On the occurrence of the Critically Endangered blond titi (Callicebus barbarabrownae): reassessment of occupied areas and minimum population size

2022 ◽  
Author(s):  
André Chein Alonso ◽  
Igor Pfeifer Coelho ◽  
Eduardo Marques ◽  
Mônica Mafra Valença-Montenegro ◽  
Raone Beltrão-Mendes ◽  
...  
Keyword(s):  
Population Size ◽  
Critically Endangered

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

Extreme rainfall-related clutch size variation in the Critically Endangered Raso Lark Alauda razae of the arid Cape Verde islands

2018 ◽  
Vol 29 (2) ◽  
pp. 321-326 ◽  
Author(s):  
M. de L. BROOKE
Keyword(s):  
Population Size ◽  
Clutch Size ◽  
Size Variation ◽  
Extreme Rainfall ◽  
Cape Verde ◽  
Critically Endangered ◽  
Strongly Correlated ◽  
Cape Verde Islands ◽  
Rainy Period ◽  
Island Endemic

SummaryThe Raso Lark Alauda razae is a single island endemic confined to the island of Raso in the Cape Verde islands. It has been studied via short (11–20 day), similarly-timed visits every year from 2001 to 2017. These November/December visits have occurred towards the end of the main rainy period (August–October) in the Cape Verdes. Average clutch size ranged from zero (no nests found) to 3.57 in different years and was strongly correlated with rainfall in the three months preceding the year’s visit, but not with population size, which varied 25-fold during the study period. Since the nomadic pursuit of rain is not an option for the Raso Lark, the species adjusts clutch size according to conditions prevailing on Raso.

scholarly journals Microhabitats Affect Population Size and Plant Vigor of Three Critically Endangered Endemic Plants in Southern Sinai Mountains, Egypt

Land ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 86 ◽  
Author(s):  
Amal M. Fakhry ◽  
Ali El-Keblawy ◽  
Hatem A. Shabana ◽  
Ibrahim El Gamal ◽  
Amir Shalouf
Keyword(s):  
Climate Change ◽  
Population Size ◽  
Endemic Species ◽  
Climate Changes ◽  
Small Population ◽  
Critically Endangered ◽  
High Mountains ◽  
Habitat Types ◽  
Growing Seasons ◽  
Steep Slopes

Endemic species on mountains often have narrow altitudinal ranges and are more threatened at the higher altitudes, especially with climate changes. However, plants could use special microhabitats at the mountain tops as proper places for surviving the climate change (i.e., refugia). We assessed population attributes of three critically endangered endemic species (Primula boveana Decne ex Duby, Rosa arabica Crep., and Silene leucophylla Boiss.) in two growing seasons (2006/2007 and 2013/2014), differing in the received rainfalls in microhabitats at the high mountains of southern Sinai. Both P. boveana and S. leucophylla had very small population size, but significantly increased in the 2013/2014 growing season which received above average rainfalls. The population of R. arabica is the smallest (around 40 individuals) and did not increase, even after the increase in rainfalls. Whereas P. boveana is present in fewer sites and grew in small number of specific microhabitats, both S. leucophylla and R. arabica were recorded in most studied sites and habitat types. Unlike R. arabica, both P. boveana and S. leucophylla were recorded in caves and steep slopes and on the top of the mountains. This indicates that these sheltered mist microhabitats are the best for future conservation of these species after climate change.

scholarly journals Endophytic fungi and latent pathogens in the sedge Carex secalina (Cyperaceae), a critically endangered species in Europe

2019 ◽  
Vol 55 (No. 2) ◽  
pp. 102-108 ◽  
Author(s):  
Górzyńska Karolina ◽  
Węgrzyn Ewa ◽  
Sandecki Rafał ◽  
Lembicz Marlena
Keyword(s):  
Endangered Species ◽  
Population Size ◽  
Endophytic Fungi ◽  
Critically Endangered ◽  
Critically Endangered Species ◽  
Colletotrichum Destructivum ◽  
Leaf Tissues ◽  
Study Sites ◽  
Roadside Area ◽  
Latent Pathogens

Endophytic fungi are widespread in plants and affect the host fitness and population size. We found 12 fungal taxa in C. secalina, a critically endangered species in several European countries, at two study sites in Poland. The most frequently occurring fungal taxa were Colletotrichum destructivum and Acremonium sp. Both taxa were found in half of the examined tussocks. The highest number of fungal taxa was noted in the C. secalina plants growing in the roadside area, where 7 of the 12 identified fungal taxa occurred. These fungi, inhabiting leaf tissues, are known for their pathogenicity but no visible symptoms of any diseases were observed on C. secalina leaves. This suggests that these fungi are latent pathogens.

scholarly journals Decline towards extinction of Mexico's vaquita porpoise ( Phocoena sinus )

2019 ◽  
Vol 6 (7) ◽  
pp. 190598 ◽  
Author(s):  
Armando M. Jaramillo-Legorreta ◽  
Gustavo Cardenas-Hinojosa ◽  
Edwyna Nieto-Garcia ◽  
Lorenzo Rojas-Bracho ◽  
Len Thomas ◽  
...  
Keyword(s):  
Population Size ◽  
Total Population ◽  
Population Decline ◽  
Credible Interval ◽  
Critically Endangered ◽  
Posterior Mean ◽  
Bayesian Credible Interval ◽  
Independent Estimate ◽  
Rate Of Decline ◽  
Passive Acoustic

The vaquita ( Phocoena sinus ) is a small porpoise endemic to Mexico. It is listed by IUCN as Critically Endangered because of unsustainable levels of bycatch in gillnets. The population has been monitored with passive acoustic detectors every summer from 2011 to 2018; here we report results for 2017 and 2018. We combine the acoustic trends with an independent estimate of population size from 2015, and visual observations of at least seven animals in 2017 and six in 2018. Despite adoption of an emergency gillnet ban in May 2015, the estimated rate of decline remains extremely high: 48% decline in 2017 (95% Bayesian credible interval (CRI) 78% decline to 9% increase) and 47% in 2018 (95% CRI 80% decline to 13% increase). Estimated total population decline since 2011 is 98.6%, with greater than 99% probability the decline is greater than 33% yr −1 . We estimate fewer than 19 vaquitas remained as of summer 2018 (posterior mean 9, median 8, 95% CRI 6–19). From March 2016 to March 2019, 10 dead vaquitas killed in gillnets were found. The ongoing presence of illegal gillnets despite the emergency ban continues to drive the vaquita towards extinction. Immediate management action is required if the species is to be saved.

scholarly journals Protected by dragons: Density surface modeling confirms large population of the critically endangered Yellow-crested Cockatoo on Komodo Island

The Condor ◽  
2020 ◽  
Author(s):  
Anna Reuleaux ◽  
Benny A Siregar ◽  
Nigel J Collar ◽  
Maria R Panggur ◽  
Ani Mardiastuti ◽  
...  
Keyword(s):  
Population Size ◽  
Local Density ◽  
Large Population ◽  
Distance Sampling ◽  
Surface Modeling ◽  
Habitat Associations ◽  
Critically Endangered ◽  
Topographic Wetness Index ◽  
Monsoon Forest ◽  
Density Surface

Abstract Intense trapping of the critically endangered Yellow-crested Cockatoo (Cacatua sulphurea) for the international pet trade has devastated its populations across Indonesia such that populations of >100 individuals remain at only a handful of sites. We combined distance sampling with density surface modeling (DSM) to predict local densities and estimate total population size for one of these areas, Komodo Island, part of Komodo National Park (KNP) in Indonesia. We modeled local density based on topography (topographic wetness index) and habitat types (percentage of palm savanna and deciduous monsoon forest). Our population estimate of 1,113 (95% CI: 587–2,109) individuals on Komodo Island was considerably larger than previous conservative estimates. Our density surface maps showed cockatoos to be absent over much of the island, but present at high densities in wooded valleys. Coincidence between our DSM and a set of independent cockatoo observations was high (93%). Standardized annual counts by KNP staff in selected areas of the island showed increases in cockatoo records from <400 in 2011 to ~650 in 2017. Taken together, our results indicate that KNP, alongside and indeed because of preserving its iconic Komodo dragons (Varanus komodoensis), is succeeding in protecting a significant population of Indonesia’s rarest cockatoo species. To our knowledge this is the first time DSM has been applied to a critically endangered species. Our findings highlight the potential of DSM for locating abundance hotspots, identifying habitat associations, and estimating global population size in a range of threatened taxa, especially if independent datasets can be used to validate model predictions.

The first egg of Jerdon's courser Rhinoptilus bitorquatus and a review of the early records of this species

2014 ◽  
Vol 41 (1) ◽  
pp. 75-93 ◽  
Author(s):  
Alan G. Knox
Keyword(s):  
Twentieth Century ◽  
Population Size ◽  
Dna Analysis ◽  
Type Specimen ◽  
Critically Endangered ◽  
Grammar School ◽  
Restricted Area ◽  
Veterinary Surgeon ◽  
The University

For most of the twentieth century, Jerdon's courser (Rhinoptilus bitorquatus) was thought to be extinct until it was rediscovered in 1986. Since then, despite much research, the bird remains poorly known. A Critically Endangered southern Indian endemic, recorded from a restricted area of about 50 square kilometres, its nocturnal habits, infrequent vocalizations, scrub-jungle habitat and low population size make it difficult to observe. Almost nothing is known about its breeding or ecology. Its nest has never been seen by an ornithologist. The first known egg of the species was recently discovered in a collection at the University of Aberdeen and its identity confirmed by DNA analysis. It had been collected by Ernest Gilbert Meaton, a veterinary surgeon at the Kolar Gold Fields, east of Bangalore. He probably obtained it in 1917, within 100 km of Kolar. Meaton's egg collection was purchased by George Falconer Rose, a successful expatriate Scot working in Calcutta, and given to Aberdeen Grammar School in 1919. In the 1970s, the school gave the collection to the University of Aberdeen, where the egg was discovered in 2008. This paper collates and reviews the early records of Jerdon's courser and examines the provenance of the egg. The type specimen of the courser now appears to be lost, but five other specimens exist in collections.

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.

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