Exotic squirrels in Argentina: the human factor

GUICHÓN, MARÍA LAURA; BENITEZ, VERÓNICA VICTORIA; ALMADA CHAVEZ, SANDRA; MESSETTA, MARÍA LAURA; GOZZI, ANA CECILIA; ZARCO, AGUSTÍN; CASSINI, GUILLERMO HERNÁN; BORGNIA REPETTO, MARIELA; DONCASTER, C PATRICK

Mendoza. Argentina.

Congreso; MC. The 10th International Mammalogical Congress; 2009

GIB-IADIZA; CCT; CONICET; IFM y SAREM

Squirrels of numerous species have been introduced into non-indigenous regions for their ornamental value, as game animals, for their fur, or for trading as pets. The Asiatic Red-Bellied Squirrel Callosciurus erythraeus is the first known introduction of a squirrel into South America, and within 30 years has achieved the status of an established invasion of major proportions. We are studying the life-history traits of the species and the features of the recipient environment that facilitate its rapid and ongoing invasion in Argentina. Association with humans already stands amongst the major determinants of its invasion success. Establishment is facilitated by habitat modification, with woodland patches of exotic trees in rural and urban areas providing suitable habitat for its arboreal habits. Spread is accelerated by translocation and commercial trafficking, followed by escape or release into the wild. The lack of native squirrels in most regions of Argentina and its charismatic appearance encourage an informal pet trade and deliberate releases. Spread is also facilitated by trees and cables along roads, railways, rivers and wind curtains, increasing the chances of long-distance dispersal. Squirrels can establish from low numbers and in highly fragmented habitats, evidenced by the main population originating from <10 individuals, and new satellite populations establishing in recent years. Our projections with a spatially-explicit model forecast a 5-fold increase in area of occupancy under the present regime of no systematic management. Repeated releases of squirrels have led to new foci of invasion in the provinces of Buenos Aires, Córdoba, and Santa Fé. Containment requires disruption of natural and human-aided dispersal. Communication to the general public is required to discourage recurrent liberations and to gain support for management actions. Control should be implemented in small, isolated foci of invasion and in priority patches within the main population, to delay arrival into valuable conservation areas.