Bradley Foster:Sonora Tiger Salamander

Sonora Tiger Salamander 

(Ambystoma tigrinum stebbinsi)

http://www.azgfd.gov/w_c/es/sonoran_tiger_salamander.shtml

http://www.azgfd.gov/w_c/es/sonoran_tiger_salamander.shtml

Description and Ecology of Organism

The Sonora tiger salamander is one of three subspecies of tiger salamanders found in Arizona. It is believed to be an endemic species and not the result of barred and Arizona tiger salamanders that were introduced by humans. They have been found in 53 ponds in the San Rafael Valley in Arizona. Young Sonora tiger salamanders will develop as either gilled aquatic adults called branchiates or as gill-less terrestrial adults known as metamorphosed Sonora tiger salamanders. Branchiate adults measure 65-165 mm and metamorphosed adults measure 45-150 mm. Breeding can begin as early as January and eggs can be found as late as May. Branchiate Sonora tiger salamanders breed in their ponds and terrestrial Sonora tiger salamanders return to the ponds to breed. Female salamanders will lay 200 to 2000 eggs which take 2-4 weeks to hatch. When larvae reach the minimum size to metamorphose they will either do so or develop as branchiates. In ponds that dry all larvae that are large enough will metamorphose while in ponds that don’t dry only about 17% that are large enough will metamorphose. Those that metamorphose have the ability to populate other ponds.

http://www.azgfd.gov/w_c/es/sonoran_tiger_salamander.shtml

Geographic and Population Changes

http://aziba.org/?page_id=550

Geographically there hasn’t been much change. Branchiate Sonora tiger salamanders stay in the ponds they were born in while terrestrial Sonora tiger salamanders stay within a few hundred meters of the pond that they were born in even though some have moved 1.5-2.0 km from that pond. Population changes are very erratic. In some years ponds will be completely empty of salamanders only to be full of them the next year.

Listing Date and Type of Listing

January 6, 1997: Federally listed as endangered with no critical habitat designated 

https://tucsonherpsociety.org/inhabitants/barred-tiger-salamander/

Cause of Listing and Main Threats to its Continued Existence (as stated in recovery plan)

1. Sonora tiger salamanders have a restricted distribution and a limited number of breeding habitats, making them vulnerable to stochastic events, such as flooding or drought. 

2. Most cienegas and standing water habitat presumably used historically by Sonora tiger salamanders for breeding have disappeared, and so today, salamanders in SRV are found almost exclusively in human-constructed cattle ponds or tanks that are small and often very dynamic habitats. 

3. Many of the salamander’s breeding ponds have been invaded by non-native fish and/or bullfrogs, which prey on salamanders and their larvae. Several salamander populations have been extirpated by fish introductions. 

4. Sonora tiger salamanders are subject to frequent die-offs as a result of disease caused by an iridovirus that kills almost all salamanders and larvae in the pond at the time. 

5. Low genetic heterozygosity for the subspecies might result in reduced fitness. 

6. Barred tiger salamanders (A. t. mavortium) have apparently been introduced to the SRV and might interbreed with Sonora tiger salamanders, swamping out characteristics that differentiate the two subspecies. 

7. Collecting Sonora tiger salamanders for bait or translocation by anglers might reduce population sizes, spread disease, and disperse non-native tiger salamanders.

Description of Recovery Plan (as summarized in recovery plan)

1. Protect and enhance salamander habitat

2. Control non-native predators (crayfish, fish and bullfrogs)

3. Control introduction, transport, and collection of tiger salamanders in San Rafael Valley

4. Develop and implement approaches to minimize frequency of die-offs

5. Monitor salamander population and their habitat

6. Conservation related research 

7. Public Education

8. Practice adaptive management in which recovery tasks are revised by USFWS in coordination with the Participation Team as pertinent new information becomes available

https://www.researchgate.net/publication/304348363_Notes_on_the_Distribution_of_Tiger_Salamanders_Presumed_Ambystoma_mavortium_stebbinsi_in_Sonora_Mexico

What Can You Do?

The Sonora Tiger Salamander is only found in a relatively small area that most people won’t be in and isn’t well known enough to have organizations that you can donate to in order to help it. If you happen to find yourself in their environment just let them be and don’t introduce fish, crawfish or bullfrogs into it.

Other Resources

http://www.azgfd.gov/w_c/es/sonoran_tiger_salamander.shtml

http://eol.org/pages/1287432/details

Sources

Collins, James P, and Jonathan Snyder. “Sonora Tiger Salamander Recovery Plan.” Oct. 2002, pp. 1–78.

“Sonoran Tiger Salamander.” Arizona Game and FIsh Department - Managing Today for Wildlife Tomorrow: Azgfd.gov, www.azgfd.gov/w_c/es/sonoran_tiger_salamander.shtml.