Biology Reference
In-Depth Information
range in which the egg mass was found; all captive animals were destroyed; and all
tadpoles and metamorphs captured at the original site were destroyed (Whitaker
and Bejakovich, 2000). Extreme rains during the survey period led to flooding that
scoured the stream having the original infestation. All uncaptured tadpoles appear
to have been destroyed by that event and no further animals have been found sub-
sequently. Hence, the eradication effort, undertaken at a very early stage of incur-
sion, has been declared a success.
I have been able to find only a few other claims for (relatively) rapid eradica-
tion of newly established reptiles or amphibians. The first is the statement by Ota
et al. (2004a) that
Bufo gargarizans
, introduced to a site in northern Okinawa,
was eradicated from that site (and, by implication, from the island) by a private
effort extending from the late 1980s through the mid 1990s. This project involved
removal of adults, eggs, and tadpoles, but details on the adopted methodologies
were not provided.
The second involves bullfrogs,
Rana catesbeiana
, first noticed at a couple of
adjacent ponds in East Sussex, England in 1996. By 1999, hundreds of tadpoles
were evident, and an eradication project was begun. This involved survey of 53
ponds and fencing of the 7 found to be infested. Within these ponds, frogs were
removed by use of aquatic traps, pit-fall traps, hand-capture, shooting, and elec-
trofishing (Banks et al., 2000; J. Foster, Natural England, personal communication,
2008). At the end of 1999, the ponds were drained so as to exterminate remaining
tadpoles, allow surviving frogs to be located and captured, and allow the pond silt
to be excavated and buried under compact soil. After several years of effort, this
operation netted a total of almost 12,000 bullfrogs, and eradication of these popula-
tions appeared successful (Fisher and Garner, 2007). However, bullfrogs have
recently appeared at another locality in Great Britain (R. Trout, Forest Research,
personal communication, 2007), control of this population is ongoing (J. Foster,
Natural England, personal communication, 2008), so complete eradication from the
island is not yet assured, though is seemingly feasible.
Similarly, several populations of bullfrogs have been eradicated from Germany.
One population was eradicated from Celle, Germany, partly by means of hunting
with shotguns (C.R. Boettger, 1941), and a second population near Böblingen
exterminated partly by means of electrofishing for tadpoles and by pond fencing
(Laufer and Waitzmann, 2002; Veenvliet and Veenvliet, 2002; Ficetola et al.,
2007b). Another pond in Meckenheim was fenced and drained, and animals
removed (Veenvliet and Veenvliet, 2002), again resulting in eradication (Ficetola
et al., 2007b). A fourth population was exterminated from Kiel by freezing
weather (Veenvliet and Veenvliet, 2002). Eradication of the same species from a
pond in the Netherlands was achieved by capturing tadpoles (Veenvliet and
Veenvliet, 2002).
Lastly, three isolated populations of
Xenopus laevis
appear to have been success-
fully eradicated in the United States. The first population was poisoned; the second
inhabited ponds at a fish hatchery, which were drained one autumn so that all
animals froze over the winter; the third was removed by trapping and may have
been assisted by severe freezing weather (Tinsley and McCoid, 1996).
