Historical ecology of the Swan Islands (Islas del Cisne) chronicles long-term anthropogenic changes in the Western Caribbean

Abstract The Swan Islands in the western Caribbean Sea are two of the most remote islands in the region given their diminutive size, distance from land masses, relative isolation from larger human settlements, and lack of accessibility historically. Despite these features, they have been highly sought out by a succession of explorers, naturalists, and biologists since the late 1800s under the guise of studying “pristine” natural places seemingly unspoiled by humans. Here we draw on a rich compendium of historical resources to provide the first synthesis of these early observations which have left a credible record of ecological changes from the pre-contact period to the present. Our detailed analysis shows that, despite their remoteness, these islands have succumbed to a host of deleterious human activities coupled with a series of catastrophic natural events. We find that these effects were minimal or non-existent during the early stages of Indigenous settlement and first European incursion, with only a brief period of localized human impacts in the mid-to late-1600s. However, centuries later in the 1850s, anthropogenic change dramatically accelerated, resulting in widespread deforestation; the introduction of invasive plants and animals; loss of seabirds and turtle nesting beaches; and the extinction of endemic species of reptiles, land snails, and a rodent. These changes contributed to a degradation of the surrounding marine environment which, coupled with severe overfishing and catastrophic natural events, culminated in a rapid collapse of coral reefs after 2007. Our findings show that an understanding of the long-term historical ecology of these unique and vulnerable islands offers valuable insights for the development of a practical and suitably ambitious strategy for their future management and restoration.