Biology Reference
In-Depth Information
prejudiced response to incursions of frogs that appear in infested nursery materials.
Success on these three islands was made possible by widespread public awareness
of these pests and the negative impacts brought about by their uncontrolled spread
on Hawaii Island, coupled with frequent surveys of the sites (nurseries and garden
centers of department stores) most likely to receive new incursions. These could be
considered additional examples of successful eradication but long-term vigilance
against reinfestation from rampant nursery populations on Hawaii Island will be
necessary. This is helped by regulatory requirement that all exported shipments
from Hawaii Island nurseries known to be infested with frogs be treated with either
concentrated citric-acid solution or hot-water spray to kill hitch-hiking frogs. Thus,
although successful eradication of coqui populations seems likely to be achieved on
Kauai and Oahu, both islands will be faced with long-term management to maintain
their expensively acquired coqui-free status.
These examples are among the more successful control operations to date,
whether applied across an entire political jurisdiction or just to single islands. More
often, control efforts that initially began with the intent to eradicate soon proved
that goal to be infeasible because population size was initially underappreciated.
Such efforts often seek to couple eradication with the gathering of biological data
useful for understanding the invasion. For example, Nile monitors,
Varanus niloti-
cus
, became established in the area around Cape Coral, Florida, in approximately
1990. In 2002, funding amounting to US$51,000 was obtained to complete what
was anticipated to be a one-year eradication program (T. Campbell, University of
Tampa, personal communication, 2007). However, in the first month of effort it
became obvious that the number of lizards present in the population was far in
excess of what could be removed with the time and funds available. Consequently,
efforts remained focused on gathering data useful for supporting future control
efforts, animals continued to be removed from the population, but eradication was not
achieved. This lizard population continues to expand numerically and geographically,
but governmental control efforts to follow up on the initial knock-down have not been
forthcoming (T. Campbell, University of Tampa, personal communication, 2007).
A virtually identical situation obtains with Burmese pythons,
Python molurus
,
in the Everglades region of South Florida. In 2002, a park biologist became con-
cerned with the large and increasing number of sightings of these snakes. There
had been 21 sightings prior to 2002 and 27 more in that year alone (Snow et al.,
2007b). He consulted outside biologists as to whether an established population
might exist and was advised against that concern - even though Dalrymple (1994)
had already called attention to remarkably high numbers of large constrictors
removed from southern Florida every year. Nonetheless, this biologist continued
to collect data on sightings and all retrieved specimens, and he has clearly dem-
onstrated that a python population is thriving in the park and expanding well
beyond that domain (Snow et al., 2007b). In 2004, it was hoped that the infesta-
tion was sufficiently limited that it might be eradicable; by 2006, it was clear that
was not the case. The large numbers of snakes that are obviously present, their
extensive range throughout a difficult-to-penetrate terrain, their high reproductive
output (up to 100 young/brood), and current lack of effective control methods
