Size and reproductive activity of a geographically-isolated population of Ambystoma jeffersonianum in east-central Illinois

Abstract

When utilizing small isolated wetlands, amphibian populations are often small in size, susceptible to stochastic extinction processes, and have little to no contact with other populations. The persistence of such populations can be ascertained only by obtaining data that allow the prediction of the population’s growth, trajectory, and propensity to achieve a sustainable size. The success of a salamander population can be determined by the number of metamorphosing larvae leaving a pond, and thus, the number recruited into the terrestrial adult population. The Jefferson salamander, Ambystoma jeffersonianum, is a state-threatened species, occurring at fewer than 15 ponds within Illinois. In 2004 and 2005 individuals at a breeding pond in Lincoln Trail State Recreation Area (LTSRA) were captured using a drift fence-pitfall trap array. Once captured, the salamanders were sexed, measured for snout-vent length, and marked using a unique combination of toe clips. I also determined the number of egg masses, average percentage of successfully hatched eggs, and number of juveniles leaving the pond. I incorporated this information into a matrix for a stage-based population model. Model simulations predicted that on average, the population at LTSRA would persist for 4 more years, with survivorship from larvae to juvenile being the most important parameter. Increasing larval to juvenile survivorship increased abundance as well as average persistence time. I suggest that the breeding pond be excavated in order to increase hydroperiod within the pond, and thus increase time needed for successful metamorphosis.

Date of Award	2005
Original language	American English
Awarding Institution	Eastern Illinois University
Supervisor	Stephen Mullin (Supervisor)