PROJECT GOAL: Quantify the benefits and costs of NWRC products and Wildlife
Services activities that aim to mitigate the impacts of wildlife diseases,
wildlife damage to agriculture and natural resources, and wildlife risks
to public health/safety.
Project Accomplishments 2006--Monitoring and Tracking:
Gambian Giant Pouched Rats in the Florida Keys
The Gambian giant pouched rat (GGPR) has become an invasive species
of concern for the State of Florida. An NWRC researcher worked with
Florida WS in 2006 to develop information for planning the species’
eradication from Grassy and Crawl Keys, where it is currently established.
A pilot eradication campaign on Crawl Key, employing population monitoring
methods developed by NWRC, was carried out in spring of 2006.
Recent camera surveys indicated no GGPR survival on Crawl Key following
Hurricane Wilma and the pilot eradication effort. As a result, eradication
efforts will now focus on the primary population on Grassy Key. The
first step in the eradication process will be to monitor Grassy Key
using a camera-indexing methodology cooperatively developed by NWRC
and WS Operations personnel. This setup will determine current GGPR
distributions and relative abundances throughout the island. Subsequent
steps this fall will include the construction and deployment of bait
stations especially designed to exclude native species. Bait-station
density will be based on the results of the camera survey, with a higher
density of bait stations in areas where GGPRs are found. Prebaiting
will be done at all bait stations with nontoxic bait to acclimate GGPRs
prior to using toxic bait.
The researcher has also been working with economists from the U.S.
Department of Interior’s U.S. Geological Survey who are attempting
to model this invasive species' impacts should it escape the Keys and
become established on the mainland. Work has focused on developing methods
to place monetary values on imperiled natural resources, such as rare
species and habitats. GGPRs likely would negatively impact agriculture
through direct crop losses, contamination of harvested crops, reduced
marketability of damaged produce, and contamination and consumption
of livestock feed. GGPRs also could negatively impact populations of
some threatened and endangered species, especially the endangered Key
Largo woodrat, the Key Largo cotton mouse, and the Lower Keys marsh
rabbit. GGPRs also have been associated with a variety of pathogenic
diseases that could be spread to humans, livestock, or other wildlife.
Dramatic Reduction in Swine Damage to an Imperiled Habitat
An NWRC researcher collaborated with Florida WS and Eglin Air Force
Base (EAFB) Natural Resources staff on studies to assess the amount
and value of damage to imperiled habitats, and the efficacy of control
measures beginning in 2003 through 2005. Only 1% of Florida's seepage
slopes remain, with EAFB containing some of the largest tracts. Feral
swine damage is among the greatest threats to this wetland habitat.
Before they initiated swine control, the research team found that areas
open to hunting had a lower percent of seepage-slope area damaged (10.9%)
than areas closed to hunting (25%). However, after only 8 months of
control in only the unhunted areas, damage dropped to just 7.2%. Control
in closed areas also impacted the open hunting areas not receiving control
(5.6%) to such an extent that damage levels in the open and closed areas
could not be distinguished statistically.
Another year of control brought damage in the closed area down to 5.6%,
while the control-free open hunting area dropped to 4.3%, again indistinguishable
from the controlled portion. Although it was applied only to the closed
hunting area, control also reduced damage in the open hunting area,
as swine move freely among areas. Precontrol, the combined value of
swine damage to seepage slopes in open and closed hunting areas was
$5.3 million. After 1.7 years of control, losses were reduced by nearly
$4 million. The benefit–cost ratio over those 1.7 years of control
was a noteworthy 27.5, meaning that every $1 invested yielded $27.50
worth of benefits. The economic benefits of control exceeded costs 55.2-fold
the first year, when control's greatest impact would be expected.
The work at EAFB concluded with a training session provided by a Georgia
Wildlife Services wildlife disease biologist on tissue-sampling methods
for testing swine for brucellosis, PRV, and CSF.
Project Goal and Objectives