Geoscience Reference
In-Depth Information
apparently has not been evaluated for negative effects on behavior, physiology,
or vulnerability to predation.
Most metal or plastic tags used on reptiles and amphibians were originally
designed for attachment to fish or birds. Such tags tend to be large and cum-
bersome, and their effect on study animals remains largely untested despite
early suspicions that they affected behavior and physical condition (Raney
1940; Woodbury 1956). It is promising that both studies evaluating the effect
of PIT tags on reptiles failed to detect effects (table 2.2), and with additional
study, they might become the standard for tagging many species of reptiles and
amphibians. However, in addition to expense and distance requirements for
reading (Germano and Williams 1993), PIT tags have the disadvantage of
being lost at a high rate by some free-ranging reptiles (Parmenter 1993; Rossi
and Rossi 1993).
MUTILATION
Until recently, most studies of reptiles and amphibians used
mutilation marking to identify individuals. One of the most common forms
of mutilation, toe clipping, has been widely used on lizards, frogs, and sala-
manders because it provides an inexpensive method of identifying individuals.
High frequency of natural toe loss in some populations of free-ranging lizards
has been used to justify its use as an acceptable marking tool (Middleburg
and Strijbosch 1988; Hudson 1996), but the natural occurrence of missing
toes does not indicate that toe loss is not traumatic. Although toe clipping
apparently does not affect the sprint performance of some lizards (Guttman
and Creasey 1973), another study (Clarke 1972) inferred from the low rate
of recapture of toe-clipped toads that the marking technique reduced survival.
Clarke (1972) also noted that recapture rates were inversely related to the
number of toes removed, and that toe-clipped toads experienced reduced dex-
terity when handling large prey. In other species, regeneration of clipped
toes can occur, thus causing problems associated with misidentification of
marked animals. However, despite the potential negative effects of toe clipping
on reptiles and amphibians, it has remained a widely used form of marking.
Clearly, the effect of this technique on reptiles and amphibians requires addi-
tional study (American Society of Ichthyologists and Herpetologists, the Her-
petologists' League, and the Society for the Study of Amphibians and Reptiles
1987).
RADIOTRANSMITTERS
Movements of reptiles and amphibians occasionally
have been monitored using a thread-loaded bobbin that unrolls a trail of
thread as the animal travels (Scott and Dobie 1980). More often, however,
