Florida Key Deer Abundance and Recovery Following New World Screwworm Infestation

Israel D. Parker^1,*, Roel R. Lopez², Nova J. Silvy³, Brian L. Pierce¹, Kate G. Watts⁴, Erin P. Myers⁵, Samantha E.J. Gibbs⁶, Donald S. Davis⁷, Jared T. Beaver², and Alison A. Lund²

¹Texas A&M Natural Resources Institute, College Station, TX 77843. ²Auburn University School of Forestry and Wildlife Science, 602 Duncan Drive Auburn AL, 36830.³Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843.⁴National Wildlife Refuge System, Branch of Refuge Biology, US Fish and Wildlife Service, Portland, OR 97232.⁵Florida Panther National Wildlife Refuge, US Fish and Wildlife Service, Immokalee, FL 34142.⁶Natural Resource Program Center, US Fish and Wildlife Service, Chiefland, FL 32626.⁷Auburn University School of Forestry and Wildlife Science, 602 Duncan Drive Auburn AL, 36830.*Corresponding author.

Southeastern Naturalist, Volume 19, Issue 2 (2020): 179–191

Abstract
An infestation of Cochliomyia hominivorax (New World Screwworm, hereafter Screwworm) was detected in the endangered Odocoileus virginianus clavium (Florida Key Deer) population in July 2016. We assessed the impact of this infestation on Florida Key Deer population abundance and recovery potential. We synthesized historical mortality and population data with new analyses including monitoring of Florida Key Deer mortalities and estimation of abundance on Big Pine Key and No Name Key (islands that support 75% of the Florida Key Deer population). We documented 135 Screwworm-related Florida Key Deer mortalities (~9–20% of the total population) during the Screwworm outbreak (July 2016–January 2017). Most mortalities occurred in the adult male population, as Screwworm flies laid eggs on open wounds sustained from sparring during mating season. The Screwworm incident was contained prior to the 2017 fawning season, which prevented substantial negative impacts on females or fawns. Historical growth rates at similar population levels and sex ratios indicated that, absent other external variables (e.g., Hurricane Irma in September 2017), the population was likely to recover.

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