Overview

A combined total of 31 species of aquatic amphibians and reptiles have been introduced into the states encompassed by USFWS Region 5 (Appendix D) of which 20 are species native to the United States but have been transplanted outside their native range, and 11 are species introduced from other countries (referred to as exotic).  Twenty-four percent of the native transplants became established and nine percent of the exotic species introduced into the region have resulted in established populations.

Numbers of Introduced Species and Established Species in Each State
In the Northeast, Massachusetts and Virginia have the most species introduced. Massachusetts has the most species established (Figures 19, 20). All states, except Virginia, in this region have a low proportion of exotic species introduced.

Figure 19. Total number of amphibian and reptile species
(native and exotic) introduced into each state.

Figure 20. Status of amphibian and reptile
species introduced into each state.

Introduction Trends Over Time
Introductions in the Northeast mirror the nation-wide trend of an increase in the number of species introduced since the 1950s (Figure 21).   Both the native transplants and the exotic imports have increased in recent years with the increased popularity in keeping amphibians and reptiles as pets.

Figure 21. Cumulative number of amphibian and reptile
species introduced into the Northeast.

Pathways
The major pathway of amphibian and reptile introductions for all states in Region 5, is pet escape/release (Figure 22). A smaller portion can be attributed to accidental transportation, such as on landscaping plants.  A few, including diamondback terrapins and bullfrogs have been intentionally stocked. The mudpuppy, Necturus maculosus, is thought to have been introduced into Massachusetts and Maine lakes through discarded bait.

Figure 22. Pathways of amphibian and reptile introductions in Region 5.

Geographic Origin of the Introduced Species
The majority of species introduced in the Northeast are native to the United States but transplanted outside their native ranges (Figure 23). Included are various species of frogs, turtles, and snakes.  Of the exotic species, most are from Asia or Central and South America and are associated with the pet trade.

Figure 23. Source regions of introduced amphibians and reptiles in Region 5.