Mongoose Research

Background

Two of my colleagues, Dr. Roy Horst, State University of New York College at Potsdam, and Dr. William Kilpatrick, University of Vermont, and I have been studying mongoose populations on St. Croix, U. S. Virgin Islands and several additional Caribbean Islands, and the Hawaiian Islands since the late 1970s. We have published three scientific papers on the population biology and biogeography^1,2, and population genetics³ of introduced mongoose populations. In our early studies we uniquely marked individual mongooses with ear tags. Unfortunately many animals lost their ear tags which made it impossible to identify recaptured individuals. Radio frequency identification devices (aka, PIT tags) became available in the late 1980s, so we switched to using this marking technique. This method involves injecting a glass encased microchip and wire coil that is encoded with a unique nine-digit number. The coil of wire powers the transponder chip upon receiving a burst of microwave radiation from a PIT tag reader. The chip then transmits the unique number to the reader which displays that number on an LCD. The data collected from our capture-mark-recapture studies on Caribbean and Hawaiian islands have allowed us to elucidate population structure (i.e., sex ratios and age structure), short- and long-term population fluctuations in various habitats, and the genetic structure of several insular populations.

The general conclusions from these studies are that mongoose live up to six years in the field, exist in an approximately equal sex-ratio, and exhibit significant philopatry although substantial long-term movements are also possible for males. Unfortunately, all movement data have been derived from trap-mark-recapture studies and are of limited value. A computer model developed by Dr. Brewer using Netlogo can generate plausible predicted patterns of mongoose population structure and movements based on different potential models of mongoose activity, but many parameters of mongoose activity are still unknown.

Current Research

In 2005, Dr. Steve Brewer, UMass-Amherst joined our merry band of mongoose researchers. Our current research focuses on studying the population biology of mongooses on Sandy Point National Widlife Refuge (SPNWR), St. Croix, U.S. Virgin Islands. SPNWR has a 3.2 km sandy beach that provides nesting habitat for leatherback, green, and hawksbill turtles. Mongoose have been identified by U.S. Fish and Wildlife Service (USFWS) biologists as a leading cause of mortality in hatchling sea turtles on this refuge.

An area of research that is key for the development of long-term turtle management plans is an evaluation of short- and long-term movement patterns of mongooses. We have not been able to collect these data because of technological limitations. For example, we need to know precise locations of traps in order to accurately determine movements of animals. Until the development of GPS technology, this has not been possible. Sandy Point NWR occupies approximately 145 hectares on a peninsula at the southwest end of St. Croix. The refuge is generally flat with the highest elevation less than two meters above sea level. The habitat is tropical dry scrub forest that supports very dense thickets that are nearly impenetrable. It is easy to get temporarily lost in these areas, and impossible to navigate using a compass. However, it is relatively easy to find specific locations using hand-held GPS units.

We are currently developing a tracking system that will allow us to record fine-grain movements of mongoose in the field.

Project Need

SPNWR has the largest turtle nesting beach in the United States and three endangered turtles (leatherback, loggerhead, and hawksbill) and one threatened sea turtle (green) are known to nest on SPNWR and/or other St. Croix beaches. Mongoose tracks are commonly observed around turtle nests and may be a significant cause of mortality in hatchling sea turtles. Our research proposes to answer the question of how frequently and when mongoose visit turtle nests. Live-trapping data collected during the past 30 years has proved insufficient to adequately address the impact of mongoose on sea turtle nests and hatchlings (c.f., Horst et al., 2001³ and Hoagland et al., 1989²). The presence of mongoose tracks adjacent to turtle nests also sheds little light on the direct impact of mongoose on sea turtle recruitment. However, once we have the technology, our proposed research will provide fine-grained movement data that will allow us to answer these and other questions about basic mongoose biology. These data will be used in the development of comprehensive mongoose management plans for SPNWR and other turtle nesting beaches on St. Croix and additional Caribbean islands inhabited by mongoose, and will insure the continued survival of sea turtle populations.

The Sandy Point Turtle Project has been monitoring sea turtle populations on Sandy Point since 1977 and the DPNR-DFW and USFWS have been contributing to and/or supervising this project since Sandy Point became a National Wildlife Refuge in 1984. The major focus of their combined efforts has been to monitor nesting behavior of turtles through RFID-tagging, nest location and enumeration, and nest monitoring. Although not completely eliminated, the negative impacts on sea turtle nests by humans has been dramatically curtailed on St. Croix. Staff at WIMARCS and previous research (c.f., Nellis and Small, 1983⁴) have identified the mongoose as a serious threat currently facing sea turtle hatchlings as they make their way from their sandy nests to the safety of the ocean waves. This conclusion is based primarily on the presence of mongoose tracks near turtle nests on the beach, rather than direct observations of animal interactions. To date, there has been limited study of mongoose movements and those studies that exist shed little light on patterns of mongoose activity.

The staff at DPNR-DFW lack the time and equipment to conduct this study. Sandy Point NWR has only two permanent employees, Refuge Manager Michael Evans and wildlife biologist Claudia Lombard. Their time is divided primarily between administrative duties, patrolling the refuge, community outreach, and helping with the turtle project. They do not have time to study the movement patterns of mongoose. The Sandy Point Turtle Team also lacks the time and expertise to study mongoose movements. Funding from this proposal will be used to pay transportation and lodging expenses for several biologists who have greater than 30 years experience trapping mongoose on St. Croix, and for equipment that will provide data for fine-grained analysis of mongoose movements.

A general model of mongoose movement will be valuable in other contexts. Sea turtles nest in many places where mongooses have been introduced throughout the region. Furthermore, mongooses impact other threatened and endangered species throughout the Caribbean including ground-nesting and shore-nesting birds, snakes, lizards, etc. Understanding mongoose movements will enable improved management and control strategies for wildlife management.

There is also a need to educate the local population about the biology of their island. Most islanders believe that mongooses were introduced 30-50 years ago to get rid of snakes. Additionally their experience with mongoose is limited to sightings of them crossing roads or stories of them being used to train pit bulls to fight or as torches to light sugar cane fields ablaze (dousing a mongoose with gasoline, lighting it on fire, and releasing it into a sugar cane field). How often, if ever, mongoose are used to train pit bulls or set cane fields on fire is not known. However, the fact is that many of the local inhabitants know little of their natural environment. By including high school students and VI University students in this project, we will help local people develop a better understanding of their own island flora and fauna. Additionally, all mongoose trapping data are, and will continue to be, available on the mongoose web site (http://mongoose.westfield.ma.edu) and all movement data will be posted there as well. This is a very rich data set that can be used in biology and mathematics classes at the high school through university level.

Objective

The objective of this project is to generate sufficient short- and long-term mongoose activity data to create a general model of mongoose movements. This model will allow DPNR-DFW and USFWS personnel to develop mongoose management plans for Sandy Point National Wildlife Refuge and other locations on St. Croix and other Caribbean islands. Data collected during this study will provide a detailed understanding of mongoose behavior near and around sea turtle nests. All data will be made available on the mongoose server (mongoose.wsc.ma.edu) and digital and paper copies will be archived at DPNR-DFW and transmitted to USFWS as it becomes available.

Expected Results or Benefits

There are four general benefits to this project: (1) generating mongoose movement data which will facilitate the development of mongoose management plans for the benefit of nesting sea turtles and the public health, (2) generating data that will contribute to the understanding of basic mongoose biology, (3) involving students in scientific research and increasing environmental awareness of local islanders, and (4) developing and testing computer technology for network analysis.

Data obtained from this project will be used to determine if mongooses visit sea turtle nests on the beach and when they do so. Additionally, we will be able to determine activity profiles of males and females which can be used to optimize capture-removal techniques in the event that mongooses are determined to be a major threat to sea turtle nests and hatchlings. By comparing accelerometer readings with video, it may be possible to recognize a number of specific activities, such as feeding, running, and sleeping, that may provide great insight into mongoose movements and activity patterns. Finally, Dr. Brewer will use the patterns of mongoose activity to improve the mongoose movement model to increase the ability to predict mongoose movements in other contexts.

Mongooses are known to be rabies vectors on several islands in the Caribbean (e.g., Puerto Rico and Trinidad) however St. Croix is currently rabies free. It is likely only a matter of time before rabies is introduced to this island as travel among islands, both legal and illegal, increases. Dogs will be the likely vector for the introduction of rabies onto St. Croix and dogs are known to attack mongooses. Accurate movement data will facilitate the development of effective mongoose control programs when rabies appears on St. Croix.

There are many unanswered questions concerning the basic ecology of mongooses. For example, despite anecdotal evidence we don't actually know if they are only active during daylight. There are unpublished observations of mongoose activity several hours after sunset and there are also data demonstrating that animals held in cages overnight lower their body temperatures 3-4 degrees celsius - indicating that animals are inactive at night. It may actually be the case that mongooses can lower their body temperatures during times of stress, during day or night, thereby conserving energy when resources are in limited supply.

Involving students (high school and college/university) in this project is a good first step in improving the environmental awareness of the entire population. We involve as many students a s possible in our research and we know that they discuss their adventures with their friends and family, therefore the potential impact on educating the public is substantial.

Approach

Teams of faculty and students will live-capture animals and fit them with electronic tracking units. A network of ground receivers will collect data from the tracking units. All of the plant species extant on Sandy Point will be identified and a GIS map of Sandy Point will be developed that divides the refuge into patches of designated vegetative types, based on the survey. A reference collection of plants will be prepared and housed at SPNWR.

Vegetation analysis, and Live-trapping and monitoring of mongoose will be conducted by collaborating faculty Drs. Buzz Hoagland (Westfield State University), Steven Brewer (University of Massachusetts Amherst), and their team. Students will include undergraduate and graduate students from Westfield State University, University of Massachusetts Amherst, University of the Virgin Islands, and two high schools on St. Croix.

A survey of plants and the vegetative ecology of the refuge will be essential for developing an effective model of mongoose movements. We will identify and prepare herbarium sheets of all of the extant species of plants on SPNWR. Using air photos and ground-truthing, teams will identify the predominate vegetative communities and categorize all areas of SPNWR into these communities.

Literature Cited

1. Hoagland, D. B. and C. W. Kilpatrick. 1999. Genetic variation and differentiation among insular populations of small Indian mongoose (Herpestes javanicus). Journal of Mammalogy, 80(1):169-179.
2. Hoagland, D. B., G R. Horst, and C. W. Kilpatrick. 1989. Biogeography and population biology of the mongoose in the West Indies. Pp. 611-634, in Biogeography of the West Indies (C. A. Woods, ed.). Sand Hill Crane Press, Gainesville, FL. 896 pp.
3. Horst, G. R., D. B. Hoagland, and C. W. Kilpatrick. 2001. The mongoose in the West Indies: The biogeography and population biology of an introduced species. Pp. 409-424, in Biogeography of the West Indies: Patterns and Perspectives (C. A. Woods and F. E. Sergile, eds.), Second Edition. CRC Press, Boca Raton, Fl. 582 pp.
4. Nellis, D. W. and V. Small. 1983. Mongoose predation on sea turtle eggs and nests. Biotropica, 15(2):159-160.