Revealing the foraging movements and diet of the White-faced Storm Petrel Pelagodroma marina in the NE Atlantic

Abstract

The White-faced Storm Petrel (WFSP) Pelagodroma marina has a widespread distribution, although virtually nothing is known about their feeding ecology and distributions at-sea. To describe their foraging areas, a total of 77 birds were equipped with 1 g-GPS loggers on Selvagem Grande, Madeira, Portugal (30° 09′ N, 15° 52′ W), during the 2018 and 2019 breeding seasons. We also assessed the diet of WFSP by analysing 17 faecal samples from chicks and 1 regurgitation from an adult using DNA metabarcoding techniques. Additionally, we collected body feathers from ten WFSP chicks to determine mercury concentration. WFSP fed mainly in deep oceanic waters, travelling up to 400 km from the colony, and did not concentrate in any well-defined, population-level foraging hotspots. Some individuals foraged along the edge of the shelf, near the African coast and the Canary Islands, especially during chick rearing. The duration of foraging trips and the total distance travelled, were, on average, 5.1 days and 723 km during the incubation period and 3.0 days and 578 km during chick rearing. The diet of WFSP was dominated by fish and cephalopods (crustacean prey were not detected), with Myctophidae (FO = 71%) representing the main fish family. WFSP often consume mesopelagic fish, in line with their preference for deep oceanic waters and with a small difference in at sea behavior (i.e., travel speed) between the diurnal and nocturnal period. The relatively high concentrations of mercury accumulated in body feathers of WFSP chicks (3.45 ± 1.44 mg kg −1 dry weight; range 1.68-6.01 mg kg −1 ) support the idea that WFSP raise their chicks mostly on mesopelagic prey from deep pelagic areas.

Migratory Movements and Activity Patterns of White-Faced Storm-Petrels Pelagodroma marina Breeding in Cabo Verde

“…We then modelled the positions using the “Solar/Satellite Geolocation for Animal Tracking (SGAT)” package (Lisovski et al ., 2012), applying Markov chain Monte Carlo (MCMC) simulations to refine the locations of the individuals, especially near the equinoxes (Halpin et al ., 2021). Within this package, we used a tolerance on the sine of the solar declination (tol) value of 0.3, and a mean speed of 10km/h in accordance with reference values obtained from the literature for White-faced Storm-petrels (Alho et al ., 2022).…”

“…Another little-known aspect of this species is its daily activity patterns at sea. During the incubation stage, birds are primarily nocturnal, while during chick-rearing, birds forage both day and night (Alho et al ., 2022). However, the daily activity patterns outside the breeding period have remained unknown so far.…”

“…This species comprises six recognised subspecies distributed along the sub-tropical waters of the Atlantic, Indian, and Pacific Oceans in both the northern and Southern hemispheres (howell & zufelt, 2019). Despite their widespread distribution, to date, only one population has been tracked, and only during the breeding season (Alho et al, 2022), not during migration, probably because of its low nest-site fidelity and the difficulty of recovering geolocators without damaging its fragile sandy burrows. In the case of north Atlantic populations, it has been suggested that White-faced Storm-petrels breeding in Cabo Verde P. marina eadesorum migrate to waters off north America, between new England and north Carolina (USA), and nova Scotia (Canada), primarily from July to early October (Watson et al, 1986;howell & zufelt, 2019).…”