Puffinus gravis
Silhouette: Juan Carlos Jerí · PhyloPic
In 3 days <5%
The great shearwater (Ardenna gravis) is a large shearwater in the seabird family Procellariidae. It breeds colonially on rocky islands in the South Atlantic. Outside the breeding season it ranges widely in the Atlantic.
The great shearwater was formally described in 1818 by the Irish naturalist Bernard O'Reilly and given the binomial name Procellaria gravis. The great shearwater is now placed in the genus Ardenna that was introduced in 1853 by Ludwig Reichenbach. The genus name Ardenna was used to refer to a seabird by Italian naturalist Ulisse Aldrovandi in 1603. The specific epithet gravis is Latin meaning "heavy" or "weighty". The species is monotypic: no subspecies are recognised.
This shearwater is 43–51 cm (16.9–20.1 in) in length with a 105–122 cm (3.5–4.0 ft) wingspan. It is identifiable by its size, dark upper parts, and white under parts, with the exception of a brown belly patch and dark shoulder markings. It has a black cap, black bill, and a white "horseshoe" on the base of the tail. The stiff flight, like a large Manx shearwater, is also distinctive. The only other large shearwaters in its range are the Cory's Shearwater and the all-dark... Wikipedia →
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Bermuda · 2022
© Luke Foster · iNaturalist · CC BY-NC 4.0
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United States · 2020
© Birder20714 · iNaturalist · CC BY-NC 4.0
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Península Valdés | 🇦🇷 Argentina | |
| 2 | Acadia National Park | 🇺🇸 United States | |
| 3 | Table Mountain National Park | 🇿🇦 South Africa | |
| 4 | Merritt Island National Wildlife Refuge | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Great Shearwater sighting in Merritt Island National Wildlife Refuge on a given day, based on 45 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 224th most-seen of the 279 birds we can rate there. Over three days the chance rises to under 5%, if each day is a fresh chance.
June
In that month about 10% of wildlife watchers report a Great Shearwater in Merritt Island National Wildlife Refuge on a given day, against under 5% in July to May, the lowest months. That is one of Merritt Island National Wildlife Refuge's wettest months, with about 180 mm of rain against 50 mm in March.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Great Shearwater sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 4 parks where we can rate Great Shearwater sightings, Merritt Island National Wildlife Refuge ranks 4th at under 5%, level with the leaders once rounded. The best odds are in Península Valdés (Argentina, under 5%), Acadia National Park (United States, under 5%) and Table Mountain National Park (South Africa, under 5%).
GBIF citizen-science records
It is estimated from how often the Great Shearwater is recorded against all the birds logged in Merritt Island National Wildlife Refuge (45 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
