Oceanodroma microsoma
Silhouette: Richard Crossley · PhyloPic
In 3 days ~20% in a week ~40%
The least storm petrel (Hydrobates microsoma) is a small seabird of the storm petrel family Hydrobatidae. It is 13–15 cm in length, with a wingspan of 32 cm. It is the smallest member of the order Procellariiformes. It was formerly defined in the genus Oceanodroma before that genus was synonymized with Hydrobates.
It breeds on islands off the Baja Peninsula and Gulf of California of Mexico in rock crevices or small burrows in soft earth and lays a single white egg.The single egg that this bird lays is white with a wreath of fine black specks around one and sometimes both ends. Like most petrels, its walking ability is limited to a short shuffle to the burrow. It is a colonial nester.
It spends the rest of the year at sea, reaching as far south as the tropical Pacific South America. It frequently can be seen well offshore of southern California in late summer and autumn. It feeds on mainly planktonic crustaceans, with a preference of larvae of spiny lobsters. It feeds similarly to other storm petrels, picking food off the surface of the water while in flight.
The least storm petrel suffers losses on some of the breeding islands, particularly from feral cats and rats. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Coiba National Park | 🇵🇦 Panama | |
| 2 | Cabo Blanco Absolute Nature Reserve | 🇨🇷 Costa Rica | |
| 3 | Cabo Pulmo National Park | 🇲🇽 Mexico |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | San Diego | 🇺🇸 United States | |
| 2 | Los Angeles | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Least Storm-Petrel sighting in Coiba National Park on a given day, based on 15 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 72nd most-seen of the 118 birds we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
June
In that month about 30% of wildlife watchers report a Least Storm-Petrel in Coiba National Park on a given day, against under 5% in February, April, July and November–December, the lowest months. That is one of Coiba National Park's wettest months, with about 510 mm of rain against 35 mm in February. May and October have too few records to rate.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Least Storm-Petrel sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 3 parks where we can rate Least Storm-Petrel sightings, Coiba National Park has the highest daily chance: about 10%. Next come Cabo Blanco Absolute Nature Reserve (Costa Rica, about 10%) and Cabo Pulmo National Park (Mexico, under 5%).
GBIF citizen-science records
It is estimated from how often the Least Storm-Petrel is recorded against all the birds logged in Coiba National Park (15 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.
