Abstract
The semi-arid ecosystem on Pinta Island, Galápagos, has experienced woody plant encroachment, likely due to the loss of ecosystem services once provided by the Pinta tortoise and the effects of now eradicated invasive goats. Ecological analog giant tortoises could replicate some lost services, but it is unclear whether they will be effective or how best to implement them. A trial group of 39 adult, non-reproductive, mixed ancestry tortoises were introduced to Pinta Island in May 2010, and their behaviors and interactions with the plant community were monitored following release. Habitat selection differed between phenotypes, with the saddlebacked type most closely replicating Pinta tortoise ecosystem services through selection of areas with high densities of adult Opuntia cactus. Simulations of aggregated tortoise-vegetation interactions indicate that greater tortoise densities could reduce woody plant encroachment through herbivory and trampling. Therefore, introducing reproductive ecological analog giant tortoises is a viable restoration strategy for Pinta Island.