Tiger Salamander
Tiger salamanders are a group of salamanders that include multiple species including Ambystoma tigrinum, Ambystoma mavoritum, and Ambystoma californiense, and Ambystoma velasci. They are all a part of the genus Ambystoma which are mole salamanders. Tiger salamanders are mainly quadrupedal and terrestrial when they are adults. As adults they can grow to be 15-20 centmeters on average with a record length of 33 centimeters.[1] The eastern tiger salamander(A. tigrium) can be distinguished by the olive or yellow markings along a black or yellow body.[1]
Range/Habitat
The eastern tiger salamander is found from southern New York to Florida along the east coast.[2] The western range is from western Ohio to Minnesota and there is a range in Texas near the gulf coast.[2] The other species of tiger salamanders can be found throughout North America except New England and the west coast[3] with the exception of the California Tiger Salamander(A. californiense) which is found mostly in the Central Valley of California with isolated populations in Santa Barbara and Sonoma.[5] Tiger salamanders as a whole spend most of their adult life on land, however they need natural fishless pools and ponds to breed.[2] The salamanders can live in grasslands, parklands, sub-alpine meadows and semi-arid regions.[4] In New York the tiger salamanders are only confirmed to exist in Long Island and they live in sandy pine barrens. The salamanders live in sandy or friable soils and need the burrows of other animals to hibernated during the winter.[3]
Role in the Food Web
Adult tiger salamanders consume small vertebrates and invertebrates.[2] The larvae of the tiger salamander mainly consumes aquatic invertebrates. However, the larvae of the tiger salamander have also been observed to consume fathead minnows and various tadpoles of diffrent species of frogs and toads including species such as bullfrogs and green frogs which are noxious to fish.[3] Cannibalism has also been observed in the larvae of the salamanders. The diet of adult tiger salamanders is mostly unknown as they rarely have food in their stomachs when digested, but they have been observed to consume various insects, mollusks, and annelids. [3] Field mice may also be taken.
Tiger salamanders may fall prey to various birds such as herons and egrets, large bullfrogs, and large fish.[5] Various large aquatic invertebrates and fish will prey upon the larvae and eggs of the salamanders, but the ponds used for breeding by the salamanders would have been selected to be fish-less. If the salamander does breed in a pond with fish it will move to deeper waters to avoid the predatory fish as opposed to its favored shallows.[3]
Life Cycle
The breeding cycle of the salamanders begins as soon as there are permanent or semi-permanent ponds that have reached temperatures around 10 degrees Celsius. During breeding the male will deposit a sperm packet at the bottom of the lake and the female will pick it up with her cloaca and then lay the eggs either singly or in clusters of 100 to 5,000 depending on the size of the female and the geographic area.[4] Hatching time varies depending on temperature, but will likely take 2-3 weeks. [1] The development of the larvae normally takes 3-4 months, but depends on prey availability, temperature, and larval density. Upon exiting, the adults will spend most of their lives in burrows only leaving ti migrate or hunt during or around rainstorms.[4]
Care in Captivity
Tiger salamanders are commonly kept as pets for either recreational or educational purposes or as research subjects. Salamanders, for the most part, are not considered good pets because of how delicate they are, how hard they are to feed, and how secretive they are.[6] This doesn't apply to tiger salamanders. They will accept food from their handlers and adapt well to captivity, unlike most salamanders.[6] Many states,like Ohio and California, have laws protecting tiger salamanders, so acquiring them may be difficult or impossible legally. Most captive tiger salamanders are wild caught and will take a little while to adapt to captivity. To house a larval tiger salamander a fully aquatic setup is required with very slowly moving water.[6] When the metamorphosis is almost complete, shown by the disappearance of the tail-fin the water should barely cover the salamander and have a way to leave the water easily when the salamander is ready.[6] The larvae shouldn't be kept with more than two other larvae or with any fish.[6] As an adult they are among the easiest salamander to keep in captivity as they need at least 4 inches of soil to burrow in, a water source, and a well ventilated cover.[1] They do not require external lighting or heating. In captivity nightcrawlers and crickets are good staple foods.[6] They do not require any additional supplements such as a calcium dust for these food sources. Waxworms and baby mice make good treats, but if they are used as a staple in the salamanders diet it would lead to the salamander becoming obese.[6]
Conservation Status
Habitat loss from development is a cause for decline in tiger salamanders.[2] Migration routes and breeding ponds can be disturbed or filled in by development causing a huge decline in population.[4] The eradication of soil dwelling vertebrates can also cause the wintering homes of the salamanders as they can't burrow too well efficiently.[4] When roads intersect the migration routes the salamanders could face fatalities via cars and other vehicles.[4] Fish and bullfrogs introduced into the salamanders' breeding ponds can prey upon the amphibians and their larvae. Agricultural chemical usage may also stunt larval growth and harm the immune systems of adults.[4]
Disease heavily impacts amphibian populations world wide. Two infectious diseases are prominent in populations of tiger salamanders; Ambystoma tigrinum virus (ATV) and amphibian chytrid fungus (Batracochytridium dendrobatidis or Bd).[4] ATV likely spreads faster with greater salamander density and closer proximity. Aggressive behaviors such as nipping, biting, and cannibalism may also spread the disease.[4] ATV has been cited to be the cause of many salamander die-offs in the northern United States and Canada. Bd is a fungal infection that is more prevalent in other amphibians than tiger salamanders. Since Bd is less likely to be found in tiger salamanders, ATV is considered to be the greatest disease threat.[4]
Sources
1. Graham, Donna. “Tiger Salamander.” Tiger Salamander, South Dakota Department of Game, Fish and Parks, Division of Wildlife, 1997, www3.northern.edu/natsource/AMPHIB1/Salama1.htm.
2. “Eastern Tiger Salamander Fact Sheet.” Freshwater Wetlands Program - NYS Dept. of Environmental Conservation, New York State Department of Environmental Conservation, www.dec.ny.gov/animals/7143.html.
3. Smith, Brian E. “Conservation Assessment of the Tiger Salamander in the Black Hills National Forest, South Dakota and Wyoming.” May 2003, www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5226872.pdf.
4. Environment Canada. “Species at Risk Public Registry - COSEWIC Assessment and Status Report on the Western Tiger Salamander Ambystoma Mavortium in Canada - 2012.” COSEWIC Assessment and Status Report on the Loggerhead Sea Turtle in Canada 2010 - Species at Risk Public Registry, Committee on the Status of Endangered Wildlife in Canada. , 17 Dec. 2015, www.registrelep-sararegistry.gc.ca/default.asp?lang=En&n=413ABB1D-1.
5. Davison, Veronica, et al. “California Tiger Salamander - Amphibians and Reptiles, Endangered Species Accounts | Sacramento Fish & Wildlife Office.” Greater Sage-Grouse | Species Information, Sacramento Fish & Wildlife Office, www.fws.gov/sacramento/es_species/Accounts/Amphibians-Reptiles/ca_tiger_salamander/.
6. Clare, John. “Tiger Salamander Care Sheet.” Reptiles Magazine, www.reptilesmagazine.com/Care-Sheets/Frogs-Amphibians/Tiger-Salamander-Care-Sheet/.
Image Sources
1. https://backyardzoologist.files.wordpress.com/
2. https://www.petcoach.co/article/tiger-salamanders-ambystoma-tigrinum-species-profile-housin/
3. https://www.caudata.org/forum/showthread.php?t=48791
4. http://extension.msstate.edu/news/feature-story/2013/msu-salamander-work-has-conservation-impact