Wilson RP, Liebsch N, Gómez-Laich A, Kay WP, Bone A, Hobson V y Siebert U. 2015. Options for modulating intra-specific competition in colonial pinnipeds: the case of harbour seals (Phoca vitulina) in the Wadden Sea. PeerJ http://dx.doi.org/10.7717/peerj.957