Distribution and spread of an introduced insular population of red-bellied squirrels (Sciurus aureogaster) in Florida

Abstract

Introduced populations of species pose one of the greatest threats to the persistence of native species. Documentation of distribution, range expansion and habitat use of introduced populations are key components of developing effective management strategies for the control and eradication of invasive species. In 2006 and 2007, we surveyed four islands in Biscayne National Park for nests to evaluate the presence of redbellied squirrels (Sciurus aureogaster) and the distribution and index of dispersion of their nests in the Florida Keys archipelago within the Atlantic Ocean. Red-bellied squirrels were initially introduced to Elliott Key, Florida, USA in in 1938. We documented evidence of squirrels on two additional islands, Sands Key and Old Rhodes Key, which adds to concerns of spread of this introduced squirrel to areas with endangered endemic insular mammals. Squirrel nests were documented only in mixed-hardwood forest, and nests had a clumped distribution within this forest type. Range expansion was a chief concern to the National Park Service, as continued spread could result in squirrels exiting the park, and prompted management action. Understanding nest site selection and distribution was critical for developing an eradication strategy for the introduced population of red-bellied squirrels from south Florida.

Patterns of Non-Native Species Introduction, Spread, and Ecological Impact in South Florida, the World's Most Invaded Continental Ecoregion

“…Not all non-native species are restricted to urban habitats, however. Introduced populations of Red-bellied squirrel (Rubrisciurus rubriventer) and Argentine black-and-white tegu, for instance, are both primarily associated with areas with greater tree cover (Klug et al 2015, Palmer 2012. Similarly, while the non-native herpetofauna of South Florida primarily resides in urban areas, this assemblage has demonstrated a capacity for utilizing urban greenspaces dominated by native vegetation (Clements et al 2019).…”

A Review of Common Factors among Successful and Failed Efforts to Eradicate Invasive Vertebrates in Florida

“…The squirrels were spotted on neighboring islands of Adams Key and Sands Key as well in the following years. Surveys in the mid-2000s found over 200 dreys (stick nests) on Elliot Key and detected the presence of Mexican Gray Squirrels on neighboring Sands Key and Old Rhodes Key (Palmer 2010). In 2007, the National Park Service (NPS) collaborated with the Caribbean Exotic Plant Management team to begin an eradication effort, focusing first on the populations residing on Old Rhodes Key and Sands Key, before moving to Elliot Key where the main population resided.…”

Sciurus aureogaster (Rodentia: Sciuridae)

“…S. aureogaster was common across much of the 10.4 km 2 tropical island within 15 years and reached nearby Adams and Sands keys (Schwartz 1952;McGuire 1969, 1975;Brown 1969Brown , 1997. Although Hurricane Andrew, a category 5 hurricane, submerged the island under a 6 m storm surge in 1992 (Ogden 1992), squirrels survived the storm ) and spread to nearby Sands Key and Old Rhodes Key, but no longer occurred on Adams Key (Palmer et al 2014). An effort to remove this introduced population from the islands of south Florida began in 2008, and 49 individuals of both color morphs had been removed from Elliott Key and Sands Key by 2012 (Pernas and Clark 2011;Palmer 2012).…”