Seabird distribution patterns observed with fishing vessel's radar reveal previously undescribed sub-meso-scale clusters
|Author(s)||Assali Camille1, 2, Bez Nicolas2, Tremblay Yann2|
|Affiliation(s)||1 : Univ Montpellier, UMR MARBEC Marine Biodivers Exploitat & Conservat, Bat 24-CC 093 Pl Eugene Bataillon, F-34095 Montpellier 5, France.
2 : Inst Rech Dev, UMR MARBEC Marine Biodivers Exploitat & Conservat, Ave Jean Monnet CS 30171, F-34203 Sete, France.
|Source||Scientific Reports (2045-2322) (Nature Publishing Group), 2017-08 , Vol. 7 , N. 7364 , P. 10p.|
|WOS© Times Cited||8|
Seabirds are known to concentrate on prey patches or at predators aggregations standing for potential feeding opportunities. They may search for prey using olfaction or by detecting visually feeding conspecifics and sub-surface predators, or even boats. Thus, they might form a foraging network. We hypothesized that conditionally to the existence of a foraging network, the visual detection ability of seabirds should have a bearing on their medium-scale distribution at sea. Using a fishing-boat radar to catch the instantaneous distribution of seabirds groups within 30 km around the vessel, we conducted a spatial clustering of the seabird-echoes. We found 7,657 clusters (i.e. aggregations of echoes), lasting less than 15 minutes and measuring 9.2 km in maximum length (median). Distances between seabirds groups within clusters showed little variation (median: 2.1 km; CV: 0.5), while area varied largely (median: 21.9 km(2); CV: 0.8). Given existing data on seabirds' reaction distances to boats or other marine predators, we suggest that these structures may represent active foraging sequences of seabirds spreading themselves in space such as to possibly cue on each others. These seabird clusters were not previously described and are size compatible with the existence of a foraging network.