Global Ecology & Conservation

Abstract

Feeding wildlife as a tourist activity is a growing industry around the world. However,providing alternative food sources can affect wildlife ecology and behaviour. In this study,we combined animal-borne cameras onfive sub-adult green turtles (Chelonia mydas) from the Bahamas with a global review to directly assess impacts of provisioning on thebehaviour of an endangered marine species for the first time. Descriptive evidence from video footage, with videos included in the manuscript, showed that the tagged turtles spent 86% of their time in shallow water (<1.5 m) at a provisioning site. All individuals observed, both tagged and untagged, actively approached people and boats, with up to 10 turtles recorded feeding on squid offered by tourists at one time. During these feeding events, multiple accounts of atypical aggressive behaviour such as biting and ramming conspecifics were recorded. Furthermore, a review of online sources revealed the wide-spread significance of turtle feeding as a tourist activity in at least 20 locations within the global range of green sea turtles, as well as five locations with regular provisioning ofeither loggerhead (Caretta Caretta) or hawksbill (Eretmochelys imbracata) turtles. At the majority of the locations, turtles were fed animal matter such as fish scraps and squid. Although sample size limited quantitative analyses, we found indications of relatively high growth rates of two tagged turtles and low seagrass intake rates of all five tagged turtles.Therefore, our results emphasize the need to further investigate the impacts of turtle provisioning on natural foraging behaviour, ecosystem functioning as well as turtle growth rates and health implications. Supplemental feeding may increase habituation and dependency of turtles on humans with risks for turtle conservation. The innovative use of animal-borne camera technology may provide novel insights to behavioural consequences of human-wildlife interactions that can aid in the management and conservation of rare or endangered species

Highlights

• Review on coralita invasion (Antigonon leptopus) on islands yielded 46 papers.

• Main influencing factors are overgrazing, human disturbance and climate change.

• Very little empirical evidence on factors influencing invasivity.

• Invasion by coralita is a symptom of land degradation, not the cause.

• Best management options are forest conservation, reforestation and grazer exclusion.

Abstract

The Caribbean islands are a hotspot for biodiversity, harboring 2.3% of the world's endemic plant species on just 0.18% of the earth surface. Due to habitat degradation, invasive species are considered a major environmental problem on these islands. The vine coralita (Antigonon leptopus Hook. & Arn.) is the most abundant invasive species on the Dutch Caribbean island of St. Eustatius. Forming thick, monospecific carpets, it is seen as a threat to biodiversity. Insight is needed as to the ecological and social factors that influence the local ecosystem's vulnerability for invasion by A. leptopus. We used a Social-Ecological Systems framework for a literature review to answer our research questions: 1) What is currently known about the social and ecological factors that make an ecosystem vulnerable for invasions by invasive species and A. leptopus in particular? 2) How much empirical evidence is provided to back up the claims made in the reviewed literature? and 3) Which research and management priorities can be identified for St. Eustatius based on this analysis? Our review yielded 46 relevant documents, of which only 21 were peer-reviewed scientific articles. We assessed the level of empirical support for each of the factors mentioned in the reviewed literature and used these to shape our conceptual Social-Ecological model. Three major factors appeared to be responsible for the vulnerability of ecosystems for A. leptopus invasion: overgrazing by feral animals (16 papers), anthropogenic disturbance (19) and climate change (6). Empirical evidence for the relation between A. leptopus invasion and social and ecological factors is scarce: only anthropogenic disturbance and overgrazing were supported by quantitative data (three papers each). Our literature review also indicates that the invasion of A. leptopus on St. Eustatius is more a symptom than a cause in itself. Efforts to manage coralita by chemical or manual removal are futile if not combined with active vegetation restoration and grazer exclusion. Conservation efforts have led to an increase in forested areas on the island, in which coralita is not present. More experimental research is needed to inform policy and management decisions, preferably on the effects of feral grazer exclusion and shading by native trees on the recovery of natural vegetation in areas now dominated by coralita.