Project Work Plan
Department of Interior USGS GE PES
Fiscal Year 2014 Study Work Plan
Study Title: Burmese pythons in the Greater Everglades: Movement, habitat use, impacts, and control tools
Current Study Start Date: 1 October, 2008
Current Study End Date: 30 September 2017, with possibility of future funding tied to progress
Location (Subregions, Counties, Park or Refuge): Southern Florida, Everglades National Park, Big Cypress National Preserve, Rookery Bay National Estuarine Research Reserve
Funding Source: GE PES
Funding History: GE PES FY2008; GE PES FY2009; GE PES FY2010; GE PES FY2011 (combined "Python impacts" with "Python movement and habitat use"); FY2012 ; FY13.
FY14 USGS Funding: GE PES
Principal Investigators: Kristen M. Hart, Robert N. Reed
USGS Project Officer: Kristen M. Hart
USGS Technical Officer: Scott Padgett
Supporting Organizations: National Park Service, University of Florida Mote Marine Lab
Associated / Linked Studies: Use of stable isotopes to examine whether Burmese are prey-switching in the core area of their range in the Everglades (Collaboration with USGS PI Amanda Demopoulos, funded from USGS Ecosystems Program); How do Burmese pythons alter mammalian communities and their ecological functions throughout the Greater Everglades ecosystem? (Collaboration with USGS PI Stephanie Romanach, funded from USGS Ecosystems Program); Burmese python population genetics (Collaboration with USGS PI Margaret Hunter, funded from USGS Ecosystems Program); Environmental DNA (eDNA) detection of the five giant constrictor snakes in Florida (Collaboration with USGS PI's Margaret Hunter, Robert Reed, Sara Oyler-McCance, funded from USGS Ecosystems Program).
Overview & Objective(s): 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 Burmese pythons exist in the United States primarily from locations within Everglades National Park (ENP), including; along the Main Park Road in the saline and freshwater glades, and mangroves, between Pay-hay-okee and Flamingo, the greater Long Pine Key area (including Hole-in-the-Donut), and the greater Shark Valley area along the Tamiami Trail (including L-67 Ext.). The non-native species has also been observed repeatedly on the eastern boundary of ENP, along canal levees, in the remote mangrove backcountry, and in Big Cypress National Preserve.
The non-native semi-aquatic python diet in southern Florida includes raccoon, rabbit, muskrat, squirrel, opossum, cotton rat, black rat, bobcat, house wren, pied-billed grebe, white ibis, limpkin, alligator and endangered Key Largo wood rat (Snow et al. 2007, Dove et al. 2011). 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.
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 Comprehensive Everglades Restoration Project (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.
The results of this project will be applied to develop a comprehensive, science-based control and containment program. The proposed project will also increase our understanding of the impacts of Burmese pythons on native fauna in DOI and surrounding lands. Dealing with established exotic species requires that we understand their movements and habitat use, status and impacts, and how to remove them. A current priority item for determining status is finding out the extent of invasion by established species. Once we know where and when the threat is occurring, we need a better understanding of how the threat may manifest itself ecologically-that is, what are the impacts of invasion? What is the ecological 'footprint' of a given (large) python? We can hypothesize that Burmese pythons compete with native snakes or affect populations of prey species; however, knowing with certainty that pythons eat wood rats, for example, better focuses eradication efforts and spurs action. A study of diet (i.e., gut content analysis, stable isotope analyses) of Burmese pythons directly addresses this issue. Further, knowing how much pythons eat through use of state-of-the-art biologging technologies (i.e., accelerometers or acceleration data loggers ADLs) allows us to forecast with more certainty predation evens and therefore impacts on native fauna.
Specific Relevance to Major Unanswered Questions and Information Needs Identified:
- The proposed project responds to needs stated in the 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).
- In January of 2008 a workshop on setting priorities for python-related research was convened. A high priority item identified for python control by participants was "Integrating Science and Management - Improving Our Understanding of the Current Range and Status of Burmese Python Snakes." In 2010 we held another workshop, with partners specifically identified for their expertise with birds and small mammals, the primary prey items of Burmese pythons in the Everglades. At the 2010 workshop, this topic identifying at-risk populations of protected species vulnerable to predation and determining extent of risk to vulnerable native fauna were designated as important tasks to be accomplished. Most recently, in November 2013, we held an inter-agency, multi-day workshop on python science, specifically to convey scientific information to managers.
- All activities in this project link directly to a previously-funded (NPS) proposal (divided into seven research Tasks, completed across 3-yrs (FY11-13). The seven NPS Tasks were:
- Task 1: Institutional strengthening and specimen/data management
- Task 2: Assessing python impacts to native wildlife
- Task 3: Relative abundance and monitoring
- Task 4: Refining visual surveys
- Task 5: Assess areal efficacy of python control along levees
- Task 6: Assess python genetics
- Task 7: Construct ACUC-compliant python holding facility
Some of the GE PES FY12 and 13 funds were budgeted to complement these specific Tasks. For example, Task 2, in order to be successful, required additional funding than those provided through NPS funding. As well, Task 1 involved completion of a custom database; we used funding from FY13 GE PES to support Lafayette, LA USGS programmer time (under direction of Craig Conzelman) to customize this database.
Status: We are drawing on the collective knowledge gained by our USGS colleagues R. Reed and G. Rodda 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 et al. 2005). For example, natural history information such as diet, thermal biology, 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).
Studies on movement and habitat use (e.g., from radiotelemetry) and trap development are now completed and were conducted in Everglades National Park and adjacent lands managed by the South Florida Water Management District. We are synthesizing thermal data from snakes previously implanted with thermal data loggers for a peer-reviewed publication with M. Dorcas (Davidson College), and the python diet data for another peer-reviewed publication with F. Mazzotti (University of Florida). Finally, we are characterizing Hg levels in pythons (for one manuscript), in collaboration with D. Krabbenhoft (USGS), and applying newly developed genetic primers (see Hunter and Hart 2013) to characterize python population genetics within the south Florida region, and continuing to analyze up to 500 specimens for use in a population genetic survey. We are also synthesizing information obtained in this project with other studies to evaluate risks of pythons to native fauna, and to make recommendations for further trapping programs and trap deployment strategies. FY2014 is a major write-up and synthesis year for our python work.
Publications so far resulting from GE PES investment:
Pittman SE, Hart KM, Cherkiss MS, Snow RW, Fujisaki I, Smith BJ, Mazzotti FJ, Dorcas ME (2014) Homing of Invasive Burmese Pythons in South Florida: Evidence for a map and compass sense in snakes. Biology Letters 10: http://dx.doi.org/10.1098/rsbl.2014.0040.
Hunter ME, Hart KM (2013) Rapid microsatellite marker development using next generation pyrosequencing to inform invasive Burmese python - Python molurus bivittatus - management. International Journal of Molecular Sciences 14(3):4793-4804.
Krysko KL, Hart KM, Smith BJ, Selby TH, Cherkiss MS, Coutu NT, Reichart RM, Nuñez, Mazzotti FJ, Snow RW (2012) Record length, mass, and clutch size in the Nonindigenous Burmese Python, Python bivittatus Kuhl 1820 (Squamata: Pythonidae), in Florida. IRCF Reptiles & Amphibians 19(4):267-20.
Dorcas ME, Willson JD, Reed RN, Snow RW, Rochford MR, Miller MA, Meshaka WE Jr, Andreadis PT, Mazzotti FJ, Romagosa CM, Hart KM (2012) Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park. Proceedings of the National Academy of Sciences, http://www.pnas.org/cgi/doi/10.1073/pnas.1115226109.
Hart KM, Schofield PJ, Gregoire DR (2012) Experimentally derived salinity tolerance of hatchling Burmese pythons (Python molurus bivittatus) from the Everglades, Florida (USA). Journal of Experimental Marine Biology and Ecology 413:56-59.
Reed RN, Hart KM, Rodda GH, Mazzotti FJ, Snow RW, Cherkiss MS, Rozar R, Goetz S (2011) A field test of attractant traps for invasive Burmese pythons (Python molurus bivittatus) in southern Florida. Wildlife Research 38:114-121.
Mazzotti FJ, Cherkiss MS, Hart KM, Snow S, Rochford MR, Dorcas ME, Reed R (2010) Cold-induced mortality of invasive Burmese Pythons in south Florida. Biological Invasions, doi http://dx.doi.org/10.1007/s10530-010-9797-5.
Fujisaki I, Hart KM, Mazzotti FJ, Rice, KG, Snow R, Rochford MR (2009) Risk Assessment of Potential Invasiveness of Exotic Reptiles to South Florida Based on Import Pathway. Biological Invasions, doi http://dx.doi.org/10.1007/s10530-009-9667-1.
Planned Products for FY14: We are in the process of analyzing and writing up 8 manuscripts, several of which should be in final draft form in FY2014. These manuscripts include major synthesis of python radiotelemetry data, use of "Judas" snakes to find other snakes, diet data, thermal data, genetic diversity, mercury loads, stable isotope fractionation and use of eDNA to detect pythons. We also anticipate attending several regional meetings in FY14 to present the synthesis of study results.
Title of Task: Burmese pythons in the Greater Everglades: Movement, habitat use, impacts, and control tools
Task Funding: GE PES
Task Leader: Kristen M. Hart
Task priority: High
Task Personnel: Mike Cherkiss
Task Summary and Objectives: One purpose of this project is to provide science support to evaluate impacts of pythons on native biological diversity. To evaluate the impacts of pythons on native biological diversity and development of control measures for Burmese pythons, we must monitor multiple aspects of wild python behavior, activity patterns, and thermal biology. This involves releasing captured pythons that have been implanted with tracking and biologging devices, as well as harvesting samples directly from pythons post-mortem. In addition, we will continue to determine the diet of Burmese pythons removed from Everglades National Park and other DOI lands. We will also summarize the movement and habitat-use data for publications. Further, we are investigating diet and prey-switching through the analysis of nitrogen and carbon stable isotope signatures in multiple tissue types (i.e., bone, muscle, skin) in collaboration with A. Demopoulos (SESC, Gainesville); this tool is useful for identifying the level at which pythons are feeding in the food chain, as well as the extent of variation in their diet over time, as different tissue types have differential turnover rates and thus provide a range of time scales for diet records. Thus, although new python samples are being collected in FY14, this is a year with intense (and necessary) manuscript write-up.
Work to be undertaken during the project and a description of the methods and procedures:
- We continue to examine the stomach and lower gastro-intestinal tracts of euthanized pythons. Methods involve extracting and washing the stomach and gastro-intestinal tract of each individual python with ethanol, followed by close stereoscopic examination for feathers, hair, teeth, bone fragments, claws and scales. An attempt is made to identify mammal, bird and reptile remains to lowest taxonomic level possible.
- Using radiotracking and GPS-tracking data, we are also summarizing python movements and habitat use for publication, but also developing spatially-explicit habitat suitability models (using all 5 years of radiotelemetry data for individual snakes) across DOI lands in south Florida.
- To record body temperatures and movement of free-ranging Burmese pythons, we surgically implant specialized GPS devices that record temperature and multiple locations throughout the day on a predetermined schedule. We take simultaneous measurement of environmental temperatures when we conduct python walk-ins to ensure at-large snakes are in good condition. We can also remotely download both temperature and location data in the field, allowing us to know what the snakes are doing while still at-large. This uses new technology that allows us to receive real time data and does not require removing the snake from the field to obtain.
- We are evaluating new tools and technologies (i.e., acceleration data loggers (ADLs) or accelerometers and implantable GPS devices) to determine very fine-scale python activity patterns. Such devices will allow us to explore the daily and hourly movement and activity patterns of pythons, and ultimately infer feeding rates for pythons at-large in the Everglades.
Specific Task Product(s):
Peer-reviewed manuscripts, likely to be submitted to Biological Invasions, Biotelemetry, and Ecology because of the high-impact factor and the high-profile nature of the Burmese python issue for the Greater Everglades.
Product (Mainly PEER REVIEWED MANUSCRIPTS), Delivery Date:
Refinement of python database, ongoing
Environment DNA (eDNA) detection of the five giant constrictor snakes in Florida, submitted March 1, 2014
Home range, habitat use, and movement patterns of non-native Burmese pythons in Everglades National Park, Florida, USA, in revision, to be resubmitted July 2014
Betrayal: Judas Burmese Pythons Snitch Locations of Conspecifics in Everglades National Park, in preparation, to be submitted August 2014
Analysis and manuscript on the diet of Burmese Pythons in Everglades National Park, Florida, USA, in preparation, to be submitted September 2014
Mercury loads in Everglades pythons, in preparation, to be submitted July 2014
Work to be undertaken during the project and a description of the methods and procedures:
We are continuing our collaboration with University of Florida investigator Dr. Robert McCleery, an expert on marsh rabbits. We are also utilizing some GE PES funding to support python genetic analysis under the direction of Dr. Hunter (SESC), and expert in Gainesville; she brings a unique specialty to the project such that we can employ state-of-the-art molecular tools (i.e., pyrosequencing, eDNA, metagenomics) to assess python detection throughout the Greater Everglades landscape. Finally, we are utilizing additional GE PES funding that remains to help complete the python facility at the Davie campus. Additional funds will go towards supporting southwest coast of Florida python tracking efforts led by Dr. Paul Andreatis (Denison University) to test python search protocols and begin a pilot radiotracking study near Rookery Bay National Estuarine Research Reserve. Finally, GE PES funding supports salary for Hart, Cherkiss and a full-time contractor under the direction of Hart, as well as publication costs.
Branch WR, Erasmus H (1984) Captive breeding of pythons in South Africa, including details of an interspecific hybrid (Python sebae natalensis x Python molurus bivittatus). Journal of the Herpetological Association of Africa 1984(30):1-10.
Colvin BA, Fall MW, Fitzgerald LA, Loope LL (2005) Review of Brown Treesnake problems and control programs: Report of observations and recommendations. Report to Office of Insular Affairs, Honolulu, Hawaii.
Dove CJ, Snow RW, Rochford MR, Mazzotti, FJ (2011) Birds Consumed by the Invasive Burmese Python (Python molurus bivittatus) in Everglades National Park, Florida, USA. Journal of Ornithology, 123 (1):126-131.
Lederer G (1956) Fortpflanzungsbiologie und Entwicklung von Python molurus molurus (Linné) und Python molurus bivittatus (Kühl). Die Aquarien- Und Terrarien-Zeitschrift 9:243-248.
National Research Council (2005) Re-engineering storage in the Everglades: Risks and opportunities. National Academies Press. Washington. DC.
Pope WR (1961) The giant snakes. Alfred A. Knopf, New York.
Snow RW, Brien ML, Cherkiss MS, Wilkins L, Mazzotti FJ (2007) Dietary habits of the Burmese python, Python molurus bivittatus, in Everglades National Park, Florida. Herpetological Bulletin, 101.
Wall F (1921) Ophidia Taprobanica or the Snakes of Ceylon. Govt. Printer, Colombo.