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Introduction
Plethodontid salamanders are notoriously difficult to mark or individually identify. Their small physical size, sensitive and slippery skin, subtlety of their markings, and their ability to regenerate toes all contribute to these difficulties. Yet, to follow the births, deaths, emigration, immigration, home range sizes and other intimacies of salamander populations biology and behavior in the field, schemes for individual marking are necessary. A common method used to mark salamanders is toe clipping. It has been described as convenient and the least expensive technique for marking salamanders (Donnelly et.al 1994). However, there is some evidence that toe-clipping has harmful effects on amphibians. Clark (1972) reported a possible negative effect on survival using toe clipping in Bufo woodhousei fowleri. Furthermore, toe-clipping is not a viable technique for long-term studies since toes regenerate. In addition to toe clipping additional marking techniques for amphibians are described in detail by Ferner (1979), Schlaepfer (1998) and Nishikawa (1988).
Recently, we have begun to experiment with a promising new technique using a fluorescent elastomer marking system (currently only manufactured by Northwest Marine Technology). Our purpose here is to report the experiences of researchers using this technique on amphibians so that others can gain from their work.
We encourage others to e-mail us their experiences with this marking technique so that we may report those too.
Thank you.
The Visible Implant Fluorescent
Elastomer (VIE) tagging system
The VIE was initially tested on fish. Amphibian tests have been conducted on: larval Northwestern Salamander (Ambystoma gracile), Pacific Giant Salamander (Dicamptodon tenebrosus), Red-backed Salamanders (Plethodon cinereus) and tadpoles of Rana lessonae and R. esculenta. The tagging system is bio-compatible and consist of two elastomer materials (color elastomer and curing agent) which are mixed at a 10:1 ratio. After mixing, the liquid elastomer material can be placed into a 0.3 cc syringes and kept in a freezer to slow hardening, which occurs within 24 hours at room temperature. The 0.3 cc syringes are used to inject the elastomer pigment into the animals. Northwest Marine Technology, Inc. web page describes two possible injection methods: hand held and air powered injector.
A total of four fluorescent colors
(red, green, orange and yellow) are used for marking. In order to mark
animals uniquely, fluorescent colors have to be combined with different
tag locations. For example, the combination of 4 colors with 4 tag locations
allows 624 uniquely marked individuals. Injected
pigments can be difficult to see in dark pigmented skins under ambient
light, but are visible under ultra-violet light. An advantage of this technique
is that the injected amount of elastomer material is relatively small,
thus this method is applicable for smaller animals. All evidence from fisheries
work indicates that the marks should be visible for the entire life of
the animal.
Studies and Field experiences with the VIE
Ambystoma
gracile and Dicamptodon tenebrosus
Plethodon
cinereus on the Coastal Plain of Maryland
Tadpoles
of Rana lessonae and R. esculenta
Plethodon
vehiculum and Hyla regilla on Vancouver Island, British Columbia
Experiments with.......Please
send your experiences with this technique to Sam
Droege
Amphibian Monitoring
Salamander
Monitoring
Literature Cited
Clark, R. D. 1972. The effect of toe clipping on survival in Fowler's toad (Bufo woodhousei fowleri). Copeia 1972: 182-185.
Donnelly, M. A., C. Guyer, J.E. Juterbock, and R. A. Alford. 1994. Techniques for marking amphibians. In W.R. Heyer, M.A. Donnelly, R. W. McDiarmid, L. C. Hayek, and M. S. Foster, Measuring and Monitoring Biological Diversity. Standard Methods for Amphibians, pp. 277-284. Smithsonian Insitiution Press, Washington, D.C.
Ferner, J. W. 1979. A review of marking techniques for amphibians and reptiles. Herpetological Circular No. 9, Society for the Study of Amphibians and Reptiles.
Nishikawa, K. C., and P.M. Service.1988. A fluorescent marking technique for individual recognition of terrestrial salamanders. J. Herpetol. 22:351-353
Schlaepfer, M. A. 1998. Use of a
Fluorescent Marking Technique on Small Terrestrial Anurans. Herpetological
Review 29(1):25-26
U.S. Department of the Interior
U.S. Geological Survey
Patuxent Wildlife Research Center
Laurel, MD, USA 20708-4038
<http://www.pwrc.usgs.gov/sally/index.html>
Contact: Sam Dreoge
<sam_droege@usgs.gov>
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