3.1.3 Marking and Identification
Anyone who is handling and/or marking amphibians or reptiles should be familiar with provincial protocols outlined in the manual, Live Animal Capture and Handling Guidelines for Wildlife Mammals, Birds, Amphibians, and Reptiles (No. 3).
Most species of amphibians in British Columbia do not have colour patterns or other external characteristics that allow individuals to be identified upon recapture, so studies requiring this information must rely on marking. For amphibians, such marking is often problematic due to their small size and smooth, delicate skin. Generally, the most practical method for marking more than a few individuals is toe-clipping, and this has been used in the vast majority of studies in which individual-specific marks were required. However, because toes can regenerate rapidly, the marks are not necessarily permanent. In addition, virtually no work has been done on the effects of toe-clipping on the survival, behaviour and recapture rates of amphibians. Some evidence suggests that adverse effects may be significant (Nishikawa and Service 1988), and Clarke (1972) has shown that toe-clipping can reduce survivorship in Fowler's Toad (Bufo woodhousei fowleri). Golay and Durrer (1994) reported that toe-clipping of natterjack toads can lead to infection and necrosis, sometimes involving the entire limb. Nevertheless, toe-clipping is the recommended method for most amphibians.
Many alternative marking schemes are available (Donnelly et al. 1994) but are not without serious drawbacks. Tags are time-consuming to attach, may harm the animals, and cannot be used with many of the smaller species. Brands (tattoo, heat, silver nitrate, and freeze) and most marking schemes using fluorescent pigments have similar problems and are not widely used by herpetologists. Methods for marking amphibian larvae include fin-clipping, and staining with dyes or fluorescent pigments. Marking by injection of fluorescent elastomere dyes under the skin is a technique which is currently under development (T. Davis and K. Ovaska, pers. comm.). Pattern mapping, in which colour patterns, scars and other features are used to identify individuals, is appropriate for a few species (e.g., Tiger Salamander), but relatively few individuals can be identified, patterns can change over time, and the method is prone to observer bias. Nevertheless, it may be useful in certain circumstances (see Donnelly et al. 1994). Rice and Taylor (1993) describe a waistband to mark anurans for long-distance identification in short-term studies.
PIT tags (passive integrated transponders) are radio-frequency identification tags about the size of a grain of rice. Each tag has a unique code that can be read with a portable scanner. PIT tags are usually implanted in the body cavity with a modified syringe. To avoid damage to the internal organs, Donnelly et al. (1994) recommends inserting PIT tags into the dorsal lymph sac rather than intrabdominally. PIT tags are not practical for larvae and smaller amphibians, are expensive, and may be less reliable than generally presumed (Germano and Williams 1993).
Turtles are relatively easy to mark and a variety of methods including the attachment of tags and branding, painting, notching or engraving the carapace (see reviews by Ferner 1979 and Plummer 1979). Shell notching or engraving are most commonly used (Mitchell 1988) and that is the method recommended here.
Ferner (1979) and Jones (1986), review marking amphibians and reptiles, and Donnelly et al. (1994) review marking amphibians. Radioactive tagging is reviewed by Ashton (1994).
Generally, the most practical method for marking more than a few individuals is toe-clipping. Because it is easy to do, fast, and inexpensive, it is by far the most common method of marking small amphibians. However, little work has been done on the effects of toe-clipping on the survival, behaviour and recapture rates of salamanders. A discussion of toe-clipping and ethical issues appears in the March 1995 issue of FROGLOG.
To mark salamanders , toads, and frogs individually, two to four toes are removed with small, good quality scissors. Generally, no more than three toes are removed, but never more than one toe from each foot. Removing two toes is optimal, because a single toe can be occasionally lost by accident or attempted predation, and a minimum number of toes cut should minimize any adverse effects caused by the procedure. An inexpensive head mounted magnifier (e.g., Magni-focuser®, Edroy Products Co., Inc., Nyack, New York) will make clipping and reading the marks easier. After the toes are clipped, the code should be read back to the data collector to ensure that the mark corresponds to what is recorded on the data sheet. It is easy to become confused as to orientation and order when toe-clipping. After finishing with each individual, the scissors should be dipped in 95% ethanol to reduce the chance of transmitting infections between salamanders, and the toes treated with the antibiotic Bactine® (Martin and Hong 1991; Donnelly et al. 1994).
The choice of a coding system is largely a matter of personal taste and experience, but it is desirable to use a system that is simple and easily recorded. Several coding schemes are presented by Donnelly et al. (1994). The coding scheme presented here will be used as the standard coding system. It is a simple symbolic coding scheme and does not require mental addition and uses a single numeric character per foot (Figure 1). Each mark is of the form 0000 where each character place corresponds to a particular foot. Numbers correspond to particular toes. No more than one toe from each foot should be excised. The code is read from the left front foot to the left back foot, to the right front foot and finally to the right back foot. Toes are counted from proximal to distal and a dorsal view is used to reduce struggling. Thus, 0320 represents toes number three on the left hind foot and number 2 on the right forefoot. For most studies, only two and three-toe marks will be needed. To avoid using the same code twice, a sheet containing all the codes should be prepared, and codes checked off as they are used. Additional numbers may be used to indicate unusual marks (e.g., 5 = foot missing; 6 = leg missing; 7 = 2 or more toes missing; 8 = toes fused; 9 = see comments). Toes that may have a function in feeding or mating should not be excised.
Toe-clipping should not be used for the Painted Turtle.
Figure 1. A symbolic coding scheme for toe-clipping.
The code is read from the left front foot to left back foot to right front foot to right back foot. At lower left, an (*) marks toes that have been clipped; this mark reads 2403. The number of toes, and which toes can be clipped, vary among species.
Painted Turtles are marked by filing notches in marginal scutes (St. Clair 1989). This is best done with a small square file. Marks are permanent. The marking code (Figure 2 ) is from Macartney and Gregory (1985) which was based on the method of Cagle (1939).
Figure 2. Carapace of a painted turtle showing marking scheme (from Macartney and Gregory 1985).