THREATS TO SALAMANDERS
The decline in amphibian populations has been both well-documented and well publicized. However, this attention is largely focused on frogs and toads. Little mention is given to salamanders or the threats that they face. This is unfortunate as the decline in salamander species is extremely significant. Around half of all the world’s salamander species are listed as Threatened by the International Union for Conservation of Nature (IUCN).
Therefore all of these species are all facing a high risk of extinction.
A further 62 species have been designated as Near-Threatened with populations that are dwindling. This means they are quickly getting closer to Threatened Status and to the brink of extinction.
Sadly for some salamanders it is already too late, as both the Yunnan Lake Newt (Cynops wolterstorffi) and Ainsworth's Salamander (Plethodon ainsworthi) have already gone extinct!
Even those species that are not experiencing population declines deserve attention and conservation to ensure that they remain healthy and stable. The issues that plague salamanders are not just exclusive to species found in the wild. Every year literally millions of salamanders are unwillingly forced into or reared in captive settings. Here they are subjected to many forms of abuse and cruelty.
Below is an overview of some of the threats that salamanders face.
One of the biggest issues affecting salamanders is the loss of their natural habitat. Many areas that were once suitable for salamanders to live have now been destroyed for developmental construction and agriculture. Habitats of all kinds are being lost at an alarming rate. Wetlands are drained, forests are logged and cut down, and waterfronts are developed. Salamanders are literally losing their homes and they are losing them rapidly! Deforestation is particularly harmful to salamanders. When the amount of shade that covers the forest floor is reduced due to the removal of trees, the increased sunlight can allow for higher temperatures to reach the forest floor. This increases the threat of desiccation. The exposed sunlight can also rapidly dry up vernal pools and temporary flooded areas on the forest floor which are crucial breeding/birthing sites. The expansion of urban areas threatens the suitable habitats that still remain.
Where natural habitats do still exist, they are often fragmented or degraded. Fragmentation occurs when healthy areas of habitat are isolated from one another. These fragmented areas are known as habitat islands. Salamander populations are affected since gene flow between the populations is prevented. This increases the occurance of inbreeding, which results in a decrease in genetic variability and the birthing of weaker individuals. Fragmented populations where inbreeding occurs often ends in a genetic bottleneck. This is an evolutionary event where a significant percentage of the population or species is killed or otherwise prevented from reproducing. Habitat fragmentation is also harmful because it often eliminates crucial requirements in the area which are critical to the survival of salamander populations. Such areas include spaces that can be utilized for thermoregulation, prey capture, breeding, and over-wintering. Without such habitat requirements populations dwindle. Breeding sites, often in the forms of vernal pools are particularly important. The loss of such areas in the form of habitat destruction can negatively affect the entire population and its reproductive output. According to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), there is some evidence that certain salamander species have individuals that return to the pond in which they were born once they reach maturity. Therefore, destruction of a breeding pond may result in loss of the entire population returning to that site. Habitat complexity is also important as it offers shelter to salamanders from both predators and human persecution.
Degradation occurs when the natural habitat has been altered and degraded to such a degree that it is unlikely that any remaining salamanders species would be able to survive. Developments and agriculture near fragmented habitats put salamanders at serious risk. As amphibians, salamanders have extremely absorbent skins. Industrial contaminants, the introduction of sedimentation into waterways, sewage run off, pesticides, oils, and other chemicals and toxic substances from developmental construction sites and human settlements can all be absorbed by salamanders. This can quickly lead to deaths. They can also cause widespread horrific deformities to occur. A study conducted at Purdue University found that out of 2,000 adult and juvenile salamanders 8 percent had visible deformities.
According to Save The Frogs, Atrazine (perhaps the most commonly used herbicide on the planet, with some 33 million kg being used annually in the US alone) can reduce survivorship in salamanders. Many products are sold with the claim that they are eco-friendly. However, these should be viewed with caution. For example, according to N.C Partners in Amphibian and Reptile Conservation, Roundup and many other surfactant-loaded glyphosate formulations are not labeled for aquatic use. When these formulations are applied to upland sites according to label instructions, the risk to surfactant-sensitive species is considered low. While this may be the case for fish it does not necessarily apply to amphibians. Salamanders that breed in water also routinely use non-aquatic areas and could easily be exposed to glyphosate formulations that contain harmful surfactants through direct application and not just incidental drift.
Habitat destruction and degradation can also effect the availability of prey items, causing unnatural declines in appropriate food sources.
Road Mortality (Roadkill)
Habitats are often isolated and cut off from one another by the roads and highways that now run through them. Countless numbers of salamanders are killed on roads and highways every year when they are hit by vehicles. Salamanders that are migrating to breeding and egg-laying sites often must cross over roads to reach such areas. Here many of the mature members of the breeding population are killed. Removing members of the breeding populations greatly limits reproductive output, this makes it incredibly hard for salamander numbers to rebound.
Roads present an additional problem because they represent a form of habitat loss. The roads that run through natural areas also fragment the existing populations, drastically making them smaller in size. This limits the gene flow and genetic diversity between the isolated populations on either side and this greatly increases the chances of extirpation. When salamanders attempt to cross roads to travel between the populations, or to critical breeding/birthing sites it greatly increases their chances of being hit and killed by vehicles.
The Wetlands Ecology and Management (2005) population projections for spotted salamander (Ambystoma maculatum) life tables imply that an annual risk of road mortality for adults of greater then 10% can lead to local population extirpation. Unfortunately, it is estimated that mortality rates can often be as high as 50 to 100%, which means populations are at extreme risk of extirpation and extinction due to road mortality. Wyman (1991) reported average mortality rates of 50.3 to 100% for hundreds of salamanders attempting to cross a paved rural road in New York State, USA. Given that this figure pertains to a rural area from over a decade ago, it is fair to assume that even higher mortality rates occur as their has been in increase in cars and roads over the years. Reducing road mortality is paramount to preserving salamander species.
Being hit and killed by vehicles is not the only threat that roads create for salamanders. Chemical run-off from vehicles contaminate roadside ditches and pools. These sites are often utilized by salamanders for breeding and birthing. According to Steven P. Brady (2012) survival in roadside pools averaged just 56%, as compared to 87% in woodland pools. Thus, an average of 36% fewer individual embryos survived to hatching in roadside versus woodland pools.
Salamanders are amphibians, and as such have a constant connection with water. Even terrestrial species must stay moist to avoid desiccation. Species also return to water to breed and lay-eggs. Unfortunately, human activities and modifications to once natural areas often causes alterations to occur in water tables, and in wetlands, ponds, and lakes. Such alterations include the drying of these areas, changes in water temperatures, the stocking of fish in ponds, and the contamination of water sources from chemical runoff from urbanized areas. The alteration of waterflows from natural areas for human usage can prevent flows that supply salamander habitats from creating important pools, ponds, and flooded areas. Any of these alterations can have catastrophic effects on salamanders and their reproductive output. The increase in human activities and recreation in natural areas and on the water affects salamanders in many negative ways. Individuals who use All-Terrain Vehicles often head off of designated trails and trample through natural areas. Here salamanders that are hiding under leaf litter and other forms of natural debris are at risk of being run-over and killed. Totally aquatic salamander species often end up being seriously injured or killed as a result of boat propellers, dredging, fishermen, and commercial fishing nets.
From an ethical point of view, most people are against animal cruelty and support efforts to minimize animal suffering and to protect species. In Saunders Comprehensive Veterinary Dictionary, animal welfare is defined as "the avoidance of abuse and exploitation of animals by humans by maintaining appropriate standards of accommodation, feeding and general care, the prevention and treatment of disease and the assurance of freedom from harassment, and unnecessary discomfort and pain.
When salamanders are subjected to cruelty by humans it is done for insignificant and trifling reasons. The usage of salamanders is not imperative to humans in anyway. Consequently then any suffering we inflict on salamanders is totally unnecessary. The only area in which salamanders are subjected to cruelty and ultimately death by humans that could be argued as necessary is when these amphibians are used as food. However, even in this instance it is not justifiable as most salamander species are far to small to provide a significant food source to humans. Secondly, in the places where salamanders are consumed their is a plethora of other food sources available, hence their are many alternatives; as such it is not crucial to consume them. The passages below highlight some of the ways in which salamanders are subjected to cruelty.
Salamanders are often captured from the wild to be sent off to the exotic pet trade. The wild-caught pet trade severely depletes already at-risk wild populations. Over 20 million wild-caught amphibians are sold every year in the U.S alone.
Salamanders are also exploited for monetary gain in other cruel ways. Firebelly Newts (genus Cynops) are sealed-up in plastic packages and sold as trinkets and keychain pets in many places across Asia. Here they are devoid of food and water and slowly die. The salamanders can survive for several weeks in the sealed keychains.
Salamanders are also captured and killed for Salamander Brandy, a beverage that actually contains a corpse of a deceased salamander in it. One of the methods in which the drink is cruelly made is to have two live salamanders tossed into a barrel of fermenting fruits and then leaving them for a month's time. After this point the mixture is then distilled.
Salamanders are also captured, killed, and consumed in certain places around the world. Species belonging to the genus Ambystoma are wild-caught for food across Mexico. Mudpuppy Salamanders (Necturus maculosus)
have turned up in food markets in Toronto, Ontario.
Both the Chinese Giant Salamander (Andrias davidianus) and Japanese Giant Salamander (Andrias japonicus) have been nearly hunted to extinction. Protective laws have been put in place to conserve Giant Salamanders, but illegal harvest still continues. In 2012 the Chinadialogue newspaper reported that among the most regularly eaten wild animals in Guangdong are Giant Salamanders.
Several species of salamanders are used as fishing bait. These include the Tiger Salamanders (genus Ambystoma)
, Mudpuppy Salamanders (genus Necturus)
, and the Dusky Salamanders (genus Desmognathus)
. Using salamanders for bait is an extremely inhumane and abusive practice as these are vertebrate animals fully capable of experiencing pain and suffering. Being forcefully stabbed with hooks inflicts extreme agony an distress upon the salamanders. Salamanders used for bait are both bred for the practice and taken directly from the wild. The majority of salamanders used for bait are wild-caught, which makes it even more barbaric; pillaging the animals from their natural habitats only then to be subjected to a painful death. This abuse of salamanders is widespread. Collins and Picco (2012) found that up to 73% of fishers used tiger salamanders as bait. According to the article Anglers Inadvertaintly Spreading Deadly Fungus (2012), in 1968 alone over 2.5 million tiger salamander larvae were sold as bait in the lower Colorado River area. That is over 2 million salamanders in one year from just one small location!
The serious amphibian diseases ranaviruses and chytrid fungus (Batrachochytrium dendrobatidis - Bd) are also being spread throughout populations and to previously healthy animals via the fishing bait trade. When infected animals are captured from the wild for this trade, and then shipped and sold in other locations they bring the diseases with them. A study conducted by James Collins, assistant director for biological sciences at the National Science Foundation (NSF) and Angela Picco of the U.S. Fish and Wildlife Service in Sacramento, found that up to 67% of anglers released tiger salamanders bought as bait into fishing waters, and 4% of bait shops put salamanders back in the wild after they were housed with infected animals. Their research also found that from March - October of 2005, 85% of Arizona bait shops sampled sold at least one ranavirus-infected tiger salamander. This is a staggering number of infected animals being introduced through this trade in just one State! In 2006, ranaviruses were detected in the tiger salamander bait trade between May and October in Arizona, New Mexico and Colorado.
Salamanders are commonly used for school dissections. In 2009 Animal welfare investigators reported that the Oakton Community College anatomy and physiology course used dozens of salamanders. These were dissected while they were still alive so students could watch their working organs before they were killed. This is a barbaric example of animal cruelty. According to the Humane Society of the United States, animals used for dissections are predominantly taken from the wild. This further contributes to the decline in salamanders. Even captive-reared species are unethical, as the animals are raised solely to be killed.
Certain salamander species are used in various Chinese medicines. The salamanders that are used for these practices are pillaged directly from the wild, which severely impacts the populations. The International Union for Conservation of Nature (IUCN) identifies harvesting for use in traditional medicines as a threat to several species of salamanders belonging to the genera Paramesotriton and Tylototriton. Other species such as the Sichuan Salamander (Batrachuperus pinchonii) and the Sword-Tailed Newt (Cynops ensicauda) are also sought after for this trade.
A fear of reptiles & amphibians is common, and salamanders may also be directly killed for this reason. The Canadian Reptile & Amphibian Conservation Network identifies persecution of herptiles as a conservation concern. According to the International Union for Conservation of Nature (IUCN), the Himalayan Salamander (Tylototriton verrucosus) is considered a bad omen and thus killed in Myanmar in certain areas. The direct persecution of an animal is among the most callous examples of cruelty.
A massive number of salamanders are being lost each year through the combination of the many threats mentioned above. This unnatural decline in salamander populations cannot rebound on its own. This is why the conservation of salamander species is required. Without assistance, many species simply cannot survive the many hazards we have created for them.
There is much about salamanders that scientists do not know. Aspects of the biology, ecology, and lifestyles of many species is a mystery. This undoubtedly means human interference is negatively affecting salamanders in ways in which we don't even know. The intricate relation between all species and the vital roles they play within eco-systems is also being altered. Such alterations can have serious consequences to not just salamanders, but many other animals as well (including humans).
Given the many threats that salamanders face, their survival now is dependent on conservation efforts. Click here
to learn what you can do to help!