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Open Access Publications from the University of California

Assessing potential for using zinc phosphide bait to control nutria on Louisiana coastal marsh


Nutria are large semi-aquatic rodents native to South America. Nutria were first introduced to the United States because of their fur, and some populations remain economically important to the fur industry. Accidental and intentional releases have permitted them to establish in wetlands across the United States. Burrowing and foraging by nutria often inflict severe damage and can be devastating to native vegetation. Nutria are recognized as at least a contributing factor to the decline of native Louisiana coastal marsh. Management plans to reduce impacts require reducing nutria populations, or where possible, eliminating them from target sites. At present, public hunting and trapping encouraged by an incentive payment program are primary approaches to reduce unwanted populations. However, alternative tools, including toxins, need to be assessed for possible use. Previous studies assessing zinc phosphide baiting have addressed nutria control on open waterways. Considerable data can be extrapolated from these prior studies and applied to baiting on coastal marshes. However, animals may respond differently to baits and baiting strategies applied to coastal marsh. We conducted a series of studies to assess the potential for developing a feasible strategy to suppress nutria populations with zinc phosphide bait on Louisiana coastal marsh. Tetracycline and metallic flakes show promise as tools for studying nutria foraging behavior. Nutria activity on rafts was marginal, probably because of their access to native vegetation. Simple audio, olfactory, and ocular cues tested as attractants to entice nutria to bait station showed marginal efficacy. Olfactory stimuli demonstrated the most potential for developing future attractants.

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