Conflicts between birds and human interests: efficacy of deterring Yellow-legged Gulls Larus michahellis by means of falconry

Abstract

Fernández-García, J.M., Gracianteparaluceta, A., Garaíta, R. 2015. 2015. Conflicts between birds and human interests: efficacy of deterring Yellow-legged Gulls Larus michahellis by means of falconry. Ecosistemas 24(2): 70-75. Doi.: 10.7818/ECOS.2014.24-2.11

Although an increasing number of conflicts between urban dwelling gulls and human activities are being reported around the world, few assessments on the success of deterring techniques have been published. We assessed the effectiveness of a Yellow-legged Gull Larus michahellis deterring service using falconry at a landfill site in Guipúzkoa (northern Spain) during the winter 2009-2010. We checked four types of indicators (abundance, behaviour, diet and dispersion of the gulls), searching for quantitative changes before and after the implementation of falconry. The reduction in the number of gulls at the landfill was immediate, drastic (-92 %) and persistent, and thereafter we did not record landing or resting gulls inside the site. The frequency of occurrence of waste remains in pellets was reduced (from 54 % to 27 %), while frequency of occurrence of the marine crab Polybius henslowii increased (from 45 % to 65 %). The proportion of dispersing gulls increased substantially (from 27 % to 91 %). The success of the falconry service was evidenced under particular conditions, namely the medium size of the landfill site, the raptor species used (hybrid falcons Falco cherrug x Falco rusticolus) and the constant presence of the falconer every day and throughout light hours. In view of our results and other assessments, these factors should be taken into account if such a persistent and high effectiveness is to be achieved elsewhere.