The conservation of threatened seabirds that are highly pelagic, such as the gadfly petrels Pterodroma spp., depends on understanding the main oceanographic determinants of their movements in order to apply the necessary management regulations and to identify and protect their key marine habitats. The present work presents for the first time information on the distribution and habitat preferences of 17 Bugio petrels Pterodroma deserta from the island of Bugio, Madeira archipelago, North Atlantic Ocean. All of the birds remained in North Atlantic waters during the pre-laying exodus, incubation and chick-rearing periods, showing a clear preference for deep, productive (high chlorophyll a levels) waters north of the Azores archipelago. There was high individual variability in migration strategies. Five wintering areas were identified: two off the Brazilian coast, one around the Cape Verde archipelago, one off the southeast coast of the United States, and one in pelagic waters in the central South Atlantic. These tended to be areas of high productivity but not of a particular sea surface temperature regime. Based on saltwater immersion data, birds were more active during the breeding season and spent more time resting on the water in wintering areas. There was also a positive correlation between the time spent on the water and the progression of full to new moon, suggesting that the birds may use moonlight to search for prey. Given its highly dispersed distribution at sea throughout the year, effective conservation of this threatened species may require management at large spatial scales.
SummaryIt is widely accepted that the gadfly petrels of the Macaronesian islands comprise three closely related and morphologically similar taxa, Petrodroma madeira from Madeira island, P. deserta (also treated as P. feae deserta) from Bugio and P. feae (also treated as P. feae feae) from Cape Verde Islands. However, the taxonomic rank of each taxon is not well defined, and has been subject to a long debate. Partial sequences of cytochrome b (893 bp) from 39 individuals (five from Madeira, 18 from nearby Bugio, and 16 from Fogo) and morphometric data from five characters from 102 individuals (74 from Bugio and 28 from Fogo in Cape Verde), were used to compare and estimate phylogenetic relationships and the taxonomic status of these petrels. In the phylogenetic analysis and sequence divergence estimation, we also include 23 sequences of 19 Pterodroma species available from GenBank. Our results show that Macaronesian gadfly petrels form a monophyletic clade. Birds from Bugio and Cape Verde are the most closely related taxa followed by those from Madeira. The group formed by the three taxa studied is closely related to Bermuda Petrel P. cahow and Black-capped Petrel P. hasitata. A hypothesis for the colonization of the islands is presented. The level of sequence divergence is sufficient to consider the populations of Bugio and Cape Verde as separate species. Reproductive isolation is supported by exclusive haplotypes and fixed changes. Despite the presence of some significant differences in bill and tarsus measurements, the two species seem to be morphologically similar because the great overlap of variation intervals in the measurements hinders identification. It therefore appears suitable for consideration as a cryptic species. An important conservation implication is that the world population of both species is very small; if treated as a full species, deserta on Bugio may qualify for uplisting to 'Vulnerable' on the IUCN Red List.
The Portuguese island of Selvagem Grande (Great Salvage) in Macaronesia is an important seabird breeding station in the eastern Atlantic. Significant populations of Cory's shearwater Calonectris diomedea (Scopoli, 1769), Bulwer's petrel Bulweria bulweria (Jardine & Selby, 1828) and little shearwater Puffinus assimilis baroli (Bonaparte, 1857) are present, and white-faced storm-petrel Pelagodroma marina (Latham, 1790) and Madeiran storm-petrel Oceanodroma castro (Harcourt, 1851) populations are of global significance. Selvagem Grande also provides diverse habitats for an extensive flora, including 11 endemic species. The 270-ha island was also inhabited by two alien invasive mammals: the European rabbit Oryctolagus cuniculus (Linnaeus, 1758) and the house mouse Mus musculus (Linnaeus, 1758). Both are known to have had adverse impacts on breeding seabirds and island vegetation. In 2002, the Natural Park of Madeira conducted a program using brodifacoum bait formulations aimed at rabbit and mouse eradication. Approximately 17 000 individual baiting points were established on a 12.5 × 12.5 m grid. Baits were also applied by hand "seeding" on steep slopes and cliffs where bait stations could not be placed. Rabbits were removed after a month. However, mice persisted for considerably longer and strategic bait applications against them continued for a further six months. Subsequent assessments by trapping, bait takes and systematic observation of signs over three years, has confirmed the removal of both alien invasive species. This paper presents information on these operations, on measures adopted to mitigate adverse impacts of the eradication program on important vertebrate non-target species, including Berthelot's pipit Anthus berthelotii Bolle, 1862 and a species of gecko Tarentola bischoffi Joger, 1984 and on the initial response of the island's ecosystem to the eradication of rabbits and mice.
The conservation status and taxonomy of the three gadfly petrels that breed in Macaronesia is still discussed partly due to the scarce information on their spatial ecology. Using geolocator and capture-mark-recapture data, we examined phenology, natal philopatry and breeding-site fidelity, year-round distribution, habitat usage and at-sea activity of the three closely-related gadfly petrels that breed in Macaronesia: Zino’s petrel Pterodroma madeira, Desertas petrel P. deserta and Cape Verde petrel P. feae. All P. feae remained around the breeding area during their non-breeding season, whereas P. madeira and P. deserta dispersed far from their colony, migrating either to the Cape Verde region, further south to equatorial waters in the central Atlantic, or to the Brazil Current. The three taxa displayed a clear allochrony in timing of breeding. Habitat modelling and at-sea activity patterns highlighted similar environmental preferences and foraging behaviours of the three taxa. Finally, no chick or adult was recaptured away from its natal site and survival estimates were relatively high at all study sites, indicating strong philopatry and breeding-site fidelity for the three taxa. The combination of high philopatry, marked breeding asynchrony and substantial spatio-temporal segregation of their year-round distribution suggest very limited gene flow among the three taxa.
Individuals within populations can use different resources, leading to ecological segregation and niche variation. This segregation could have direct impacts on the migratory strategy or breeding success, thus affecting the overall population and community dynamics and, ultimately, survival. In this study, we assessed the inter-annual and within individual foraging ecology of an endemic and highly threatened seabird species, the Desertas petrel Pterodroma deserta, during the breeding and non-breeding phases. We combined 54 annual tracks (26 individuals; 2009-2013) obtained with light-level loggers (Global Location Sensing or GLS loggers) with stable isotope analyses (δ 15 N and δ 13 C) of blood (plasma and cells) and feathers. Wide-ranging tracking data show that this species is a generalist predator, able to adapt to very different habitats. All birds remained faithful to their selected non-breeding areas over the years leading to very high spatial, temporal and trophic consistency among years (i.e. usually with intracorrelation coefficient values, which is an index of repeatability of > 40%). During both the breeding and non-breeding seasons, individual birds showed narrow and segregated isotopic niches, indicating a high level of specialization and limited choice of prey and habitats. The conservation of a seabird with such a dispersive (species-level) yet consistent (individual-level) non-breeding distribution pattern represents a challenge in marine policy terms. On the one hand, such a consistent temporal and spatial pattern will help with defining core areas for conservation, which could be protected through specific management measures or by the establishment of marine protected areas. Yet, their relatively large size (on average 4000 km 2 ) and extent over both national and international waters, where different legislative frameworks apply, will require the coordinated action by many nations, international organizations and multilateral environmental agreements.
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