Feral Swine

Who let the hogs out? In Florida, it originally was the Spanish explorer Hernando de Soto about a half millennium ago in 1539 who introduced feral swine (Sus scrofa) to Florida (Towne and Wentworth 1950), and many additional introductions have followed since. This species has the greatest reproductive potential of all free-ranging large mammals in the United States (Wood and Barrett 1979; Hellgren 1999), which combined with a general absence of large predators over much of their range results in continued population increases and range expansions. Swine are well-known for their depredations on crops, livestock and wildlife (e.g., Choquenot 1996; Seward et al. 2004; USDA 2002). In addition, feral swine in Florida have been documented to harbor as many as 45 parasites and infectious diseases (Forrester 1991).

Feral swine are a recreational game animal in Florida, and consequently would not be targeted for eradication (even if that was possible). Furthermore, some claim they are a vital food source for the highly endangered Florida panther (Maehr et al. 1990) (Felis concolor coryi). Conversely, feral swine are also a threat to the Florida panther through transmission of pseudorabies virus, as prey-to-panther transmission has been documented to result in the death of the panther (Glass et al. 1994).

The negative environmental impacts of feral swine often require intensive local control. A premium is placed on sanctuaries for protection and preservation of habitats and species in Florida, especially because much of the natural habitat in Florida has been lost to development. There is an ongoing battle in many parts of the state to protect rare habitats from swine damage (e.g., Florida Natural Areas Inventory 1990). Feral swine in Florida have contributed to the decline of at least 22 plant species and 4 species of amphibians listed as rare, threatened, endangered, or of special concern (USDA 2002). Control efforts typically concentrate on conserving special habitats or species, especially in parks and refuges.

Considerable applied research in Florida has been directed towards development of practical in-field methods for implementing, enhancing and evaluating swine removal for resource protection (Engeman et al. 2007b). Methods have been developed for characterizing swine distribution and relative abundance (Engeman et al. 2001, 2007c), and for assessing damage levels in a variety of habitats (Engeman et al. 2003, 2004b, 2007c). An important complement to estimating damage levels was development of credible means to monetarily value their environmental damage (Engeman et al. 2004a). The ability to place monetary values on damage allows the results of management actions to be evaluated in the same metric (dollars) as management expenses. Universally, economic analyses have shown the benefits for swine removal to be remarkable compared to management costs (Engeman et al. 2003; 2004b; 2007c), and to also supersede habitat conservation benefits derived from hunting (Engeman et al. 2007c).

The ability to value the habitat resource provides an effectual economic management tool for evaluating conservation approaches. Economic analyses can greatly assist managers on how to most efficiently and effectively allocate limited funds towards habitat conservation. Ultimately, many conservation funding decisions are made on a political level by people without high levels of training or expertise in biological sciences. While it is essential to obtain high-quality data to understand the biological impacts of management efforts, placing conservation issues in an economic context can greatly enlighten the political decision making process on swine removal and has been a driving force for expanding conservation efforts through swine removal (Engeman et al. 2007b).

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