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Written by Rowan Caulkins
March 2022
Many different types of animals can be found everywhere in the world. There are estimated to be about 8.7 million different species in the world. These can be found in the tropical rainforests of South America like the poison dart frog and jaguar, or in one’s backyard, like the common garter snake and gray squirrel.
However, for many of these animals, their habitat is being destroyed by climate change and other types of human activity. This destruction of habitat has led to a decline in the numbers of many wild animals. Habitats such as rainforests have fallen victim to deforestation, which occurs when trees are cut down to produce paper and wood products or to make space for agriculture.
For example, the Wyoming Toad, an amphibian species once found around Mortensen Lake in Albany County, Wyoming, is an example of what can happen to an animal species in only 30 years. In the late 70s, the Wyoming Toad was reported to have been completely extinct in the wild due to disease, pests, and increased irrigation, among other things. Today, thanks to the collaboration of Wyoming's federal agencies, landowners, and the University of Wyoming, there are now around 1,500 of these toads in the wild in 2022.
In particular, red-leg disease has taken its toll on the Wyoming Toad. This health problem is just one of the common diseases found in frogs and toads. It receives its name from the redness that can be seen on the lower abdomen and legs of an infected amphibian. Anemia, lethargy, extreme weight loss, open sores on the skin/nose/toes, and fluid in the abdominal cavity are all symptoms of this disease. The disease–which may also be airborne–is thought to be caused by a bacterium that is found in contaminated water and food.
In addition, a commonly-used pesticide, Malathion, has had a damaging effect on theWyoming Toad. Malathion, used by farmers, protects crops and eradicates mosquitos. Malathion, combined with the bacterial infection that causes red-leg disease, may have been a factor in the increased mortality rate in the Wyoming Toad.
Another factor in reduced numbers of Wyoming Toads may be increased irrigation, which was introduced to the state of Wyoming in 1894 with the passing of the Carey Act. This irrigation has reduced wetlands and, therefore, has reduced access to water which amphibians need to survive. Less wetlands available means the toad habitat has been reduced. While there have been wetland habitats created by irrigation, the quality of these wetlands greatly decreases in dry years.
However, the main reason for the problems encountered by the Wyoming Toad may be a fungus known as the Chytrid Fungus, which toads cannot avoid in their natural habitat. This fungus causes an infectious disease in amphibians known as chytridiomycosis. The most common symptoms of chytridiomycosis include flaking skin and lethargy. The disease kills amphibians by preventing them from properly regulating the water and salt levels in their bodies, ultimately causing their hearts to stop.
Often the tadpoles of frogs and toads have been found to carry the disease. However, they will only be affected by chytridiomycosis after metamorphosing, a process which occurs when a frog or toad goes from being a tadpole to a froglet or toadlet. As a result, many of the toads killed by this disease have been very young.
Another amphibian facing extinction is the golden poison dart frog. For reasons much different than those of the Wyoming Toad, the golden poison dart frog is classified as an endangered species. Endangered species are a type of species that is not yet extinct, but may become extinct if changes are not made. They are similar to threatened or extinct species in the wild. The obvious difference is this: an endangered species is identified as being in more danger of extinction than a threatened species but not in as much danger as a species categorized as extinct in the wild.
Threatened species are animal species that face the risk of endangerment, but are not yet at as much risk of becoming extinct as an endangered species. A species considered extinct in the wild is a species that only exists in captivity and cannot be found anywhere in the wild.
The golden poison dart frog has been classified as an endangered species due to its dwindling numbers caused by the destruction of its habitat. These little frogs can be found within a small area of rainforest on the Pacific coast of Colombia in South America. These rainforest habitats are threatened by deforestation.
The golden poison dart frog gets its name from a deadly toxin secreted from its skin, making it a common last meal for any animal that finds itself desperate enough to take a bite. There are very few creatures immune to this poison. In fact, there is only one known predator for this little poison frog, making it one of the few creatures that has almost completely negated the danger of predators. Its only predator is the fire-bellied snake which is known for its immunity to the poison of the frog.
Its bright colors serve as a warning to predators, telling them that this little frog is not something they should have on their plate. It is lucky these creatures have such a bright warning, as the toxin only needs to be the equivalent to 2-3 grains of salt to kill an adult human.
However, this toxin is not initially present in the frogs. As the frog grows, they must dine on a selection of insects and other invertebrates to synthesize with the toxin they possess. Invertebrates are animals that don’t have or develop a spine. Creatures like bugs, spiders, and jellyfish are all examples of invertebrates.
The toxin these frogs possess is a very rare type of toxin, only found in a few birds of Papua New Guinea, four Papuan beetles, and three poisonous frogs (including the golden poison frog).
It is unclear which of the frog’s prey items provides the potent alkaloid giving them such high levels of toxicity, or whether they simply modify the toxins available to them to produce a far more effective poison, similar to other members of some of the frog family known as dendrobates.
Another animal commonly associated with deadly toxins is the snake. There are many types of snakes and there are few that actually possess venom. Only 10-15% of snake species worldwide are actually venomous.
Among the majority of snake species, there is the non-venomous Antiguan racer snake. This snake is non-venomous and in the mid-90s held the title of the rarest snake on the planet since only 50 specimens of its type still existed on the planet.
These little snakes were once common natives to the islands of Antigua and Barbuda, before they faced extinction due to the introduction of black rats and Asian mongooses. These invasive species were introduced via ships carrying European settlers and slaves in the late 15th century.
The racer snake did not have any natural predators on these islands, so the introduction of these two invasive predators was a massive change in the racer habitat. The rats, introduced by accident, would eat the eggs of the racer snakes. The mongooses were introduced to the islands of Antigua and Barbuda as a method of ridding the islands of the rats. However, mongooses are diurnal, meaning they preferred to hunt during the day, which led to these animals targeting species that the settlers didn’t intend. A few of the animals that the mongooses preyed upon were ground-nesting birds, frogs, lizards, and the Antiguan racer snake.
The diet of this variety of snake consists mostly of lizards found in the thick forests on the Antiguan and Barbudan islands. These snakes are typically ambush predators, meaning they will camouflage themselves in leaves and wait for their prey. Antiguan ground lizards are an example of prey the racer might be found eating.
Luckily for these snakes, Flora and Fauna International (FFI) has been working to eradicate the invasive species that have threatened the Antiguan racer snakes. FFI has also reintroduced these snakes to offshore islands that have no invasive predators.
A difficulty in the repopulation of these snakes is that they seem to have a low resistance to the common snake mites, which are not naturally found in Antigua. Snake mites will feed on the blood of snakes. This can lead to death, if too many mites are present. The Antiguan racer snake’s poor resistance to mites has ended some attempts at captive breeding.
The first instance of their captive breeding problem was shown in a program attempted at Jersey Zoo in 1996 when five adult racers were sent to the zoo. The female snakes managed to lay 11 eggs. Only five hatched. In the end, the program was a failure because 9 of the 10 snakes died due to the common snake mite.
Thanks to the efforts of the FFI and their partners, despite these sorts of setbacks, the population of Antiguan racer snakes increased to over 1.1 thousand in 2008. The island relocation strategy to increase repopulation is planned to be used on another island snake species as well, known as the St Lucia racer, which suffered the same fate as the Antiguan racers and is estimated to have fewer than 20 individuals in the year 2022.
These 3 animals are only a few of the thousands of animal species facing the risk of extinction. There are over 7,000 animal species that have been classified as endangered in 2022. Due to factors such as global warming, habitat loss, and invasive species introduction, the next mass extinction is estimated to occur as soon as the year 2050.
Taking action to reduce carbon emissions, purchasing goods that have been produced in a sustainable manner, and recycling waste made from materials such as plastic or cardboard could very well be the first steps to prevent such a mass extinction to occur in the next few decades.
Because every species contributes to the natural order of life, by killing them off mankind is inevitably killing themselves.
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