--- title: "European Storm Petrel (Hydrobates pelagicus) | AnimalTracks.wiki" description: "The Atlantic's smallest seabird, weighing about 25 grams but migrating from the north-east Atlantic to winter off southern Africa." image: "https://animaltracks.wiki/images/animals/european-storm-petrel-1.webp" published: "2026-09-06" updated: "2026-09-28" --- # European Storm Petrel (*Hydrobates pelagicus*) > **Status**: Checked against 10 sources, listed under Sources below. > **Tagline**: The Atlantic's smallest seabird, weighing about 25 grams but migrating from the north-east Atlantic to winter off southern Africa. > **Soundtrack Vibe**: 2000s Pop-Rock & Emo // Tokio Hotel, "Monsoon" > **Soundtrack Links**: [Spotify](https://open.spotify.com/track/1Bc9ktRpchBN04kCHFT3Lz) | [YouTube](https://www.youtube.com/watch?v=Cn6_XQf_cZ4) > **Vibe Match**: Drama and howling storm energy for a seabird weighing about 25 grams that feeds mainly by hovering just over the sea, picking plankton off the surface. ## Biological Superpowers & Stats - **Taxonomy**: *Hydrobates pelagicus* - **Danger Level**: Low - **Conservation Status**: Least Concern ([IUCN Red List](https://doi.org/10.2305/iucn.uk.2021-3.rlts.t22698477a166331807.en)) - **Superpower**: Runs on stomach oil while incubating (if that oil supplies all its energy, it accounts for 76% of the weight lost each day on the nest), and its chicks can apparently recognize their own body odor - **Habitat**: Pelagic north-east Atlantic and Mediterranean waters, nesting in crevices in stone walls, boulder beaches and old buildings, and wintering as far as the seas off southern Africa - **Diet**: Mainly plankton picked from the sea surface by hovering; the Mediterranean subspecies feeds mainly by diving for pelagic fish instead - **Tags**: bird, ocean, pelagic, carnivore ## Natural History & Behavior ## The Atlantic's Smallest Seabird The **European Storm Petrel** (*Hydrobates pelagicus*) is the smallest seabird in the Atlantic Ocean. British ringing data show most adults weigh between 22.5 and 29.1 grams, with a wing just over 12 centimeters long. The oldest ringed storm petrel on the BTO's books reached 38 years and 17 days, a record set in 2017, and the BTO gives a typical life expectancy of 11 years for a bird that reaches breeding age, with breeding typically starting at four. Despite its size, it migrates from breeding colonies in the north-east Atlantic to wintering grounds off southern Africa, in the south Atlantic and Indian oceans. ## Fuel From Its Own Gut A study of storm petrels breeding in artificial nest chambers measured how fast sitting birds burn energy, both from their carbon dioxide output and from how quickly they lose weight. A shift on the egg usually ends when the foraging partner returns, and the partner comes back once it has regained a threshold body mass of about 31 grams, however long it has spent at sea. > **A gut that doubles as a fuel tank** If a sitting storm petrel's energy during incubation comes entirely from the oil stored in its stomach, as the study assumed, then burning that oil accounts for 76 percent of the weight it loses each day on the nest. ## Hunting Where It's Darkest Many nocturnal seabirds forage more under moonlight, but GPS tracking of storm petrels from one colony found that offshore they forage under the darkest conditions, a pattern strongly influenced by cloud cover. The researchers suggest smell probably helps the birds detect patches of prey at night, and that bioluminescence may help them spot individual prey by eye. Atlantic birds feed mainly by hovering over the surface and picking off plankton, but the larger, heavier-billed Mediterranean subspecies, *melitensis*, feeds mainly by diving for pelagic fish. ## Crevices, Scent and Rats Storm petrels are active in their colonies only at night. On Shetland's Mousa they nest in crevices in dry stone walls, boulder beaches, rock scree and abandoned buildings. Experiments found that chicks can apparently recognize their own body odor, even when tested against the scent of another storm petrel chick, and the researchers suggest such individual odors may help a bird recognize its nest. Mousa has no mice, rats or cats, and its only mammalian predator, the Eurasian otter, rarely takes storm petrel nests; a 2014 study reported that the colony had more than doubled in size since 1996. Across a survey of about 300 western Mediterranean islands, rat presence was a limiting factor, at the regional scale, only for the storm petrel's abundance, while the three shearwater species there were shaped more by island characteristics. ## Frequently Asked Questions ### Are more male or female storm petrels caught migrating past Portugal? Far more female. Researchers used DNA to sex pre-breeding birds drawn in by recorded calls on their northward migration past south-west Europe, and found the catch ran 80.8% to 89.7% female across seven years. Samples from breeding colonies showed no such bias, and the researchers suggest the sexes may differ in migration route or in their colony-prospecting behaviour during migration. *(Source: [Medeiros et al. 2012]())* ### How long does a storm petrel chick take to fledge? BTO nest records show both parents incubate the single egg, typically for 38 to 50 days. Once hatched, the downy chick typically takes 56 to 73 days to fledge. *(Source: [BTO BirdFacts]())* ### Do storm petrel chicks pick up parasites in their burrows? In a cave colony on Espartar Island in Spain's Balearic Islands, researchers studied the soft tick Ornithodoros maritimus. Fewer chicks survived deep in the cave, the most infested area, than near the entrance, and chicks carrying more ticks were in poorer body condition. Some pools of ticks tested positive for a Borrelia bacterium with 99% sequence identity to B. turicatae, a relapsing-fever Borrelia. *(Source: [Sanz-Aguilar et al. 2020]())* ### Is the Mediterranean storm petrel really the same bird as the Atlantic one? Birds of the World lists them as two subspecies of one species, but notes the Mediterranean race "may be better treated as a distinct species." It is larger, with a heavier bill and a proportionally smaller tail. The two also differ in voice and coloration, and the Mediterranean birds breed earlier. *(Source: [Carboneras, Jutglar & Kirwan 2020]())* ## Sources 1. [Storm Petrel. BTO BirdFacts.]() 2. [Hydrobates pelagicus. The IUCN Red List of Threatened Species 2021: e.T22698477A166331807.]() 3. [Bolton (1996). Energy expenditure, body-weight and foraging performance of Storm Petrels Hydrobates pelagicus breeding in artificial nesting chambers. Ibis.]() 4. [Medeiros et al. (2012). Molecular Evidence for Gender Differences in the Migratory Behaviour of a Small Seabird. PLoS ONE.]() 5. [Wilkinson et al. (2026). Under the cover of darkness: Foraging behaviour increases on cloudy, new moon nights in a pelagic seabird. Ibis.]() 6. [Carboneras, Jutglar & Kirwan (2020). European Storm-Petrel (Hydrobates pelagicus). Birds of the World.]() 7. [Watson, Bolton & Monaghan (2014). Out of sight but not out of harm's way: Human disturbance reduces reproductive success of a cavity-nesting seabird. Biological Conservation.]() 8. [Ruffino et al. (2009). Invasive rats and seabirds after 2,000 years of an unwanted coexistence on Mediterranean islands. Biological Invasions.]() 9. [Belliure, Mínguez & De León (2003). Self-odour recognition in European storm-petrel chicks. Behaviour.]() 10. [Sanz-Aguilar et al. (2020). Infestation of small seabirds by Ornithodoros maritimus ticks: Effects on chick body condition, reproduction and associated infectious agents. Ticks and Tick-borne Diseases.]() *Published September 6, 2026. 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