Meeting data needs to inform recovery, conservation and management of imperiled flatwoods salamanders
The federally listed flatwoods salamanders (Ambystoma bishopi and A. cingulatum) are at imminent risk of extinction. To inform recovery, management, and conservation efforts, we asked: (1) How much of their historic range is still occupied? (2) Have losses of breeding sites threatened the sustainability of larger metapopulations? (3) Does designated critical habitat reflect the conservation needs of each species? (4) How do we best establish assurance colonies, breeding programs, and execute reintroductions/translocations? (5) Last, while habitat is being restored, what immediate actions are crucial to maintain populations on the landscape? We addressed the first three questions by compiling locality data and calculating the average distance between neighboring breeding ponds, the total quantity of designated habitat, the size of critical habitat units (CHU), land use within each CHU, and the percentage of CHU’s located on private lands. To address questions 4 and 5 we used structured decision-making (SDM) to evaluate alternatives and make decisions regarding how best to develop assurance colonies and captive breeding programs, implement reintroductions and/or translocations, and how best to maintain extant natural populations during restoration.
We obtained locality data for 458 historical locations which, in recent years, have decreased to just 49 occupied sites (as of 2014) across the combined range for both species (an 89.3% decline in the number of known populations). The average distance between neighboring breeding sites ranged from 8.0 km prior to 1999 to 28.3 km from 2010 to present. Because individual salamanders probably do not disperse more than 1-2 km within a generation and multi-generation gene flow likely is limited to ≤ 5-10 km, loss of flatwoods salamander populations over time has possibly created severe isolation that may be a critical component of this on-going decline. There is 5.5 times more designated critical habitat area for A. cingulatum (Threatened) than there is for A. bishopi (Endangered). The median size of CHU’s for A. bishopi is significantly smaller, comprised of a significantly higher percentage of agriculture and disturbed habitat types, and predominantly located on private lands. Our preliminary analyses within the SDM framework indicated that establishing replicated, captive breeding populations in combination with reintroductions would be necessary to maximize population persistence. Moreover, maintaining the status quo of habitat management is not sufficient to increase occupancy of suitable sites. Rather, an “emergency response plan” consisting of in situ head-starting, translocations, and habitat restoration will be necessary to increase occurrence on the landscape.