M. Magalhães

Bio: M. Magalhães is an academic researcher from Departamento de Oceanografia e Pescas. The author has contributed to research in topics: Ecological niche & Spatial ecology. The author has an hindex of 1, co-authored 1 publications receiving 11 citations.

Future Directions in Conservation Research on Petrels and Shearwaters

Abstract: Shearwaters and petrels (hereafter petrels) are highly adapted seabirds that occur across all the world’s oceans. Petrels are a threatened seabird group comprising 124 species. They have bet-hedging life histories typified by extended chick rearing periods, low fecundity, high adult survival, strong philopatry, monogamy and long-term mate fidelity and are thus vulnerable to change. Anthropogenic alterations on land and at sea have led to a poor conservation status of many petrels with 52 (42%) threatened species based on IUCN criteria and 65 (52%) suffering population declines. Some species are well-studied, even being used as bioindicators of ocean health, yet for others there are major knowledge gaps regarding their breeding grounds, migratory areas or other key aspects of their biology and ecology. We assembled 38 petrel conservation researchers to summarize information regarding the most important threats according to the IUCN Red List of threatened species to identify knowledge gaps that must be filled to improve conservation and management of petrels. We highlight research advances on the main threats for petrels (invasive species at breeding grounds, bycatch, overfishing, light pollution, climate change, and pollution). We propose an ambitious goal to reverse at least some of these six main threats, through active efforts such as restoring island habitats (e.g., invasive species removal, control and prevention), improving policies and regulations at global and regional levels, and engaging local communities in conservation efforts.

Foraging areas, offshore habitat use, and colony overlap by incubating Leach's storm-petrels Oceanodroma leucorhoa in the Northwest Atlantic.

Abstract: Despite their importance in marine food webs, much has yet to be learned about the spatial ecology of small seabirds. This includes the Leach's storm-petrel Oceanodroma leucorhoa, a species that is declining throughout its Northwest Atlantic breeding range. In 2013 and 2014, we used global location sensors to track foraging movements of incubating storm-petrels from 7 eastern Canadian breeding colonies. We determined and compared the foraging trip and at-sea habitat characteristics, analysed spatial overlap among colonies, and determined whether colony foraging ranges intersected with offshore oil and gas operations. Individuals tracked during the incubation period made 4.0 ± 1.4 day foraging trips, travelling to highly pelagic waters over and beyond continental slopes which ranged, on average, 400 to 830 km from colonies. Cumulative travel distances ranged from ~900 to 2,100 km among colonies. While colony size did not influence foraging trip characteristics or the size of areas used at sea, foraging distances tended to be shorter for individuals breeding at the southern end of the range. Core areas did not overlap considerably among colonies, and individuals from all sites except Kent Island in the Bay of Fundy foraged over waters with median depths > 1,950 m and average chlorophyll a concentrations ≤ 0.6 mg/m3. Sea surface temperatures within colony core areas varied considerably (11-23°C), coincident with the birds' use of cold waters of the Labrador Current or warmer waters of the Gulf Stream Current. Offshore oil and gas operations intersected with the foraging ranges of 5 of 7 colonies. Three of these, including Baccalieu Island, Newfoundland, which supports the species' largest population, have experienced substantial declines in the last few decades. Future work should prioritize modelling efforts to incorporate information on relative predation risk at colonies, spatially explicit risks at-sea on the breeding and wintering grounds, effects of climate and marine ecosystem change, as well as lethal and sub-lethal effects of environmental contaminants, to better understand drivers of Leach's storm-petrel populations trends in Atlantic Canada.

Ontogenic changes in habitat and trophic ecology in the Antarctic squid Kondakovia longimana derived from isotopic analysis on beaks

Abstract: The life histories of cephalopods are still not well described. Stable isotopic analysis of cephalopod beaks is an effective method to study the habitat and trophic ecology of this group of organisms. As beaks grow continuously throughout squid’s life without replacement, we hypothesised that analysing different sections along the beak will provide information on the ontogenetic shifts during the individual’s lifetime. Here we used the Southern Ocean squid Kondakovia longimana as a model species to test the reliability of this method along the beaks of Antarctic species. Growing patterns show that beaks grow throughout the squid lifetime by a continuous deposition of material. This new material can influence the results of the stable isotopic analysis. δ13C and δ15N values (from − 26.3 to − 20.6‰ and from + 3.2 to + 8.2‰, respectively) from different beak regions indicated that K. longimana inhabits regions spanning a wide latitudinal range, and the trophic level at which it feeds increases throughout its lifetime. Stable isotopic analysis of different sections of the cephalopod beak is a reliable technique to study habitat and trophic ecology throughout Antarctic squid’s lifetime. Stable isotopic results showed an increase in δ15N values from the tip of the rostrum to the end of the hood and crest, in the upper beak, and to the free corner of lateral wall and wing in the lower beak. Our results also suggested that the upper beak is the best beak to study ontogenetic shifts, mainly in initial stages of the cephalopods’ life, presenting lower values of δ15N than the lower beak.

Metabarcoding, stables isotopes, and tracking: unraveling the trophic ecology of a winter-breeding storm petrel (Hydrobates castro) with a multimethod approach

Abstract: Detailed information on diet and foraging ecology is scarce for most small seabirds such as storm petrels. In this study, we used molecular techniques, stable isotope analysis, and geolocators to study the diet, trophic ecology, and at-sea distribution of Madeiran storm petrels (Hydrobates castro) breeding in Farilhoes Islet, Portugal, in 2015–2017. The diet of Madeiran storm petrels was dominated by fish for both sexes and study years, with Gadidae representing the main prey family. In 2017, females also fed on Aulopiformes, Stomiiformes and Myctophiformes, which were not identified in the other groups, suggesting some degree of inter-annual and intersexual plasticity in their diet. The carbon isotopic ratios of birds during 2017 were significantly higher when compared to 2015, which might be related to foraging near coastal areas in 2017. Indeed, tracking data for 2017 show that birds foraged near the colony and near the West African coast. Overall, both sexes of this species exhibited a similar trophic ecology and diet during the breeding season. However, intersexual differences occurred during the non-breeding season, when females showed significantly lower nitrogen isotopic ratios than males (in 2016), and the lowest niche overlap between sexes occurred. This, together with the fact that environmental conditions appeared less favourable in 2016 suggests that intersexual differences in the foraging ecology of this species may be related with environmental conditions.

High-resolution multi-marker DNA metabarcoding reveals sexual dietary differentiation in a bird with minor dimorphism.

Abstract: Although sexual dietary differentiation is well known in birds, it is usually linked with significant morphological dimorphism between males and females, with lower differentiation reported in sexually monomorphic or only slightly dimorphic species. However, this may be an artifact of poor taxonomic resolution achieved in most conventional dietary studies, which may be unable to detect subtle intraspecific differentiation in prey consumption. Here, we show the power of multi-marker metabarcoding to address these issues, focusing on a slightly dimorphic generalist passerine, the black wheatear Oenanthe leucura. Using markers from four genomic regions (18S, 16S, COI, and trnL), we analyzed fecal droppings collected from 93 adult black wheatears during the breeding season. We found that sexes were rather similar in bill and body features, though males had a slightly thicker bill and longer wings and tail than females. Diet was dominated in both sexes by a very wide range of arthropod species and a few fleshy fruits, but the overall diet diversity was higher for males than females, and there was a much higher frequency of occurrence of ants in female (58%) than male (29%) diets. We hypothesize that the observed sexual differentiation was likely related to females foraging closer to their offspring on abundant prey, while males consumed a wider variety of prey while foraging more widely. Overall, our results suggest that dietary sexual differentiation in birds may be more widespread than recognized at present and that multi-marker DNA metabarcoding is a particularly powerful tool to unveiling such differences.