High in the mountains of our Costa Rican retreat, you might expect to encounter an abundance of toucans, jays, and hummingbirds. But venture beyond the cloud forests and towards the vastness of the Pacific Ocean, and you might glimpse a creature unlike any other – the enigmatic Band-rumped Storm-Petrel.

While not a resident of our mountain retreat itself, these fascinating seabirds grace the Costa Rican coastline, particularly the waters off the Osa Peninsula and Cocos Island. So, for today’s blog, we’ll take a flight (pun intended) away from the mountains and set our sights on the Band-rumped Storm-Petrel, a master of the open ocean.

A Master of Disguise (Almost)

The Band-rumped Storm-Petrel is a small seabird, measuring just 19-21 cm in length. Its plumage is primarily a dark, smoky black, with the namesake feature being a prominent white band adorning the uppertail – a vital marker for identification. However, differentiating the Band-rumped Storm-Petrel from its close relatives, Leach’s Storm-Petrel and Wilson’s Storm-Petrel, can be tricky. Look for the following subtle distinctions:

• Tail shape: The Band-rumped Storm-Petrel boasts a squarer tail, compared to the deeper fork of Leach’s Storm-Petrel.
• Flight style: While Leach’s Storm-Petrel has a more erratic, jolting flight pattern, the Band-rumped Storm-Petrel exhibits a smoother, powerful flight with long glides and high arcs.
• Upperwing bar: The white band on the upperwing of the Band-rumped Storm-Petrel is typically fainter and doesn’t reach the leading edge of the wing, unlike some other storm-petrels.

A Nocturnal Navigator

Unlike the vibrant birdsong that fills our mountain retreat, the Band-rumped Storm-Petrel is a creature of the night. Strictly nocturnal at breeding sites to avoid predators like gulls and hawks, they only come ashore after dark. Their walking ability is limited to a waddling shuffle, but their wings transform them into aerial acrobats at sea.

These birds are masters at riding the wind currents, barely needing to flap their wings. They skim the ocean surface with incredible agility, often following ships in search of scraps tossed overboard. Their diet consists primarily of small fish, squid, and crustaceans, which they snatch up while skimming the waves.

A Species shrouded in Mystery

The Band-rumped Storm-Petrel is a bird of vast range, spanning across tropical and subtropical waters in both the Atlantic and Pacific Oceans. Intriguingly, some scientists suspect there might be multiple, distinct populations within the species, with breeding grounds scattered across far-flung locations like Hawaii, the Galapagos Islands, and even the Atlantic archipelagos.

Here in Costa Rica, the Band-rumped Storm-Petrel’s breeding habits remain somewhat of a mystery. While sightings are documented off the Pacific coast, pinpointing their exact breeding colonies within Costa Rica requires further research.

Witnessing a Wonder

Spotting a Band-rumped Storm-Petrel from the shore is a rare feat. However, boat trips specifically designed for birdwatching, particularly those venturing offshore near the Osa Peninsula and Cocos Island, offer the best chance of encountering these enigmatic birds. Keep your eyes peeled for their dark silhouette skimming the waves just after dusk, and with a bit of luck, you might witness the breathtaking aerial dance of the Band-rumped Storm-Petrel.

While you may not encounter this wonder directly at our mountain retreat, understanding the diverse avian life of Costa Rica – from the mountain peaks to the ocean depths – paints a richer picture of this incredible country. So, the next time you’re on the Pacific coast, keep an eye out for the elusive Band-rumped Storm-Petrel, a testament to the hidden wonders that Costa Rica holds.

For more information, please view our comprehensive guide about the birds of Costa Rica