Poaching vs. patrolling: effects on conservation of Cory’s Shearwater Calonectris diomedea borealis colonies

Abstract

SummaryNegative effects of poaching on seabird populations are not usually evaluated quantitatively when assessing seabird colony conservation status, nor are they generally considered a major concern. We demonstrate that poaching is still intense in the Canary Islands, and has negative consequences for the conservation of seabird colonies. We quantified the effects of poaching of Cory’s Shearwater fledglings on breeding success on different islands in the Canaries, comparing colonies that suffer from intense, medium, or no poaching. Poaching reduced the breeding success of affected colonies to almost a third, potentially causing the future extinction of the colony. Only colonies with intense wardening campaigns reached high values of reproductive success, showing that government surveillance in conjunction with volunteers from different NGOs is a very effective approach in reducing poaching. A population sensitivity analysis was also conducted to provide data on the factors that most affect the performance of the model. Although population growth and mean final population size varied with increases and decreases in mortality and carrying capacity, only harvesting resulted in a probability of 100% of extinction in 20–40 years. To promote seabird conservation in regions such as the Canary Islands, a core archipelago for seabird species in the Atlantic, poaching control should be elevated by society to a level of urgency, requiring dedicated funding and mobilisation of experts and volunteers to adequately address it through education, prevention and enforcement.