Deer/Panther Model: A Simulation Model for Florida Panthers and White-tailed Deer in the Everglades and Big Cypress Landscapes

ATLSS Deer/Panther model development was deferred while extensive scenario evaluations were being produced during 1998 and 1999 for the Central and Southern Florida Comprehensive Study Review (Restudy). Model development has now resumed, and efforts are ongoing to enhance the realism of the model and expand the model area to include areas to the north and west of Big Cypress National Preserve (BCNP).

The Deer/Panther model was designed to be used as a management and evaluation tool to analyze the relative effects of alternative water management scenarios on long-term population dynamics of the Florida panthers and their primary prey species, white-tailed deer. Originally conceived as one component of a group of interconnected ATLSS models and driven by an improved and expanded SFWMD Hydrology Model, the model's projected functionality has been somewhat compromised by the necessary modifications of original plans. These modifications resulted in an indefinite delay in the planned provision of expanded hydrology inputs from the District and postponement of development of a vegetation succession model. A description of the Deer/Panther model in early development was presented at the Florida Panther Conference in Ft. Myers in November 1994 (Comiskey et al. 1997).

A management decision made as part of ongoing panther recovery efforts has also impacted model development. Eight females of the closely related Texas subspecies (Puma concolor stanleyana) were introduced into South Florida population (Puma concolor coryi) in 1995 to enhance genetic variability of the inbred Florida panthers. The habitat use patterns, interactions and significant reproductive contributions of these panthers and their offspring, now estimated to make up about half of the entire South Florida panther population, has necessitated reevaluation and reformulation of panther behavior rules for the model.

The following efforts have been undertaken to make Deer/Panther simulations more realistic and computationally efficient:

Analyses of radio telemetry data and a review of published literature about panthers in South Florida led to the realization that panther population dynamics cannot be realistically modeled within the the original ATLSS model area, restricted by availability of hydrologic inputs from the SFWMD Hydrology Model. An approach to providing an expanded model area has been developed, including the production of ATLSS High Resolution Hydrology estimates at the 500-m and 100-m scales of resolution.
The underlying habitat type map for the Deer/Panther model is provided by the Florida GAP Analysis Vegetation Map, developed by Florida Cooperative Fish and Wildlife Research Unit, University of Florida at Gainesville (U.S. Geological Survey, Biological Resources Division). A stable version of the FGAP vegetation map (Version 6.6) has recently become available, and the extensive work required to adapt this new and substantially modified version for use in Deer/Panther is near completion. The vegetation component of Deer/Panther, which provides spatial and temporal variation in available forage for the deer herd, is being modified to provide realistic levels of Type I, II, and III forage based on the FGAP Version 6.6 vegetation types, and deer and panther behaviors which are influenced by habitat type are also being modified to account for the habitat map change.
The most recent version of the evolving ATLSS landscape classes has been incorporated into Deer/Panther, dramatically reducing the run-time required for simulations. Final timings and comparisons to observational data have been deferred until incorporation of the new habitat map has been completed.
The predictive capabilities of an individual-based model are closely tied to the realism of the decision rules which determine how individual animals move across the landscape, interact with one another and respond to their environment. The definition of these rules is in turn tied to the availability and interpretation of empirical observations about these behaviors and movement patterns. The success of the genetic introgression project has changed the course of panther recovery, and contradicted and confounded published theories and opinions about panther ecology in South Florida, including ideas about habitat use, home range establishment, female fecundity, kitten survival, and dispersal patterns. F1 panthers and their offspring have been vigorous and healthy thus far, showing none of the heart and reproductive problems seen in the Florida panthers. Comparison of pre- and post-introgression monitoring data provides many insights into panther habitat use and relative fecundity, suggesting the degree to which reproductive fitness and kitten survival of Florida panthers may have been compromised by generations of inbreeding.

For example, panther literature has reflected the commonly held perception that Big Cypress south of I-75 could not sustain a breeding population of panthers because of thinning forest cover and poor soils. However, the largest population expansion over the past two years has taken place in this area. With this in mind, the telemetry data set of panther location observations (1981-1995) on which preliminary panther behavior rules for the Deer/Panther model were based has been expanded to include observations through December 1999 so that recent trends can be reflected in revised behavior rules. Observations from January--July 2000 are now available and will be incorporated as soon as data are received. The ATLSS PanTrack Tool is being used to display and analyze panther telemetry data for the purpose of redefining behavior rules for use in the Deer/Panther Model.
Work has begun on an ATLSS model of vegetation succession in South Florida, which will enhance the predictive capabilities of Deer/Panther as well other ATLSS models.

The ATLSS Deer/Panther Model and the PanTrack telemetry viewing tool were subjects of poster presentations at the Greater Everglades Ecosystem Restoration (G.E.E.R.) Science Conference held in Naples, Florida, December 11-15, 2000, hosted by The Science Coordination Team, a committee of the South Florida Ecosystem Restoration Task Force and Working Group.

Principal Deer/Panther model developer Jane Comiskey accepted a position on the USFWS Florida Panther Subteam of MERIT (Multi-Species Ecosystem Recovery Implementation Team) and has participated in the work of this committee since December 1999. The coming year is shaping up to be a pivotal one for panther monitoring and recovery. Decisions are being made about the value of monitoring data, the validity of past interpretations of accumulated data, the level of effort at which monitoring of panthers should continue, the need for multiple capture teams operating in South Florida, and the apportioning of recovery tasks among the cooperating agencies. A recent restructuring has taken place of groups directing panther recovery, and a major revision of the Florida Panther Recovery Plan is being produced by the Jacksonville office of USFWS. As part of this revision, decisions will be made about the future course of genetic introgression and about possible reintroduction of panthers into other parts of their historic range. ATLSS hopes to use the knowledge and experience accumulated over the period of Deer/Panther Model development to make useful contributions to the decision-making process.