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Siroski PA, Ciocan H, Hilevski S, Larriera A. Increasing Population Status of Broad-Snouted Caiman ( Caiman latirostris) Based on Sustainable Use Strategies in a Managed Protected Area in Santa Fe, Argentina. Animals (Basel) 2024; 14:1288. [PMID: 38731292 PMCID: PMC11083647 DOI: 10.3390/ani14091288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024] Open
Abstract
People and crocodilians have engaged in interactions since the earliest human settlements. After many years of escalating non-regulated use, coupled with emerging threats such as habitat modification, environmental pollution, and the exponential growth of human populations, natural crocodilian populations have been pushed to the brink of extinction. To prevent this, various initiatives have implemented strategies to prevent local extinction. Reinforcing wild populations through reintroductions and head-starting programs has been considered the safest approach to recovering crocodilian populations. Subsequently, the concept of sustainability emerged. In the case of many historically exploited crocodilian species, it became evident that rational utilization need not adversely affect population status; on the contrary, there were clear signs of recovery when local communities were involved. In 1990, the broad-snouted caiman (Caiman latirostris) was in a critical state due to decades of poaching and the aforementioned threats. In response, the "Monitoring and restocking program of the broad-snouted caiman for management purposes", commonly known as Proyecto Yacaré, was established to study population abundance and assess the biological, ecological, and social response to this management methodology. As a result of the eggs's harvest, a proportion equivalent to or greater than what would have survived in natural conditions was released into the original habitat where the eggs were collected. The surplus was allocated for leather and meat production with a focus on economic and environmentally sustainable practices, without affecting biodiversity or threats to the managed species. The in situ work carried out by this program has been crucial for the recovery of broad-snouted caiman populations under the "incentives for conservation" system, whereby local communities receive benefits for nest identification and egg harvesting. Over time, conservation incentives have become significant contributors to regional economies. This study illustrates how C. latirostris populations increased due to the implementation of egg harvesting by local communities in a natural reserve for management purposes. This population increase was detected through continuous night monitoring and an analysis of the number of nests in the area. Currently, C. latirostris populations have transitioned from being among the most threatened to becoming one of the most abundant throughout their distribution area. Based on the analyzed information, we may affirm that the commercial value of these species is one of the most relevant aspects contributing to the sustainability of these programs, primarily due to the change in perception generated among local communities. Therefore, identifying and controlling factors affecting these programs are fundamental for the conservation of these species.
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Affiliation(s)
- Pablo Ariel Siroski
- Laboratorio de Ecología Molecular Aplicada, Instituto de Ciencias Veterinarias del Litoral, Universidad Nacional del Litoral/Consejo Nacional de Investigaciones Científicas y Técnicas, Esperanza 3080, Santa Fe, Argentina;
- Ministerio de Ambiente y Cambio Climático, Gobierno de Santa Fe, Santa Fe 3000, Santa Fe, Argentina;
| | - Hernán Ciocan
- Ministerio de Ambiente y Cambio Climático, Gobierno de Santa Fe, Santa Fe 3000, Santa Fe, Argentina;
- Laboratorio de Zoología Aplicada, Universidad Nacional del Litoral (FHUC/UNL/MAyCC), Santa Fe 3000, Santa Fe, Argentina;
| | - Samuel Hilevski
- Laboratorio de Ecología Molecular Aplicada, Instituto de Ciencias Veterinarias del Litoral, Universidad Nacional del Litoral/Consejo Nacional de Investigaciones Científicas y Técnicas, Esperanza 3080, Santa Fe, Argentina;
- Laboratorio de Zoología Aplicada, Universidad Nacional del Litoral (FHUC/UNL/MAyCC), Santa Fe 3000, Santa Fe, Argentina;
| | - Alejandro Larriera
- Laboratorio de Zoología Aplicada, Universidad Nacional del Litoral (FHUC/UNL/MAyCC), Santa Fe 3000, Santa Fe, Argentina;
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Scheelings TF, Koehler AV, Gasser RB. New records of Hepatozoon and Oswaldofilaria from saltwater crocodiles ( Crocodylus porosus) in Australia. Int J Parasitol Parasites Wildl 2024; 23:100926. [PMID: 38560660 PMCID: PMC10981083 DOI: 10.1016/j.ijppaw.2024.100926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 03/17/2024] [Accepted: 03/17/2024] [Indexed: 04/04/2024]
Abstract
Diseases affecting wild Australian saltwater crocodiles (Crocodylus porosus) are rarely reported due to the difficulty in capturing animals and obtaining samples. In this investigation, we identified two haemoparasites (Hepatozoon and a filarial nematode) in saltwater crocodiles in Darwin, Australia. Light microscopic examination identified Hepatozoon in 7/7 (100%) wild crocodiles and in 2/20 (10%) of captive ones. When genomic DNAs from these same samples were further investigated using polymerase chain reaction (PCR)-based sequencing, we detected Hepatozoon in all 27 blood samples. Using both microscopy and PCR-based sequencing, we detected a filarial worm (proposed to be Oswaldofilaria) in one of 20 captive crocodiles. The sequence data were compared with sequence data available in public databases, and phylogenetic analyses indicated that the operational taxonomic units of Hepatozoon and Oswaldofilaria discovered here in these crocodiles are likely new species. This study is the first to use molecular tools to explore haemoparasites in Australian saltwater crocodiles and highlights the importance of health investigations in poorly studied vertebrate hosts.
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Affiliation(s)
- T. Franciscus Scheelings
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Anson V. Koehler
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Robin B. Gasser
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
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3
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Utkarsha Manish Chavan, Borkar MR. Population trends of Mugger Crocodile and human-crocodile interactions along the Savitri River at Mahad, Maharashtra, India. JOURNAL OF THREATENED TAXA 2022. [DOI: 10.11609/jott.7934.14.11.22118-22132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
In this paper, we report monitoring of a resident population of Mugger Crocodile Crocodylus palustris (Lesson, 1831) along a stretch of 3.5 km of the river Savitri on the outskirts of Mahad town of Raigad District in Maharashtra, on monthly basis from 2014 to 2021. This river is increasingly becoming a sink of anthropogenic wastes emerging from adjacent settlements impacting its habitat value, and puts the reptile side by side with humans and human-wastes that could be a cause of rising incidents of crocodile mortality in the recent times here, as also reported from elsewhere. Savitri River has been a fishing ground for local indigenous communities, who also use the river bank for washing clothes and utensils, and for swimming. Such proximity between people and crocodiles creates a potential for negative interaction. This long term study monitored the Mugger population trends for the last eight years at four transect stretches along the river. Counts are suggestive of a healthy viable population of Mugger in this river currently, but a future conflict situation cannot be ruled out. Being generalist feeders, Muggers can sustain themselves on fish, and scavenge on dumped carrion and other anthropogenic organic wastes. With the exception of a few sporadic incidents of aggression by the Muggers at this location, no human casualties have been reported thus far, however, this does not rule out fatal reciprocal interactions in future and hence a few practical mitigation measures have been suggested.
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4
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Campbell MA, Udyawer V, Jardine TD, Fukuda Y, Kopf RK, Bunn SE, Campbell HA. Dietary shifts may underpin the recovery of a large carnivore population. Biol Lett 2022; 18:20210676. [PMID: 35472283 PMCID: PMC9042529 DOI: 10.1098/rsbl.2021.0676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Supporting the recovery of large carnivores is a popular yet challenging endeavour. Estuarine crocodiles in Australia are a large carnivore conservation success story, with the population having extensively recovered from past heavy exploitation. Here, we explored if dietary changes had accompanied this large population recovery by comparing the isotopes δ13C and δ15N in bones of crocodiles sampled 40 to 55 years ago (small population) with bones from contemporary individuals (large population). We found that δ13C and δ15N values were significantly lower in contemporary crocodiles than in the historical cohort, inferring a shift in prey preference away from marine and into terrestrial food webs. We propose that an increase in intraspecific competition within the recovering crocodile population, alongside an increased abundance of feral ungulates occupying the floodplains, may have resulted in the crocodile population shifting to feed predominantly upon terrestrial food sources. The number of feral pigs consumed to sustain and grow crocodile biomass may help suppress pig population growth and increase the flow of terrestrially derived nutrients into aquatic ecosystems. The study highlights the significance of prey availability in contributing to large carnivore population recovery.
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Affiliation(s)
- Mariana A Campbell
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
| | - Vinay Udyawer
- Australian Institute of Marine Science, Darwin, NT, Australia
| | - Timothy D Jardine
- School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK, Canada.,Australian Rivers Institute, Griffith University, Nathan, QLD, Australia
| | - Yusuke Fukuda
- Department of Environment, Parks and Water Security, Darwin, NT, Australia
| | - R Keller Kopf
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
| | - Stuart E Bunn
- Australian Rivers Institute, Griffith University, Nathan, QLD, Australia
| | - Hamish A Campbell
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
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5
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Fukuda Y, McDonald PJ, Crase B. Lost to the Sea: Predicted Climate Change Threats to Saltwater Crocodile Nesting Habitat. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.839423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Climate change is predicted to have devastating impacts on apex predators such as eliminating their required habitats. Crocodilians are no exception as most species require freshwater for nesting, and such freshwater habitats are particularly vulnerable to saltwater inundation (SWI) caused by the sea level rise (SLR) from global warming. Here, we examined the impacts of climate change on saltwater crocodiles Crocodylus porosus in terms of the potential loss of nesting habitat in the Northern Territory, Australia; an area that contains the world’s most extensive nesting habitat for the species. Our spatial model, derived from 730 nest locations and selected environmental features, estimated a total of 32,306.91 km2 of current suitable habitat across the study region. The most important variable was distance to perennial lakes (71.0% contribution, 87.5% permutation importance), which is negatively correlated with nesting habitat suitability. We found that projected changes in temperature and rainfall by 2100 could impact the area of suitable nesting habitat negatively or positively (0.33% decrease under low future emission climate scenario, and 32.30% increase under high emission scenario). Nevertheless, this can be canceled by the strong negative impact of SLR and concomitant SWI on nesting areas. A portion (16.40%) of the modeled suitable habitat for a subsection of our study area, the Kakadu Region, were already subject to > 0.25 m SWI in 2013. The suitable area for nesting in this region is predicted to be further reduced to 1775.70 km2 with 1.1 m SLR predicted for 2100, representing 49.81% loss between 2013 and 2100. Although the estimates of habitat loss do not account for the potential creation of new habitat, nor for the uncertainty in the degree of future SLR, our results suggest that SLR driven by continuing global warming can be the major threat to mound-nest-building crocodilians including C. porosus, rather than direct impacts from changes in temperature and rainfall. The degree of impact on saltwater crocodiles will be determined by the interplay between the loss of nesting habitat, which would appear inevitable under current global warming, and the ability to expand into new areas created by the expansion of the tropics.
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6
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Iijima M, Qiao Y, Lin W, Peng Y, Yoneda M, Liu J. An intermediate crocodylian linking two extant gharials from the Bronze Age of China and its human-induced extinction. Proc Biol Sci 2022; 289:20220085. [PMID: 35259993 PMCID: PMC8905159 DOI: 10.1098/rspb.2022.0085] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A solid phylogenetic framework is the basis of biological studies, yet higher level relationships are still unresolved in some major vertebrate lineages. One such group is Crocodylia, where the branching pattern of three major families (Alligatoridae, Crocodylidae and Gavialidae) has been disputed over decades due to the uncertain relationship of two slender-snouted lineages, gavialines and tomistomines. Here, we report a bizarre crocodylian from the Bronze Age of China, which shows a mosaic of gavialine and tomistomine features across the skeleton, rendering support to their sister taxon relationship as molecular works have consistently postulated. Gavialine characters of the new Chinese crocodylian include a novel configuration of the pterygoid bulla, a vocal structure known in mature male Indian gharials. Extinct gavialines have repeatedly evolved potentially male-only acoustic apparatus of various shapes, illuminating the deep history of sexual selection on acoustic signalling in a slender-snouted group of crocodylians. Lastly, a cutmark analysis combined with accelerator mass spectrometry (AMS) radiocarbon dating of bone remains demonstrated that two individuals from Shang and Zhou dynasties in Guangdong, China, suffered head injuries and decapitation. Archaeological evidence together with historical accounts suggests the human-induced extinction of this unique crocodylian only a few hundred years ago.
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Affiliation(s)
- Masaya Iijima
- School of Resource and Environmental Engineering, Hefei University of Technology, 193 Tunxi Road, Baohe, Hefei, Anhui 230009, People's Republic of China,Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA,Nagoya University Museum, Furocho, Chikusa-Ku, Nagoya, Aichi 464-8601, Japan
| | - Yu Qiao
- School of Resource and Environmental Engineering, Hefei University of Technology, 193 Tunxi Road, Baohe, Hefei, Anhui 230009, People's Republic of China
| | - Wenbin Lin
- Xinhui Museum, 12 Gongyuan Road, Xinhui, Jiangmen, Guangdong 529199, People's Republic of China
| | - Youjie Peng
- Shunde Museum, Bishui Road, Shunde, Foshan, Guangdong 528300, People's Republic of China
| | - Minoru Yoneda
- The University Museum, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
| | - Jun Liu
- School of Resource and Environmental Engineering, Hefei University of Technology, 193 Tunxi Road, Baohe, Hefei, Anhui 230009, People's Republic of China
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7
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Fukuda Y, Moritz C, Jang N, Webb G, Campbell H, Christian K, Lindner G, Banks S. Environmental resistance and habitat quality influence dispersal of the saltwater crocodile. Mol Ecol 2021; 31:1076-1092. [PMID: 34865283 PMCID: PMC9299799 DOI: 10.1111/mec.16310] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 11/15/2021] [Accepted: 11/22/2021] [Indexed: 11/29/2022]
Abstract
Landscape genetics commonly focuses on the effects of environmental resistance on animal dispersal patterns, but there is an emerging focus on testing environmental effects on emigration and settlement choices. In this study, we used landscape genetics approaches to quantify dispersal patterns in the world's largest crocodilian, the saltwater crocodile (Crocodylus porosus), and demonstrated environmental influences on three processes that comprise dispersal: emigration, movement and settlement. We found that both environmental resistance and properties of the source and destination catchments (proportion of breeding habitat) were important factors influencing observed dispersal events. Our habitat quality variables related to hypotheses about resource competition and represented the ratio of breeding habitat (which limits carrying capacity), suggesting that competition for habitat influences emigration and settlement choices, together with the strong effect of environmental resistance to movement (where high-quality habitat was associated with greatest environmental permeability). Approximately 42% of crocodiles were migrants from populations other than their sampling locations and some outstandingly productive populations had a much higher proportion of emigration rather than immigration. The distance most commonly travelled between source and destination was 150-200 km although a few travelled much longer distances, up to 600-700 km. Given the extensive dispersal range, individual catchments or hydrographic regions that combine two or three adjacent catchments are an appropriate scale for population management.
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Affiliation(s)
- Yusuke Fukuda
- Research School of Biology and Center for Biodiversity Analysis, The Australian National University, Canberra, ACT, Australia.,Department of Environment, Parks and Water Security, Northern Territory Government, Darwin, Northern Territory, Australia
| | - Craig Moritz
- Research School of Biology and Center for Biodiversity Analysis, The Australian National University, Canberra, ACT, Australia
| | - Namchul Jang
- Namchul Photography, Palmerston, Northern Territory, Australia
| | - Grahame Webb
- Wildlife Management International Pty Ltd, Darwin, Northern Territory, Australia
| | - Hamish Campbell
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and the Environment, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Keith Christian
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and the Environment, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Garry Lindner
- Parks Australia, Australian Government, Jabiru, Northern Territory, Australia
| | - Sam Banks
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and the Environment, Charles Darwin University, Darwin, Northern Territory, Australia
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8
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Booth H, Arias M, Brittain S, Challender DWS, Khanyari M, Kuiper T, Li Y, Olmedo A, Oyanedel R, Pienkowski T, Milner-Gulland EJ. “Saving Lives, Protecting Livelihoods, and Safeguarding Nature”: Risk-Based Wildlife Trade Policy for Sustainable Development Outcomes Post-COVID-19. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.639216] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The COVID-19 pandemic has caused huge loss of life, and immense social and economic harm. Wildlife trade has become central to discourse on COVID-19, zoonotic pandemics, and related policy responses, which must focus on “saving lives, protecting livelihoods, and safeguarding nature.” Proposed policy responses have included extreme measures such as banning all use and trade of wildlife, or blanket measures for entire Classes. However, different trades pose varying degrees of risk for zoonotic pandemics, while some trades also play critical roles in delivering other key aspects of sustainable development, particularly related to poverty and hunger alleviation, decent work, responsible consumption and production, and life on land and below water. Here we describe how wildlife trade contributes to the UN Sustainable Development Goals (SDGs) in diverse ways, with synergies and trade-offs within and between the SDGs. In doing so, we show that prohibitions could result in severe trade-offs against some SDGs, with limited benefits for public health via pandemic prevention. This complexity necessitates context-specific policies, with multi-sector decision-making that goes beyond simple top-down solutions. We encourage decision-makers to adopt a risk-based approach to wildlife trade policy post-COVID-19, with policies formulated via participatory, evidence-based approaches, which explicitly acknowledge uncertainty, complexity, and conflicting values across different components of the SDGs. This should help to ensure that future use and trade of wildlife is safe, environmentally sustainable and socially just.
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9
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Duncan RP, Dexter N, Wayne A, Hone J. Eruptive dynamics are common in managed mammal populations. Ecology 2020; 101:e03175. [DOI: 10.1002/ecy.3175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 11/06/2022]
Affiliation(s)
- Richard P. Duncan
- Institute for Applied Ecology University of Canberra Canberra Australian Capital Territory2601Australia
| | - Nick Dexter
- Booderee National ParkParks Australia Village Road Jervis Bay Jervis Bay Territory2540Australia
| | - Adrian Wayne
- Department of Biodiversity, Conservation and Attractions Locked Bag 2 Manjimup Western Australia6258Australia
| | - Jim Hone
- Institute for Applied Ecology University of Canberra Canberra Australian Capital Territory2601Australia
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10
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Roe D, Dickman A, Kock R, Milner-Gulland EJ, Rihoy E, 't Sas-Rolfes M. Beyond banning wildlife trade: COVID-19, conservation and development. WORLD DEVELOPMENT 2020; 136:105121. [PMID: 32834392 PMCID: PMC7388857 DOI: 10.1016/j.worlddev.2020.105121] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
One of the immediate responses to COVID-19 has been a call to ban wildlife trade given the suspected origin of the pandemic in a Chinese market selling and butchering wild animals. There is clearly an urgent need to tackle wildlife trade that is illegal, unsustainable or carries major risks to human health, biodiversity conservation or meeting acceptable animal welfare standards. However, some of the suggested actions in these calls go far beyond tackling these risks and have the potential to undermine human rights, damage conservation incentives and harm sustainable development. There are a number of reasons for this concerns. First calls for bans on wildlife markets often include calls for bans on wet markets, but the two are not the same thing, and wet markets can be a critical underpinning of informal food systems. Second, wildlife trade generates essential resources for the world's most vulnerable people, contributing to food security for millions of people, particularly in developing countries. Third, wildlife trade bans have conservation risks including driving trade underground, making it even harder to regulate, and encouraging further livestock production. Fourth, in many cases, sustainable wildlife trade can provide key incentives for local people to actively protect species and the habitat they depend on, leading to population recoveries. Most importantly, a singular focus on wildlife trade overlooks the key driver of the emergence of infectious diseases: habitat destruction, largely driven by agricultural expansion and deforestation, and industrial livestock production. We suggest that the COVID-19 crisis provides a unique opportunity for a paradigm shift both in our global food system and also in our approach to conservation. We make specific suggestions as to what this entails, but the overriding principle is that local people must be at the heart of such policy shifts.
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Affiliation(s)
- Dilys Roe
- International Institute for Environment and Development (IIED) and IUCN Sustainable Use and Livelihoods Specialist Group (SULi), United Kingdom
| | - Amy Dickman
- Wildlife Conservation Research Unit (WildCRU), University of Oxford, United Kingdom
| | - Richard Kock
- Royal Veterinary College, London and IUCN Wildlife Health Specialist Group, United Kingdom
| | | | | | - Michael 't Sas-Rolfes
- Oxford Martin Programme on Illegal Wildlife Trade and School of Geography and the Environment, University of Oxford, United Kingdom
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11
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Porras Murillo LP, Cambronero EM. Analysis of the Interactions Between Humans and Crocodiles in Costa Rica. SOUTH AMERICAN JOURNAL OF HERPETOLOGY 2020. [DOI: 10.2994/sajh-d-18-00076.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Laura Patricia Porras Murillo
- Instituto Internacional en Conservación y Manejo de Vida Silvestre, Universidad Nacional, Costa Rica. Apartado Postal 1350-3000, Heredia, Costa Rica
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12
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Wang X, Zhao L, Wang RW, Fang SG. Mate success affects sex ratio strategies in structured population. Ecol Modell 2020. [DOI: 10.1016/j.ecolmodel.2020.109104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Zhao L, Fang LM, Wan QH, Fang SG. Male density, a signal for population self-regulation in Alligator sinensis. Proc Biol Sci 2020; 286:20190191. [PMID: 30966994 PMCID: PMC6501674 DOI: 10.1098/rspb.2019.0191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The regulation of population density is suggested to be indirect and occurs with a time-lag effect, as well as being female centred. Herein, we present a quantitative analysis on the precise, timely and male-dominated self-regulation of Chinese alligator (Alligator sinensis) populations. Analysis of 31 years of data revealed gender differences in regulation patterns. Population dynamics were restricted by male density rather than population density, and population growth was halted (birth rate = 0) when male density exceeded 83.14 individuals per hectare, until some males were removed, especially adult males. This rapid and accurate response supports the notions of intrinsic mechanisms and population-wide regulation response. Furthermore, density stress affected mating success rather than parental care to juveniles, i.e. females avoided unnecessary reproduction costs, which may represent an evolutionary advantage. Our findings highlighted the importance of further studies on related physiological mechanisms that focus on four characteristics: quantity breeds quality, gender differences, male density thresholds and nonlinearity.
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Affiliation(s)
- Lan Zhao
- 1 MOE Key Laboratory of Biosystems Homeostasis and Protection, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University , Hangzhou 310058 , People's Republic of China
| | - Li-Ming Fang
- 2 Changxing Chinese Alligator Nature Reserve , Changxing 313100 , People's Republic of China
| | - Qiu-Hong Wan
- 1 MOE Key Laboratory of Biosystems Homeostasis and Protection, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University , Hangzhou 310058 , People's Republic of China
| | - Sheng-Guo Fang
- 1 MOE Key Laboratory of Biosystems Homeostasis and Protection, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University , Hangzhou 310058 , People's Republic of China
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14
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Somaweera R, Nifong J, Rosenblatt A, Brien ML, Combrink X, Elsey RM, Grigg G, Magnusson WE, Mazzotti FJ, Pearcy A, Platt SG, Shirley MH, Tellez M, Ploeg J, Webb G, Whitaker R, Webber BL. The ecological importance of crocodylians: towards evidence‐based justification for their conservation. Biol Rev Camb Philos Soc 2020; 95:936-959. [DOI: 10.1111/brv.12594] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 02/20/2020] [Accepted: 02/25/2020] [Indexed: 12/27/2022]
Affiliation(s)
- Ruchira Somaweera
- CSIRO Health and Biosecurity Floreat WA 6014 Australia
- School of Biological Sciences, University of Western Australia Crawley WA 6009 Australia
| | - James Nifong
- IFAS‐Fort Lauderdale Research & Education Center, University of Florida Fort Lauderdale FL 33314 USA
| | - Adam Rosenblatt
- University of North Florida 1 UNF Drive, Jacksonville FL 32224 USA
| | - Mathew L. Brien
- Queensland Parks and WildlifeDepartment of Environment and Science Cairns QLD 4870 Australia
| | - Xander Combrink
- Department of Nature ConservationTshwane University of Technology Pretoria South Africa
| | - Ruth M. Elsey
- Louisiana Department of Wildlife and Fisheries Rockefeller Wildlife Refuge Grand Chenier LA 70643 USA
| | - Gordon Grigg
- School of Biological SciencesUniversity of Queensland St Lucia QLD 4072 Australia
| | - William E. Magnusson
- Coordenação da Biodiversidade, Instituto Nacional da Pesquisas da Amazônia Manaus 69067 Brazil
| | - Frank J. Mazzotti
- Department of Wildlife Ecology and ConservationEverglades Research and Education Center, University of Florida Gainesville FL 32603 USA
| | - Ashley Pearcy
- Section for Ecoinformatics and Biodiversity, Department of BioScienceAarhus University Aarhus Denmark
| | - Steven G. Platt
- Wildlife Conservation Society ‐ Myanmar Program Yangon Myanmar
| | - Matthew H. Shirley
- Tropical Conservation InstituteFlorida International University Miami FL 33181 USA
| | | | - Jan Ploeg
- Australian National Centre for Ocean Resources and Security, Innovation Campus, University of Wollongong Wollongong NSW 2522 Australia
| | - Grahame Webb
- Wildlife Management International Karama NT 0812 Australia
- Research Institute for the Environment and Livelihoods, Charles Darwin University Casuarina NT 0810 Australia
| | - Rom Whitaker
- The Madras Crocodile Bank Trust & Centre for Herpetology Mahabalipuram 603104 India
| | - Bruce L. Webber
- CSIRO Health and Biosecurity Floreat WA 6014 Australia
- School of Biological Sciences, University of Western Australia Crawley WA 6009 Australia
- Western Australian Biodiversity Science Institute Perth WA 6000 Australia
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15
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Fukuda Y, Webb G, Manolis C, Lindner G, Banks S. Translocation, genetic structure and homing ability confirm geographic barriers disrupt saltwater crocodile movement and dispersal. PLoS One 2019; 14:e0205862. [PMID: 31461452 PMCID: PMC6713319 DOI: 10.1371/journal.pone.0205862] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 05/21/2019] [Indexed: 11/18/2022] Open
Abstract
Translocated saltwater crocodiles (Crocodylus porosus) in the Northern Territory (NT) of Australia often return to their original capture sites, which complicates management interventions aimed at reducing human-crocodile conflict. We examined the spatial events implicated in this homing ability, using ARGOS satellite tracking devices. Five large male C. porosus (3.03 m to 4.02 m TL) were shifted and released 100-320 km from their capture sites, and 3 additional ones (3.67 m to 4.23 m TL) were released at their site of capture as controls. Translocated crocodiles were more mobile than the controls, and moved at sea in the direction of their original capture site. However, they were unable or unwilling to swim around a geographic structure, Cobourg Peninsula, which prevented homing being achieved in all five cases. Two control crocodiles remained near their capture sites, but one, after the first year, made a 900km journey for six months, before returning to its original capture and release site. Genetic analysis of tissue samples from nests across the NT coast demonstrated significant genetic structure across the coast, and confirmed that Cobourg Peninsula contributes to genetic differentiation among populations along the NT coast. These results provide new insights into C. porosus movements, which have management significance for the maintenance of public safety.
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Affiliation(s)
- Yusuke Fukuda
- Department of Environment and Natural Resources, Northern Territory Government, Palmerston, Northern Territory, Australia
- Research School of Biology, Australian National University, Acton, Australian Capital Territory, Australia
- * E-mail:
| | - Grahame Webb
- Wildlife Management International Pty. Limited, Karama, Northern Territory, Australia
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and the Environment, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Charlie Manolis
- Wildlife Management International Pty. Limited, Karama, Northern Territory, Australia
| | - Garry Lindner
- Parks Australia, Australian Government, Jabiru, Northern Territory, Australia
| | - Sam Banks
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and the Environment, Charles Darwin University, Darwin, Northern Territory, Australia
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Oommen MA, Cooney R, Ramesh M, Archer M, Brockington D, Buscher B, Fletcher R, Natusch DJD, Vanak AT, Webb G, Shanker K. The fatal flaws of compassionate conservation. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2019; 33:784-787. [PMID: 30977162 DOI: 10.1111/cobi.13329] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/06/2019] [Indexed: 06/09/2023]
Affiliation(s)
- Meera Anna Oommen
- Dakshin Foundation, 1818, 5th Main, 9th Cross, Sahakar Nagar C Block, Bengaluru, 560092, India
| | - Rosie Cooney
- IUCN CEESP/SSC Sustainable Use and Livelihoods Specialist Group, c/ Rue Mauverney 28, 1196, Gland, Switzerland
- Fenner School of Environment and Society, Australian National University, 0200, ACT, Australia
| | - Madhuri Ramesh
- Dakshin Foundation, 1818, 5th Main, 9th Cross, Sahakar Nagar C Block, Bengaluru, 560092, India
| | - Michael Archer
- PANGEA Research Center, School of Biological, Earth & Environmental Sciences, University of New South Wales Sydney, NSW, 2052, Australia
| | - Daniel Brockington
- Sheffield Institute for International Development, University of Sheffield, Sheffield, South Yorkshire, S10 2TN, U.K
| | - Bram Buscher
- Sociology of Development and Change, Wageningen University, De Leeuwenborch, Hollandseweg 1, 6707, Wageningen, KN, The Netherlands
- Department of Geography, Environmental Management and Energy Studies, University of Johannesburg, South Africa
- Department of Sociology and Social Anthropology, Stellenbosch University, Stellenbosch, South Africa
| | - Robert Fletcher
- Sociology of Development and Change, Wageningen University, De Leeuwenborch, Hollandseweg 1, 6707, Wageningen, KN, The Netherlands
| | - Daniel J D Natusch
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Abi T Vanak
- Centre for Biodiversity and Conservation, ATREE Royal Enclave, Sriramapura, Jakkur Post, Bengaluru, 560064, India
- School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
- DBT/Wellcome Trust India Alliance Fellow, Hyderabad, India
| | - Grahame Webb
- Wildlife Management International Pty. Limited, P.O. Box 530, Karama, NT, 0813, Australia
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, 0909, Australia
- IUCN-SSC Crocodile Specialist Group, c/ Rue Mauverney 28, 1196, Gland, Switzerland
| | - Kartik Shanker
- Dakshin Foundation, 1818, 5th Main, 9th Cross, Sahakar Nagar C Block, Bengaluru, 560092, India
- Centre for Ecological Sciences Indian Institute of Science, Bengaluru, 560012, India
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Estuarine crocodiles in a tropical coastal floodplain obtain nutrition from terrestrial prey. PLoS One 2018; 13:e0197159. [PMID: 29874276 PMCID: PMC5991389 DOI: 10.1371/journal.pone.0197159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 04/27/2018] [Indexed: 11/23/2022] Open
Abstract
The estuarine crocodile (Crocodylus porosus) is one of the largest and most widespread crocodilians in the world. Although considered an apex species, the role of the estuarine crocodile in aquatic foodwebs is poorly understood; we know what crocodiles ingest, but not what nourishes them. In this study, we used a combination of stable isotope measurements (δ13C, δ15N, and δ34S) and direct feeding observations to identify the source of nutrition of estuarine crocodiles in Kakadu National Park, Northern Australia. Our results show that most crocodiles sampled (size 850 – 4200mm, with 76% of them being > 2.5 m) consume a large variety of prey, however a large proportion of their nutrition is derived from terrestrial prey. Introduced species such as water buffaloes (Bubalus bubalis) and pigs (Sus scrofa) could contribute between 53 and 84% to the nutrition of the sampled crocodiles. The isotopic composition of large crocodiles (total length > 3 m) suggested possible increase in marine prey consumption with size (R2 = 0.30; p = 0.005). Additionally, we found crocodiles sampled in the dry season had on average higher terrestrial contributions compared to crocodiles sampled during the wet season (84.1 ± 2.4% versus 55.4 ± 7.0%). Overall, we found that terrestrial prey are important source of nutrition for many crocodiles in this region where introduced herbivorous mammals are abundant.
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Brackhane S, Webb G, Xavier FM, Gusmao M, Pechacek P. When conservation becomes dangerous: Human-Crocodile conflict in Timor-Leste. J Wildl Manage 2018. [DOI: 10.1002/jwmg.21497] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Sebastian Brackhane
- Chair of Remote Sensing and Landscape Information Systems; Faculty of Environment and Natural Resources, University of Freiburg; Tennenbacherstr. 4 79106 Freiburg Germany
| | - Grahame Webb
- Wildlife Management International; PO Box 530 Karama, NT, 0813 Australia; and Research Institute for the Environment and Livelihoods, Charles Darwin University; Darwin NT 0909 Australia
| | - Flaminio M.E. Xavier
- Ministry for Development of Housing, Planning and Environment; Biodiversity Directorate; Fomento Building, Rua Dom Aleixo Côrte-Real Mandarin Dili, Timor-Leste
| | - Marcal Gusmao
- Center for Climate Change and Biodiversity; National University of Timor-Leste, Avenida Cidade de Lisboa; Dili, Timor-Leste
| | - Peter Pechacek
- Food and Agriculture Organization of the United Nations-Sub-regional Office for Central Asia (FAO-SEC); Ivedik Cad. 55 06170 Ankara Turkey
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Cruz J, Windels SK, Thogmartin WE, Crimmins SM, Grim LH, Zuckerberg B. Managing individual nests promotes population recovery of a top predator. J Appl Ecol 2018. [DOI: 10.1111/1365-2664.13062] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Jennyffer Cruz
- Department of Forest and Wildlife Ecology University of Wisconsin – Madison Madison WI USA
| | | | - Wayne E. Thogmartin
- U.S. Geological Survey Upper Midwest Environmental Sciences Center La Crosse WI USA
| | - Shawn M. Crimmins
- College of Natural Resources University of Wisconsin – Stevens Point Stevens Point WI USA
| | | | - Benjamin Zuckerberg
- Department of Forest and Wildlife Ecology University of Wisconsin – Madison Madison WI USA
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Commercial harvests of saltwater crocodileCrocodylus porosuseggs by Indigenous people in northern Australia: lessons for long-term viability and management. ORYX 2017. [DOI: 10.1017/s0030605317000217] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
AbstractSustainable commercial use of native wildlife is an alternative economic means of land use by Indigenous people in remote rural areas. This situation applies within large tracts of land owned by Indigenous people across northern Australia. The commercial use of saltwater crocodilesCrocodylus porosusis a growing industry in Australia's Northern Territory. Although Indigenous people sell crocodile eggs and hatchlings, the majority of harvesting and incubation is done by non-indigenous people from less remote areas. One Indigenous community has been heavily involved in this industry and now manages its own harvest and incubation programme. We present a case study of this programme, which has transitioned from outside agencies managing the harvest, to complete local ownership and management. Egg harvests and incubation success rates declined by 40% following the switch to local management. Income increased, as did production costs; in particular, royalty payments made to Indigenous landowners. The declines reflect the community's motives for engaging in the industry, which have been socially rather than commercially driven, and damage to nesting habitat by feral animals. The increase in royalties reflects the need to compete with non-indigenous harvesters from outside the township, who are strictly commercially driven. Harvesting, incubation and trade in crocodile eggs and hatchlings can form a viable and sustainable enterprise for remote Indigenous communities. However, efficiency needs to be improved to fulfil the need for a reliable and dependable supply chain, and regulatory institutions should give Indigenous harvesters sufficient freedom to pursue innovative and viable livelihood options.
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Acharya KP, Khadka BK, Jnawali SR, Malla S, Bhattarai S, Wikramanayake E, Köhl M. Conservation and Population Recovery of Gharials (Gavialis gangeticus) in Nepal. HERPETOLOGICA 2017. [DOI: 10.1655/herpetologica-d-16-00048.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Krishna Prasad Acharya
- Department of National Parks and Wildlife Conservation, Ministry of Forests and Soil Conservation, Kathmandu, Nepal
| | | | | | - Sabita Malla
- World Wildlife Fund Nepal Program, Kathmandu, Nepal
| | | | | | - Michael Köhl
- University of Hamburg, World Forestry, Hamburg, Germany
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22
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Edwards GP, Webb GJ, Manolis SC, Mazanov A. Morphometric analysis of the Australian freshwater crocodile (Crocodylus johnstoni). AUST J ZOOL 2017. [DOI: 10.1071/zo16079] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We conducted a morphometric analysis of 279 Crocodylus johnstoni, using specimens from the McKinlay River (n = 265) and Arnhem Land (n = 14), to meet the management need for predicting body size of C. johnstoni from isolated body parts. The results also allow reconstruction of C. johnstoni dimensions for comparison with other crocodilian species. We detected sexual dimorphism in some body measurements from the McKinlay River, and geographic variation in the morphology of McKinlay River and Arnhem Land populations, but differences were slight. There is pronounced allometric growth in C. johnstoni in the immediate post-hatching phase, largely due to elongation of the snout after exiting the confines of the egg. We compared the size, shape and relative growth of C. johnstoni with that of other crocodilian species for which equivalent data are available, but particularly the other Australian crocodile, Crocodylus porosus. C. porosus has a proportionately longer tail and a shorter but wider snout than C. johnstoni, and we discuss possible ecological correlates of these and other differences.
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23
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Body size drives allochthony in food webs of tropical rivers. Oecologia 2016; 183:505-517. [DOI: 10.1007/s00442-016-3786-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 11/19/2016] [Indexed: 10/20/2022]
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24
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Warner JK, Combrink X, Calverley P, Champion G, Downs CT. Morphometrics, sex ratio, sexual size dimorphism, biomass, and population size of the Nile crocodile (Crocodylus niloticus) at its southern range limit in KwaZulu-Natal, South Africa. ZOOMORPHOLOGY 2016. [DOI: 10.1007/s00435-016-0325-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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25
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Stier AC, Samhouri JF, Novak M, Marshall KN, Ward EJ, Holt RD, Levin PS. Ecosystem context and historical contingency in apex predator recoveries. SCIENCE ADVANCES 2016; 2:e1501769. [PMID: 27386535 PMCID: PMC4928970 DOI: 10.1126/sciadv.1501769] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 04/30/2016] [Indexed: 05/28/2023]
Abstract
Habitat loss, overexploitation, and numerous other stressors have caused global declines in apex predators. This "trophic downgrading" has generated widespread concern because of the fundamental role that apex predators can play in ecosystem functioning, disease regulation, and biodiversity maintenance. In attempts to combat declines, managers have conducted reintroductions, imposed stricter harvest regulations, and implemented protected areas. We suggest that full recovery of viable apex predator populations is currently the exception rather than the rule. We argue that, in addition to well-known considerations, such as continued exploitation and slow life histories, there are several underappreciated factors that complicate predator recoveries. These factors include three challenges. First, a priori identification of the suite of trophic interactions, such as resource limitation and competition that will influence recovery can be difficult. Second, defining and accomplishing predator recovery in the context of a dynamic ecosystem requires an appreciation of the timing of recovery, which can determine the relative density of apex predators and other predators and therefore affect competitive outcomes. Third, successful recovery programs require designing adaptive sequences of management strategies that embrace key environmental and species interactions as they emerge. Consideration of recent research on food web modules, alternative stable states, and community assembly offer important insights for predator recovery efforts and restoration ecology more generally. Foremost among these is the importance of a social-ecological perspective in facilitating a long-lasting predator restoration while avoiding unintended consequences.
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Affiliation(s)
- Adrian C. Stier
- National Center for Ecological Analysis and Synthesis, 735 State Street, Santa Barbara, CA 93101, USA
- School of Aquatic and Fishery Sciences, University of Washington, 1122 Northeast Boat Street, Seattle, WA 98105, USA
| | - Jameal F. Samhouri
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA
| | - Mark Novak
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA
| | - Kristin N. Marshall
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA
| | - Eric J. Ward
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA
| | - Robert D. Holt
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Phillip S. Levin
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA
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26
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Population Ecology of American Crocodile (Crocodylus acutus) in Coiba National Park, Panama. J HERPETOL 2015. [DOI: 10.1670/13-193] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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27
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Fukuda Y, Tingley R, Crase B, Webb G, Saalfeld K. Long-term monitoring reveals declines in an endemic predator following invasion by an exotic prey species. Anim Conserv 2015. [DOI: 10.1111/acv.12218] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Y. Fukuda
- Northern Territory Department of Land Resource Management; Palmerston NT Australia
| | - R. Tingley
- School of BioSciences; The University of Melbourne; Melbourne VIC Australia
| | - B. Crase
- Department of Biological Sciences; National University of Singapore; Singapore
| | - G. Webb
- Wildlife Management International Pty. Limited; Sanderson NT Australia
- School of Environmental Research; Charles Darwin University; Darwin NT Australia
| | - K. Saalfeld
- Northern Territory Department of Land Resource Management; Palmerston NT Australia
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28
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Fukuda Y, Manolis C, Saalfeld K, Zuur A. Dead or Alive? Factors Affecting the Survival of Victims during Attacks by Saltwater Crocodiles (Crocodylus porosus) in Australia. PLoS One 2015; 10:e0126778. [PMID: 25961294 PMCID: PMC4427299 DOI: 10.1371/journal.pone.0126778] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 04/07/2015] [Indexed: 02/06/2023] Open
Abstract
Conflicts between humans and crocodilians are a widespread conservation challenge and the number of crocodile attacks is increasing worldwide. We identified the factors that most effectively decide whether a victim is injured or killed in a crocodile attack by fitting generalized linear models to a 42-year dataset of 87 attacks (27 fatal and 60 non-fatal) by saltwater crocodiles (Crocodylus porosus) in Australia. The models showed that the most influential factors were the difference in body mass between crocodile and victim, and the position of victim in relation to the water at the time of an attack. In-water position (for diving, swimming, and wading) had a higher risk than on-water (boating) or on-land (fishing, and hunting near the water's edge) positions. In the in-water position a 75 kg person would have a relatively high probability of survival (0.81) if attacked by a 300 cm crocodile, but the probability becomes much lower (0.17) with a 400 cm crocodile. If attacked by a crocodile larger than 450 cm, the survival probability would be extremely low (<0.05) regardless of the victim's size. These results indicate that the main cause of death during a crocodile attack is drowning and larger crocodiles can drag a victim more easily into deeper water. A higher risk associated with a larger crocodile in relation to victim's size is highlighted by children's vulnerability to fatal attacks. Since the first recently recorded fatal attack involving a child in 2006, six out of nine fatal attacks (66.7%) involved children, and the average body size of crocodiles responsible for these fatal attacks was considerably smaller (384 cm, 223 kg) than that of crocodiles that killed adults (450 cm, 324 kg) during the same period (2006-2014). These results suggest that culling programs targeting larger crocodiles may not be an effective management option to improve safety for children.
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Affiliation(s)
- Yusuke Fukuda
- Northern Territory Department of Land Resource Management, Palmerston, Northern Territory, Australia
- * E-mail:
| | - Charlie Manolis
- Wildlife Management International Pty. Limited, Karama, Northern Territory, Australia
| | - Keith Saalfeld
- Northern Territory Department of Land Resource Management, Palmerston, Northern Territory, Australia
| | - Alain Zuur
- Highland Statistics Limited, Newburgh, United Kingdom
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29
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Campbell HA, Dwyer RG, Wilson H, Irwin TR, Franklin CE. Predicting the probability of large carnivore occurrence: a strategy to promote crocodile and human coexistence. Anim Conserv 2014. [DOI: 10.1111/acv.12186] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- H. A. Campbell
- School of Biological Sciences; The University of Queensland; St. Lucia Queensland Australia
- School of Environment & Rural Science; University of New England; Armidale New South Wales Australia
| | - R. G. Dwyer
- School of Biological Sciences; The University of Queensland; St. Lucia Queensland Australia
| | - H. Wilson
- School of Biological Sciences; The University of Queensland; St. Lucia Queensland Australia
| | | | - C. E. Franklin
- School of Biological Sciences; The University of Queensland; St. Lucia Queensland Australia
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30
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Fukuda Y, Saalfeld K. Abundance of Saltwater Crocodile Hatchlings is Related to Rainfall in the Preceding Wet Season in Northern Australia. HERPETOLOGICA 2014. [DOI: 10.1655/herpetologica-d-13-00096r3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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Fukuda Y, Manolis C, Appel K. Featured article: Management of human-crocodile conflict in the Northern Territory, Australia: Review of crocodile attacks and removal of problem crocodiles. J Wildl Manage 2014. [DOI: 10.1002/jwmg.767] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yusuke Fukuda
- Northern Territory Department of Land Resource Management; P.O. Box 496 Palmerston Northern Territory 0831 Australia
| | - Charlie Manolis
- Wildlife Management International Pty. Limited; P.O. Box 530 Karama Northern Territory 0813 Australia
| | - Kristen Appel
- Parks and Wildlife Commission of the Northern Territory; P.O. Box 496 Palmerston Northern Territory 0831 Australia
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32
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Platt SG, Elsey RM, Liu H, Rainwater TR, Nifong JC, Rosenblatt AE, Heithaus MR, Mazzotti FJ. Frugivory and seed dispersal by crocodilians: an overlooked form of saurochory? J Zool (1987) 2013. [DOI: 10.1111/jzo.12052] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - R. M. Elsey
- Louisiana Department of Wildlife and Fisheries; Rockefeller Wildlife Refuge; Grand Chenier LA USA
| | - H. Liu
- Department of Earth and Environment; Florida International University; Miami FL USA
- Center for Tropical Plant Conservation; Fairchild Tropical Botanic Garden; Coral Gables FL USA
| | | | - J. C. Nifong
- Department of Biology; University of Florida; Gainesville FL USA
| | - A. E. Rosenblatt
- Department of Biological Sciences; Marine Sciences Program; Florida International University; Miami FL USA
| | - M. R. Heithaus
- School of Environment, Arts and Society; Florida International University; Miami FL USA
| | - F. J. Mazzotti
- Department of Wildlife Ecology and Conservation; Fort Lauderdale Research and Education Center; University of Florida; Davie FL USA
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Home range utilisation and long-range movement of estuarine crocodiles during the breeding and nesting season. PLoS One 2013; 8:e62127. [PMID: 23650510 PMCID: PMC3641080 DOI: 10.1371/journal.pone.0062127] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 03/19/2013] [Indexed: 11/19/2022] Open
Abstract
The estuarine crocodile (Crocodylus porosus) is the apex-predator in waterways and coastlines throughout south-east Asia and Australasia. C. porosus pose a potential risk to humans, and management strategies are implemented to control their movement and distribution. Here we used GPS-based telemetry to accurately record geographical location of adult C. porosus during the breeding and nesting season. The purpose of the study was to assess how C. porosus movement and distribution may be influenced by localised social conditions. During breeding, the females (2.92 ± 0.013 metres total length (TL), mean ± S.E., n = 4) occupied an area<1 km length of river, but to nest they travelled up to 54 km away from the breeding area. All tagged male C. porosus sustained high rates of movement (6.49 ± 0.9 km d(-1); n = 8) during the breeding and nesting period. The orientation of the daily movements differed between individuals revealing two discontinuous behavioural strategies. Five tagged male C. porosus (4.17 ± 0.14 m TL) exhibited a 'site-fidelic' strategy and moved within well-defined zones around the female home range areas. In contrast, three males (3.81 ± 0.08 m TL) exhibited 'nomadic' behaviour where they travelled continually throughout hundreds of kilometres of waterway. We argue that the 'site-fidelic' males patrolled territories around the female home ranges to maximise reproductive success, whilst the 'nomadic' males were subordinate animals that were forced to range over a far greater area in search of unguarded females. We conclude that C. porosus are highly mobile animals existing within a complex social system, and mate/con-specific interactions are likely to have a profound effect upon population density and distribution, and an individual's travel potential. We recommend that impacts on socio-spatial behaviour are considered prior to the implementation of management interventions.
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34
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Estimation of Total Length from Head Length of Saltwater Crocodiles (Crocodylus porosus) in the Northern Territory, Australia. J HERPETOL 2013. [DOI: 10.1670/11-094] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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35
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Finger Jr JW, Adams AL, Thomson PC, Shilton CM, Brown GP, Moran C, Miles LG, Glenn TC, Isberg SR. Using phytohaemagglutinin to determine immune responsiveness in saltwater crocodiles (Crocodylus porosus). AUST J ZOOL 2013. [DOI: 10.1071/zo13041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Immune responsiveness, the ability of an organism to effectively respond immunologically following antigenic exposure, is an essential component of life history, as organisms require effective immune functionality in order to grow, survive and reproduce. However, immune status is also associated with concomitant trade-offs in these physiological functions. Herein we demonstrate the validation of phytohaemagglutinin (PHA) injection in saltwater crocodiles, Crocodylus porosus, to assess cellular immune responsiveness. Following injection of 2 mg mL–1 PHA into the hind toe webbing, we observed a peak swelling response 12 h after injection, with PHA inducing increased thickness compared with webs injected with phosphate-buffered saline (PBS) (F5,518 = 145.13, P < 0.001). Subsequent injections increased responsiveness relative to the primary injection response (F5,290 = 2.92, P = 0.029), suggesting that PHA exposure induced immunological memory, a tenet of acquired immunity. Histological examination revealed that PHA-injected toe webs displayed increased numbers of leukocytes (granulocytes, macrophages, and lymphocytes) relative to PBS-injected webs, with peak leukocytic infiltrate observed 12 h after injection. We suggest the use of PHA injection in crocodilians as a measure of cellular immune responsiveness in agricultural (production and animal welfare), ecological, and toxicological contexts.
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Brien ML, Webb GJ, Lang JW, Christian KA. Intra- and interspecific agonistic behaviour in hatchling Australian freshwater crocodiles (Crocodylus johnstoni) and saltwater crocodiles (Crocodylus porosus). AUST J ZOOL 2013. [DOI: 10.1071/zo13035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We examined agonistic behaviour in hatchling Australian freshwater crocodiles (Crocodylus johnstoni) at 2 weeks, 13 weeks, and 50 weeks after hatching, and between C. johnstoni and saltwater crocodiles (Crocodylus porosus) at 40–50 weeks of age. Among C. johnstoni, agonistic interactions (15–23 s duration) were well established by two weeks old and typically involved two and occasionally three individuals, mostly between 17 : 00 and 24 : 00 hours in open-water areas of enclosures. A range of discrete postures, non-contact and contact movements are described. The head is rarely targeted in contact movements with C. johnstoni because they exhibit a unique ‘head raised high’ posture, and engage in ‘push downs’. In contrast with C. porosus of a similar age, agonistic interactions between C. johnstoni were conducted with relatively low intensity and showed limited ontogenetic change; there was also no evidence of a dominance hierarchy among hatchlings by 50 weeks of age, when the frequency of agonistic interactions was lowest. Agonistic interactions between C. johnstoni and C. porosus at 40–50 weeks of age were mostly low level, with no real exclusion or dominance observed. However, smaller individuals of both species moved slowly out of the way when a larger individual of either species approached. When medium- or high-level interspecific interactions did occur, it was between similar-sized individuals, and each displayed species-specific behaviours that appeared difficult for contestants to interpret: there was no clear winner or loser. The nature of agonistic interactions between the two species suggests that dominance may be governed more strongly by size rather than by species-specific aggressiveness.
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Wallace K, Leslie A, Coulson T. Re-evaluating the effect of harvesting regimes on Nile crocodiles using an integral projection model. J Anim Ecol 2012; 82:155-65. [PMID: 22963590 DOI: 10.1111/j.1365-2656.2012.02027.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 07/09/2012] [Indexed: 11/30/2022]
Abstract
Crocodile populations are size-structured, and for populations that are subject to harvesting, removal is typically size selective. For this reason, size-structured matrix models are typically used to analyse the dynamics of crocodile populations. The boundaries between the size classes used to classify individuals in these models are typically chosen arbitrarily. This is problematic because results can depend upon the number and width of size classes. The recent development of continuous character population models termed integral projection models (IPM) has removed the need to arbitrarily classify individuals. These models are yet to be applied to harvested animal populations. Using information obtained from the literature, we develop an IPM for crocodiles. We use perturbation analyses to investigate how altering size-specific demographic rates influences the population growth rate and the strength of selection on snout to vent length. We find that perturbations can lead to complex responses. Sensitivity analysis to population growth and fertility selection reveals that the smallest animals and the sizes of early breeding individuals and their eggs may have more influence on these population biology parameters than previously thought. Although our model is relatively simple, our results show that IPM can be used to gain theoretical insight into the possible consequences of altering size-specific demographic rates on the population and evolutionary ecology of harvested populations.
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Affiliation(s)
- Kevin Wallace
- Division of Ecology and Evolution, Imperial College London, Silwood Park, Ascot, Berkshire, SL5 7PY, UK.
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Nair T, Thorbjarnarson JB, Aust P, Krishnaswamy J. Rigorous gharial population estimation in the Chambal: implications for conservation and management of a globally threatened crocodilian. J Appl Ecol 2012. [DOI: 10.1111/j.1365-2664.2012.02189.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Patrick Aust
- Centre for Herpetology; Madras Crocodile Bank Trust; P.O. Box 4; Mamallapuram; Tamil Nadu; 603104; India
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Austin BJ, Corey B. Factors contributing to the longevity of the commercial use of crocodiles by Indigenous people in remote Northern Australia: a case study. RANGELAND JOURNAL 2012. [DOI: 10.1071/rj11082] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Access to land and resources has not, in itself, been sufficient for improving the wellbeing of Indigenous people living in remote regions of Australia. Much of the land has limited potential for mainstream market-based economic development. However, some Indigenous Australians have been able to use wildlife commercially to realise economic opportunities and to enhance their capacity to engage in natural resource management on their land. In this paper, a case study is presented of one such enterprise which has managed a crocodile egg-harvesting operation from a remote township for almost 15 years. Using a sustainable livelihoods approach to conduct field observations and semi-structured interviews, key factors were identified that had contributed to the longevity of this operation. These were minimal anti-use sentiment, demonstrably sustainable harvests, the market, the institutional context, parent-organisation support, activating and enhancing capitals and capabilities, and locally relevant enterprise activity. The crocodile egg-harvesting activity investigated is an example of a community-governed natural resource-based enterprise that has been able to engage Indigenous people in market-based economic activity in remote northern Australia. The findings have potential value to Indigenous peoples and communities, development practitioners, policy-makers and natural resource managers interested in the sustainable use of wildlife and Indigenous economic development.
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