Conservation and the scarecrow effect: Can human activity benefit threatened species by displacing predators?

• Published in: Biological conservation Vol. 143; no. 9; pp. 2156 - 2163
• Main Authors: Leighton, Patrick A., Horrocks, Julia A., Kramer, Donald L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2010; Kidlington, Oxford: Elsevier Science Ltd; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied ecology; Beaches; Biological and medical sciences; Conservation; Conservation, protection and management of environment and wildlife; Disturbances; Ecotourism; Egg predator; Fundamental and applied biological sciences. Psychology; General aspects; Habitats; Herpestes auropunctatus; Human disturbance; Human influences; Nesting; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Predators; Risk-disturbance hypothesis; Sea turtles; Trait-mediated indirect interactions (TMII); Vegetation; Egg predator; Risk-disturbance hypothesis; Trait-mediated indirect interactions (TMII); Human disturbance; Ecotourism; Herpestes auropunctatus; Carnivora; Endangered species; Egg; Interaction; Conservation; Risk; Wild life; Perturbation; Scarer; Tourism; Vertebrata; Mammalia; Human activity; Predator; Anthropogenic factor; Environmental protection
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2010.05.028

Most wild animals show direct negative responses to human disturbance; however, disturbance may also have positive indirect effects by altering species interactions. In the Caribbean, introduced mongooses ( Herpestes javanicus) are an important diurnal predator of the nests of critically endangered hawksbill sea turtles ( Eretmochelys imbricata). We asked whether daytime visitor activity could benefit hawksbills by reducing mongoose activity in nesting habitat. We used track monitoring sites to measure how mongooses alter their space use in response to fluctuating human beach use and availability of hawksbill nests, and we estimated the indirect impact of human disturbance on nest predation for 5 years of hawksbill nesting. Human activity substantially decreased mongoose use of nesting habitat. Mongoose activity increased with abundance of nests and was lower at the edge than the interior of patches of beach vegetation, but neither factor altered relative sensitivity to disturbance. We estimated that, in addition to deterring mongooses from accessing nests on the open beach, human activity has the potential to reduce predation of nests in vegetation by up to 56% at our site, with the greatest per capita impact at low (<50) visitor numbers. Many forms of human activity negatively affect sea turtles, but our study indicates that there are positive aspects of daytime use of nesting beaches. Optimizing the trade-off between positive and negative impacts of disturbance could provide a useful approach for regulating tourist activity in critical habitat for threatened species.