A Bird-Eye View on the Spatio-Temporal Variability of The
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A bird-eye view on the spatio-temporal variability of the seasonal cycle in the Northern Humboldt Current System : the case of Guanay cormorant, Peruvian booby and Peruvian pelican Giannina Paola Passuni Saldana To cite this version: Giannina Paola Passuni Saldana. A bird-eye view on the spatio-temporal variability of the seasonal cycle in the Northern Humboldt Current System : the case of Guanay cormorant, Peruvian booby and Peruvian pelican. Ecosystems. Université Montpellier, 2016. English. NNT : 2016MONTT161. tel-01686594 HAL Id: tel-01686594 https://tel.archives-ouvertes.fr/tel-01686594 Submitted on 17 Jan 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Délivré par l’Universit é de Montpellier Préparée au sein de l’école doctorale GAIA : Biodiversité, Agriculture, Alimentation, Environnement, Terre, Eau Et de l’unité de recherche Marine Biodiversity, Exploitation and Conservation Spécialité : Ecosystèmes et sciences agronomiques Présentée par Giannina Paola Passuni Saldana A bird-eye view on the spatio-temporal variability of the seasonal cycle in the Northern Humboldt Current System: the case of Guanay cormorant, Peruvian booby and Peruvian pelican Soutenue le 15 avril devant le jury composé de M. Ronan FABLET, Professeur, Universite de Rapporteur Bretagne Occidentale M.Daniel ORO, Directeur de Recherche, Consejo Rapporteur Superior de Investigaciones Cientificas M. Etienne DANCHIN, Directeur de Recherche, Examinateur CNRS M. Alexis CHAIGNEAU, Chargee de Recherche, Examinateur IRD M. Thierry BOULINIER, Directeur de Recherche, Examinateur CNRS M.Christophe BARBRAUD, Charge de Recherche, Co-directeur de these CNRS Mme.Sophie BERTRAND, Charge de Recherche, Directrice de these IRD 㻌 㻌 㻌 㻌 To the all hard working women 㻌 㻌 㻌 㻌 Aves estercolarias de las islas, multiplicada voluntad del vuelo, celeste magnitud, innumerable emigración del viento de la vida, cuando vuestros cometas se deslizan enarenando el cielo sigiloso del callado Perú, vuela el eclipse. Oh lento amor, salvaje primavera que desarraiga su colmada copa y navega la nave de la especie con un fluvial temblor de agua sagrada desplazando su cielo caudaloso hacia las islas rojas del estiércol. Yo quiero sumergirme en vuestras alas, ir hacia el Sur durmiendo, sostenido por toda la espesura temblorosa. Ir en el río oscuro de las flechas con una voz perdida, dividirme en la palpitación inseparable. Después, lluvia del vuelo, las calcáreas islas abren su frío paraíso donde cae la luna del plumaje, la tormenta enlutada de las plumas. El hombre inclina entonces la cabeza ante el arrullo de las aves madres, y escarba estiércol con las manos ciegas que levantan las gradas una a una, raspa la claridad del excremento, acumula las heces derramadas, y se prosterna en medio de las islas de la fermentación, como un esclavo, saludando las ácidas riberas que coronan los pájaros ilustres. (Phalacro-corax XXII, Canto General. Pablo Neruda) 㻌 㻌 Abstract The Northern Humboldt Current System (NHCS) is a place of a high biological activity due to an intense coastal upwelling. It supports one of the biggest forage fish populations, the Peruvian anchovy, and the world-leading monospecific fishery in terms of landings. The NHCS also hosts large, although variable, seabird populations, composed among others by three guano-producing sympatric species: the Guanay cormorant ( Phalacrocorax bougainvillii ), the Peruvian booby (Sula variegata ) and the Peruvian pelican ( Pelecanus thagus ), which all feed primarily on anchovy. In this work we reviewed the fluctuations of these three seabird populations, focusing on the seasonal cycle of their breeding, to address the following questions: How different are the seasonality of reproduction among species? To what extent may they be plastic in space and time? What from the natural environment and the anthropogenic activities impact more the breeding of seabirds? We addressed these questions using the monthly occupancy of breeders (1) in >30 Peruvian sites between 06°S and 18°S and from 2003 to 2014; and (2) in one site during three decadal periods (1952-1968, 1972-1989, 2003-2014). We also used environmental covariates from satellite and at-sea monitoring such as oceanographic conditions, prey abundance, availability and body conditions, and fisheries pressure covariates. We used multiseason occupancy models to characterize the seasonality of breeding and relate it with environmental covariates. We also used functional principal component analysis for classifying the differences in seasonality among sites, and random forest regression for analyzing the relative contribution of covariates in the variability of the seasonal breeding. We found that in average seasonal breeding mainly started during the austral winter/ early spring and ended in summer/ early fall, this pattern being stronger in boobies and pelicans than in cormorants. The breeding onset of seabirds is timed so that fledging independence occurs when primary production, prey conditions and availability are maximized. This pattern is unique compared with other upwelling ecosystems and could be explained by the year-round high abundances of anchovy in the NHCS. The average seasonal breeding may differ among nesting sites. Seabirds breed earlier and are more persistent when colonies are larger, located on islands, within the first 20km of the coast, at lower latitudes and with greater primary production conditions. These results suggest that in the NHCS, the seasonality of breeding is more influenced by local environmental conditions than by large-scale environmental gradients. These results provide critical information to a better coordination of guano extraction and conservancy policies. Seabirds may also adapt the seasonality of their breeding to drastic ecosystem changes caused by regime shifts. We found that the three study species exhibited a gradient of plasticity regarding the seasonality of their breeding. Cormorants showed a greater plasticity, modulating the timing 㻌 㻌 and magnitude on their breeding seasonality. This is probably authorized by the greater foraging flexibility offered its great diving capacities. Fixed onset and magnitudes of breeding in boobies may be related to their specific foraging strategy and/or to changes of prey items when anchovy stock was low. We also suggested that boobies may adapt other fecundity traits as growth rate of chicks to lower abundance of anchovy. The specific differences in the adaptation of seasonal breeding allow seabirds to take profit differently from local prey conditions or to face differently regime shifts. Further researches, implementing a large-scale capture-recapture methodology in parallel with monthly census, are proposed in order to fulfill gaps in the basic knowledge on vital traits (adult survival, first age at reproduction, and juvenile recruitment) which are critical parameters to evaluate the dynamic of a population. 㻌 㻌 Résumé Le Système Nord du Courant de Humboldt (SNCH) est le lieu d’une forte activité b iologique due à un upwelling côtier intense. Il abrite l’une des plus grandes populations de l’anchois du Pérou soumis à la plus grande pêcherie monospécifique au monde. Le SNCH héberge aussi de grandes, quoique variables, populations d’oiseaux, composées entre autres de trois espèces sympatriques productrices de guano : le cormoran guanay ( Phalacrocorax bougainvillii ), le fou péruvien ( Sula variegata ) et le pélican péruvien ( Pelecanis thagus ), qui se nourrissent toutes principalement d’anchois. Dans ce travail, nous examinons les fluctuations de ces trois populations d’oiseaux marins, en nous concentrant sur le cycle saisonnier de leur reproduction, pour aborder les questions suivantes : Dans quelle mesure les saisonnalités de reproduction diffèrent elles entre espèces ? Dans quelle mesure sont-elles plastiques dans le temps et dans l’espace ? Qu’est ce qui, des conditions environnementales et des activités anthropogéniques affecte le plus la reproduction des oiseaux marins ? Nous abordons ces questions en utilisant des données de présence de reproducteurs (1) dans plus de 30 sites péruviens répartis entre 06°S et 18°S, et entre 2003 et 2014 ; et (2) dans un site, pendant trois périodes décennales (1952-1968, 1972-1989, 2003-2014). Nous utilisons aussi des covariables environnementales d’origine satelitale ou de campagnes à la mer décrivant les conditions océanographiques, l’abondance, l’accessibilité et la condition des proies, ainsi que des covariables décrivant la pression de pêche. Nous utilisons des mo dèles d’occupation multi - saisonniers pour caractériser la saisonnalité de la reproduction et la relier aux covariables environnementales. Nous mettons également en œuvre des analyses en composantes principales fonctionnelles pour classifier les différences de saisonnalité entre sites, et des forêts aléatoires de régression pour analyser la contribution relative des covariables à la variabilité de la saisonnalité de reproduction. Nous mettons en évidence qu’en moyenne, la reproduction démarre au cours de l’h