Assessment of Small Mammal Demographics and Communities in Everglades National Park

Science Center Objects

The decline of mammal populations in Everglades National Park (ENP) over the last 20 years is likely to influence the ecology of the Everglades system and the likelihood of successful Everglades restoration.

Small mammals make up a large proportion of python diet

Small mammals make up a large proportion of python diet

The Science Issue and Relevance: The decline of mammal populations in Everglades National Park (ENP) over the last 20 years is likely to influence the ecology of the Everglades system and the likelihood of successful Everglades restoration. Published and unpublished accounts suggest that populations of mammals have declined in ENP. There is mounting evidence that predation by the non-native invasive Burmese python (Python molurus bivittatus) has contributed to these declines in the Greater Everglades ecosystem (GE). Recent findings by USGS scientists found that pythons were the dominant predator (77%) of released rabbits in ENP. Using marsh rabbits (Sylvilagus palustris) as a model, they found the probability of finding marsh rabbits decreased to about 0% with increased proximity to Flamingo, essentially “ground zero” for python invasion. Yet, marsh rabbit occurrence was about 100% in all wetland habitat types >120km from Flamingo. In addition to rabbits, little is known about the response of small mammals in the GE that appear to make up a large proportion of python diet, with rodents accounting for 57% of the gut contents of pythons examined from 2003-2008. Thus, it is likely that pythons are having a drastic impact on the small mammal communities in the GE.

 Methodology for Addressing the Issue: Live trapping of small mammals will be conducted within roughly 8 hectares near Rock Reef Pass and another 8 hectares at Chekika in Everglades National Park. The Rock Reef Pass study area was chosen because it was previously used in a small mammal study by USGS and university scientists. We will compare our data with existing data from the 1990s, pre-python invasion. The Chekika area is currently the area where most pythons are captured at ENP.

Future Steps: Understanding why and how mammals in the GE are declining is critical to the underlying dynamics that drive these populations. Rodents make up a large portion of the diet of pythons in the GE, but unlike other many larger mammals in the system they still appear to be prevalent throughout the landscape. Nonetheless, it is likely that the survival and reproduction of mammals are drastically changed by pythons and that small mammal communities are driven by the sensitivity or each species to python predation. The population-level data that we will collect for this study will allow us to have critical base-line data on small mammals that can be used to set management and conservation priorities for current python invasion.

 

Live trapping for small mammals

Live trapping for small mammals 

Study areas in Everglades NP and Big Cypress NP

Study areas in Everglades NP and Big Cypress NP