations for conservation programmes.