scholarly journals Defining favourable reference values for bird populations in Italy: setting long-term conservation targets for priority species

2010 ◽  
Vol 21 (1) ◽  
pp. 107-118 ◽  
Author(s):  
MATTIA BRAMBILLA ◽  
MARCO GUSTIN ◽  
CLAUDIO CELADA
Keyword(s):  
Population Size ◽  
Reference Values ◽  
Spatial Scales ◽  
Conservation Status ◽  
Bird Species ◽  
Population Viability Analysis ◽  
Breeding Density ◽  
Isolated Populations ◽  
Conservation Targets

SummarySetting favourable reference values (FRV) for conservation targets may help in assessing the conservation status of species and habitats. FRVs should be expressed through population size or demographic parameters that are likely to ensure the long-term persistence of a species across its range. We developed a conceptual framework for defining FRVs for Italian birds included in Annex I of the European Union’s Wild Birds Directive 79/409/CEE. The approach was based on demographic trends, current population size and the minimum viable population concept. We subdivided bird species according to abundance at the national scale, spatial distribution in discrete isolated populations and/or biogeographic categories. FRVs based on population viability analysis (PVA) were provided for populations of less than 2,500 pairs. For species with more than 2,500 pairs and a wide, more or less continuous range, the FRV was expressed in terms of breeding density at different spatial scales for non-colonial species. Out of the 88 species considered, we were able to formulate FRVs based on PVA for 47 populations belonging to 21 species, and breeding density for 15 further species; lack of adequate data prevented us from defining FRVs for the remaining species. Further work should focus on the translation of FRV density values into population size and on the definition of reference values for range and habitat.

scholarly journals Can we reestablish a self-sustaining population? A case study on reintroduced Crested Ibis with population viability analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yashuai Zhang ◽  
Fang Wang ◽  
Zhenxia Cui ◽  
Min Li ◽  
Xia Li ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Carrying Capacity ◽  
Wild Population ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Viability Analysis ◽  
Crested Ibis ◽  
Reintroduced Population

Abstract Background One of the most challenging tasks in wildlife conservation and management is clarifying which and how external and intrinsic factors influence wildlife demography and long-term viability. The wild population of the Crested Ibis (Nipponia nippon) has recovered to approximately 4400, and several reintroduction programs have been carried out in China, Japan and Korea. Population viability analysis on this endangered species has been limited to the wild population, showing that the long-term population growth is restricted by the carrying capacity and inbreeding. However, gaps in knowledge of the viability of the reintroduced population and its drivers in the release environment impede the identification of the most effective population-level priorities for aiding in species recovery. Methods The field monitoring data were collected from a reintroduced Crested Ibis population in Ningshan, China from 2007 to 2018. An individual-based VORTEX model (Version 10.3.5.0) was used to predict the future viability of the reintroduced population by incorporating adaptive patterns of ibis movement in relation to catastrophe frequency, mortality and sex ratio. Results The reintroduced population in Ningshan County is unlikely to go extinct in the next 50 years. The population size was estimated to be 367, and the population genetic diversity was estimated to be 0.97. Sensitivity analysis showed that population size and extinction probability were dependent on the carrying capacity and sex ratio. The carrying capacity is the main factor accounting for the population size and genetic diversity, while the sex ratio is the primary factor responsible for the population growth trend. Conclusions A viable population of the Crested Ibis can be established according to population viability analysis. Based on our results, conservation management should prioritize a balanced sex ratio, high-quality habitat and low mortality.

scholarly journals An assessment of the distribution, population size and conservation status of the Santa Marta Foliage-gleaner Automolus rufipectus: a Sierra Nevada de Santa Marta endemic

2015 ◽  
Vol 25 (4) ◽  
pp. 451-465 ◽  
Author(s):  
ESTEBAN BOTERO-DELGADILLO ◽  
NICHOLAS BAYLY ◽  
CAMILA GÓMEZ ◽  
PAULO C. PULGARÍN-R. ◽  
CARLOS ANDRÉS PÁEZ
Keyword(s):  
Population Size ◽  
Sierra Nevada ◽  
Forest Cover ◽  
Conservation Status ◽  
Bird Species ◽  
Environmental Niche ◽  
Coffee Plantations ◽  
Habitat Transformation ◽  
Elevation Range ◽  
Area Of Occupancy

SummaryThe Santa Marta Foliage-gleaner Automolus rufipectus is one of 19 endemic bird species found in the Sierra Nevada de Santa Marta (SNSM) in northern Colombia but until recently it was considered a sub-species of the Ruddy Foliage-gleaner Automolus rubiginosus. Consequently, published information on its distribution and ecology is lacking, and while it is classified as near- threatened, this designation was based on limited quantitative data. To improve our knowledge of the Santa Marta Foliage-gleaner’s geographical distribution, elevation range, population density, habitat use and conservation status, we analysed both historical and recent site locality records and carried out variable distance transects within forested habitats and shade coffee plantations. We modelled the environmental niche of the species and subsequently estimated its extent of occurrence and area of occupancy, as well as population size. Our results consistently showed that the distribution of the Santa Marta Foliage-gleaner is more restricted than previously considered, both geographically and by elevation (we redefine elevation range as 600–1,875 m). This suggests that the species is more at risk of habitat transformation and combined with our estimates of population size (< 10,000 individuals), it is likely that the species will be uplisted to a higher threat category. More positively, and contrary to published accounts, we found that approximately 40% of the species’ range lies within protected areas. Nevertheless, we recommend the implementation of strategies to maintain forest cover on the western flank of the SNSM and further research to better define the species’ habitat needs and population dynamics.

scholarly journals Density and population viability of coastal marten: a rare and geographically isolated small carnivore

2017 ◽  
Author(s):  
Mark A Linnell ◽  
Katie Moriarty ◽  
David S Green ◽  
Taal Levi
Keyword(s):  
Population Size ◽  
Extinction Risk ◽  
Conservation Status ◽  
Population Viability Analysis ◽  
Credible Interval ◽  
The United States ◽  
Population Viability ◽  
Coastal Forests ◽  
Private Lands ◽  
Geographically Isolated

Pacific martens (Martes caurina) in coastal forests of Oregon and northern California in the United States are rare and geographically isolated, prompting a petition for listing under the Endangered Species Act. If listed, regulations have the potential to substantially influence land-use decisions and forestry on public and private lands, but no estimates of population size, density, and viability of remnant marten populations are available for evaluating their conservation status. We used GPS telemetry, territory mapping, and spatial mark-recapture to estimate population size and density within the current extent of Pacific martens in central Oregon, within coastal forest in the Oregon dunes national recreational area. We then estimated population viability at differing levels of human-caused mortality (e.g. roadkill). We estimated 63 adult martens (95% Credible Interval: 58-73) and 73 (range: 46-91) potential territories across two subpopulations separated by a large barrier (Umpqua River). Marten density was 1.02 per km2, the highest reported in North America. Using population viability analysis, extinction risk for a subpopulation of 30 martens ranged from 34% to 100% with two or more annual human-caused mortalities. Absent broad-scale restoration of forest to conditions which support marten populations, limiting human-caused mortalities would likely have the greatest conservation impact.

scholarly journals Dramatic decline of François' langur Trachypithecus francoisi in Guangxi Province, China

Oryx ◽  
2007 ◽  
Vol 41 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Youbang Li ◽  
Chengming Huang ◽  
Ping Ding ◽  
Zheng Tang ◽  
Chris Wood
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Guangxi Province ◽  
Isolated Populations ◽  
Term Survival ◽  
Management Planning ◽  
Management Measures ◽  
Species Survival ◽  
Dramatic Decline ◽  
Trachypithecus Francoisi

Interviews with local people and a survey were carried out in 23 counties of south-west Guangxi Province from April 2002 to June 2003 to evaluate the conservation status of François' langur Trachypithecus francoisi and assess the extent and nature of threats to the species' survival. François' langurs were found in only 10 counties compared with their presence in 23 counties before 1990. The total population size is estimated to be 307 individuals in 14 isolated populations. This represents a 90% decrease in population size since the early 1980s and an 85% decrease since the mid 1990s. The primary threat to the langur is hunting, mainly for traditional medicine. Our results suggest that conservation efforts for the species have been ineffectual during the last decade and, even within reserves, few direct management measures seem to have been taken to protect and conserve the langurs. Without the instigation of such measures it seems likely that François' langur will disappear both inside and outside reserves. To ensure the long-term survival of Francois' langur in Guangxi Province increased investment and improved management, planning, and training of reserve managers and staff is required, with a particular focus on the key remaining reserves and sites for the langur. Some of this work is now underway.

Is the Carpentarian Rock-rat Zyzomys palatalis critically endangered?

2006 ◽  
Vol 12 (2) ◽  
pp. 134 ◽  
Author(s):  
David M. J. S. Bowman ◽  
Daniel L McIntyre ◽  
Barry W. Brook
Keyword(s):  
Conservation Status ◽  
Species Conservation ◽  
Population Viability Analysis ◽  
Critically Endangered ◽  
Isolated Populations ◽  
Forest Habitat ◽  
Viability Analysis ◽  
Area Of Occupancy ◽  
Closed Forest ◽  
Minimum Number

The Carpentarian Rock-rat Zyzomys palatalis is a rare conilurine rodent with a global distribution restricted to a small area of sandstone escarpments in the Gulf of Carpentaria region of the Northern Territory. Previous assessments of its World Conservation Union (IUCN) status in 1996 had classified the species as Critically Endangered based on the restricted area of occupancy and a putative decline in the extent and quality of its closed forest habitat due to uncontrolled landscape fires. A later population viability analysis confirmed that habitat loss was potentially the single most important threatening process. Here we argue that the species should be reclassified as Vulnerable, on the basis of the following new evidence: (1) the assumption that it was a closed forest specialist was not supported by a radiotracking study, which showed that on average 43% of an individual's monitored time was spent in the forest-savannah margin, and (2) analysis of repeat historical aerial photography has shown that the core closed forest habitat has in fact increased by 36% over the last 50 years. This has lead to an increase of 140 in the minimum number of equivalent Z. paJatalis territories, from 387 to 587, when home range overlaps and utilization of the savannah margins are considered. Reclassification of the species' conservation status should be accompanied with: (i) genetic studies of relatedness between isolated populations; (ii) monitoring and maintenance of the integrity of the landscapes, including creeklines that connect patches; and (iii) consideration of the introduction of captive bred specimens into an adjacent unoccupied fragments.

scholarly journals Global distribution and conservation status of ecologically rare mammal and bird species

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nicolas Loiseau ◽  
Nicolas Mouquet ◽  
Nicolas Casajus ◽  
Matthias Grenié ◽  
Maya Guéguen ◽  
...  
Keyword(s):  
Human Development ◽  
Rare Species ◽  
Human Development Index ◽  
Ecosystem Functioning ◽  
Conservation Status ◽  
Bird Species ◽  
Ecosystem Processes ◽  
Potential Contribution ◽  
Development Index

Abstract Identifying species that are both geographically restricted and functionally distinct, i.e. supporting rare traits and functions, is of prime importance given their risk of extinction and their potential contribution to ecosystem functioning. We use global species distributions and functional traits for birds and mammals to identify the ecologically rare species, understand their characteristics, and identify hotspots. We find that ecologically rare species are disproportionately represented in IUCN threatened categories, insufficiently covered by protected areas, and for some of them sensitive to current and future threats. While they are more abundant overall in countries with a low human development index, some countries with high human development index are also hotspots of ecological rarity, suggesting transboundary responsibility for their conservation. Altogether, these results state that more conservation emphasis should be given to ecological rarity given future environmental conditions and the need to sustain multiple ecosystem processes in the long-term.

scholarly journals Out of the darkness: the first comprehensive survey of the Critically Endangered Anjouan Scops Owl Otus capnodes

2014 ◽  
Vol 25 (3) ◽  
pp. 322-334 ◽  
Author(s):  
KATHLEEN E. GREEN ◽  
BRONWEN M. DANIEL ◽  
SAMUEL P. LLOYD ◽  
ISHAKA SAID ◽  
AMELAID HOUMADI ◽  
...  
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Distance Sampling ◽  
Bird Species ◽  
Iucn Red List ◽  
Critically Endangered ◽  
Encounter Rate ◽  
Wet Season ◽  
Point Counts ◽  
Comprehensive Survey

SummaryAlthough birds are among the best studied taxa, many of the globally threatened species lack the information required to fully assess their conservation status and needs. One such species is the Anjouan Scops Owl Otus capnodes which was presumed extinct until its rediscovery to science in 1992. Based on the limited extent and decline of the moist forests in the highlands of Anjouan in the Comoro Islands, a population size of only 100–200 pairs was estimated and the species was classified as ‘Critically Endangered’. The current study is the first comprehensive survey ever conducted on this species, and aimed to establish the current distribution and population size. Point counts with distance sampling were conducted across the agroforestry and forest zones of Anjouan in both a dry and wet season. A niche suitability model predicted the species distribution to be wider than expected with owls observed as low as 300 m altitude and in highly modified agroforestry habitats. However, the encounter rate in natural relatively undisturbed forest was significantly greater than in other habitats. The wider than expected geographic range of O. capnodes supports a possible downlisting of this species on the IUCN Red List to ‘Endangered’. Population size was found to be far greater than previously thought, at approximately 3,450 individual owls in the dry season and 5,450 in the wet season. These results show the importance of investing in robust surveys of poorly known and cryptic bird species, and provide up to date and important information for landscape scale conservation planning in the Comoros Islands.

scholarly journals Conservation status of birds on Mindoro, Philippines

1992 ◽  
Vol 2 (4) ◽  
pp. 303-325 ◽  
Author(s):  
Guy C. L. Dutson ◽  
Tom D. Evans ◽  
Thomas M. Brooks ◽  
Desiderio C. Asane ◽  
Robert J. Timmins ◽  
...  
Keyword(s):  
Forest Cover ◽  
Conservation Status ◽  
Bird Species ◽  
Concerted Action ◽  
Medium Term ◽  
Lowland Forest ◽  
Risk Of Extinction ◽  
Forest Remnants ◽  
The Status

SummaryFour weeks of fieldwork in the forests of Mindoro, Philippines, in 1991 has elucidated the status of the six bird species endemic to the island. Of these, Ducula mindorensis and Otus mindorensis are high-altitude species with restricted ranges and in need of active conservation in the medium term. Three of the four lowland species, Gallicolumba platenae, Centropus steerü and Penelopides mindorensis are under immediate threat of extinction through forest clearance and fragmentation, while the fourth, Dicaeum retrocinctum, s i not under immediate threat but is certainly at risk of extinction in the long term. Whilst deforestation is an enormous problem across the entire Philippines, Mindoro is the smallest centre of endemism with the least forest cover after the Sulu Islands. Extinctions are believed inevitable within the next 10 years unless concerted action is urgently taken. The Halcon range must receive attention in order to conserve the montane species, but more urgent by far is the preservation of lowland forest remnants, concentrating on central-west Mindoro.

scholarly journals Twenty-year assessment of Lignum-vitae (Guaiacum sanctum, Zygophyllaceae) in the Palo Verde National Park of Costa Rica

2019 ◽  
Vol 67 (6) ◽  
Author(s):  
Ulises Balza ◽  
Roland Charles De Gouvenain
Keyword(s):  
Costa Rica ◽  
National Park ◽  
Conservation Status ◽  
Population Viability Analysis ◽  
Tree Age ◽  
Greater Antilles ◽  
Vital Rates ◽  
Guaiacum Sanctum ◽  
Palo Verde National Park

Introduction: The Lignum-vitae (Guaiacum sanctum; Zygophyllaceae) of Mesoamerica and the Greater Antilles, is threatened over much of its range. We evaluated whether a G. sanctum population in the Palo Verde National Park of Costa Rica is viable in the long term. Methods: Using two demographic studies, one in 1997 and the other in 2017, we estimated survival and fecundity rates for each tree age class, population growth rate (lambda), and vital rates elasticities, and we used a density-independent deterministic population model to project the long-term trend of that population. Results: The estimated vital rates during the last 20 years suggested that this population is rapidly decreasing. Although some age classes increased in abundance, seedlings are rare and the plants that recruited in 1997 have not yet reached reproductive maturity. Our results suggest that the current abundance of G. sanctum within the national park may not be a good indicator of its long-term conservation status, and from our population viability analysis, we estimated that the population we studied would decrease to less than 1 % of its current size within the next 200 years. Conclusions: Landscape-scale ecosystem deterioration affecting the greater PVNP region, such as loss of seed dispersers and suppression of disturbances, may offset the passive protection of G. sanctum within park boundaries. Relying on the overall strict protection afforded by the location of the population within the Palo Verde National Park may not be sufficient to conserve this population of G. sanctum. We recommend that more proactive experimental protection and/or restoration measures, possibly including disturbance treatments, be implemented within a research program.

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