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- Oceanic seabirds chase tropical cyclonesPublication . Ventura, Francesco; Sander, Neele; Catry, Paulo; Wakefield, Ewan; De Pascalis, Federico; Richardson, Philip L; Granadeiro, José P.; Silva, Monica C.; Ummenhofer, Caroline C.In late summer and autumn, the passage of intense tropical cyclones can profoundly perturb oceanic and coastal ecosystems. Direct negative effects on individuals and marine communities can be dramatic, especially in the coastal zone,1–4 but cyclones can also enhance pelagic primary and secondary production.5–9 However, cyclone impacts on open ocean marine life remain poorly understood. Here, we investigate their effects on the foraging movements of a wide-ranging higher predator, the Desertas petrel (Pterodroma deserta), in the mid-latitude North Atlantic during hurricane season. Contrary to previously studied pelagic seabirds in tropical and mid-latitude regions,10,11 Desertas petrels did not avoid cyclones by altering course, nor did they seek calmer conditions within the cyclone eye. Approximately one-third of petrels tracked from their breeding colony interacted with approaching cyclones. Upon encountering strong winds, the birds reduced ground speed, likely by spending less time in flight. A quarter of birds followed cyclone wakes for days and over thousands of kilometers, a behavior documented here for the first time. Within these wakes, tailwind support was higher than along alternative routes. Furthermore, at the mesoscale (hours–weeks and hundreds of kilometers), sea surface temperature dropped and surface chlorophyll sharply increased, suggesting direct effects on ocean stratification, primary production, and therefore presumably prey abundance and accessibility for surface-feeding petrels. We therefore hypothesize that cyclone wakes provide both predictably favorable wind conditions and foraging opportunities. As such, cyclones may have positive net effects on the demography of many mid-latitude pelagic seabirds and, likely, other marine top-predators.
- Exposure of an endangered seabird species to persistent organic pollutants: Assessing levels in blood and link with reproductive parametersPublication . Campioni, Letizia; Oró-Nolla, Bernat; Granadeiro, José P.; Silva, Monica C.; Madeiros, Jeremy; Gjerdrum, Carina; Lacorte, SilviaOcean contamination, particularly from persistent organic pollutants (POPs), remains a significant threat to marine predators that occupy high trophic positions. Long-lived procellariform seabirds are apex predators in marine ecosystems and tend to accumulate contaminants. Prolonged exposure to pollutants negatively affects their fitness including reproductive success. Low breeding success may represent a hurdle for the restoration of small and endangered seabird populations, including several highly threatened gadfly petrels. Here we investigated the annual variation (2019 and 2022) in organochlorine pesticide (OCP), polychlorinated biphenyl ether (PCB), polybrominated diphenyl ether (PBDE), and polycyclic aromatic hydrocarbon (PAH) exposure in the endangered Bermuda petrel (Pterodroma cahow), and the relationship between female contaminant burden and breeding parameters. We found that petrels were exposed to a wide range of pollutants (33 out of 55 showed
- No evidence of inbreeding depression despite a historical severe bottleneck in the endangered Bermuda petrel (Pterodroma cahow)Publication . Afonso, Rita O.; Pina-Martins; Friesen, Vicki; SUN, ZHENGXIN; Letizia, Campioni; Madeiros, Jeremy; Silva, Monica C.The Bermuda petrel Pterodroma cahow is an island endemic seabird that belongs to the Procellariiformes, one of the most endangered orders of birds. Historical records suggest a significant population size decline following human settlement in Bermuda, bringing the species to near extinction. Since the 1950s, the population has been recovering aided by the implementation of an ongoing conservation plan. However, it still faces several threats, and negative genetic effects resulting from that drastic decline are to be expected, including inbreeding and genetic drift. We studied genetic diversity and levels of inbreeding, and their effects on individual fitness and mating choice. We also tested for a genetic signature of the recent demographic bottleneck. For this, we analyzed variation in thousands of nuclear single-nucleotide polymorphisms derived from double digest restriction site-associated DNA sequencing and 1 mitochondrial gene (cytochrome oxidase I). The results revealed that the Bermuda petrel suffered a recent genetic bottleneck and shows low mitochondrial diversity compared with other petrel species. Conversely, nuclear diversity was similar to that of other endangered petrels. Inbreeding levels were not high overall, although some individuals were highly inbred. However, we found no evidence that individual inbreeding or relatedness between mates affected hatching success, or that mate choice is influenced by kinship in this very small population.
- Diet of non-breeding leach’s storm-petrels (Hydrobates leucorhous) in the sub-polar frontal zone of the North AtlanticPublication . C. Silva, Monica; Catry, Paulo; Newton, Jason; Nunes, Vera L; Wakefield, EwanABSTRACT: In order to understand the drivers of the distribution and abundance of pelagic seabirds it is necessary to know what they eat, yet there remains little detailed, geo-referenced information on the diets of pelagic seabird. In particular, due to sampling difficulties, information is lacking for non-breeding stages, smaller species, such as storm-petrels, and r· Hydrobatesemote oceanic areas, which may include important diversity hotspots. In this study, we aimed to characterize the trophic ecology of Leach’s storm-petrels foraging in the vicinity of the North Atlantic Current and Evlanov Seamount Marine Protected Area using a combination of survey methods. On a cruise undertaken in June 2017 to characterize the distribution and ecology of seabirds in the region, nineteen Leach’s storm-petrels were caught, sampled and released unharmed. Regurgitations and faecal samples were collected, as well as blood and feather tissues for stable isotope analyses. Of the 12 males, 6 females and 1 unsexed bird, 84% were in active flight feather moult, suggesting they were non-breeders. Prey species, assayed via molecular metabarcoding, were dominated by mesopelagic fish, principally lanternfishes (Myctophidae) and hatchetfishes (Sternoptychidae), but also included cephalopods and crustaceans. Additionally, almost half of the birds had microplastics in their regurgitates. Stable isotopic ratios did not differ significantly between sexes. Our results, combined with those of previous studies, suggest that within the oceanic North Atlantic, Leach’s storm-petrels feed at a similar trophic level to much larger seabirds, targeting mesopelagic fishes that are a key component of the North Atlantic pelagic food web.