scholarly journals Range expansion, density and conservation of the Araucaria Tit-spinetail Leptasthenura setaria (Furnariidae) in Argentina: the role of araucaria Araucaria angustifolia (Araucariaceae) plantations

2007 ◽  
Vol 17 (4) ◽  
pp. 341-349 ◽  
Author(s):  
Gustavo Sebastián Cabanne ◽  
Gustavo Andrés Zurita ◽  
Sergio Hugo Seipke ◽  
María Isabel Bellocq
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Distance Sampling ◽  
Suitable Habitat ◽  
Araucaria Angustifolia ◽  
Fragmented Habitat ◽  
North East ◽  
Forestry Practices

AbstractThe Araucaria Tit-spinetail Leptasthenura setaria (Furnariidae) is a globally Near Threatened species. Its habitat, the araucaria (Araucaria angustifolia) rainforest of south-east Brazil and north-east Argentina, is highly fragmented and reduced to nearly 10% of its original range. The species has also been recorded in commercial araucaria plantations that comprise about 80% of its suitable habitat in Argentina. This situation provides an opportunity for the conservation of the Araucaria Tit-spinetail in a human-modified landscape. We assessed the occurrence of the species in the region and estimated its density and total population size in araucaria plantations in Argentina. We discuss the value of plantations in the conservation of the bird, and evaluate its conservation status in Argentina using IUCN criteria. The density of the tit-spinetail in araucaria plantations, estimated by a distance sampling method, was 9 birds ha−1. The overall population size in commercial plantations appears to be large (>7,000 birds), showing that araucaria plantations play an important role in the conservation of the bird. However, plantations must not replace the native araucaria forest because the former are an intrinsically fragmented habitat influenced primarily by economic factors and forestry practices. The long-term conservation and restoration of araucaria rainforest in Argentina and Brazil must be guaranteed to conserve the Araucaria Tit-spinetail and other species associated with this rainforest. Based on the restricted and very fragmented habitat, the Araucaria Tit-spinetail should be regarded as Vulnerable in Argentina.

scholarly journals Estimated Density, Population Size and Distribution of the Endangered Western Hoolock Gibbon (Hoolock hoolock) in Forest Remnants in Bangladesh

Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 490
Author(s):  
Habibon Naher ◽  
Hassan Al-Razi ◽  
Tanvir Ahmed ◽  
Sabit Hasan ◽  
Areej Jaradat ◽  
...  
Keyword(s):  
Population Size ◽  
Tropical Forests ◽  
Forest Regeneration ◽  
Distance Sampling ◽  
Suitable Habitat ◽  
Careful Evaluation ◽  
Maxent Model ◽  
Maxent Modeling ◽  
Forest Remnants ◽  
Density Population

Tropical forests are threatened worldwide due to deforestation. In South and Southeast Asia, gibbons (Hylobatidae) are important to seed dispersal and forest regeneration. Most gibbons are threatened due to deforestation. We studied the western hoolock gibbon (Hoolock hoolock) in Bangladesh to determine population size and extent of suitable habitat. We used distance sampling to estimate density across 22 sites in northeastern and southeastern Bangladesh. We used Maxent modeling to determine areas of highly suitable habitat throughout Bangladesh. Density was estimated to be 0.39 ± 0.09groups/km2, and the total estimated population was 468.96 ± 45.56 individuals in 135.31 ± 2.23 groups. The Maxent model accurately predicted gibbon distribution. Vegetation cover, isothermality, annual precipitation, elevation and mean temperature of the warmest quarter influenced distribution. Two areas in the northeast and two areas in the southeast have high potential for gibbon conservation in Bangladesh. We also found significantly more gibbons in areas that had some level of official protection. Thus, we suggest careful evaluation, comprehensive surveys and restoration of habitats identified as suitable for gibbons. We recommend bringing specific sites in the northeastern and southeastern regions under protection to secure habitat for remaining gibbon populations.

scholarly journals The Specificities of the Temperature Regime of Seasonaly Freezing Soils of Tundra Landscape of European North East of Russia

2017 ◽  
pp. 3-21 ◽  
Author(s):  
D. A. Kaverin ◽  
A. V. Pastukhov
Keyword(s):  
Temperature Regime ◽  
Snow Accumulation ◽  
Soil Freezing ◽  
North East ◽  
European North ◽  
Soil Temperature Regime ◽  
Taiga Soils ◽  
The Impact

The specificities of temperature regime of automorphic clayey soils forming under the suffruticous and shrub vegetation within the zone of tundra and forest tundra in the European North-East were studied. As the objects of investigation we chose the organic cryometamorphic soils and cryometamorphic gleezems; in the both soil types the CRM cryometamorphic horizon is developed. The soils are formed in conditions of long-termed seasonal freezing at the absence (deep occurrence) of the permafrost rocks. The dynamics near the zero temperatures (zero curtains) is characterized. The hypothesis, concerning the role of zero curtains in the sustaining of the specific angular-grainy structure within the mass of cryometamorphic horizons is formulated. The mass of cryometamorphic horizons and the depth of present-day zero curtains, which observed at the long-term seasonal soil freezing, correlate to each other. The impact of suffruticous and shrub vegetation on the specificities of winter and summer soil temperature regime is determined. We discovered that the main differences between the soils developing under suffruticous and shrub vegetation tundras are stipulated by the different intensity of the snow accumulation within these areas. The soils that are developed under the shrub vegetation are warmer than soils developed under the suffruticous tundra, where permafrost may occur at the depth of 2-3 cm. In general, seasonaly freezing tundra soils are located in the middle of the range of the automorphic clay loamy soils in the tundra-taiga ecotone of European North-East of Russia, and occupy the niche between permafrost tundra and non-permafrost north taiga soils.

scholarly journals Current status and conservation of the Endangered Przewalski's gazelle Procapra przewalskii, endemic to the Qinghai–Tibetan Plateau, China

Oryx ◽  
2012 ◽  
Vol 46 (1) ◽  
pp. 145-153 ◽  
Author(s):  
Chunlin Li ◽  
Zhigang Jiang ◽  
Xiaoge Ping ◽  
Jing Cai ◽  
Zhangqiang You ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Population Size ◽  
Conservation Status ◽  
Distance Sampling ◽  
Current Status ◽  
Qinghai Lake ◽  
Conservation Strategies ◽  
Lake Basin ◽  
Domestic Livestock ◽  
Procapra Przewalskii

AbstractIn 2008 Przewalski's gazelle Procapra przewalskii, endemic to the Qinghai–Tibetan Plateau, China, was recategorized from Critically Endangered to Endangered on the IUCN Red List. The species is still, however, threatened, and the human population and accompanying domestic livestock are increasing around Qinghai Lake. Here we provide up-to-date information on the distribution and population size of the species, evaluate its current conservation status and discuss the difficulties of protecting this gazelle species. We used both distance sampling and total counts to survey 16 sites where the species has been reported and found it at 13 of these, occupying a total area of c. 250 km2. Population size estimated from distance sampling (1,635) and total counts (1,544) was similar. About 20% of the gazelles located were in newly discovered areas for the species. The results indicate an overall growth in the population of Przewalski's gazelle since 2003, although some subpopulations have declined or been extirpated. In spite of conservation efforts Przewalski's gazelle is still threatened by habitat degradation and loss, habitat fragmentation, fencing, intensified competition with domestic livestock and predation. Further growth of this gazelle population is constrained by limited habitat availability and human–gazelle conflict. We recommend that management and conservation strategies need to incorporate comprehensive knowledge of the gazelle, long-term monitoring, and captive breeding of injured and orphaned gazelles to form a potential pool of individuals for future reintroductions to the historical range of the species outside the Qinghai Lake basin.

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 and vocal and morphological description of the Grand Comoro Scops Owl Otus pauliani Benson 1960

1991 ◽  
Vol 1 (2) ◽  
pp. 123-133 ◽  
Author(s):  
M. Herremans ◽  
M. Louette ◽  
J. Stevens
Keyword(s):  
Conservation Status ◽  
Distinct Species ◽  
Forest Loss ◽  
Morphological Description ◽  
Suitable Habitat ◽  
North West ◽  
The North ◽  
Acridotheres Tristis ◽  
Indian Myna

SummaryThe Grand Comoro Scops Owl Otus pauliani, confined to forest on Mount Karthala on Grand Comoro, Indian Ocean, is a distinct species based on the evidence of its plumage and voice. In November 1989 studies of territorial calling birds at night revealed its presence between 1,000 and 1,900 m on the north, west and south flanks of the volcano, on which there exists some 10,000 ha of suitable habitat. As territory sizes may be only 5 ha, the population could well be over 1,000 pairs but, although this is encouraging, there remains a long-term threat from forest loss through habitat fragmentation (fires, logging) and the spread of the Indian Myna Acridotheres tristis.

Predictions of the impacts of changes in population size and environmental variablitity on Leadbeater's possum, Gymnobelideus leadbeateri McCoy (Marsupialia: Petauridae) using population viability analysis: an application of the computer program VORTEX.

1993 ◽  
Vol 20 (1) ◽  
pp. 67 ◽  
Author(s):  
DB Lindenmayer ◽  
RC Lacy ◽  
VC Thomas ◽  
TW Clark
Keyword(s):  
Computer Program ◽  
Population Size ◽  
Carrying Capacity ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Suitable Habitat ◽  
Viability Analysis ◽  
Nest Sites ◽  
Leadbeater's Possum

Population Viability Analysis (PVA) uses computer modelling to simulate interacting deterministic and stochastic factors (e.g. demographic, genetic, spatial, environmental and catastrophic processes) that act on small populations and assess their long-term vulnerability to extinction. The computer program VORTEX was used in a PVA of Leadbeater's possum, Gymnobelideus leadbeateri McCoy, an endangered arboreal marsupial that is restricted to the montane ash forests of the central highlands of Victoria. PVA was used to examine the impacts of changes in the size of subpopulations and the effects of environmental variation. Our analyses demonstrated that an annual linear decline in the carrying capacity in all or parts of the habitat will lead to the extinction of G. leadbeateri in those areas. Mean time to extinction was related to the rate of annual decrease. This conclusion is of practical and management importance as there is presently a decline in suitable habitat because of an annual loss of more than 3.5% of trees with hollows, which provide nest sites for G. leadbeateri. Because nest sites are a factor that limits populations of G. leadbeateri, the species could be lost from large areas within the next 50 years. PVA was also used to determine the viability of populations in areas, such as oldgrowth forest, where there is not likely to be a steady decline in habitat carrying capacity resulting from the loss of trees with hollows. This allowed an analysis of the cumulative impacts of small population size, environmental variation and genetic factors, which showed that, for a 100-year projection, simulated populations of 200 animals or more remained demographically stable and experienced a less than 10% decline in predicted genetic variability. However, the relatively simplified nature of population modelling and the suite of assumptions that underpin VORTEX mean that the probability of extinction of populations of this size may be greater than determined in this study. As a result, it is possible that only populations of more than 200 animals may persist in the long term where suitable habitat can be conserved or established and subsequently maintained without a reduction in carrying capacity.

Estimating the population size of a threatened arboreal marsupial: use of distance sampling to dispense with ad hoc survey techniques

2010 ◽  
Vol 37 (6) ◽  
pp. 512 ◽  
Author(s):  
Paul J. de Tores ◽  
Sue Elscot
Keyword(s):  
Land Use ◽  
Population Size ◽  
Ad Hoc ◽  
Conservation Status ◽  
Distance Sampling ◽  
Potential Effect ◽  
Decision Makers ◽  
Biological Information ◽  
Line Transect ◽  
Land Use Decisions

Context. Long-term land-use decisions potentially affecting the conservation status of rare fauna are often based on a dearth of relevant biological information and population estimates are regularly derived from ad hoc methodologies. This can significantly affect the outcomes from development assessment and approval processes. Aim. Our aims were to apply distance-sampling techniques to derive robust, quantitative estimates of the population size of a threatened arboreal marsupial, the western ringtail possum (Pseudocheirus occidentalis Thomas, 1888), demonstrate the advantages of this approach and, in doing so, provide conservation managers, decision makers and consultants with a reliable framework for surveying the species. Methods. We used line-transect sampling to derive estimates of density and abundance for P. occidentalis at two sites in south-western Western Australia where estimates were previously derived through ad hoc techniques. Key results. Our findings support the assertion that previous surveys of P. occidentalis populations have underestimated the population size to a varying extent at both of our survey sites. Land-use and development-application decisions have previously been based on similar surveys. Conclusions. Distance sampling, if applied routinely when surveying P. occidentalis, will reduce the uncertainty associated with derived estimates of abundance. Implications. Appropriate use of distance-sampling methods will enable managers and decision makers to assess more quantitatively the potential effect from, and place appropriate approval conditions on, proposals that modify or destroy P. occidentalis habitat. The use of the program Distance will enable such decisions to be based on robust, repeatable estimates of population size, with quantified confidence limits and variance estimates.

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