Are snake populations in widespread decline
TL;DR: The authors' results show that, of 17 snake populations from the UK, France, Italy, Nigeria and Australia, 11 have declined sharply over the same relatively short period of time with five remaining stable and one showing signs of a marginal increase.
Abstract: Long-term studies have revealed population declines in fishes, amphibians, reptiles, birds and mammals. In birds, and particularly amphibians, these declines are a global phenomenon whose causes are often unclear. Among reptiles, snakes are top predators and therefore a decline in their numbers may have serious consequences for the functioning of many ecosystems. Our results show that, of 17 snake populations (eight species) from the UK, France, Italy, Nigeria and Australia, 11 have declined sharply over the same relatively short period of time with five remaining stable and one showing signs of a marginal increase. Although the causes of these declines are currently unknown, we suspect that they are multi-faceted (such as habitat quality deterioration, prey availability), and with a common cause, e.g. global climate change, at their root.
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TL;DR: The results provide the first analysis of the global conservation status and distribution patterns of reptiles and the threats affecting them, highlighting conservation priorities and knowledge gaps which need to be addressed urgently to ensure the continued survival of the world’s reptiles.
720 citations
Cites background from "Are snake populations in widespread..."
...Recently reported local declines in snake and lizard populations (Cagle, 2008; Reading et al., 2010; Sinervo et al., 2010) suggest localised elevated extinction risks for both taxa....
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TL;DR: New findings are provided which demonstrate that O. ophiodiicola is widely distributed in eastern North America, has a broad host range, is the predominant cause of fungal skin infections in wild snakes and often causes mild infections in snakes emerging from hibernation.
Abstract: Since 2006, there has been a marked increase in the number of reports of severe and often fatal fungal skin infections in wild snakes in the eastern USA. The emerging condition, referred to as snake fungal disease (SFD), was initially documented in rattlesnakes, where the infections were believed to pose a risk to the viability of affected populations. The disease is caused by Ophidiomyces ophiodiicola , a fungus recently split from a complex of fungi long referred to as the Chrysosporium anamorph of Nannizziopsis vriesii (CANV). Here we review the current state of knowledge about O. ophiodiicola and SFD. In addition, we provide original findings which demonstrate that O. ophiodiicola is widely distributed in eastern North America, has a broad host range, is the predominant cause of fungal skin infections in wild snakes and often causes mild infections in snakes emerging from hibernation. This new information, together with what is already available in the scientific literature, advances our knowledge of the cause, pathogenesis and ecology of SFD. However, additional research is necessary to elucidate the factors driving the emergence of this disease and develop strategies to mitigate its impacts. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’.
166 citations
TL;DR: It is argued that the use of an indicator species approach needs to be better justified because it has the potential to create significant problems and attempts to quantify surrogacy relationships may reveal that the alternative of direct measurement of particular entities of environmental or conservation interest will be the best option.
Abstract: The enormity and complexity of problems like environmental degradation and biodiversity loss have led to the development of indicator species and other surrogate approaches to track changes in environments and/or in biodiversity. Under these approaches particular species or groups of species are used as proxies for other biota, particular environmental conditions, or for environmental change. The indicator species approach contrasts with a direct measurement approach in which the focus is on a single entity or a highly targeted subset of entities in a given ecosystem but no surrogacy relationships with unmeasured entities are assumed. Here, we present a broad philosophical discussion of the indicator species and direct measurement approaches because their relative advantages and disadvantages are not well understood by many researchers, resource managers and policy makers. A goal of the direct measurement approach is to demonstrate a causal relationship between key attributes of the target ecosystem system (for example, particular environmental conditions) and the entities selected for measurement. The key steps in the approach are based on the fundamental scientific principles of hypothesis testing and associated direct measurement that drive research activities, management activities and monitoring programs. The direct measurement approach is based on four critical assumptions:(1) the ‘right’ entities to measure have been selected, (2) these entities are well known, (3) there is sufficient understanding about key ecological processes and (4) the entities selected can be accurately measured. The direct measurement approach is reductionist and many elements of the biota, many biotic processes and environmental factors must be ignored because of practical considerations. The steps in applying the indicator species approach are broadly similar to the direct measurement approach, except surrogacy relationships also must be quantified between a supposed indicator species or indicator group and the factors for which it is purported to be a proxy. Such quantification needs to occur via: (1) determining the taxonomic, spatial and temporal bounds for which a surrogacy relationship does and does not hold. That is, the extent of transferability of a given surrogate such as an indicator species to other biotic groups, to landscapes, ecosystems, environmental circumstances or over time in the same location can be determined; and (2) determining the ecological mechanisms underpinning a surrogacy relationship (for example, through fundamental studies of community structure). Very few studies have rigorously addressed these two tasks, despite the extremely widespread use of the indicator species approach and similar kinds of surrogate schemes in virtually all fields of environmental, resource and conservation management. We argue that this has the potential to create significant problems; thus, the use of an indicator species approach needs to be better justified. Attempts to quantify surrogacy relationships may reveal that, in some circumstances, the alternative of direct measurement of particular entities of environmental or conservation interest will be the best option.
164 citations
Universidad del Valle de Guatemala1, University of Kansas2, United Nations University3, Rivers State University of Science and Technology4, Vietnam Academy of Science and Technology5, Oxford Brookes University6, California State University, Fullerton7, University of Cologne8, University of Lomé9, Adnan Menderes University10
TL;DR: In this article, the authors reviewed the global reptile pet trade, its impacts, and its contribution to the over-harvesting of species and populations, in light of current international law.
163 citations
Cites background from "Are snake populations in widespread..."
...Wild populations of the Gaboon viper (Bitis gabonica) have also been negatively impacted due to similar and additional threats (Reading et al., 2010)....
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TL;DR: Physical contact with animals appears to be a crucial element to improve schoolchildren's attitude for an unpopular organism, and the results support the promotion of field trips that include physical contact with wildlife over the current trend in the educational systems that promote virtual approaches.
Abstract: The general public prefers to support conservation projects that focus on a few, easily “loveable” species; consequently most of biodiversity is neglected. It is essential to redress such bias and to educate children about the value of a wide diversity of organisms, including those labeled by social bias as less appealing. Because snakes are among the most disliked animals, they are suitable candidates for such endeavor. We evaluated the impact of a single field trip on the attitudes of more than 500 schoolchildren. The participants were involved in snake catching and were allowed to manipulate nonvenomous snakes. The organizers limited their intervention to providing natural history information and carefully avoided saying that snakes should be protected. We used pre- and post-field trip questionnaires to gauge the feelings of the children. Although pre-surveys suggested that many schoolchildren like snakes a priori, their attitudes improved following field experience: almost all children declar...
92 citations
References
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01 Jan 2006
TL;DR: In this article, a recent mass extinction associated with pathogen outbreaks is tied to global warming, and the timing of losses in relation to changes in sea surface and air temperatures is analyzed.
Abstract: As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with ‘very high confidence’ (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.
1,636 citations
TL;DR: Public attitudes about the need for conservation of reptiles are probably linked to concern about amphibian declines and deformities, and counts of “officially” recognized endangered and threatened species are likely to grossly underestimate the actual number of imperiled s pecies.
Abstract: A s a group [reptiles] are nei t h er ‘good ’n or ‘b ad ,’ but ia re intere s ting and unu su a l , a l t h o u gh of m i n or i m port a n ce . If t h ey should all disappe a r, it wo u l d not make mu ch differen ce one way or the other ”( Zim and Smith 1953, p. 9 ) . Fortu n a tely, this op i n i on from the Golden Gu i de Series does not persist tod ay; most people have com e to recogn i ze the va lue of both reptiles and amph i bians as an i n tegral part of n a tu ral eco s ys tems and as heralds of envi ron m ental qu a l i ty (Gibbons and Stangel 1999). In recent ye a rs , as overa ll envi ron m ental aw a reness among the p u blic has incre a s ed , con cerns have come to inclu de intere s t in the eco l ogical state of reptile and amph i bian spec i e s t h em s elves and of t h eir habi t a t s . In c re a s ed aw a reness may s tem from bet ter edu c a ti on abo ut threats to bi od ivers i ty in gen era l , and to reptiles and amph i bians in parti c u l a r, a n d po s s i bly even from an innate attracti on to these taxa ( Kell ert and Wi l s on 1993). From the perspective of many nonscientists, the two vertebrate classes comprising reptiles and amphibians, collectively referred to as the herpetofauna, are interchangeable. For example,the Boy Scout merit badge pamphlet for herpetology was called simply Reptile Study from 1926 to 1993 (Conant 1972, Gibbons 1993), and major zoos (e.g., National Zoo in Washington, DC; Zoo Atlanta; and San Diego Zoo) use only the name “reptile” to refer to the facility that houses both amphibians and reptiles. Thus, public attitudes about the need for conservation of reptiles are probably linked to concern about amphibian declines and deformities (Alford and Richards 1999, Johnson et al. 1999, Sessions et al. 1999), which have been the subject of numerous, well-documented scientific studies. Because amphibians are distributed worldwide, but herpetologists who document amphibian declines are not, it is difficult to accurately assess what portion of amphibian populations are experiencing significant declines or have already disappeared. Furthermore, the means of determining a species’ conservation status is a rigorous and time-intensive process, and therefore counts of “officially” recognized endangered and threatened species are likely to grossly underestimate the actual number of imperiled s pecies (Ta ble 1). The worl dwi de amph i bian decl i n e probl em , as it has come to be known, has garnered significant attention not only among scientists but also in the popular media and in political circles.
1,624 citations
TL;DR: It is shown that a recent mass extinction associated with pathogen outbreaks is tied to global warming, and it is proposed that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks.
Abstract: As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with 'very high confidence' (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.
1,528 citations
TL;DR: More studies are needed to connect the suspected mechanisms underlying both classes of hypotheses with quantitative changes in amphibian population sizes and species numbers, and to identify the hypotheses and conditions under which the various causes operate alone or together.
Abstract: Reports of malformed amphibians and global amphibian declines have led to public concern, particularly because amphibians are thought to be indicator species of overall envi- ronmental health. The topic also draws scientific attention because there is no obvious, simple answer to the question of what is causing amphi- bian declines? Complex interactions of several anthropogenic factors are probably at work, and understanding amphibian declines may thus serve as a model for understanding species declines in general. While we have fewer answers than we would like, there are six leading hypotheses that we sort into two classes. For class I hypotheses, alien species, over-exploitation and land use change, we have a good understanding of the ecological mechanisms underlying declines; these causes have affected amphibian populations negatively for more than a century. However, the question remains as to whether the magnitude of these negative effects increased in the 1980s, as scientists began to notice a global decline of amphibians. Further, remedies for these problems are not simple. For class II hypotheses, global change (including UV radiation and global climate change), contaminants and emerging infectious diseases we have a poor, but improving under- standing of how each might cause declines. Class II factors involve complex and subtle mechanistic underpinnings, with probable interactions among multiple ecological and evolutionary variables. They may also interact with class I hypotheses. Suspected mechanisms associated with class II hypotheses are relatively recent, dating from at least the middle of the 20th century. Did these causes act independently or in concert with pre- existing negative forces of class I hypotheses to increase the rate of amphibian declines to a level that drew global attention? We need more studies that connect the suspected mechanisms underlying both classes of hypotheses with quantitative changes in amphibian population sizes and species numbers. An important step forward in this task is clari- fying the hypotheses and conditions under which the various causes operate alone or together.
972 citations
"Are snake populations in widespread..." refers background in this paper
...…(Pounds et al. 2006; LaDeau et al. 2007), over-exploitation (Whitehead et al. 1997) or climate change (Collins & Storfer 2003; Reading 2007), while for others, the causes remain either unclear (Kiesecker et al. 2001; Collins & Storfer 2003) or unknown (Gibbons et al. 2000; Winne et al. 2007)....
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...…et al. 2000; Feyrer et al. 2007), disease (Pounds et al. 2006; LaDeau et al. 2007), over-exploitation (Whitehead et al. 1997) or climate change (Collins & Storfer 2003; Reading 2007), while for others, the causes remain either unclear (Kiesecker et al. 2001; Collins & Storfer 2003) or unknown…...
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TL;DR: Climate-induced reductions in water depth at oviposition sites have caused high mortality of embryos by increasing their exposure to UV-B radiation and, consequently, their vulnerability to infection, indicating the role of large-scale climatic patterns involving the tropical Pacific.
Abstract: Amphibian populations have suffered widespread declines and extinctions in recent decades. Although climatic changes, increased exposure to ultraviolet-B (UV-B) radiation and increased prevalence of disease have all been implicated at particular localities, the importance of global environmental change remains unclear. Here we report that pathogen outbreaks in amphibian populations in the western USA are linked to climate-induced changes in UV-B exposure. Using long-term observational data and a field experiment, we examine patterns among interannual variability in precipitation, UV-B exposure and infection by a pathogenic oomycete, Saprolegnia ferax. Our findings indicate that climate-induced reductions in water depth at oviposition sites have caused high mortality of embryos by increasing their exposure to UV-B radiation and, consequently, their vulnerability to infection. Precipitation, and thus water depth/UV-B exposure, is strongly linked to El Nino/Southern Oscillation cycles, underscoring the role of large-scale climatic patterns involving the tropical Pacific. Elevated sea-surface temperatures in this region since the mid-1970s, which have affected the climate over much of the world, could be the precursor for pathogen-mediated amphibian declines in many regions.
718 citations
"Are snake populations in widespread..." refers background in this paper
...…(Pounds et al. 2006; LaDeau et al. 2007), over-exploitation (Whitehead et al. 1997) or climate change (Collins & Storfer 2003; Reading 2007), while for others, the causes remain either unclear (Kiesecker et al. 2001; Collins & Storfer 2003) or unknown (Gibbons et al. 2000; Winne et al. 2007)....
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...1997) or climate change (Collins & Storfer 2003; Reading 2007), while for others, the causes remain either unclear (Kiesecker et al. 2001; Collins & Storfer 2003) or unknown (Gibbons et al....
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