scholarly journals Estimates of abundance and apparent survival of coastal dolphins in Port Essington harbour, Northern Territory, Australia

2014 ◽  
Vol 41 (1) ◽  
pp. 35 ◽  
Author(s):  
Carol Palmer ◽  
Lyndon Brooks ◽  
Guido J. Parra ◽  
Tracey Rogers ◽  
Debra Glasgow ◽  
...  
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Local Population ◽  
Northern Territory ◽  
Systematic Sampling ◽  
Northern Australia ◽  
Apparent Survival ◽  
Photo Identification ◽  
Population Size Estimates ◽  
Sampling Protocols

Context Three dolphin species occur in coastal waters of monsoonal northern Australia: the Australian snubfin (Orcaella heinsohni), humpback (Sousa sp.) and the bottlenose (Tursiops sp.). Their overall population size and trends are poorly known, and their conservation status has been difficult to resolve, but can be expected to deteriorate with likely increased development pressures. Aims We sought to provide an estimate of abundance, and apparent survival, of the three dolphin species at the largely undeveloped harbour of Port Essington (325 km2), Northern Territory, with repeated sampling over a 2.9-year period. Given increasing obligations to undertake population assessments for impact studies at proposed development sites, we assess the strengths and limitations of a systematic sampling program. Methods We used photo-identification data collected during systematic boat-based transect surveys undertaken from 2008 to 2010 and Pollock’s robust capture–recapture design model. Key results Total abundance estimates for the three species were variable across different sampling periods. The estimated number of individuals in the sampled area varied per sampling episode from 136 (s.e. 62) to 222 (s.e. 48) for snubfin, from 48 (s.e. 7) to 207 (s.e. 14) for humpbacks and from 34 (s.e. 6) to 75 (s.e. 9) for bottlenose dolphins. Apparent survival was estimated for snubfin at 0.81 (s.e. 0.11), humpbacks at 0.59 (s.e. 0.12) and bottlenose at 0.51 (s.e. 0.17) per annum. Key conclusions (1) The values derived here provide some of the only estimates of local population size for these species across monsoonal northern Australia; (2) population-size estimates varied considerably among seasons or sampling episodes; (3) the low apparent survival probabilities indicated that many individuals may move at scales larger than the study area; (4) density of snubfin and humpback dolphins in the present study area exceeded the few other estimates available for these species elsewhere in Australia. Implications The present study provided the first baseline estimates of abundance and apparent survival for three coastal dolphin species in monsoonal northern Australia. Such information is becoming increasingly important as development pressures intensify in coastal areas. Sampling protocols for future monitoring and impact assessment need an enhanced consideration of seasonality and scale issues.

Corrigendum to: Estimates of abundance and apparent survival of coastal dolphins in Port Essington harbour, Northern Territory, Australia

2015 ◽  
Vol 42 (4) ◽  
pp. 371
Author(s):  
Carol Palmer ◽  
Lyndon Brooks ◽  
Guido J. Parra ◽  
Tracey Rogers ◽  
Debra Glasgow ◽  
...  
Keyword(s):  
Population Size ◽  
Coastal Waters ◽  
Conservation Status ◽  
Northern Territory ◽  
Systematic Sampling ◽  
Northern Australia ◽  
Apparent Survival ◽  
Impact Studies ◽  
Sampling Program ◽  
Repeated Sampling

Context Three dolphin species occur in coastal waters of monsoonal northern Australia: the Australian snubfin (Orcaella heinsohni), humpback (Sousa sp.) and the bottlenose (Tursiops sp.). Their overall population size and trends are poorly known, and their conservation status has been difficult to resolve, but can be expected to deteriorate with likely increased development pressures. Aims We sought to provide an estimate of abundance, and apparent survival, of the three dolphin species at the largely undeveloped harbour of Port Essington (325km2), Northern Territory, with repeated sampling over a 2.9-year period. Given increasing obligations to undertake population assessments for impact studies at proposed development sites, we assess the strengths and limitations of a systematic sampling program.

scholarly journals Population size estimates of pink river dolphins (Inia geoffrensis) using mark-recapture methods on photo-identification

2014 ◽  
Vol 9 (2) ◽  
pp. 132-139 ◽  
Author(s):  
Catalina Gómez-Salazar ◽  
Hal Whitehead ◽  
Fernando Trujillo
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Freshwater Ecosystems ◽  
Mark Recapture ◽  
Photo Identification ◽  
Population Size Estimate ◽  
Population Size Estimates ◽  
Inia Geoffrensis ◽  
Colombian Amazon ◽  
Size Estimates

Population size estimates of pink river dolphins (Inia geoffrensis) are critical to assess the conservation status of this species and the impacts of increasing human stressors in freshwater ecosystems. Photo-identifications of Inia dolphins were collected between February 2007 and August 2009 in two locations of the Colombian Amazon and Orinoco river basins. Population sizes of Inia were obtained by using the closed (Petersen) mark-recapture model on photo-identifications. The total population size estimate for right/left side individuals was 129/71 Inia dolphins (CV=0.36/0.35) in the Amazon location and 125/58 Inia dolphins (CV=0.77/0.69) in the Orinoco location. The survey and analysis protocols were designed to try to meet mark-recapture assumptions. However, photo-identification was incomplete in both study areas, and there could be recruitment and unequal probabilities of capture due to preferences of individuals for certain areas. Further effort should be focused towards expanding the photo-identification catalogues and creating long-term monitoring programs.

scholarly journals Estimating abundance of a recovering transboundary brown bear population with capture-recapture models

2021 ◽  
Author(s):  
Cecile Vanpe ◽  
Blaise Piedallu ◽  
Pierre-Yves Quenette ◽  
Jerome Sentilles ◽  
Guillaume Queney ◽  
...  
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Brown Bear ◽  
Home Range Size ◽  
Management Decision ◽  
Lower Survival Rate ◽  
Population Size Estimates ◽  
Management Decision Making ◽  
Annual Population ◽  
Capture Recapture

Abundance of small populations of large mammals may be assessed using complete counts of the different individuals detected over a time period, so-called minimum detected size (MDS). However, as population is growing larger and its distribution is expanding wider, the risk of under-estimating population size using MDS is increasing sharply due to the rarely fulfilled assumption of perfect detection of all individuals of the population, and as a result, the need to report uncertainty in population size estimates becomes crucial. We addressed these issues within the framework of the monitoring of the critically endangered Pyrenean brown bear population that was on the edge of extinction in the mid-1990s with only five individuals remaining, but was reinforced by 11 bears originated from Slovenia since then. We used Pollock's closed robust design (PCRD) capture-recapture models applied to the cross-border non-invasive sampling data from France, Spain and Andorra to provide the first published annual abundance estimates of the Pyrenean brown bear population and its trends over time. Annual population size increased and displayed a fivefold rise between 2008 and 2020, reaching > 60 individuals in 2020. Detection heterogeneity among individuals may stem from intraspecific home range size disparities making it more likely to find signs of individuals who move more. We found a lower survival rate in cubs than in adults and subadults, since the formers suffer from more mortality risks (such as infanticides, predations, mother death or abandonments) than the latters. Our study provides evidence that the PCRD capture-recapture modelling approach can provide reliable estimates of the size of and trend in large mammal populations, while minimizing bias due to inter-individual heterogeneity in detection probabilities and allowing the quantification of sampling uncertainty surrounding these estimates. Such information is vital for informing management decision-making and assessing population conservation status.

scholarly journals Waterbird population estimates for a key staging site in Kazakhstan: a contribution to wetland conservation on the Central Asian flyway

2008 ◽  
Vol 18 (1) ◽  
pp. 71-86 ◽  
Author(s):  
Holger Schielzeth ◽  
Götz Eichhorn ◽  
Thomas Heinicke ◽  
Johannes Kamp ◽  
Maxim A. Koshkin ◽  
...  
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Steppe Zone ◽  
Wetland Conservation ◽  
Conservation Strategies ◽  
Population Estimates ◽  
The South ◽  
Migration Routes ◽  
South West ◽  
Population Size Estimates

AbstractRealistic population size estimates for waterbirds are crucial for the application of wetland conservation strategies, since the identification of internationally important wetlands is based on local numbers relative to the population size of the respective species. Central Asia is a poorly surveyed region that is situated at the intersection of migration routes that lead waterbirds from Western Siberia to the south-west (South-West Asia, East Africa) and to the south-east (South Asia, India). We calculated waterbird population estimates for the Tengiz–Korgalzhyn region, a large wetland complex in the steppe zone of Central Kazakhstan, based on waterbird surveys conducted between 1999 and 2004. For 20 of 43 species analysed the region supported more than 5% of the relevant flyway populations. Five species occurred with more than 40% of the flyway totals, including the Endangered White-headed Duck Oxyura leucocephala and the Vulnerable Dalmatian Pelican Pelecanus crispus. Peak numbers were recorded in summer and autumn and for most species numbers were more than an order of magnitude lower on spring migration compared with autumn migration. We identified 72 individual sites that held more than 20,000 waterbirds or more than 1% of a particular flyway population at least once. These sites are likely to constitute priorities for conservation. The general conservation status of the region is favourable, since many of the important sites are located within a strict nature reserve. However, outside the reserve hunting, fishing and powerline casualties represent conservation issues that should be monitored more carefully in the future.

Observations of the 'Critically Endangered' bare-rumped sheathtail bat Saccolaimus saccolaimus Temminck (Chiroptera: Emballonuridae) on Cape York Peninsula, Queensland.

2001 ◽  
Vol 23 (2) ◽  
pp. 185 ◽  
Author(s):  
S Murphy
Keyword(s):  
Papua New Guinea ◽  
Solomon Islands ◽  
Conservation Status ◽  
New Guinea ◽  
Fire Regimes ◽  
Wide Distribution ◽  
Northern Territory ◽  
Critically Endangered ◽  
Northern Australia ◽  
Cape York

THE bare-rumped sheathtailed bat Saccolaimus saccolaimus is a poorly understood species that has a wide distribution covering parts of India, Sri Lanka, Thailand, Myanmar, Malaya, Indonesia, New Guinea, the Solomon Islands and Northern Australia (Bonaccorso 1998). First collected in Australia by De Vis near Cardwell, the current known distribution in Queensland (Qld) extends from Bowen to Cooktown with one isolated specimen collected near Coen on Cape York Peninsula (Hall 1995; Duncan et al. 1999). It has also been recorded in the Alligator River area in the Northern Territory (McKean et al. 1981). The conservation status of S. saccolaimus in Qld has recently been defined as ?Critically Endangered?, and the species has not been recorded anywhere in Australia for at least 18 years (Duncan et al. 1999; Menkhorst and Knight 2001). The likely reasons for the apparent decline are unclear, but may involve land-clearing and changed fire regimes in the coastal zone where it is thought to occur (Duncan et al. 1999). In contrast, Bonaccorso (1998) considers S. saccolaimus to be secure, albeit also poorly known in Papua New Guinea.

Population size, survival and reproductive rates of northern Norwegian killer whales (Orcinus orca) in 1986–2003

2013 ◽  
Vol 94 (6) ◽  
pp. 1277-1291 ◽  
Author(s):  
Sanna Kuningas ◽  
Tiu Similä ◽  
Philip S. Hammond
Keyword(s):  
Population Size ◽  
Killer Whale ◽  
Survival Rates ◽  
Clupea Harengus ◽  
Orcinus Orca ◽  
Adult Males ◽  
Killer Whales ◽  
Apparent Survival ◽  
Photo Identification ◽  
Reproductive Rates

A long-term photo-identification study of killer whales (Orcinus orca) in northern Norway was initiated in 1986, when their prey the Norwegian spring-spawning herring (Clupea harengus) started to winter in a complex fjord system. The aim of this work was to estimate population size and apparent survival rates in this killer whale population using photo-identification and mark–recapture techniques with data collected during October–December 1986–2003. Total population size was estimated to be highest in 2003: 731 individuals (SE = 139, 95% CI = 505–1059) using a model taking heterogeneity of capture probabilities into account. Apparent survival of adult males and adult females was estimated using the Cormack–Jolly–Seber model as 0.971 (SE = 0.008) and 0.977 (SE = 0.009), respectively. Calving intervals ranged from 3 to 14 years (mean = 5.06, SE = 0.722). These are the first estimates of northern Norwegian killer whale population parameters, allowing their dynamics to be investigated and comparisons to be made with killer whale populations globally.

Targeted sampling successfully detects the cryptic and declining arboreal marsupial (Phascogale pirata) in northern Australia

2020 ◽  
Vol 26 (4) ◽  
pp. 395
Author(s):  
Hayley M. Geyle ◽  
Leigh-Ann Woolley ◽  
Hugh F. Davies ◽  
John C. Z. Woinarski ◽  
Brett P. Murphy
Keyword(s):  
Conservation Status ◽  
Study Finding ◽  
Northern Territory ◽  
Northern Australia ◽  
Wet Season ◽  
Breast Height ◽  
Nest Boxes ◽  
Targeted Sampling ◽  
Large Trees ◽  
Survey Effort

The threatened northern brush-tailed phascogale (Phascogale pirata) is one of the most poorly known mammals in Australia. While the few available records indicate a decline in its distribution and abundance, it has not previously been subject to intensive targeted survey. Here, we trialled a specifically tailored methodology for detection of P. pirata, with the aim of informing ongoing survey and monitoring of this species. We deployed 50 motion-sensor cameras (spaced closely together in a grid 500×1000m) on Melville Island (Northern Territory, Australia), between June 2018 and May 2019. Cameras were baited and secured to trees ~3m above the ground on a bracket facing the trunk. We selected for large (>30cm diameter at breast height [DBH]) trunks of the dominant tree species (Eucalyptus miniata, E. tetrodonta and Corymbia nesophila). We detected P. pirata 16 times on eight cameras over the duration of the study, finding that detection was most likely on large (DBH >41.5cm) E. tetrodonta trees during the wet season. Our results indicate that survey effort for this species should be seasonally targeted and focussed on large trees. However, the efficacy of additional methods (nest boxes, Elliott traps) and a comparison between detections on arboreal versus ground-based cameras requires further investigation. We highlight the importance of conducting additional work on this species, as little is known about its ecology, population trends and threats, making it difficult to assess its conservation status. Without more targeted work, P. pirata is at risk of slipping into extinction unnoticed.

Distribution and conservation status of the rare plants Melaleuca triumphalis and Stenostegia congesta (Myrtaceae), Victoria River district, northern Australia

2006 ◽  
Vol 54 (7) ◽  
pp. 641 ◽  
Author(s):  
Beth Crase ◽  
Ian D. Cowie ◽  
Carrie R. Michell
Keyword(s):  
National Park ◽  
Conservation Status ◽  
Landscape Scale ◽  
Northern Territory ◽  
Rare Plants ◽  
Habitat Requirements ◽  
Northern Australia ◽  
Digital Elevation ◽  
Rivers And Streams ◽  
Scale Data

Targeted searches of approximately 150 km of cliff lines for two rare sandstone shrubs, Melaleuca triumphalis Craven and Stenostegia congesta A.R.Bean, thought to be restricted to the Victoria River gorge system within Gregory National Park, increased the number of known populations from 3 and 6 to 31 and 37, respectively. Both species occur predominantly in rocky and often fire-protected niches on sandstone cliffs and scree slopes, and are frequently associated with permanent drip-lines and seepage areas. Although their broad habitat requirements are similar, the two species do occur in slightly different niches. The data presented here suggest that M. triumphalis is reasonably fire tolerant, whereas S. congesta appears to be more fire sensitive. Weeds and introduced animals are not thought to pose a threat to these rare species. Models developed using remotely sensed and landscape-scale data (digital elevation models, radiometrics, geology and distance to rivers and streams) suggest that these species may also occur outside Gregory National Park in other areas of the Northern Territory such as on Bullo River and Bradshaw stations and in Keep River National Park. It is suggested that both species be regarded as Vulnerable under the IUCN guidelines.

Demography of the northern quoll (Dasyurus hallucatus) in the most arid part of its range

2019 ◽  
Vol 100 (4) ◽  
pp. 1191-1198
Author(s):  
Lorna Hernandez-Santin ◽  
Judy A Dunlop ◽  
Anne W Goldizen ◽  
Diana O Fisher
Keyword(s):  
Population Size ◽  
Habitat Quality ◽  
Local Population ◽  
Population Characteristics ◽  
Population Declines ◽  
Population Size Estimates ◽  
Population Sizes ◽  
Harsh Climate ◽  
Rocky Habitats ◽  
Carnivorous Marsupial

Abstract The northern quoll (Dasyurus hallucatus) is a carnivorous marsupial that has suffered severe population declines over the last 50 years and is now listed as Endangered. The Pilbara region of Western Australia is a semi-arid area that represents an extreme of the northern quoll’s range. The overall objective of this study was to assess population characteristics of northern quolls at two rocky sites in the Pilbara, focusing on body condition, reproductive timing, population size, and sex-specific survival. We interpret these in the context of variation in habitat quality and the harsh climate. We found that reproduction occurred later in the year than in populations at more mesic locations where quolls have been previously studied, although their life history and demography were otherwise similar to that in other parts of their range. Contrary to our expectations, post-mating mortality of males was not complete. Population sizes differed between sites, suggesting that these rocky habitats varied in habitat quality. We suggest that local population size estimates can guide decisions on the relative importance of sites to ensure the long-term conservation of the species, given impacts of mining and the imminent invasion of introduced cane toads (Rhinella marina).

scholarly journals Conservation status of threatened and endemic birds of New Britain, Papua New Guinea

2017 ◽  
Vol 28 (3) ◽  
pp. 439-450
Author(s):  
ROBERT A. DAVIS ◽  
GUY DUTSON ◽  
JUDIT K. SZABO
Keyword(s):  
Population Size ◽  
Papua New Guinea ◽  
Oil Palm ◽  
Conservation Status ◽  
Bird Species ◽  
New Guinea ◽  
Old Growth Forest ◽  
Population Size Estimates ◽  
New Britain ◽  
Size Estimates

SummaryNew Britain in the Bismarck Archipelago of Papua New Guinea supports 14 endemic bird species and together with New Ireland, forms an Endemic Bird Area that supports 38 restricted range species. Extensive conversion of lowland forest to oil palm plantations resulted in the loss of over 20% of forest under 100 m altitude between 1989 and 2000. However the rate of loss has subsequently slowed (2.2% loss across all altitudes between 2002 and 2014), and much forest remains at higher altitudes: 72% of New Britain remained forested (including secondary forest) in 2014. Despite the ongoing high threat and rich endemic bird fauna, the state of knowledge of the conservation status of birds in New Britain is very poor. We use an unprecedented dataset based on 415 hours of bird surveys conducted in oil palm plantations, as well as primary and secondary forests at all altitudes, to revise the IUCN status of New Britain’s birds. These data indicate that six species of elevated conservation concern are less dependent on old-growth forest than previously assessed. We recommend reduced population size estimates for one species, New Britain Kingfisher Todiramphus albonotatus. We recommend increased population size estimates for seven species: Pied Cuckoo-dove Reinwardtoena browni, Yellowish Imperial Pigeon Ducula subflavescens, Green-fronted Hanging Parrot Loriculus tener, Blue-eyed Cockatoo Cacatua opthalmica, Violaceous Coucal Centropus violaceous, New Britain Boobook Ninox odiosa and New Britain Thrush Zoothera talaseae. Despite our comprehensive surveys, Slaty-backed Goshawk Accipiter luteoschistaceus, New Britain Sparrowhawk Accipiter brachyurus, New Britain Bronzewing Henicophaps foersteri and Golden Masked-owl Tyto aurantia remain very rarely recorded and require further assessment. With ongoing habitat loss, particularly in lowland areas, New Britain’s birds urgently require more attention.

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