Markham's Storm Petrel

The Markham's storm petrel, Hydrobates markhami, is a seabird of notable elegance, named in honor of the British explorer Albert Hastings Markham. It is a large and slender member of the Hydrobatidae family, with a wingspan stretching between 49 and 54 cm. The plumage is predominantly black to sooty brown, adorned with a distinctive grayish bar that diagonally crosses the upper wing surface, creating a striking visual contrast.

Identification Tips

When observing the Markham's storm petrel, look for its deeply forked tail and slender wings with pointed tips. The plumage exhibits a gradation of colors, from a dull lead-gray gloss on the head, neck, and mantle to a more pronounced brown with wear. The crescent-shaped grayish bar on the upper wing is a key feature for identification. Both sexes appear similar, with no discernible morphological differences.

Habitat

This species is a true denizen of the marine environment, spending the majority of its life at sea. It is endemic to the nutrient-rich waters of the Humboldt Current off the coasts of Ecuador, Peru, and northern Chile.

Distribution

Markham's storm petrel ranges across the Pacific Ocean, from southern Mexico to central Chile, and as far west as 118°W longitude. However, it is most commonly found within the Humboldt Current system.

Behaviour

The Markham's storm petrel exhibits a monogamous breeding pattern and is known for its nocturnal visits to nesting sites, avoiding daylight exposure. The breeding season is characterized by significant variability in timing, both within and between colonies. At sea, these birds are often solitary or in small flocks, displaying a leisurely flight with intermittent glides and shallow wingbeats.

Song & Calls

The vocal repertoire of the Markham's storm petrel includes a series of "purrs," "wheezes," and "chatters," particularly when adults are in their nests.

Breeding

Breeding occurs in the arid landscapes of the Atacama Desert, where the birds nest in natural cavities within salt crusts. Each pair produces a single egg per season, laid on the bare ground of the nest cavity. The timing of breeding varies widely, with some colonies beginning as early as April and others as late as August.

Similar Species

The Markham's storm petrel can be challenging to distinguish from the black storm petrel (Hydrobates melania) and the dark morph of Leach's storm petrel (Hydrobates leucorhous). Key differences include the length of the tarsus relative to the foot and the distinctiveness of the gray wing bar.

Diet and Feeding

The diet consists primarily of fish, cephalopods like octopuses, and crustaceans. Approximately ten percent of the stomach contents indicate scavenging behavior, suggesting a degree of opportunistic feeding near the ocean's surface.

Conservation status

The IUCN lists the Markham's storm petrel as Near Threatened, with an estimated population between 150,000 and 180,000 individuals. The species faces threats from habitat destruction due to mining activities and light pollution, which disorients fledglings during their initial flight to the sea, leading to significant mortality rates.