Biodiversity Conservation from the Perspective of Diet Composition of the Domestic Goat ( Capra hircus ) On Socotra Island (Yemen) - What Goat’s Excrements Can Reveal About the Landscape

Abstract

Goats are known as some of the most impactful invasive mammals on islands and are now considered the sixth greatest threat to plant communities worldwide due to uncontrolled and extensive grazing. The negative impact of the growing population of semi-feral animals on endemic plants in Socotra Island (Yemen) is well known. Yet, there is virtually no data on the proportion of individual endangered plant species in the diet of goats. It is also unknown whether and to what extent goats consume non-native plants, and what factors influence the overall composition of their diet. This study is the first to focus on the dietary habits of domestic goats on the island of Socotra using DNA barcoding of plant remains in goat excrements. We hypothesize that goats browse on woody plants, including tree seedlings, mainly during the dry season, as in the rainy season, there are sufficient grass and herbs. Therefore, the dry season is crucial for the survival of woody plant seedlings, when high mortality of saplings is not caused only by drought but also by overgrazing. Our results are consistent with this hypothesis. We found a statistically significant positive correlation between the dry season and woody plants grazing and a negative correlation between altitude and grazing of endemics. The reduction of goat’s abundance on the island is a necessary management measure to ensure the tree protection and their regeneration, which should be accompanied by a change of goat grazing system and active support of tree regeneration.