Time filter

Source Type

Jervis Bay Village, Australia

Fukuda Y.,Environment and the Arts and Sport | Webb G.,Wildlife Management International Pty. Ltd | Webb G.,Charles Darwin University | Manolis C.,Wildlife Management International Pty. Ltd | And 4 more authors.
Journal of Wildlife Management | Year: 2011

Saltwater crocodiles (Crocodylus porosus) in the Northern Territory of Australia were protected in 1971, after a severe population decline resulting from 26 yr of intense commercial hunting. By that time wild saltwater crocodiles were rarely sighted anywhere and they were commercially extinct in areas where they had once been abundant. Standardized monitoring by spotlight surveys started in 1975 and provided relative density indices over time (1975-2009) as a unique record of the post-protection recovery of a wild crocodilian population. We examined the survey data for populations at 12 major tidal rivers, individually and as a single subpopulation. The pattern of recovery in the subpopulation in both abundance and biomass was approximated by logistic curves, predicting 5.26 non-hatchling crocodiles weighing 387.64 kg sighted per kilometer of river in 2010. We predicted potential carrying capacity as 5.58 non-hatchling crocodiles (5.73% higher than 2010) weighing 519.0 kg (25.31% higher than 2010). Individual rivers showed largely different abundance and biomass among rivers. The statistical model that best described the recovery in individual rivers was not always logistic. However, where it was logistic, expected carrying capacity of different rivers showed considerable variation in abundance and biomass. The variation indicates different habitat quality among the rivers. Recovery occurred despite various consumptive uses, particularly a widespread egg-harvest program, which has been an integral part of the incentive-driven conservation program for saltwater crocodiles in the Northern Territory since 1983. We suggest that the saltwater crocodile population of the Northern Territory is achieving full recovery from uncontrolled hunting in 1945-1971. Although saltwater crocodiles are considered an important natural resource, their increase in number, size, and distribution is posing management issues for public safety. Continuation of human-crocodile conflict management through public education and strategic removal of problem crocodiles will be essential. Copyright © 2011 The Wildlife Society. Source

Kool J.,Geoscience Australia | Appleyard S.,CSIRO | Bax N.,Institute for Marine and Antarctic Studies | Ford J.,University of Melbourne | And 7 more authors.
Bulletin of Marine Science | Year: 2015

Marine scientists and environmental managers engaged in a roundtable discussion at the Australian Marine Sciences Association conference in July 2014 to identify areas where linkages could be improved between the two groups. Here, we summarize the key themes and outcomes from the discussion, including the need to clearly define management objectives, to identify the scale of the issue, to conduct effective science communication, to address uncertainty, and to perform iterative engagement. We also discuss some of the challenges inherent in establishing new linkages, and provide a set of examples where effective collaborations have been achieved between marine ecologists and environmental managers working in Australia. © 2015 Rosenstiel School of Marine & Atmospheric Science of the University of Miami. Source

Populations of Saltwater Crocodiles (Crocodylus porosus) have been monitored in the Northern Territory since the species' protection. This monitoring relies on standardized spotlight surveys in which crocodiles are counted and classified by estimated total length (TL). Although the accurate estimation of TL is important for analyses, often crocodiles are submerged and their TL is estimated from their heads, which may be visible above the water surface. With some variation, it is generally thought that TL of a crocodile is seven times the length of the animal's head. This study examined the ratio of TL to head length (HL) from morphological measurements of 2,755 Saltwater Crocodiles caught in various locations in the Northern Territory. The results showed that the generic ratio for crocodiles ranging from 38 to 503 cm was 7.01. The ratio increased logistically from 6.7 to 7.1 for crocodiles in the 120-420-cm size range in TL in 30-cm intervals. We suggest that TL can be reliably estimated from HL at least for crocodiles in 120-420 cm in the wild, with the use of the generic and size-specific ratios calculated for the various size classes at every 30 cm. The size-specific estimation for animals <120 cm or >420 cm was not possible because of limited sample sizes in these crocodile size ranges, although a few reliable records suggest that a ratio increasingly becomes larger and 1:8 should be used for crocodiles >510 cm in TL. Copyright 2013 Society for the Study of Amphibians and Reptiles. Source

Gouramanis C.,Nanyang Technological University | De Deckker P.,Australian National University | Wilkins D.,Parks Australia | Dodson J.,Chinese Academy of Sciences
Marine and Freshwater Research | Year: 2016

Numerous saline playa lakes exist across the arid, semiarid and temperate regions of Australia. These playa lakes exhibit a diverse range of hydrological conditions to which the Australian aquatic invertebrate biota have become adapted and which the biota can utilise as refugia in times of hydrological deterioration. Saline playas also yield palaeoenvironmental records that can be used to infer lacustrine and catchment responses to environmental variability. We present a palaeoenvironmental record recovered from Two Mile Lake, a saline playa from southern Western Australia. Dating, based on quartz optical luminescence and 14C accelerator mass spectrometry of biogenic carbonates and organic fibres, suggests that most of the sediment was rapidly deposited at 4.36±0.25 thousand years ago. Ostracods and non-marine foraminifera preserved in the sediment show periods of faunal colonisation of the lake with oscillations between hypersaline and oligosaline conditions. The geochemistry of ostracod valves and foraminifera tests suggests higher-frequency variability within the lake, and palynological changes indicate landscape changes, possibly in response to fire. The Two Mile Lake record highlights the utility of saline playas as archives of environmental change that can be used to guide wetland health management, particularly under the impacts of a changing climate. Journal compilation © CSIRO 2016. Source

Woinarski J.C.Z.,Charles Darwin University | MacRae I.,Parks Australia | Flores T.,Parks Australia | Detto T.,Parks Australia | And 5 more authors.
Emu | Year: 2016

An endemic subspecies of Buff-banded Rail (Gallirallus philippensis) is restricted to the Cocos (Keeling) Islands, a group of 27 islands, with total area of ∼15km2, in the north-eastern Indian Ocean. Human settlement led to marked environmental degradation of the 26 islands in the southern atoll of the group. The Cocos Buff-banded Rail declined severely, with the last confirmed record from islands in the southern atoll in 1991. The subspecies has persisted, however, with a population of ∼800 individuals, on a single island, Pulu Keeling, 24km north of the southern atoll. A recovery plan for this endangered subspecies recommended reintroduction to a suitable island in the southern atoll. This paper provides a brief overview of the history and status of the subspecies, and describes an April 2013 reintroduction of 39 rails from Pulu Keeling to the 1-km2 Horsburgh Island in the southern atoll. This program has had at least short-term success, with monitoring showing successful recruitment in the reintroduced population, and its increase to ∼54 individuals by October 2014 and ∼121 individuals by June 2015. Much of the world's loss of biodiversity has been from, and continues to occur on, islands: this project demonstrates that well-considered mitigation of threats and translocation programs can provide solutions to this challenge. © BirdLife Australia 2016. Source

Discover hidden collaborations