scholarly journals Updated range metrics and a global population estimate for the Critically Endangered Philippine Eagle using a spatial ensemble habitat model

2021 ◽  
Author(s):  
Luke J Sutton ◽  
Jayson C Ibañez ◽  
Dennis I Salvador ◽  
Rowell L Taraya ◽  
Guiller S Opiso ◽  
...  
Keyword(s):  
Population Size ◽  
Species Distribution Model ◽  
Extinction Risk ◽  
Habitat Model ◽  
Critically Endangered ◽  
Biological Information ◽  
Distribution Model ◽  
Population Estimate ◽  
Area Of Occupancy ◽  
Global Population

Many range-restricted taxa are currently experiencing severe population declines yet lack fundamental biological information regarding distribution and population size. Establishing baseline estimates for both these key biological parameters is however critical for directing long-term monitoring and conservation planning for at-risk range-restricted species. The International Union for the Conservation of Nature (IUCN) Red List uses three spatial range metrics that define species distributions and inform extinction risk assessments: extent of occurrence (EOO), area of occupancy (AOO) and area of habitat (AOH). However, calculating all three metrics using standard IUCN approaches relies on a geographically representative sample of locations, which for rare species is often spatially biased. Here, we apply model-based interpolation using an ensemble Species Distribution Model (SDM), correlating occurrences with remote-sensing derived environmental covariates, to calculate IUCN range metrics and a global population estimate for the Critically Endangered Philippine Eagle (Pithecophaga jefferyi). Our ensemble averaged SDM had high predictive accuracy and was able to identify key areas of Philippine Eagle habitat across the species global range. We estimated an AOH = 49,426 km2 and from this metric calculated a maximum EOO = 609,697 km2 and a minimum EOO = 273,794 km2, with an AOO = 54,695 occupied cells. Based on inferred habitat from the AOH metric and territorial habitat area from home range estimates, we provide an updated global population estimate of 677 breeding pairs (range: 549-772 pairs), or 1354 mature individuals, across the entire Philippine Eagle range. We demonstrate that even when occurrence sampling is geographically biased, robust habitat models can be built which enable quantification of IUCN range metrics and a baseline population size estimate. In the absence of adequate location data for many rare and threatened taxa, our method is a promising spatial modelling tool with widespread applications, in particular for island endemics facing high extinction risk.

scholarly journals First census of the white-shouldered ibis Pseudibis davisoni reveals roost-site mismatch with Cambodia's protected areas

Oryx ◽  
2012 ◽  
Vol 46 (2) ◽  
pp. 236-239 ◽  
Author(s):  
Hugh L. Wright ◽  
Nigel J. Collar ◽  
Iain R. Lake ◽  
Net Norin ◽  
Rours Vann ◽  
...  
Keyword(s):  
Protected Areas ◽  
Population Size ◽  
Critically Endangered ◽  
Population Estimate ◽  
Term Survival ◽  
Long Term Survival ◽  
Global Population

AbstractThe population size of the Critically Endangered white-shouldered ibis Pseudibis davisoni has always been poorly known. The first-ever census across Cambodia in 2009–2010 using simultaneous counts at multiple roost sites found substantially more birds than previously estimated, with a minimum of 523 individuals. The census allowed us to make a revised global population estimate of 731–856 individuals, increasing hope for the species' long-term survival. However, the largest subpopulations are imminently threatened by development and c. 75% of the birds counted in Cambodia were outside protected areas.

scholarly journals Estimating change in the geographical range and population size of Hinde's Babbler Turdoides hindei

2003 ◽  
Vol 13 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Philip Shaw ◽  
John Musina ◽  
Patrick Gichuki
Keyword(s):  
Protected Areas ◽  
Population Size ◽  
Geographical Range ◽  
Population Estimates ◽  
Extent Of Occurrence ◽  
Area Of Occupancy ◽  
Species Area ◽  
Gains And Losses ◽  
Global Population

Hinde's Babbler Turdoides hindei is a globally threatened Kenyan endemic, which during the 1990s, was known from just seven localities. Based mainly on surveys undertaken in 2000–2001, we estimate the species's global population size and compare recent changes in its “extent of occurrence” and “area of occupancy”. Historically, Hinde's Babbler has been recorded from c. 40 10 × 10 km squares; 27 pre-1980 and 19 subsequently, suggesting that its area of occupancy has declined by about 30%. In contrast, its extent of occurrence has declined by only 8%, this measure being less sensitive to the balance of gains and losses occurring near the centre of its range. During surveys in 1994 and 2000–2001, 157 groups were located, containing 665 birds, 75% of which were found at two intensively cultivated sites. Some 97% of birds were located in, or adjacent to, five Important Bird Areas, but only 8% were found within legally protected areas. Two extrapolated population estimates are presented, based on the number of birds likely to have been missed at survey sites, and the species' area of occupancy. These suggest that the global population of Hinde's Babbler is likely to fall within the range of 1,500–5,600 birds.

Global population size of a critically endangered lemur, Perrier's sifaka

2007 ◽  
Vol 10 (2) ◽  
pp. 254-262 ◽  
Author(s):  
M. A. Banks ◽  
E. R. Ellis ◽  
Antonio ◽  
P. C. Wright
Keyword(s):  
Population Size ◽  
Critically Endangered ◽  
Global Population

Extinction Risk Evaluation and Population Size Estimation of Bothrops insularis (Serpentes: Viperidae), a Critically Endangered Insular Pitviper Species of Brazil

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Carlos Roberto Abrahão ◽  
Ligia Grazzielli Amorim ◽  
Adriana Melo Magalhães ◽  
Carlos Renato Azevedo ◽  
José Henrique Hildebrand Grisi-Filho ◽  
...  
Keyword(s):  
Population Size ◽  
Risk Evaluation ◽  
Extinction Risk ◽  
Population Size Estimation ◽  
Critically Endangered ◽  
Size Estimation

scholarly journals Using Species Distribution Model to Estimate the Wintering Population Size of the Endangered Scaly-Sided Merganser in China

PLoS ONE ◽  
2015 ◽  
Vol 10 (2) ◽  
pp. e0117307 ◽  
Author(s):  
Qing Zeng ◽  
Yamian Zhang ◽  
Gongqi Sun ◽  
Hairui Duo ◽  
Li Wen ◽  
...  
Keyword(s):  
Population Size ◽  
Species Distribution ◽  
Species Distribution Model ◽  
Distribution Model ◽  
Wintering Population

scholarly journals Assess the Extinction Risk of Mountain Endemic Plants in Egypt Under the Current Climatic Condition: A Case Study of Endemic Silene Species

2021 ◽  
Vol 2 (5) ◽  
pp. 34-47
Author(s):  
Karim Omar ◽  
Ibrahim Elgamal
Keyword(s):  
Species Distribution Model ◽  
Extinction Risk ◽  
Field Research ◽  
Iucn Red List ◽  
Red List ◽  
Ex Situ ◽  
Distribution Model ◽  
High Mountain ◽  
Endemic Plant

The process of developing a conservation programme for endemic plant species, in particular those with a small geographical size in mountain ecosystems, whether in situ of ex situ, is a very complex matter, especially if data on the state of the environment and conservation are unavailable. Silene leucophylla and Silene oreosinaica are perennial plants endemic to St. Catherine Protected Area (SCPA), which locate at South Sinai, Egypt. For long time, the second species has not been observed in the field. As a result, the purpose of this study was to increase understanding of the two species' ecological and conservation statuses by: The first step is to confirm their existence on the ground; the second step is to determine the present ecological and conservation conditions through an extinction risk assessment by using IUCN Red List methodology; and the third step is the use of Species Distribution Model (SDM) to locate and extract current appropriate habitat suitability. The field research, which was conducted between March to December 2017, resulted in building knowledge of the current distribution, characteristics of current species populations, and status of ecology and habitat, in addition to identifying the main threats. Both species have been recorded in 20 major sites, in a very restricted area, particularly in a high mountain region (19 sites of Silene leucophylla and 3 sites of S. oreosinaica), with Extent of Occurrence about 468.2 km2 for Silene leucophylla and 24.5 km2 for S. oreosinaica. The population size was very small and fragmented and the extreme drought and overgrazing clearly affected both species. Based on the collected data, the extinction risk was calculated as Critically Endangered for S. oreosinaica and as Endangered for S. leucophylla according to IUCN Red List. For both species, appropriate habitat is concentrated in the high mountain ranges in the central north section of the SCPA, according to SDM. For Silene leucophylla, a presence probability of 20.5 km2 was anticipated, whereas for S. oreosinaica, a presence probability of 62.1 km2 had been predicted. Conservation methods are advocated both in situ (via recovery) and ex situ (by seed collecting and storage, awareness building, and grazing control).

scholarly journals Status assessment of the Critically Endangered Azores Bullfinch Pyrrhula murina

2011 ◽  
Vol 21 (4) ◽  
pp. 477-489 ◽  
Author(s):  
RICARDO S. CEIA ◽  
JAIME A. RAMOS ◽  
RUBEN H. HELENO ◽  
GEOFF M. HILTON ◽  
TIAGO A. MARQUES
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Distance Sampling ◽  
Iucn Red List ◽  
Range Size ◽  
Critically Endangered ◽  
Survey Method ◽  
Mountain Range ◽  
Laurel Forest ◽  
Area Of Occupancy

SummaryThe Azores Bullfinch is endemic to the island of São Miguel (Azores, Portugal). Its status was uplisted to Critically Endangered in 2005 on the basis of an extremely small and declining population that was considered to be restricted to a very small mountain range (43 km2), in a single location, within which the spread of invasive plants constituted a threat to habitat quality. Nevertheless, information was mostly inferred, or the product of, non-systematic studies. In order to carry out a complete assessment of the conservation status we analysed: (i) population trend, calculated from annual monitoring 1991–2008, (ii) population size, and (iii) range size, obtaining estimates in a single morning study in 2008 involving the simultaneous participation of 48 observers. Contrary to previous inferences, the population is no longer decreasing, although quality of laurel forest habitat continues to decline due to the persistent threat of invasive species. Population size (mean ± SE) was estimated at 1,064 ± 304 individuals using distance sampling methods, although the estimate was very sensitive to the survey method used. Range size estimates (extent of occurrence and area of occupancy) were 144 km2 and 83 km2 respectively. Given the present information, we propose the downlisting of Azores Bullfinch to Endangered on the IUCN Red List.

scholarly journals First formal estimate of the world population of the Critically Endangered spoon-billed sandpiper Calidris pygmaea

Oryx ◽  
2016 ◽  
Vol 52 (1) ◽  
pp. 137-146 ◽  
Author(s):  
Nigel A. Clark ◽  
Guy Q. A. Anderson ◽  
Jing Li ◽  
Evgeny E. Syroechkovskiy ◽  
Pavel S. Tomkovich ◽  
...  
Keyword(s):  
Population Size ◽  
Breeding Population ◽  
Critically Endangered ◽  
World Population ◽  
South East Asia ◽  
Russian Arctic ◽  
Age Classes ◽  
Long Distance ◽  
The World ◽  
Global Population

AbstractThe spoon-billed sandpiper Calidris pygmaea is a Critically Endangered shorebird that breeds in the Russian arctic and winters in coastal and estuarine habitats in South-east Asia. We report the first formal estimate of its global population size, combining a mark–resighting estimate of the number of leg-flagged individuals alive in autumn 2014 with an estimate of the proportion of birds with flags from scan surveys conducted during the same period at a migration stop-over site on the Jiangsu coast of China. We estimate that the world breeding population of spoon-billed sandpipers in 2014 was 210–228 pairs and the post-breeding population of all age classes combined was 661–718 individuals. This and related methods have considerable potential for surveillance of the population size of other globally threatened species, especially widely dispersed long-distance migrants.

First systematic sampling approach to estimating the global population size of the Critically Endangered Blue-throated Macaw Ara glaucogularis

2020 ◽  
pp. 1-19 ◽  
Author(s):  
SEBASTIAN K. HERZOG ◽  
OSWALDO MAILLARD Z. ◽  
TJALLE BOORSMA ◽  
GUSTAVO SÁNCHEZ-ÁVILA ◽  
VÍCTOR HUGO GARCÍA-SOLÍZ ◽  
...  
Keyword(s):  
Population Size ◽  
Critically Endangered ◽  
Population Estimates ◽  
Suitable Habitat ◽  
Landsat 8 ◽  
Entire Area ◽  
Positive Effects ◽  
Population Size Estimates ◽  
Global Population ◽  
Sampling Approach

Summary Reliable population size estimates are imperative for effective conservation and management of globally threatened birds like the ‘Critically Endangered’ Blue-throated Macaw Ara glaucogularis. Endemic to one of South America’s largest grassland floodplains, the Llanos de Moxos in northern Bolivia, the species’ global population size is uncertain. The region’s inaccessibility renders the application of traditional methods for obtaining bird population estimates impracticable or cost prohibitive. We developed a simultaneous, multilocality, double-sampling approach combined with quantitative habitat availability analyses to obtain the first rigorous population size estimate for the Blue-throated Macaw. We established 11 survey areas across its three subpopulations that were visited twice by one team in each subpopulation over a 23-day period in the 2015 dry season and obtained additional count data from two roost sites. We classified suitable habitat (palm forest islands) using Landsat 8 images and CLASlite forest monitoring software. We extrapolated the number of macaws detected (conservative estimate of the total number of macaws [CETN], highest single count [HSC]) per 100 ha of suitable habitat in each survey area to the entire area of suitable habitat in all subpopulations combined, corrected for the species’ range occupancy of 34.3%. The total number of Blue-throated Macaws detected by survey (CETN) and roost site counts was 137. Across all survey areas, the number of macaws per 100 ha of suitable habitat was 4.7 for the first and 4.4 for the second period for CETN and 3.2 and 3.4, respectively, for HSC data. Corresponding global population estimates were 426–455 (CETN) and 312–329 (HSC) individuals. Other recent research and anecdotal data support these estimates. Although it would be premature to propose downlisting the species to ‘Endangered’, our findings indicate that it has a larger population and slightly larger range than previously thought, and that the positive effects of conservation actions are now becoming apparent.

scholarly journals Conservation biology of threatened Mediterranean chasmophytes: The case of Asperula naufraga endemic to Zakynthos island (Ionian islands, Greece)

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246706 ◽  
Author(s):  
Anna-Thalassini Valli ◽  
Vassiliki Lila Koumandou ◽  
Gregoris Iatrou ◽  
Marios Andreou ◽  
Vasileios Papasotiropoulos ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Extinction Risk ◽  
Conservation Status ◽  
Small Population ◽  
Ex Situ ◽  
Current Conservation ◽  
Ionian Islands ◽  
Small Population Size ◽  
Area Of Occupancy

Asperula naufraga is a rare and threatened obligate chasmophyte, endemic to Zakynthos island (Ionian islands, Greece). In this study, we provide a combined approach (including monitoring of demographic and reproductive parameters and study of genetic diversity) to assess the current conservation status of the species and to estimate its future extinction risk. The five subpopulations of A. naufraga were monitored for five years (2014–2018). Population size markedly fluctuated between 68–130 mature individuals during the monitoring period. The extent of occurrence (EOO) was estimated at 28.7 km2 and the area of occupancy (AOO) was 8 km2. Stage-structure recordings were similar for all subpopulations, characterized by high proportions of adult and senescent individuals, following a common pattern, which has been observed in other cliff-dwelling plants. Preliminary genetic analysis with SSRs markers revealed low heterozygosity within subpopulations and significant departure from H-W equilibrium, which combined with small population size suggest increased threat of genetic diversity loss. Our results indicate that the species should be placed in the Critically Endangered (CR) IUCN threat category, while according to Population Viability Analysis results its extinction risk increases to 47.8% in the next 50 years. The small population size combined with large fluctuations in its size, low recruitment and low genetic diversity, indicate the need of undertaking effective in situ and ex situ conservation measures.

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