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Distribution and at-sea activity of a nocturnal seabird, the Bulwer's petrel Bulweria bulwerii, during the incubation period

Publication . Dias, Maria P.; Romero, Joana; Granadeiro, José Pedro; Catry, Teresa; Pollet, Ingrid L.; Catry, Paulo

Bulwer'spetrelsarenocturnalseabirdsthatmostlypreyonmesopelagicfauna.Asaerialforagersand shallowdivers,theirfeedingopportunitiesarelimitedbynear-surfaceavailabilityoftheirprey,whichis highlyvariablebothtemporally(reflectingdiurnalandlunarcycles)andspatially.Herewestudiedhow Bulwer'spetrelscopewiththeseconstraintsbyanalysingtheirat-seadistributionandactivityduringthe incubationperiod.Wetrackedthemovementsof20birdsfromSelvagemGrande(NEAtlantic)duringa completelunarcycle,andrecorded30foragingtripsthatlasted11daysonaverage.Birdswereboth distributedaroundthecolonyandinwatersclosetotheAzoreanarchipelago(mid-Atlantic)located 1700kmaway,andweresignificantlymoreactiveatnight(especiallyjustaftersunsetandbeforesunrise), whenmesopelagicfaunaisalsoclosertotheseasurfaceduetotheirdielverticalmigrations.Bulwer's petrelsspentsignificantlymoretime flyingduringmoonlight,althoughtheeffectofthemoonwasrela- tivelyweak(ca.10–15%differencebetweenmoonlitanddarkperiodsofthenight),andnotobviouswhen birdswereforaginginmid-Atlanticwaters,whichwerealsotargetedmoreoftenduringfull-moon.These resultsrevealkeyadaptationsoftheBulwer'spetreltothehighlydynamicecologyofitsmesopelagicprey.

2016Journal article

Restricted access

Absence of haemosporidian parasite infections in the long-lived Cory’s shearwater: evidence from molecular analyses and review of the literature

Publication . Campioni, Letizia; Martínez-de la Puente, Josué; Figuerola, Jordi; Granadeiro, José P.; Silva, Mónica C.; Catry, Paulo

The apparent scarcity or absence of blood parasites in some avian groups, such as seabirds, has been related to intrinsic and extrinsic factors including host immunological capacity, host-parasite assemblage, and ecological parameters, but also to reduced sensitivity of some methods to detect low parasite prevalence/intensities of infection. Here, we examined the haemosporidian parasite prevalence in a breeding population of Cory's shearwater Calonectris diomedea borealis, a long-distance migrant seabird, nesting in the Macaronesian region, in the Eastern Atlantic. Previous studies on Calonectris diomedea complex were based on small sample sizes providing weak evidence for a lack of infections by haemoparasites. Here, we investigated the presence of both parasite infections in C. d. borealis and larvae of potential mosquito vectors on the area. By employing a PCR-based assay, we extensively examined the prevalence of blood parasites belonging to the genera Plasmodium, Haemoproteus, and Leucocytozoon in 286 individuals from different life stages (i.e., chicks, immatures, sabbatical, and breeding adults), facing their specific energetic trade-offs (immunological functions vs. life history activities). We sampled immatures and adult shearwaters, of different sexes, ages, and migratory origins, from two sub-colonies. None of the sampled individuals were infected by these parasites, supporting the hypothesis that there was no in situ or ex situ transmission of vector-borne parasites in marine habitats irrespective of host's life stage and in spite of the presence of the potential Plasmodium vector Culiseta longiareolata breeding in the area. These results suggest that the lack of transmission of haemosporidian parasites on Selvagem Grande may be related to the lack of suitable dipteran vectors at the study sites, which may result from the geographic isolation of this area.

2017Journal article

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Dispersal of green turtles from Africas' largest rookery assessed through genetic markers

Publication . Patrício, Ana Rita; Formia, Angela; Barbosa, Castro; Broderick, Annette C.; Bruford, Michael; Carreras, Carlos; Catry, Paulo; Ciofi, Claudio; Regalla, Aissa Said; Godley, Brendan John

Marine turtles are highly migratory species that establish multiple connections among distant areas, through oceanic migration corridors. To improve the knowledge on the connectivity of Atlantic green turtles Chelonia mydas, we analysed the genetic composition and contribution to juvenile aggregations of one of the world's largest rookeries at Poilao Island, Guinea-Bissau. We amplified 856 bp mitochondrial DNA (mtDNA) control region sequences of this population (n = 171) containing the similar to 490 bp haplotypes used in previous studies. Haplotype CM-A8 was dominant (99.4%), but it divided in 2 variants when the whole 856 bp was considered: CM-A8.1 (98.8%) and CM-A8.3 (0.6%). We further identified the haplotype CM-A42.1 (0.6%), found previously only in juvenile foraging grounds at Argentina, Brazil and Equatorial Guinea. The Poilao breeding population was genetically different from all others in the Atlantic (FST range: 0.016-0.961, p < 0.001). An extensive 'many-to-many' mixed-stock analysis (MSA) including 14 nesting populations (1815 samples) and 17 foraging grounds (1686 samples) supported a strong contribution of Poilao to West Africa (51%) but also to the Southwest Atlantic (36%). These findings, in particular the strong connectivity within West Africa, where illegal harvesting is still common, should motivate conservation partnerships, so that population protection can be effectively extended through all life stages. Our study expands the knowledge on migration patterns and connectivity of green turtles in the Atlantic, evidences the importance of larger sample sizes and emphasizes the need to include more finely resolved markers in MSAs and more genetic sampling from West African foraging grounds to further resolve the connectivity puzzle for this species.

2017Journal article

Open access

Genetic population structure of black-browed and Campbell albatrosses, and implications for assigning provenance of birds killed in fisheries

Publication . Burg, Theresa M.; Catry, Paulo; Ryan, Peter G.; Phillips, Richard A.

1. Previous genetic studies found evidence of at least three distinct groups of black‐browed Thalassarche melanophris and Campbell Thalassarche impavida albatrosses in the Southern Ocean. Almost 350 individuals including samples from additional breeding sites on the Falkland Islands and South Georgia Island were screened using mitochondrial DNA. 2. The new sequence data using lineage specific PCR primers provided further support for the taxonomic split of T. melanophris and T. impavida and separate management of the two distinct T. melanophris groups. 3. In total, 207 black‐browed albatrosses killed in longline fisheries were screened. Approximately 93% of the bycaught birds from the Falkland Islands belonged to the Falkland mtDNA group and the remaining birds had mtDNA from the Widespread T. melanophris group; these proportions were similar to those in the local Falklands breeding population. The South African and South Georgia bycatch samples predominantly comprised the Widespread T. melanophris group, with only one bird from each area containing Falkland mtDNA. Lastly, 81% of the albatrosses bycaught off New Zealand had T. impavida mtDNA and the remaining four birds were Widespread T. melanophris. These differences in bycatch composition matched what is known from tracking and banding data about the at‐sea distribution of black‐browed albatrosses. 4. Based on the mtDNA results and current population trends, consideration should be given to assigning regional IUCN status for the different breeding populations.

2017Journal article

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Flexible migratory choices of Cory’s shearwaters are not driven by shifts in prevailing air currents

Publication . Dell’Ariccia, Gaia; Benhamou, Simon; Dias, Maria P.; Granadeiro, José Pedro; Sudre, Joel; Catry, Paulo; Bonadonna, Francesco

Wind conditions strongly affect migratory costs and shape flyways and detours for many birds, especially soaring birds. However, whether winds also influence individual variability in migratory choices is an unexplored question. Cory's shearwaters (Calonectris borealis) exhibit migratory flexibility, changing non-breeding destination across the Atlantic Ocean within and between years. Here, we investigated how wind dynamics affect the spatiotemporal migratory behaviour and whether they influence individual choices of non-breeding destination. We analysed 168 GLS tracks of migratory Cory's shearwaters over five years in relation to concurrent wind data. We found no evidence for an association of the use of specific paths or destinations with particular wind conditions. Our results suggest that shearwaters deliberately choose their non-breeding destination, even when the choice entails longer distances and higher energetic costs for displacement due to unfavourable wind conditions en route. Favourable winds trigger migration only when directed towards specific areas but not to others. Despite their dependence on wind for dynamic soaring, Cory's shearwaters show a high individuality in migratory behaviour that cannot be explained by individual birds encountering different meteorological conditions at departure or during migratory movements.

2018Journal article

Open access