USGS - science for a changing world

South Florida Information Access (SOFIA)


projects > burmese pythons in the greater everglades: movement, habitat use, impacts, and control tools > work plan

Project Work Plan

Department of the Interior USGS GE PES

Fiscal Year 2008 Study Work Plan

Project Title: Movements and Habitat Use of Burmese Pythons in the Southern Everglades
Study Start Date: 2007
Study End Date: 2010
Web Sites:
Location (Subregions, Counties, Park or Refuge): Everglades National Park and southern Everglades
Funding Source: GE PES and CESI
Other Complementary Funding Source(s): CESI
Funding History: FY07; proposed FY08
Principal Investigator(s): Kenneth G. Rice, Frank J. Mazzotti
Project Personnel: Michael Rochford
Supporting Organizations: University of Florida
Associated/Linked Projects: This project is cofunded with NPS CESI

Overview & Objective(s): The recent colonization of Everglades National Park and adjacent areas by Burmese pythons (Python molurus bivittatus) has created significant new challenges for restoration of this world-renowned ecosystem including impacts to endangered species as evidenced through the recent finding of predation by the python on the endangered Key Largo Woodrat. Not only are the hydrologic techniques traditionally applied to restoration of the Everglades insufficient for controlling this new threat, but snake management is an underdeveloped specialty that has been elaborated only for two comparatively-small terrestrial/arboreal snakes, the brown tree snake on Guam and the Habu in the Ryukyu Islands. Like the python, these snakes not only threaten human health but also seriously disrupt natural ecological processes. In the case of Guam, the snake's introduction resulted in a catastrophic loss of biodiversity. The control techniques developed for those island snakes (traps, searches, dog-aided searches, habitat modifications, prey-base control, and toxicants) may be applied to Burmese pythons in the Everglades. However, modifications to accommodate the unique wetland character of the Everglades and the suite of nontarget species present in south Florida's reptile-rich continental environment will be necessary. Other modifications are needed to optimize control effectiveness by matching control tool application to behavior, morphology, and ecology of Python molurus. For example, effective siting and spacing of traps must accommodate habitat use, size, and movement rates of the python. We propose to initiate the highest priority task outlined in a recent workshop of invasive snake management experts (July 2005–Invasive Snake/Reptiles Management and Response Workshop, West Palm Beach, Florida): Conduct strategic field studies of python life history. This is critical for restoration of the Everglades to prepython conditions. If successful, this activity will benefit not only Everglades NP, but also vulnerable conservation areas throughout southern Florida (Big Cypress National Preserve, water conservation areas), the remainder of the peninsula, and coastal southeastern U.S.

The purpose of this project is to provide science support to evaluate the impacts of pythons on native biological diversity and development of control measures for Burmese pythons. The objectives of this project are to:

  1. Determine habitat use and movements of pythons,
  2. Synthesize results on natural history of pythons in an adaptive framework to evaluate relationships between ecosystem restoration and habitat modification on control of pythons,
  3. Synthesize results on natural history of pythons to provide a preliminary assessment of the impacts of pythons on native species,
  4. Develop spatially explicit habitat suitability to evaluate Everglades restoration alternatives on the spread and establishment of pythons.

Specific Relevance to Major Unanswered Questions and Information Needs Identified: The proposed project responds to needs stated in the BAA and DOI Science Plan for research to develop effective control methods for exotic aquatic vertebrates, for research into the life history of non-native species, and to determine impacts of exotic species on native species on federally managed lands. Specific projects that could affect the ultimate distribution and abundance of pythons in southern Florida include the Combined Structural and Operational Plan (CSOP) for modified water deliveries to Everglades National Park and Decompartmentalization of Water Conservation Area 3 (Decomp).

Status: In FY07 we conducted a radiotelemetry study on a total of eight Burmese pythons within and adjacent to Everglades National Park. Three of these snakes were released 10+ kilometers from their original capture site and, as water levels rose over the summer, made large movements to return to their respective capture sites. Also, we were able to use these pythons to help us find and remove others. On one occasion we tracked an adult male and found it with at least six other pythons, including a large female. By using this strategy we were also able to discover a gravid female with 85 vitelogenic follicles. This marks a record clutch size for Python molurus bivittatus in Florida. We intend to publish a manuscript of our work and report our findings to personnel at Everglades National Park in order to provide recommendations for management.

Recent Products: In FY07, one journal manuscript was published. We also gave several presentations at Local and National Conferences.

Planned Products: We plan on submitting further manuscripts on the final results of this study to peer-reviewed journals. We will present results of our study at national and international meetings during FY08.

B. WORK PLAN
Title of Task: Relative distribution, abundance, and demographic structure of the American alligator in relation to habitat, water levels, and salinities.
Task Funding: USGS Greater Everglades Priority Ecosystems Science (GE PES)
Task Leaders: Kenneth G. Rice, Frank J. Mazzotti, and Skip Snow
Phone: 352-264-3544
FAX: 352-378-4956
Task Status (proposed or active): Active
Task priority: High
Time Frame for Task 1: FY07FY10
Task Personnel: Michael Rochford, University of Florida

Task Summary and Objectives: The Burmese python (Python molurus bivittatus), a native to southeast Asia, can reach a length greater than twenty feet (Wall 1921, Pope 1961). This python is a long lived (15–25 years) behavioral, habitat, and dietary generalist, capable of producing large clutches of eggs (8–107) (Lederer 1956, Branch and Erasmus 1984). Observations of pythons exist primarily from three locations in Everglades National Park: (1) along the Main Park Road in the saline and freshwater glades, and mangroves, between Pay-hay-okee and Flamingo, (2) the greater Long Pine Key area (including Hole-in-the-Donut), and (3) the greater Shark Valley area along the Tamiami Trail (including L-67 Ext.). They have also been observed repeatedly on the eastern boundary of ENP, along canal levees, in the remote mangrove backcountry, and in Big Cypress National Preserve. Since 1995, more than 156 Burmese pythons have been captured and removed or found dead on the road. In recent years (2003–2005) individuals of all size classes have been seen with increasing regularity in and around Everglades National Park. Measured total length for snakes recovered ranged from two feet to fourteen feet, including five hatchling sized animals recovered in the summer of 2004, and two hatchlings captured in 2005.

The non-native semiaquatic pythons’s diet in the Everglades includes raccoon, rabbit, muskrat, squirrel, opossum, cotton rat, black rat, cat (kitten), House Wren, Pied-billed Grebe, White Ibis, and Limpkin. As Python molurus is known to eat birds, and also known to frequent wading bird colonies in their native range, the proximity of python sightings to the Paurotis Pond and Tamiami West Wood Stork rookeries is troubling. The potential for pythons to eat Mangrove Fox squirrels and Cape Sable Seaside sparrows, and to compete with Indigos snakes is also of concern.

As do other non-native aquatic species, Burmese pythons present a potential threat to successful ecological restoration of the greater Everglades (NRC 2005). Pythons are now established and breeding in south Florida. Python molurus bivittatus has the potential to occupy the entire footprint of the CERP, adversely impacting valued resources across the landscape. Proposed management and control actions must include research strategies and further evaluation of potential impacts of pythons. In July of 2005, an Invasive Snake/Reptile Management and Response Workshop was convened. Workshop participants came from all over the continental U.S. and Pacific Islands and represented experience with invasive reptile management from around the world. Based on this collective experience, participants recommended strategic actions in three broad areas; (1) python control, (2) rapid response to introductions of invasive amphibians and reptiles in south Florida, and (3) public outreach and education. Initially the highest priority item identified for python control by participants was radio-tracking to determine movements and habitat use. The objectives of this task are to:

  1. Determine habitat use and movements of pythons,
  2. Synthesize results on natural history of pythons in an adaptive framework to evaluate relationships between ecosystem restoration and habitat modification on control of pythons,
  3. Synthesize results on natural history of pythons to provide a preliminary assessment of the impacts of pythons on native species,
  4. Develop spatially explicit habitat suitability to evaluate Everglades restoration alternatives on the spread and establishment of pythons.

Work to be undertaken during the proposal year and a description of the methods and procedures: The proposed study design and methods are direct results of the Invasive Snake/Reptile Management and Response Workshop (2005), and take advantage of collective knowledge gained from battling reptile invasions elsewhere, primarily brown tree snakes on Pacific Islands. Important lessons learned from these areas are that invasions have to be taken seriously, the response needs to be immediate, comprehensive and thorough, and that research is instrumental in developing effective control and containment measures (Colvin and others, 2005). For example, natural history information such as diet, movements and habitat use can be used to determine how to design, deploy, and bait traps, evaluate impacts on native species, and develop recommendations for habitat modification (e.g. clearing or mowing vegetation) and ecosystem restoration (e.g. removal of levees and re-establishment of hydrological patterns).

Based on lessons learned from brown tree snakes, the most potentially effective methods for control and containment of reptiles in natural areas include canine and visual searches, habitat modification, and trapping. Visual searches and training of a python-tracking canine are underway in Everglades National Park. We propose to conduct research on habitat use and movements, and synthesize information obtained in this project with other studies to evaluate risks of pythons to native fauna, and to make recommendations for trapping programs, habitat modification and ecosystem restoration.

Subtask 1. Determine habitat use and movements of pythons. Workshop participants unanimously agreed that research to determine effective containment and control measures was the highest priority item. The central preliminary question is the extent to which control measures can be located exclusively on berms (i.e., not dependent on costly and difficult travel in and through wetlands). For this purpose we need a better understanding of natural history and habitat use by pythons in Florida. Some information is available on diet from captured snakes (and more will be obtained), however habitat use and movements of pythons remains virtually unknown. With a couple of notable exceptions of sightings of pythons in the Everglades backcountry, most of the sightings of pythons have been along road beds, levees, or other elevated surfaces. The extent and probability of python invasion into wilderness areas of Everglades National Park must be evaluated. Control of invasion is most effective using trapping in habitats where pythons are concentrated. If all pythons visit berms and other disturbed areas then trapping should focus there. Trapping should also be concentrated during the time of year when snakes are moving (Goodyear 1994, Minton and Minton 1973). Radiotelemetry is the best method for determining habitat use and extent and timing of movements of snakes (Reinert 1993).

Using animals secured through ENP control efforts such as trapping and hand capture, 20–30 adult pythons will each be outfitted with two vhf beacon radio transmitters over a two year period. Double transmitters will be used in each python to reduce the chance of loosing the animal in the wild. Transmitters will be implanted intraperitoneally (Reinert and Cundall 1982; Weatherhead and Anderka 1984; Hardy and Greene 1999, 2000). Temperature sensors will be incorporated into the transmitter package to investigate thermal requirements of the python and the effects of thermal behavior on microhabitat selection. Pythons will initially be tracked daily and the intensity of tracking will be adjusted depending on behavior of the telemetered snakes. Twenty-four hour surveillance will be conducted at least monthly. Tracking towers and aerial tracking will be used as necessary to follow pythons. All python locations will be recorded on fine scale maps and by GPS receiver. Locations of pythons will be managed by relational database and GIS program. Habitats associated with locations will be determined through GIS mapping and inspection of locations.

Subtask 2. Synthesis of information for risk assessment. We have taken advantage of the best available scientific information and technical experience from experts to design a science support program for eradication of pythons. It is essential to continuously synthesize incoming information from experiments and monitoring and apply it to modify control and containment actions. For example, diet data from trapped pythons can be used to modify trapping procedures; data on spatial and temporal patterns will feedback into determining where and when to trap pythons. Furthermore, natural history data such as diet analysis will be used to evaluate impacts of pythons on native species and habitat and movement data will be applied to developing habitat modification recommendations such as mowing berms to reduce suitability of habitat for pythons. All python data can be used to create a spatially explicit habitat suitability model that can be used to evaluate impacts of ecosystem restoration alternatives on establishment and spread of pythons. Continuously synthesizing and integrating data into the containment and control program will provide an adaptive management approach to eradication of pythons.

Specific Task Product(s): The results of this project will be applied to develop a comprehensive, science-based control and containment program. The proposed project takes advantage of best available information to perform the highest priority research on python control and risk assessment. Within the project there will be an adaptive component that will synthesize and integrate project results as they occur and make them available to control programs. Results of this project can also be applied to risk analyses of invasion by pythons and relationship of pythons to habitat management. A spatially explicit habitat suitability model will be developed to evaluate impacts of Decomp and CSOP on suitability of existing habitat for pythons and the potential for spread and establishment in new areas.

Literature Cited:
Bayliss, P., 1987. Survey methods and monitoring within crocodile management programmes. In: Webb, G. J. W., Manolis, S. C., and Whitehead, P. J. (eds.), Wildlife Management: Crocodiles and Alligators. Chipping Norton, New South Wales: Surrey Beatty and Sons, pp. 157-175.

Leslie, A.J.,1997. The ecology and physiology of the Nile crocodile, Crocodylus niloticus, in Lake St. Lucia, Kwazulu/Natal, South Africa: Philadelphia, Pennsylvania, Drexel University, Ph.D. dissertation.

Woodward, A. R., and C. T. Moore, 1990. Statewide Alligator Surveys. Final Report: Bureau of Wildlife Research. Tallahassee, Florida: Florida Game and Freshwater Fish Commission, 24 p.

Deliverables and timelines: Reporting schedule is described below. Semiannual reports are due six months after contract initiation, and annual and final reports are due 12 months after contract start. Milestones and deliverables for each report are described below.

Year Deliverable Content/Milestones/Products
1 Semiannual Progress report
1 Annual 10–15 pythons telemetered
2 Semiannual Progress report
2 Annual 10–15 additional pythons telemetered
3 Semiannual Progress report
3 Annual

Summary and analysis of telemetry data, draft habitat suitability model

4 Semiannual Progress report
4 Annual Risk analysis and evaluation of ecosystem restoration and habitat modifications

Work to be undertaken during future FYs and proposed funding: This project is cofunded by CESI and will assume level funding to FY07 (less the reduction for FY08). In future years, we hope to attain funding from USFWS and USNPS to add to the objectives of this project and move with our partners towards providing management solutions concerning the python.