The froglogger is revolutionzing conservation efforts around the world where wildlife monitoring is either time-intensive, physically difficult or too expensive. The system may be used to monitor any wildlife that make audible sounds such as frogs, birds, wolves, insects, marine life (using hydrophone) or many other species.
In the past there was a good chance that no matter where you lived you weren’t too far away from an area where you could hear frogs calling.
That’s changed. The populations of frogs are declining in many areas of the world. Whether in an urban area or in a rain forest there used to be a healthy population of frogs and toads but in some of these areas the populations are declining or in some cases have completely disappeared.
What’s causing this decline? Evidence points to habitat loss, climate changes, UV radiation, contaminants and pollutants, disease, and predation by invasive species. One question is that while the declines are occurring in urban areas as suspected there are also declines in unsuspected places like our protected national parks.
More study is necessary to determine what is causing these declines. To do these studies it is mandatory that we have methods of monitoring frog populations. The use of the “froglogger” was introduced in papers by Michael E. Dorcas and Charles Peterson over 13 years ago. Since that time various improvements have been made in these automatic recording systems. These instruments are now in use by utility companies, state departments of natural resources, USGS, colleges and universities, NASA, and by independent environmental engineering companies.
The original automated recording system (ARS) described by Peterson & Dorcas (1994), and now commonly known as a Froglogger, enables the researcher to use unattended recording over long periods of time for later analysis. This enables the monitoring of animal calls for long periods of time that would be impossible for a person or too expensive. For example, you can record a few minutes every hour during several days or weeks. Some froglogger users install as many as 20 units over a large area to monitor populations of frogs, birds, wolves, insects, marine life (using hydrophone) or many other species.
As an example of the important and valuable information that can be obtained only by using a Froglogger is the paper by Bridges and Dorcas (2000). They found that Rana sphenocephala, which was described previously as calling during early spring and early fall, was also very active calling during the summer, but between 2:00 and 5:00.
Previously unknown populations of anurans in the US are being detected with the help of a portable automated recording system. It uses a timer/controller to automatically activate an audio recorder to log animal vocalizations in the field. It is self-contained, portable and weather resistant.
Michael Dorcas, once a postdoctoral fellow at Savannah River Ecology Laboratory and now a biology professor at Davidson College, designed the 'froglogger' with help from his father, Eugene Dorcas, an electrical engineer, and Charles Peterson, his doctoral degree advisor at Idaho State University in 1994. Drs. Dorcas and Peterson have used the system to monitor populations of western chorus frogs, southwestern toads and Pacific chorus frogs in Utah and Idaho. They have also been monitoring frogs and toads, including the potentially threatened gopher frog, at the US Department of Energy's Savannah River Site in collaboration with Whit Gibbons, Justin Congdon, Tracey Tuberville and other colleagues at the Ecology Laboratory. The froglogger is now also used to monitor the endangered Houston Toad in SE Texas.
Other scientists from across the country and around the world are also using automated recording systems to monitor populations of frogs and birds. In a number of cases, these systems have detected species otherwise thought to have been absent.
In one of the most dramatic cases, Dr. Richard Seigel of Southeastern Louisiana University detected a breeding population of barking tree frogs at the Merritt Island National Wildlife Refuge at Kennedy Space Center, Florida, where the species was previously represented by only a single road-killed specimen, in spite of 19 years of field work.
In Ohio, researchers Michael Walton and Ralph Gibson of Cleveland State University detected a population of leopard frogs at a site where they were thought to have become extinct. In other cases, state and federal wildlife officials are using frogloggers to monitor sensitive or endangered species and to gather information for federally mandated environmental impact statements.
Literature cited:
Frog-logger: an Automated Recording System, the Open University
Corn, P. S., E. Muths, and W. M. Iko. 2000. A comparison in Colorado of three methods to monitor breeding amphibians. Northwestern Naturalist 81:22-30.
Crouch, W. P., and P. W. C. Paton. 2000. Using egg mass counts to monitor wood frog populations. Wildlife Society Bulletin 28:895-901.
Heyer, W. R. 1994. Recording frog calls. Pp. 285-287 in: Measuring and monitoring biological diversity: Standard methods for amphibians.
Heyer, W. R., M. A. Donnelly, R. W. McDiarmid, L. C. Hayek, and M. S. Foster (eds.). Smithsonian Institution Press, Washington, D.C.
Holloway, S. 1997. Survey protocols for the stream-breeding frogs of far east Gippsland: the application of habitat modeling and an assessment of techniques. M.S. Thesis, University of Canberra, Canberra, Australia.
Mazanti, L. E. 1999. The effects of atrazine, metalochlor and chlorpyrifos on the growth and survival of larval frogs under laboratory and field conditions. Ph.D. Thesis, University of Maryland, College Park, MD.
Mitchell, J. C. 2000. Amphibian monitoring methods and field guide. Smithsonian Institution Conservation Research Center, Front Royal, VA.
Mitchell, J.C., and C.T. Georgel. 2001. Seasonal and daily calling patterns of frogs on Fort A.P. Hill, Virginia: results from froglogger surveys. Final Report to Environmental and Natural Resources Division, Fort A.P. Hill, Bowling Green, VA. 48 pp.
Osborne, W. S., and N. A. McElhinney. 1996. Status, habitat and preliminary observations on calling of the green and golden bell frog Litoria aurea on Bowen Island, Jervis Bay National Park. Australian Zoologist 30:218-223.
Parris, K. M., T. W. Norton, and R. B. Cunningham. 1999. A comparison of techniques for sampling amphibians in the forests of south-east Queensland, Australia. Herpetologica 55:271-283.
Seigel, R. A., R. B. Smith, J. Demuth, L. M. Ehrhart, and F. F. Snelson, Jr. 2002. Amphibians and reptiles of the John F. Kennedy Space Center, Florida: A long-term assessment of a large protected habitat (1975-2000). Florida Scientist 65:1-12.
Taylor, A., G. Watson, G. Grigg, and H. McCallum. 1996. Monitoring frog communities: an application of machine learning. AAAI/IAAI 2: 1564-1569.
Van Gelder, J. J., and H. C. M. Hoedemaekers. 1971. Sound activity and migration during the breeding period of Rana temporaria L., R. arvalis Nilsson, Pelobates fuscus Laur. and Rana esculenta L. Journal of Animal Ecology 40:559-568.