Long-term changes in the breeding seasonality of Peruvian seabirds and regime shifts in the Northern Humboldt Current System
|Author(s)||Passuni Giannina1, Barbraud Christophe2, Chaigneau Alexis3, Bertrand Arnaud4, Oliveros-Ramos Ricardo5, Ledesma Jesus5, Castillo Ramiro5, Bouchon Marilu5, Bertrand Sophie4|
|Affiliation(s)||1 : Nelson Mandela Univ, Dept Zool, POB 77000, ZA-6031 Port Elizabeth, South Africa.
2 : Univ La Rochelle, Ctr Etud Biol Chize, CNRS, UMR7372, F-79360 Villiers En Bois, France.
3 : Univ P Sabatier, Lab Etud Geophys & Oceanog Spatiale, IRD, CNES,CNRS,UMR, 14 Ave Edouard Belin, F-31400 Toulouse, France.
4 : IRD, UMR MARBEC, Marine Biodivers Exploitat & Conservat, Ave Jean Monnet,BP 171, F-34203 Sete, France.
5 : Inst Mar Peru IMARPE, Esquina Gamarra & Gen Valle S-N Chucuito, Callao, Peru.
|Source||Marine Ecology Progress Series (0171-8630) (Inter-research), 2018-06 , Vol. 597 , P. 231-242|
|WOS© Times Cited||8|
|Keyword(s)||Onset of breeding, Environmental cues, Oxycline depth, NHCS, Northern Humboldt Current System, Phalacrocorax bougainvillii, Sula variegata, Pelecanus thagus|
In the highly productive Northern Humboldt Current System, 3 seabird species, the Guanay cormorant Phalacrocorax bougainvillii, the Peruvian booby Sula variegata and the Peruvian pelican Pelecanus thagus, commence breeding in austral spring, coinciding with the lowest availability of their prey, the Peruvian anchovy Engraulis ringens. This strategy ensures the matching of increased prey availability when young achieve independence in summer. This pattern was observed during the last decade when anchovy was abundant. However, over the last century, the abundance of anchovy has varied widely due to contrasting interdecadal regimes in oceanographic conditions and fishing activity. We hypothesized that these regime shifts affected the abundance and availability of prey and may have conditioned the breeding seasonality of seabirds. We examined the timing and magnitude of the onset of breeding using dynamic occupancy models and related these parameters to the seasonality of oceanographic conditions, abundance of anchovy and fishing pressure. During a regime of lower anchovy abundance (1977-1990), cormorants showed the highest flexibility, adjusting the timing of breeding from spring to winter and skipping reproduction in the worst conditions. Boobies showed the lowest flexibility, maintaining the same magnitude and timing of onset of breeding in spring. Pelicans showed intermediate flexibility, foregoing breeding during the worst conditions, but maintaining the onset of breeding in spring. The 3 species used sea surface temperature as a cue for the initiation of breeding. Furthermore, given their better diving abilities, cormorants could monitor prey availability changes associated with the reversion in the seasonality of the oxycline depth.