Abstract: The North American Reporting Center for Amphibian Malformations was established to provide a conduit of information about, and a systematic data base on, malformed amphibians. This article describes the Reporting Center and the variety of features available at its Web site, presents an example of a summary analysis that can be conducted with its data, discusses caveats about the data, and makes recommendations about systematic surveys to better understand patterns and trends in the incidence of malformed amphibians.
Key words: amphibians, data base, deformities, malformations, World-Wide Web.
Johnson, Douglas H., Suzanne C. Fowle, and Jeffrey A. Jundt. 2000. The North American reporting center for amphibian malformations. Journal of the Iowa Academy of Science 107(3):123-127.
This resource should be cited as:Johnson, Douglas H., Suzanne C. Fowle, and Jeffrey A. Jundt. 2000. The North American reporting center for amphibian malformations. Journal of the Iowa Academy of Science 107(3):123-127. Jamestown, ND: Northern Prairie Wildlife Research Center Online. http://www.npwrc.usgs.gov/resource/herps/malform/index.htm (Version 26MAR2001).
Geographic Representation
The core feature of the Reporting Center is a map of the United States and Canada. Each county or census district for which we have one or more reports is highlighted. Different colors distinguish counties with confirmed records of malformed amphibians from those where amphibian monitoring was conducted, but no malformed animals were detected.
Selecting a state or province brings up a larger-scale map, on which individual counties are outlined. Counties are colored according to the categories described in the previous paragraph, but, in addition, counties with recent (since 1986) reports are distinguished from those with only historic (before 1986) reports.
By selecting a particular county or census district, the user retrieves a table summarizing the reports for that area. A separate summary is given for each visit to a field site and each species encountered; data include the month and year of the visit, common and scientific names of the species, the number of specimens examined that appeared normal, the number with malformations evident, and the types of malformations observed.
Only confirmed reports are included in the Web site. The coordinator of the Reporting Center determines on a case-by-case basis whether or not a report should be considered confirmed prima facie. Two reporting forms are available on the Web site for individuals with different levels of expertise. The technical form is used by biologists; those reports are treated as confirmed. Individuals without specific training in biology use the nontechnical reporting form. For nontechnical reports we ask the reporter if any photos of the animal were taken. If so, we request a copy, either through the mail when their film is developed, or scanned and sent digitally over the Internet. In other cases, the reports are forwarded to a biologist who has volunteered to serve as a verifier for a particular area. If the biologist gets the opportunity to verify the report, he or she replies to the Reporting Center, either confirming the report or not. Individuals reporting malformed animals who appear to be knowledgeable about the issue, such as indicated by using specific anatomical terms to describe the malformations, are telephoned to gain further insight. Many of these reports are considered confirmed after speaking with the individuals who may not be trained biologists, but clearly are interested and knowledgeable in biology. Unconfirmed reports are stored in a data base, but not presented on the Web site.
Descriptive Information
Basic information about the issue of malformed amphibians is presented in non-technical terms, providing a layperson with a quick introduction to the topic. Alternative hypotheses about the causes of malformations are offered, as objectively as possible.
Illustrations of Typical Malformations
A variety of malformations are illustrated with photographs provided by cooperators. These are intended to exemplify the kinds of malformations typically encountered, so that observers will know what to look for. Included types are misshapen, extra, missing, or split limbs; cutaneous fusion; missing eye; and abnormal jaw.
Species Identification Guide
The Reporting Center recently added an identification guide to help observers determine the species of amphibian they find. Included for a number of species and subspecies are one or more photographs, descriptions of key features, and information on its geographical range. We attempt to illustrate the variation in colors shown by certain species and to show ventral as well as dorsal views, to facilitate identification of specimens in the hand. The initial emphasis is on species most commonly reported to the Center.
Sources of Additional Information
Visitors to the Web site can access other information on amphibian malformations. Pertinent articles from a number of newspapers and magazines are posted, as are news releases and articles from newsletters such as Froglog. A searchable bibliography on malformed amphibians and related topics is available. Many entries were provided by Canadian Wildlife Service collaborators; other entries are added regularly. Also included are hot links to other Web sites that deal with related issues.
Technical Information
The Reporting Center provides certain kinds of information of a more technical nature. These include draft standard field forms for recording malformations, protocols developed by the U.S. Fish and Wildlife Service (FWS) for surveying malformed amphibians on national wildlife refuges, and a code of practice for amphibian fieldwork developed by the Declining Amphibian Populations Task Force. Information about the Amphibian Malformations Listserver is given, including instructions for joining it and an archive of past messages. The listserver was conceived and developed by the U.S. Geological Survey (USGS) Patuxent Wildlife Research Center.
Instructions for Submitting Reports
The Reporting Center allows submission of reports directly over the Internet. Two sets of instructions for doing so are provided. One set is for nonbiologists, for whom technical details are minimized. Requested information includes the observer's name and contact information, location and date of sighting, species of amphibian, its approximate size, description of the malformation, the number of non-malformed amphibians encountered, and habitat description. Instructions for biologists are similar, except that they are asked more specifically to distinguish developmental malformations from possible injuries.
Acknowledgments Section
Here we thank individuals who assisted in the development of the Reporting Center by offering guidance, bibliographies, photographs, or other contributions, as well as the designers of the Web site and the Web authors.
What's New?
When the Web site is updated, the "What's New?" feature lists the changes that have been made. These include additional resources, new articles, and the like. Also listed are states and counties with new reports of malformed amphibians, or with negative reports. The data base is updated to reflect the latest reports about every two weeks during summer, and somewhat less frequently at other times of the year.
To facilitate reporting, the Reporting Center also has established a toll-free number (800-238-9801), which can be used to report observations of malformed amphibians or results of systematic surveys.
Most of the reports submitted to the Center were from opportunistic findings; that is, someone found a malformed amphibian and submitted a report of it. Such reports do not permit an assessment of the true incidence of malformations, for they are obviously biased toward sites with malformed animals, and often normal-appearing amphibians are not noted or recorded. There are at least two exceptions. First, the Minnesota Pollution Control Agency has conducted systematic surveys of anurans at various locations in that state. Second, the U.S. Fish and Wildlife Service conducted surveys at numerous wildlife refuge lands in its Northeast and Great Lakes regions. Refuge managers in those regions were asked to sample two randomly chosen sites on each refuge, attempt to capture 100 or more frogs and toads at each site, and determine how many of them had malformations and what the types were. Refuge staff used protocols developed by FWS and USGS collaborators.
For the analysis presented here, we used only reports that included a substantial number of normal-appearing, as well as any malformed, amphibians. That restriction was made to reduce the effect of the opportunistic reporting of only malformed animals. Only reports of at least ten animals, all species combined, were included. Reports before 1986 were excluded, to better reflect the current situation.
The data base at present (September 1998) contains records of 452 sites that meet the criteria described above (Table 1). Of these, 136 were from the national wildlife refuge survey and 316 were from other sources. Of the states and provinces, Minnesota has by far the most reports, 169 in total. Vermont, with 39 reports, and Wisconsin, with 30, follow (Table 1). Of the types of malformations, missing limbs or digits were reported at more sites (236) than other types, followed by eye abnormalities (69), extra limbs or digits (48), and jaw deformities (27). One hundred and seventy-six (39%) of the sites had no observed malformed animals (Table 1). This rate differed between refuge sites (61% reporting no malformed animals) and non-refuge sites (29%).
Table 1. Number of sites included in analysis, and number with types of malformations reported. | |||||||||
Number of sites | Number of sites with malformation type | ||||||||
State/Province | Refuges | Other | Total | Missing | Extra | Eye | Jaw | Any | None |
British Columbia | 0 | 5 | 5 | 0 | 0 | 0 | 0 | 0 | 5 |
California | 0 | 9 | 9 | 5 | 6 | 3 | 0 | 6 | 3 |
Connecticut | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 |
Delaware | 2 | 1 | 3 | 1 | 0 | 0 | 0 | 1 | 2 |
Florida | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 0 |
Illinois | 8 | 3 | 11 | 2 | 0 | 2 | 0 | 4 | 7 |
Indiana | 3 | 1 | 4 | 1 | 0 | 0 | 0 | 1 | 3 |
Iowa | 5 | 0 | 5 | 2 | 1 | 1 | 0 | 2 | 3 |
Kansas | 2 | 0 | 2 | 0 | 0 | 0 | 0 | 0 | 2 |
Louisiana | 2 | 0 | 2 | 0 | 1 | 0 | 0 | 1 | 1 |
Maine | 9 | 2 | 11 | 4 | 1 | 2 | 0 | 5 | 6 |
Maryland | 1 | 21 | 22 | 2 | 0 | 0 | 1 | 3 | 19 |
Massachusetts | 0 | 5 | 5 | 1 | 2 | 1 | 0 | 4 | 1 |
Michigan | 6 | 4 | 10 | 4 | 1 | 2 | 0 | 7 | 3 |
Minnesota | 30 | 139 | 169 | 104 | 17 | 40 | 19 | 119 | 50 |
Mississippi | 0 | 2 | 2 | 0 | 0 | 1 | 0 | 1 | 1 |
Missouri | 14 | 0 | 14 | 4 | 0 | 0 | 0 | 4 | 10 |
Montana | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 |
Nebraska | 3 | 0 | 3 | 0 | 0 | 0 | 0 | 0 | 3 |
Nevada | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
New Hampshire | 2 | 6 | 8 | 6 | 0 | 2 | 0 | 6 | 2 |
New Jersey | 8 | 9 | 17 | 11 | 1 | 1 | 2 | 11 | 6 |
New York | 3 | 0 | 3 | 1 | 0 | 0 | 0 | 1 | 2 |
North Dakota | 6 | 5 | 11 | 7 | 1 | 0 | 1 | 7 | 4 |
Ohio | 2 | 4 | 6 | 4 | 2 | 1 | 1 | 5 | 1 |
Oklahoma | 0 | 3 | 3 | 1 | 0 | 0 | 0 | 1 | 2 |
Ontario | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 |
Oregon | 0 | 7 | 7 | 4 | 5 | 0 | 0 | 6 | 1 |
Quebec | 0 | 19 | 19 | 9 | 0 | 0 | 0 | 9 | 10 |
South Carolina | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 0 |
South Dakota | 10 | 4 | 14 | 6 | 0 | 2 | 1 | 8 | 6 |
Tennessee | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 |
Texas | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
Vermont | 2 | 37 | 39 | 38 | 1 | 4 | 0 | 38 | 1 |
Virginia | 3 | 0 | 3 | 1 | 0 | 1 | 0 | 2 | 1 |
Washington | 0 | 6 | 6 | 3 | 4 | 3 | 1 | 5 | 1 |
West Virginia | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 0 |
Wisconsin | 13 | 17 | 30 | 10 | 2 | 2 | 0 | 12 | 18 |
Total | 136 | 316 | 452 | 236 | 48 | 69 | 27 | 276 | 176 |
The percentage of animals examined that had malformations varied widely among states and provinces (Table 2). Delaware, with 28.9% of 315 animals sampled showing malformations was highest by far. All malformed animals were bullfrog (see Table 3 for scientific names) tadpoles with missing appendages, from a single pond that also contained fish, so the possibility exists that they might have been injured, rather than malformed. In addition, regardless of the cause, the data reflect but a single site. Oregon had the next highest rate, 18.5%; most of the malformed animals were Pacific treefrogs with extra limbs. California, with a very large sample of more than 12,000 amphibians, had a high rate (17.2%), including large samples of long-toed salamanders, western toads, and Pacific treefrogs.
A number of species were involved in the reports examined (Table 3), although not all were included in the analysis, due to the criterion of having at least ten animals at a site. Most frequent were the northern leopard frog (352 reports) and green frog (142 reports).
Table 3. Species included in North American Reporting Center for Amphibian Malformations files, and number of sites with reports for each. | |
Species | Number of sites |
Northern leopard frog (Rana pipiens) | 352 |
Green frog (Rana clamitans melanota) | 142 |
Bullfrog (Rana catesbeiana) | 72 |
Wood frog (Rana sylvatica) | 65 |
American toad (Bufo americanus) | 61 |
Southern leopard frog (Rana utricularia) | 53 |
Mink frog (Rana septentrionalis) | 40 |
Gray treefrog (Hyla versicolor/chrysoscelis) | 28 |
Fowler's toad (Bufo woodhousii fowleri) | 24 |
Pacific treefrog (Hyla regilla) | 22 |
Spring peeper (Pseudacris crucifer) | 20 |
Pickerel frog (Rana palustris) | 15 |
Tiger salamander (Ambystoma tigrinum) | 12 |
Western toad (Bufo boreas) | 10 |
Chorus frog (Pseudacris triseriata) | 9 |
Northern cricket frog (Acris crepitans crepitans) | 9 |
Spotted salamander (Ambystoma maculatum) | 7 |
Rough-skinned newt (Taricha granulosa) | 7 |
Cascades frog (Rana cascadae) | 6 |
Blue-spotted salamander (Ambystoma laterale) | 6 |
Cricket frog (Acris crepitans) | 6 |
Green treefrog (Hyla cinerea) | 4 |
Canadian toad (Bufo hemiophrys) | 5 |
Northwestern salamander (Ambystoma gracile) | 5 |
Red-legged frog (Rana aurora) | 5 |
Long-toed salamander (Ambystoma macrodactylum) | 4 |
Eastern narrowmouth toad (Gastrophryne carolinensis) | 3 |
Eastern spadefoot toad (Scaphiopus holbrookii) | 3 |
Southern cricket frog (Acris gryllus) | 3 |
Woodhouse's toad (Bufo woodhousii) | 3 |
Barking treefrog (Hyla gratiosa) | 2 |
Blanchard's cricket frog (Acris crepitans blanchardi) | 2 |
Dusky gopher frog (Rana capito) | 2 |
Mississippi slimy salamander (Plethodon mississippi) | 2 |
Mole salamander (Ambystoma talpoideum) | 2 |
Ornate chorus frog (Pseudacris ornata) | 2 |
Pine woods treefrog (Hyla femoralis) | 2 |
Plains leopard frog (Rana blairi) | 2 |
Smallmouth salamander (Ambystoma texanum) | 2 |
Southern chorus frog (Pseudacris nigrita nigrita) | 2 |
Southern toad (Bufo terrestris) | 2 |
Upland chorus frog (Pseudacris triseriata feriarum) | 2 |
Red-spotted newt (Notophthalmus viridescens viridescens) | 2 |
Western redback salamander (Plethodon vehiculum) | 2 |
Great Plains narrowmouth toad (Gastrophryne olivacea) | 1 |
Jefferson salamander (Ambystoma jeffersonianum) | 1 |
Boreal toad (Bufo boreas boreas) | 1 |
Bronze frog (Rana clamitans clamitans) | 1 |
Clouded salamander (Aneides ferreus) | 1 |
Cope's gray tree frog (Hyla chrysoscelis) | 1 |
Couch's spadefoot (Scaphiopus couchii) | 1 |
Carpenter frog (Rana virgatipes) | 1 |
Eastern American toad (Bufo americanus americanus) | 1 |
Eastern green toad (Bufo debilis debilis) | 1 |
Eastern newt (Notophthalmus viridescens) | 1 |
Gulf Coast toad (Bufo valliceps) | 1 |
Marbled salamander (Ambystoma opacum) | 1 |
Northern redback salamander (Plethodon cinereus) | 1 |
Pig frog (Rana grylio) | 1 |
Rich Mountain salamander (Plethodon ouachitae) | 1 |
Rio Grande leopard frog (Rana berlandieri) | 1 |
Redback salamander (Plethodon cinereus) | 1 |
Silvery salamander (Ambystoma platineum) | 1 |
Southern redback salamander (Plethodon serratus) | 1 |
Spotted frog (Rana pretiosa) | 1 |
Squirrel treefrog (Hyla squirella) | 1 |
Texas toad (Bufo speciosus) | 1 |
Western (California) toad (Bufo boreas halophilus) | 1 |
Western chorus frog (Pseudacris triseriata triseriata) | 1 |
Second, the "true" rate of malformation should be based on very young animals, recent metamorphs, for example. If, as seems very likely, malformed animals are likely to die sooner than their normal cohorts, the incidence of malformations among populations of older animals will be biased low.
Third, despite carefully prescribed protocols and instructions, it is not always easy to identify malformations with certainty. Missing limbs or digits may represent injuries, rather than malformations. While every effort was made to exclude likely injuries, it cannot be assured that all such reports were distinguished.
Fourth, the incidence of malformations can vary dramatically in space and time. Research by the Minnesota Pollution Control Agency has demonstrated that a site may harbor only normal-appearing amphibians on one occasion, but have amphibians with an elevated rate of malformations the very next year (J. Helgen, Minnesota Pollution Control Agency, pers. comm.).
Ideally, to gain a clearer understanding of the patterns and trends in the incidence of malformed amphibians, systematic surveys should be conducted in a variety of areas and repeated in time. Standardized protocols must be followed. Surveys timed to capture recent metamorphs are best, so that the incidence of malformations can be determined before any affected animals die. In some circumstances, surveys of larval amphibians can be used, although certain species are difficult to distinguish, especially by a nonherpetologist. In addition to conducting surveys specifically to evaluate malformations, it would be useful for scientists involved in capturing substantial numbers of amphibians to take note of any malformations that occur, and to report those data. Even if no malformed animals are encountered, the information can be used to evaluate the true extent of the problem.
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