Deformed Frog Survey Protocols
Adapted from Robert Hay, Bureau of Endangered Resources, WI Dept of Natural Resources
and Methodology for Surveying Malformed Frogs on National Wildlife Refuges
The primary survey goal is to determine the presence of deformities by species, and the prevalence, type and distribution of deformities at a variety of wetland types throughout Michigan. This information will be used to help scientists target areas for further study.
Site Selection & Timing
Wetlands to be monitored for frog deformities should have known frog breeding activity. An evening auditory survey should be conducted at least once in April and again in late May or early June to determine all of the frog species present. Deformed frog surveys should ideally occur in late-June, mid-July and mid-late August in order to sample the range of species during metamorphosis. It is best to sample froglets (froglets with four legs and tail but still aquatic), and metamorphs (recently transformed from a tadpole) as they are just leaving the water. Predation rates on deformed frogs are expected to be high. Green, mink and bullfrogs typically overwinter as tadpoles and transform in mid-summer.
Rubber boots or waders Live wells - plastic gallon buckets with lids or clear plastic habitat containers
Dip nets Camera and film
Site data sheets Frog deformity checklist sheets
Clipboard & pencil Frog ID poster (laminated)
Peat moss Water sampling kits (thermometer, pH, DO)
Insect repellant (apply by using the back of your hands to protect frogs’ skin)
The goal is to capture 50-100 froglets per wetland site. Have students work in groups of 4-5 per group. Assign responsibilities to each group member: record data, catch frogs with net, catch frogs with hands, carry live well, ID frogs that are caught and look for deformities.
When approaching the water’s edge, frogs will likely jump in. Wait patiently for them to resurface. Then, move your net carefully toward the frog, coming at it head-on. Flip the net over the frog quickly, plunging it several inches beneath the water surface. Retract the handle.
A recommended way to observe each froglet is to hold them under the front legs with the frog facing you and the hind legs dangling down. Check that both eyes, front legs, and rear legs are present and symmetrical. Count the toes (four on front feet; five on rear feet). If the abnormality is obviously trauma-related (predated, leg broken during capture, etc.), then record as normal.
If you observe any deformed frogs, please complete a deformity data sheet for each deformed frog, in addition to, the site survey data sheet for the entire site. Also, photograph each deformed frog found, then release the frog to where it was captured. A camera with a manual electronic flash and a macro lens (or extension tubes) will provide the best photograph. Captured frogs should be kept in a live well with ½” water and wet moss, or in a large container or 5 gallon plastic bucket, half filled with water to prevent frogs from reaching the bottom with their legs and being able to jump out.
Developed by the Western UP Center for Science, Math and Environmental Education (formerly Center for Science and Environmental Outreach) and the School of Forestry & Wood Products at Michigan Technological University. This project was made possible by citizens who contributed to the Michigan NonGame Wildlife Fund on the Michigan income tax form or by a direct donation to the Fund. The Michigan NonGame Wildlife Fund is administered by the Michigan Department of Natural Resources Wildlife Division.