John Woolard

Monitoring predators to optimize their management for marine turtle nest protection

Abstract The fundamental conservation focus for Hobe Sound National Wildlife Refuge (HSNWR), Florida is to provide protected nesting habitat for three threatened or endangered marine turtle species. Turtle nesting and hatching spans from early spring to fall each year. Left unchecked, nest predation by raccoons and armadillos would destroy most turtle nests. Predators are removed to protect nests, primarily with a one person-month contract using control specialists. We maximized the efficiency of predator removal by using a passive tracking index to: (1) optimize the timing and strategy for predator removal, (2) minimize labor by identifying areas where predator removal would have maximal effect, (3) examine beach invasion patterns of predators, (4) assess efficacy of removal efforts, (5) provide anticipatory information for future turtle nesting seasons, and (6) serve as a detection method for invasion by additional species known to depredate turtle nests. An overall nest predation rate of 28% resulted, whereas the rate for the previous year was 42% when the same level of contracted predator removal was applied, but without monitoring predators. One year before that, predator removal was done without contracts with specialists and predation was 48%. Up to 95% of the nests were destroyed in the years prior to predator removal. Using 2000 data on numbers of nests, clutch sizes, and emergence rates, we estimated the number of hatchlings that would have been lost assuming that the predation rates observed from four predator removal scenarios at HSNWR would have occurred in 2000. Historical predation of 95% would have resulted in 120,597 hatchlings lost in 2000. Predator removal as part of regular refuge operations would have reduced this number to 62,481. Addition of a contract with control specialists would have further reduced the number lost to 53,778. Addition of temporal and spatial monitoring for predator removal reduced losses to 36,637.

Dramatic reduction in predation on marine turtle nests through improved predator monitoring and management

We describe improvements to monitoring/ indexing methodology for predators of marine turtle nests on the east coast of Florida, and the resulting marine turtle conservation implications from integrating the methodology into predator management. A strip transect from dune line to the shore improved an already successful design for monitoring raccoons, and was also sensitive for armadillos. The data were integrated into predator management operations to effectively and efficiently remove the species responsible for turtle nest predation. Tracking plot data also served to validate predator patterns of behavior relative to turtle nesting and improve prospects for preventive predator management strategies. Perhaps the most important finding is that predation at a beach historically suffering nearly complete losses (95%) of marine turtle nests had nest predation reduced to nominal levels (9.4%). For 2002 this predation level represents an estimated 69,000 additional hatchling turtles produced over historical predation rates, and 16,700 additional hatchlings over the previous lowest predation rate.

Prevalence and economic value of feral swine damage to native habitat in three Florida state parks

SUMMARY Feral swine (Sus scrofa) adversely affect the environment in many of the places where they have been introduced. Such is the case in Florida, but quantification and economic evaluation of the damage can provide objective bases for developing strategies to protect habitats. Swine damage to native wet pine-flatwoods at three state parks in Florida was monitored from winter 2002 to winter 2003. Economic valuations of damage were based on the US dollar amounts that wetland regulators have allowed permit applicants to spend in attempts to replace lost resources. The parks had different swine management histories and the damage patterns differed among them over time. Swine were intensively removed in 2000 from the first park, and it initially had the lowest habitat damage at 1.3%, but as a result of natural and artificial population growth this damage rose to 5.4% by the conclusion of the study, and was valued at US

Monitoring changes in feral swine abundance and spatial distribution

19 193‐36 498 ha � 1 . The second park had no history of swine harvest and, over the monitoring period, damage escalated from 2.6%‐6.4%, with an associated value of US

Rapid assessment for a new invasive species threat: the case of the Gambian giant pouched rat in Florida

22 747‐43 257 ha � 1 . Swine were managed as game animals in the third park prior to its inclusion into the state parks system in 2000. Within this park, the proportion of area damaged decreased from 4.3%‐1.5%, valued at US

Damage reduction estimates and benefit-cost ratios for feral swine control from the last remnant of a basin marsh system in Florida

5 331‐10 138 ha � 1 . This

Impacts from control operations on a recreationally hunted feral swine population at a large military installation in Florida

Swine ( Sus scrofa ) have been introduced in many places throughout the world, and in many places they adversely affect the environment, economically impact agriculture, and/or harbour diseases transmittable to domestic livestock or humans. An easily applied method to assess their abundance is an important need for their management. To monitor efficacy of a swine control programme in Florida, data from passive tracking plots provide an index of feral swine abundance. The same track data coupled with plot locations to numerically describe the spatial pattern of swine activity gave an index of pervasiveness, and a simple rate of interception of damage sites to index damage was used. The assessments were conducted in January, May, and August 2000 in Jonathan Dickinson State Park, Florida, USA. Between the first two assessments a swine control programme removed 25 feral swine from the 8.3 km 2 study area, after which the value of the passive tracking index was reduced by 81% and the fresh damage index by 89%, while the index of spatial pattern (pervasiveness index) showed only a small localized concentration after control. In the three months following the second assessment, Park personnel removed three additional swine from the study area, and a follow-up assessment indicated slightly less swine activity than immediately after the post-control assessment, however the index of pervasiveness showed a similar spatial pattern of activity as the initial assessment, possibly indicating re-invasive pressure. The passive tracking plots proved to be an uncomplicated, easily applied means to gather data for assessing and comparing swine abundance and distribution.

An ideal combination for marine turtle conservation: exceptional nesting season, with low nest predation resulting from effective low-cost predator management

The Gambian giant pouched rat (Cricetomys gambianus) is a large rodent that has established a breeding population in the Florida Keys. Should it successfully disperse to mainland Florida, it could continue spreading through much of North America where significant negative ecological and agricultural consequences could result. We rapidly developed the information for implementing an efficient and successful eradication program before dispersal to the mainland occurs. This included development of monitoring and indexing methods and their application to define the animals range, the development of baits attractive to Gambian giant pouched rats, efficacy testing of toxicants, and development of bait-delivery devices that exclude native animals. Gambian giant pouched rats appeared confined to the western two-thirds of Grassy Key, but have dispersed across a soil-filled causeway west to Crawl Key. We identified preferred habitat characteristics and potential dispersal pathways. We developed photographic and tracking tile methods for detecting and indexing Gambian giant pouched rats, both of which work well in the face of high densities of non-target species. We identified a commercial anticoagulant bait and we developed a zinc phosphide (an acute toxicant) bait matrix that were well accepted and effective for controlling Gambian giant pouched rats. We also developed a bait station for delivering toxic bait to Gambian giant pouched rats without risk to native species. We consider that the criteria are met for a successful eradication to commence.

Adaptive and economic management methods for feral hog control in Florida

The introduction of swine ( Sus scrofa ) has adversely affected the environment of many natural habitats throughout the world. Basin marshes are dwindling ecosystems in Florida that are especially vulnerable to damage by feral swine. In January 2003, the estimated amount of swine damage to the exposed portion of the last remnant of a basin marsh system in Savannas Preserve State Park (SPSP) was 19% (an area of 5 ha). Economic valuations for the swine damage were based on the monetary amounts that wetland regulators have allowed permit applicants to spend in mitigation attempts to replace lost wetland resources. In 2003, the area of natural habitat damaged by swine had a total value of US

THE PATH TO ERADICATION OF THE GAMBIAN GIANT POUCHED RAT IN FLORIDA

1 238 760–4 036 290. The SPSP implemented a contract for swine control throughout 2003 in all areas of the Park. The damage to the basin marsh was re-estimated in January 2004, after swine removal. The damage sampling transects remained the same as the 2003 survey, but damage was significantly reduced, with 31% of sampling transects showing damage in January 2004 versus 92% in January 2003. Similarly, the total area of swine damage had decreased to 0.95 ha, and the value of the lost habitat had been reduced to US