Identifying plausible scenarios for the establishment of invasive Burmese pythons (Python molurus) in Southern Florida

Abstract

Successful invasions of secretive alien species often go unrecognized until spread has exceeded the point where control or eradication is feasible. In such situations, understanding factors that contributed to establishment can be critical to preventing subsequent introductions of previouslysuccessful invaders or ecologically similar species. The Burmese python (Python molurus bivittatus), a native to Southeast Asia, is abundant in the pet trade and is now well-established in southern Florida. Although there can be little argument that the ultimate source of Florida pythons was the pet industry, there has been limited consideration of biological support for scenarios that may have lead to their establishment. In this study we use information on python capture rates and biologically-derived population growth models to evaluate the plausibility of various scenarios for python establishment. Our results indicate that scenarios involving relatively recent establishment (post-1990) require large numbers (100-1,000) of founders or unrealistically high juvenile survivorship. Intentional simultaneous release of large numbers of pythons is unlikely and accidental release of large numbers of founders is inconsistent with the spatial and temporal pattern of pythons captures in the region. We conclude that the most parsimonious scenario for establishment of pythons in Florida involves the release of a relatively small number of founders prior to 1985. Our results demonstrate that for pythons and other species with low inherent detection probabilities, early action during incipient phases of an invasion is critical and understanding likely introduction scenarios is important for preventing similar situations from occurring elsewhere or with other species.

Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park

“…First, the timing of the python proliferation in ENP (19) coincides with reductions in mammal abundances. Second, spatial variation in encounter rates of mammals correlates strongly with the spread of pythons throughout ENP and surrounding areas.…”

Evaluating GPS biologging technology for studying spatial ecology of large constricting snakes

“…Burmese pythons have likely been established and breeding in ENP since the mid-1980s [35]. Their remarkable crypsis makes them impossible to study by direct observation [36], so most of what we know about their movement patterns and habitat selection is based on VHF radio tracking in ENP [18,32,37].…”

A reassessment of historical records of avian introductions to Australia: no case for propagule pressure

“…Numerous examples exist of species introductions that have led to serious ecological and economic consequences (e.g. Savidge 1987;Willson et al 2011). These consequences may include disruption of fire regimes, disease and pest problems, loss of harvested natural resources and indirect effects (Mooney 2005).…”

“…A reliance only on propagule size could mislead analyses of potential invasive species. Indeed, several successful invaders originated from small propagules (e.g., Simberloff 2009;Van Houtan et al 2009;Willson et al 2011) and other species failed to become established despite releases of large numbers (e.g. Labisky 1961; Peacock and Abbott 2010).…”