Some demographics of the extirpation from the wild of eastern barred bandicoots (Perameles gunni) in 1988-91, near Hamilton, Victoria, Australia

1995 ◽  
Vol 22 (3) ◽  
pp. 289 ◽  
Author(s):  
TW Clark ◽  
JP Gibbs ◽  
PW Goldstraw

The threatened, free-ranging mainland poplation, of the eastern barred bandicoot in the Hamilton area of Victoria declined to near extinction in late 1992. Demographic changes associated with the decline were monitored from 1988 to 1992. About 200 different animals were captured in 1988,49 in 1989, 16 in 1990, 3 in 1991 and 3 in 1992; capture rates (number of bandicoots captured per trap-night) displayed a similar pattern: 0.5 in 1988,O.l in 1989,0.05 in 1990,0.05 in 1991 and 0.02 in 1992. Observed declines lay within the 5% confidence intervals predicted by a demographic model for a population subjected to a removal rate of 14 animals per three months (the number removed for captive breeding by managers). Removal of bandicoots to stock a captive population hastened the demise of the wild population by about seven years; however, even in the absence of removals of animals, extinction was impending within 5-10 years. Sex ratios were male-biased in all years except 1988; the bias may have resulted from stochastic events. Average litter sizes did not differ between the 1988 population and subsequent populations, except for the 1991 population, in which a predominance of non-reproductive females contributed to a strong decline in average litter size. These demographic trends illustrate how the synergy between stochastic and deterministic forces can rapidly drive a small population to extinction.

2013 ◽  
Author(s):  
Clifford Frith

This book tells the fascinating success story of saving the flightless Woodhen of Lord Howe Island. This unique large rail, an iconic and highly endangered Australian bird, was at the very brink of extinction with just 15 individuals found in 1980, when bold and risky actions were taken to save it. The book begins with the discovery and ecology of Lord Howe Island. It then details the history of the Woodhen, its place among the rails and their evolution of flightlessness, the planning, implementation and trials, tribulations and successes of the captive breeding programme and the way in which the wild population recovered. The ecology, behaviour and breeding biology of this unique flightless island rail are also discussed. The text is accompanied by numerous photographs and drawings. This is a story of survival, yet the bird remains highly endangered as it is under constant potential threat, which could tip it over the brink and to extinction. The Woodhen provides gripping insights into the potential for both losing and saving vertebrate species. Winner of a 2014 Whitley Awards Certificate of Commendation for Historical Zoology.


2010 ◽  
Vol 107 (5) ◽  
pp. 2147-2152 ◽  
Author(s):  
Chad D. Huff ◽  
Jinchuan Xing ◽  
Alan R. Rogers ◽  
David Witherspoon ◽  
Lynn B. Jorde

The genealogies of different genetic loci vary in depth. The deeper the genealogy, the greater the chance that it will include a rare event, such as the insertion of a mobile element. Therefore, the genealogy of a region that contains a mobile element is on average older than that of the rest of the genome. In a simple demographic model, the expected time to most recent common ancestor (TMRCA) is doubled if a rare insertion is present. We test this expectation by examining single nucleotide polymorphisms around polymorphic Alu insertions from two completely sequenced human genomes. The estimated TMRCA for regions containing a polymorphic insertion is two times larger than the genomic average (P < <10−30), as predicted. Because genealogies that contain polymorphic mobile elements are old, they are shaped largely by the forces of ancient population history and are insensitive to recent demographic events, such as bottlenecks and expansions. Remarkably, the information in just two human DNA sequences provides substantial information about ancient human population size. By comparing the likelihood of various demographic models, we estimate that the effective population size of human ancestors living before 1.2 million years ago was 18,500, and we can reject all models where the ancient effective population size was larger than 26,000. This result implies an unusually small population for a species spread across the entire Old World, particularly in light of the effective population sizes of chimpanzees (21,000) and gorillas (25,000), which each inhabit only one part of a single continent.


Oryx ◽  
1999 ◽  
Vol 33 (2) ◽  
pp. 152-159 ◽  
Author(s):  
John Thorbjarnarson ◽  
Wang Xiaoming

AbstractThe Chinese alligator Alligator sinensis is one of the world's most endangered reptiles. At one time widespread throughout much of the lower Yangzi River basin, the remaining wild individuals are now restricted to a small area in southern Anhui Province and perhaps in adjacent Zhejiang Province. Population estimates conducted in the 1980s suggested that only 500–735 wild individuals remained at that time. Current figures suggest that the wild population is c. 400 individuals and continues to decline. The principal factor contributing to historic population decline has been habitat loss, but deliberate killing of alligators and the heavy use of pesticides have also had significant negative effects. The current conservation programme in Anhui Province is based on captive breeding and the establishment of a reserve for small groups of wild alligators. However, the inferred recent decline in the size of the wild population suggests that the reserve design is inadequate for the long-term survival of alligators. Programmes to survey the status of the remaining wild populations and evaluate the feasibility of establishing new wild populations by reintroducing captive-bred animals are currently being developed.


2015 ◽  
Vol 2 (1) ◽  
pp. 598
Author(s):  
Arista Setyaningrum ◽  
Pipit Noviyani ◽  
Bambang Agus Suripto

<p>Bali Myna (Leucopsar rothschildi) is Bali’s endemic bird. Their number is decreasing gradually in the wild (Balen et al., 2000). Its bright color of white feather and blue skin that surrounded its eye have made them easy to be hunted when it perched on abranch. Bali Myna was classified as endangered species by International Union of Conservation and Natural resources (IUCN) in 1977 (Whitten et al. 1999). There is a captive breeding in Tegal Bunder, Bali Barat National Park (BBNP) called Bali Myna Guidance Centre to increase wild population as an effort to prevent extinction. There, its conditions should be monitored regularly to keep them in prime condition, before being released for breeding purpose. Their condition could be controlled by monitoring their daily activities.</p>


2021 ◽  
Author(s):  
◽  
Tanya M. Karst

<p>A small population (n=58) of Maud Island frogs, Leiopelma pakeka, was translocated to the Zealandia wildlife sanctuary in Wellington, New Zealand in 2006/2007. The 29 frogs that were released into a predator-proof enclosure, along with some of their progeny, are currently spread over three separate predator-proof enclosures. However, their status has not been assessed since 2011. With the aim of establishing a viable, freeranging population, the remaining 29 frogs were released into forested habitat around the original enclosure. In 2010, the translocation of the free-ranging population was assessed as a failure, citing too few founding individuals, inadequate habitat, predation by little spotted kiwi (LSK), Apteryx owenii, and predation by house mice, Mus musculus, as potential factors. This thesis re-addresses the status of L. pakeka in the three enclosures, as well as the potential predation of these threatened endemic frogs by LSK and mice. Survival of L. pakeka in the three enclosures was estimated by nocturnal emergence over 11 ve-night capture periods from October 2012 - August 2013. Identi cation of individuals was via photography utilizing distinguishable skin patterns and iris vessel (eye venation) patterns. The relocation of six adults after a 2011 census, including one inadvertently missed frog found during this study, left 19 adult frogs in the original enclosure, which continued to survive well, with 18 adults recaptured. In addition, juveniles of varying ages were seen throughout this study. In total, 34 recently metamorphosed froglets were released into a second enclosure over the years of 2008, 2009 and 2011. Night monitoring indicated only 8 individuals had survived, but a full enclosure census on 8 May 2013 revealed 12 of the 34 individuals (35%) had survived. Three of these frogs were then relocated to the Te Mahanga, publicly viewed enclosure. Emergence during the 11-month period indicated that the six frogs relocated to this enclosure from the original enclosure in October 2011 had survived; however, only two out of the three frogs that were relocated there after the May census had emerged. Additionally, two juveniles of unknown age were also seen in this enclosure. Potential predation by LSK was assessed by a ve-night video analysis (23-28 June 2013) of foraging behavior in the presence of mesh-protected L. pakeka. Out of the 668 videos reviewed, only three videos provided foraging behavior that helped ascertain whether LSK exhibited a potential interest in L. pakeka as a prey item. These videos showed that LSK failed to indicate a strong response to the presence of the frog, suggesting that the LSK in Zealandia do not have a strong predatory interest in L. pakeka. To investigate the potential causes of the free-range translocation failure, the habitat was enhanced with more rocks, a kiwi-exclusion fence was erected, and a further 101 L. pakeka were translocated from Maud Island to Zealandia on 2 December 2012. The frogs' survival as well as mouse activity levels (indicated by the presence of mouse prints in tracking tunnels) were monitored over nine ve-night capture periods from 17 December 2012 - 2 August 2013. Eighty-six out of the 101 translocated frogs were recaptured. Identi cation of individuals was via photography utilizing distinguishable skin patterns and iris vessel (eye venation) patterns, or by unique toe-clip combinations. Despite previous assessments, four surviving adults from the 2006/2007 translocation were recaptured as well as 12 of their progeny, resulting in a total of 117 Maud Island frogs for this study. Jolly-Seber analysis indicated high overall survival (0.914, 0.87/0.94, 95%CI), but temporally the population estimates indicated a negative regression starting at the second capture period (slope= -4.69, -6.70/- 2.68, 95%CI). With overall frog emergence, a negative binomial generalized linear model did not show signi cance in mouse activity levels, precipitation during sampling nor precipitation in the previous 24 hours (p>0.05). However, temperature did show a positive correlation to overall frog emergence (p<0.001) while relative humidity approached signi cance (p=0.0517) and indicated a potential positive trend. This study could not conclusively indicate whether A. owenii or M. musculus prey upon L. pakeka. However, it does suggest that the protected predator-proof enclosures may provide appropriate conditions for the ongoing survival and successful breeding of the endemic anuran. The study also suggests that LSK do not have a strong predatory response to the presence of Maud Island frogs, nor did increased levels of mouse activity have a signi cant e ect on the emergence of the 117 Maud Island frogs. Additionally, the discovery of the four survivors and 12 of their o spring indicates that the original translocation did not entirely fail. This newly acquired knowledge suggests that with the current mammal eradication program, Zealandia may continue with the establishment of a viable, free-ranging population of L. pakeka. Continued monitoring of all Maud Island frogs in the Zealandia sanctuary is recommended as a conservation measure, especially as mice have now established on its original island habitat.</p>


2020 ◽  
Author(s):  
Bradley P. Smith ◽  
Shennai G. Palermo ◽  
Lyn Watson

As we enter an era of global mass extinctions, it is important to tackle wildlife research and conservation from multiple fronts, including those made available by wildlife organisations, zoos and sanctuaries. Captive studies are particularly useful when studying free-ranging populations is difficult, and/or when controlled conditions are required. Yet, despite the significant role that they play in supporting research and conservation of species and ecosystems, they are rarely recognised in the scientific literature. Here we present a case study of the Australian Dingo Foundation (ADF), a private organisation and captive breeding facility that actively supports research and conservation efforts relating to the dingo ( Canis dingo). Over the past decade (2010 to 2020), the ADF has facilitated research across eight research disciplines that include archaeology, behaviour, biology, cognition, evolutionary psychology, non-lethal management, reproduction and parental behaviour, and vocalisations. This has resulted in at least 21 published scientific studies which are summarised in this paper. As this case study demonstrates, captive facilities have the potential to contribute to the understanding and conservation of dingoes by providing practical alternatives to, and/or supplement studies of free-ranging populations. We conclude by outlining some of the implications and limitations of conducting research using captive dingo populations.


Behaviour ◽  
2014 ◽  
Vol 151 (4) ◽  
pp. 403-419 ◽  
Author(s):  
Benjamin C. Jellen ◽  
Sean P. Graham ◽  
Robert D. Aldridge ◽  
Ryan L. Earley

Oestrogen (e.g., 17β-estradiol, E2) stimulates vitellogenesis, female sexual behaviour, and induces sex pheromone production throughout vertebrates. Therefore, the quantification of its role in any one these may prove challenging; particularly in taxa such as snakes where mating coincides with vitellogenesis. Studies examining steroid hormones in snakes are further confounded by the typical sampling interval (monthly) which is likely insufficient to observe the brief hormone fluctuations associated with an oestrus period. Thus, the relationship between oestrus and endogenous sex steroids in snakes remains equivocal. We sampled plasma E2 of 12 radio-equipped free-ranging adult female northern watersnakes (Nerodia sipedon) twice weekly during the 2008–2009 mating periods. Reproductive females experienced a large E2 surge coincident with shedding, movement, and male accompaniment indicating that endogenous E2 is involved in oestrus, a phenomenon that has previously not been documented in snakes.


1993 ◽  
Vol 41 (4) ◽  
pp. 325 ◽  
Author(s):  
AML Colagross ◽  
A Cockburn

Group formation may help animals reduce their risk of predation and allow more time for activities other than vigilance against predators. Eastern grey kangaroos, Macropus giganteus, are gregarious and form open-membership groups. Vigilance behaviour of free-ranging kangaroos was observed in relation-to number of individuals within the group, sex and reproductive status of individuals, proximity to cover and position within the group. Our data support the view that kangaroos adjust their behaviour in relation to the risk of predation. Reproductive females, individuals on the periphery of the group and individuals in groups far from cover were most vigilant. Contrary to previous reports, vigilance behaviour was not influenced by group size except through the edge effect-the tendency of the proportion of individuals on the periphery of the group to decline as group size increases.


2010 ◽  
Vol 8 ◽  
pp. 71 ◽  
Author(s):  
Tero Härkönen ◽  
Erik Isakson

The small population of harbour seals in the Baltic proper descend from seals that entered into the Baltic some 8,000 years ago. They form a genetically separate population with private alleles not present elsewhere. They were hunted close to extinction in the beginning of the 20th century and experienced a severe bottle-neck with perhaps only ten reproductive females in the 1970s. Protective measures and reduction of xenobiotic substances have improved the situation, and the hauled-out moulting population size was 588 in 2008, and about 100 pups have been born annually during the past few years. The protective measures in the form of banned hunting and establishment of protected areas will suffice to allow the population to grow, but the population will not reach favourable conservation status within foreseeable future.


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