Research Efforts at Finca de la Tortuga
There are three main areas of study that are being conducted at the Institute at this time:
- Research on Tortoise Communication and Social Behavior
- Research on the Requirements for Successful Assurance Colonies Management to Produce Stock for the Purposes of Later Relocation or Reintroduction of Highly Endangered Species
- The Biodiversity of the Preserve and the Brooksville Ridge
Gopher Tortoise Communication and Social Behaviour
The Ashton Biological Preserve supports nearly 400 gopher tortoises (Gopherus polyphemus) living on the 200-acre upland savannah. Over the past four years, we have been marking and keeping track of the history of all the tortoise burrows on the property. This gives us the best way to determine changes in the tortoise population. The population has grown considerably in this time mainly because we have been burning the property to maintain a more tortoise-friendly habitat (long leaf pine-turkey oak sandhills). This enhances tortoise food forage (which we are also studying).
The tortoise population has grown by both immigration and reproduction. We have now marked 400 tortoises and we have data on many going back well over 10 years. We have also been marking and keeping track of all the burrows on the Preserve. These on going projects have already provided us with a great deal of information that tells us that short term studies may be giving us a false impression of tortoise populations, ages, and movements of tortoises over the landscape. We will continue these studies and as we have interns or students, we will track movements using radio telemetry, and other more intensive work. Our work with foraging will continue. We have now found that tortoises are commonly using more than 150 species of plants on the Preserve, and more than 400 species of plants across their range. There is much work to be done by botanist as well as herpetologists to tell which of these are keys to go health and prosperity of a tortoise population.
Great Discovery - Tortoise Communicating in Very Low Frequency Sound
Over the years, we have noticed that tortoises seem to have some form of social structure which may be why they live in small groups or pods. Tortoises from many different directions and groups seem to be able to find food like beans growing in deer food plots all at the same time. How do they do this. Some species of tortoises like Indian Star Tortoises (Geochelone elegans) seem to be extremely social, especially females prior to the nesting season. One of our interns spent months observing this behavior and determined that in fact there appears to be a female hierarchy. We were sure that there were more methods of communication than the head bobs and squeaks we could barely hear.
In the summer of 2004, Elizabeth von Muggenthaler, President of the Fauna Communications Society, Acoustical Society of America came to the Preserve and we successfully recorded the first low frequency sound communications in tortoises. These were only preliminary findings and we hope to acquire the equipment to study tortoise communication and tie it to specific behaviors.
Biodiversity of the Preserve and Surrounding Brooksville Ridge
Since the mid 1990’s we have been collecting observation data on the presence of all vertebrates and vascular plants on the Preserve and surrounding areas. We will of course continue this work. We would like to expand this work to include invertebrates. A small collection of unusual invertebrates has been made including all the ticks we have seen thus far. We would like to expand this to including all invertebrates, especially those that have been found only on the Brooksville ridge or are thought to possibly occur here.
We have very healthy populations of Eastern Indigo Snakes (Drymarchon corias), Southern Hognose (Heterodon simus), and Florida Pine Snakes (Pituophis m. mutigus) just to name a few. Thanks to a small grant from the Pennsylvania State Museum, many individuals of these species have been tagged. We now want to set up a series of drift fences so capture of snakes is more frequent and can gather more data.
Geomys or pocket gophers may well be more of a keystone species in sandhills that the gopher tortoises. In the late 1980’s we were following small lizards, snakes and frogs in the sandhills. We (Dick Franz, Walt Timmerman and I) tagged these animals with Cobalt 60 radioactive tags so we could trace their movements. We were originally studying their ability to go around drift fences without getting caught (they do). We also found that all of the species we studied went down to the Geomys burrows and spent a great deal of time there. They in fact used these like highway tunnels. We want to study the biodiversity of the Geomys burrow. Some entomologists at Florida State University are finding a number of new species in them.
Assurance Colony Research
The definition of an assurance colony is a group of collections, which have been developed to sustain a species of chelonian over time for use in some form of conservation effort. In most cases we assume that these are highly endangered species, which may be extinct very soon in the wild or, fairly common species, which are in peril because of massive exploitation such as many species in Southeast Asia. The concept of the Assurance Colonies Collection Complex includes a mixture of collections from individual private collections, zoos, commercial, research, and collections in situ.
We are conducting studies on how to develop a collection that allows turtles and tortoises to live in conditions which allow them to establish home ranges, establish social behavior, reproduce and receive most of their nutritional requirements from natural foods. We try to provide the tortoises with appropriate habitat and provide husbandry in a way that keeps stress levels down to what one would assume would be found in nature. We do not provide prophylaxis treatments to our research animals because we feel that it is important that these animals and their offspring must have the physical and genetic tools to live with potentially pathogenic organisms. We are trying to determine how we can balance costs, space and at the same time achieve chelonians that are behaving in a nearly wild fashion.
Four years ago the Institute sponsored a worldwide round table on Chelonian Relocation and the development of Assurance Colonies. The results of that work will hopefully be published by 2005. The Institute is carrying on studies and offers Research Travel Programs to collect data on habitat and behavior of various species that are or are being considered for Chelonian Assurance Colonies. (See Travel Programs) These are colonies of chelonians that are highly endangered or that may be extinct in the wild. The colonies are established with the goal of sustaining the most fit animals and those most similar to the stock taken from the original habitat of the species. Virtually no pre-emptive medications are given, nor are diseases treated. (There are no treatments for most serious chelonian diseases.) No chlorinated water is given to the tortoises.
- Forage and Foraging Behavior
Comparing forage in original habitat of the species with that of the upland savannah habitat at the Institute. Augmenting native grasses as needed.
Comparing forage behavior (if known) in the wild with that in the semi-wild habitat and comparing that with the foraging behavior of the gopher tortoise (Gopherus polyphemus), of which there is a large native wild population on the Preserve.
Observing that the species establishes and maintains a home range, and then looking at the microhabitat used under various conditions.
Behavior during drought, growing season, winter and cold weather.
Social behavior (non-breeding) and the apparent tolerance level of contact or acceptance in home range; and competition, hierarchy or pecking order nesting competition. Sound communication (ultra and low frequency).
Breeding behavior, mate selection, male-to-male and female-to-female interactions.
Nesting sites, times, relation to weather and food availability, fecundity related to social order (if there is one), incubation (in situ and in incubator).
- Growth rates and maturity
- Health and how tortoises remain healthy through foraging and use of the environment.
Much of this work is done by our interns, who write thesis papers or prepare papers for submission to various journals.
Species that have been or are now being studied under the 3-5 year plan include the African spurred tortoise (1990-94); Indian star tortoise (1992-present); Chaco tortoise (2000-2003); radiated tortoise (2000-present); marginated tortoise (2001-present); Madagascar spider tortoise, P. a. brygooi (2002-present). This study is being carried out in conjunction with Conservation International and a major donation by Mr. and Mrs Eric Slov of multiple pairs of adult Pyxis and the ABRPI.
The Institute is a member of the Asian Turtle Consortium and cooperates with other researchers and tortoise collection managers to share information and exchange animals (F2). We also cooperate with institutions and individuals in other countries and organizations, freely sharing data and information. A common question asked of us is whether we belong to the TSA. The answer is no: For ethical reasons, of which there were many, the Institute decided to withdraw its membership in that organization. We hope to rejoin that organization when these matters have been resolved.