Chapter 16 - Galapagos tortoises in a changing climate

Abstract

Over the coming century, climate change is positioned to cause substantial global impacts likely cascading down to every ecosystem. For the Galapagos Archipelago, a warmer and wetter future is expected. What are the ramifications for Galapagos tortoises? Warmer and wetter conditions will likely bring higher growth rates of plants in all ecosystems. This, in turn, may increase food availability and increase the extent of habitat suitable for foraging Galapagos tortoises. Projections based solely on changes in habitat suitability suggest the possibility for tortoise populations to increase by 13%. Increased foraging will likely increase tortoise growth rates, reducing the age at maturity and thereby increasing population growth rates and standing densities. However, these positive influences may be undercut by declines in recruitment due to increased rainfall that could threaten the viability of tortoise eggs. The saddleback form, unique to Galapagos tortoises among living turtles, may devolve under the wetter, greener future conditions predicted archipelago-wide for the Galapagos.