Markham's storm petrel


Markham's storm petrel is a species of storm petrel in the family Hydrobatidae. An all-black seabird, Markham's storm petrel is described as hard to differentiate from the black petrel Loomelania melania in life, and was once described as conspecific, or biologically identical, with Tristram's storm petrel Oceanodroma tristrami. It inhabits open seas in the Pacific Ocean around Peru, Chile, and Ecuador, but only nests in northern Chile and Peru, with 95% of all known breeding populations in 2019 found in the Atacama Desert. First described by British ornithologist Osbert Salvin in 1883, the bird was named in honor of Albert Hastings Markham, a naval officer who collected a specimen off Peru.
Markham's storm petrel nests in natural cavities or interstices in saltpeter, with pairs producing one egg per season. After hatching, fledglings make their way to sea, and can be either attracted to or disoriented by artificial lights. The diet of Markham's storm petrel consists of fish, cephalopods, and crustaceans, with about ten percent of stomach contents traceable to scavenging according to a 2002 study. Since at least 2012, Markham's storm petrel has been listed as an endangered species in Chile, and, in 2019, the International Union for Conservation of Nature classified the conservation status of Markham's storm petrel as Near Threatened due to habitat loss on its nesting grounds. The , a department of the of Chile, has undertaken conservation efforts in the country.

Taxonomy

The storm petrel family, Hydrobatidae, is a group of seabirds characterized by long legs and a high adaption to marine environments; within it, the subfamily Oceanitinae comprises storm petrels mostly endemic to the southern hemisphere, with the subfamily Hydrobatinae predominately endemic to the northern. In Handbook of the Birds of the World, vol. 1, Carboneras states Hydrobatidae probably diverged from other petrels at an early stage, with storm petrel fossils rare, only found dating from the Upper Miocene in California. Wilson's storm petrel Oceanites oceanicus may have been the first storm petrel to inhabit the Northern Hemisphere, thus possibly originating the subfamily Hydrobatinae of which Markham's storm petrel is a member. In Hydrobatinae, Markham's storm petrel is a member of the genus Oceanodroma, and is comparatively large compared to other members in the genus, which also comprises small seabirds. The only other genus in the subfamily Hydrobatinae is Hydrobates, which contains solely the European storm petrel Hydrobates pelagicus and its subspecies.
British ornithologist Osbert Salvin first described the Markham's storm petrel as Cymochorea markhami in 1883. Markham's storm petrel is named after Sir Albert Hastings Markham, a British explorer and naval officer who picked up a specimen off Peru. The bird was thought by ornithologist James L. Peters in 1931 as conspecific, or biologically identical, with Tristram's storm petrel Oceanodroma tristrami, though the two species were later distinguished by size. Similarly, ornithologist Reginald Wagstaffe considered Tristram's storm petrel a subspecies of Markham's storm petrel in 1972, though current practice as of 2008 recognized them as different species. In 2016, the IUCN reclassified Oceanodroma markhami as Hydrobates markhami based on reclassification in HBW and BirdLife International Illustrated Checklist of the Birds of the World, volume 1, by Hoy et al. The genus Oceanodroma was found to be paraphyletic with respect to Hydrobates and all former Oceanodroma species were transferred to Hydrobates.
Its name in Spanish literature is Golondrina de mar negra.

Description

Markham's storm petrel is an all-black to sooty brown storm petrel with a :wikt:plumbeous|plumbeous gloss on its head, neck and mantle in fresh plumage. Its :wikt:ventral|ventral area, :wikt:caudad|caudad from the neck, and wing lining are blackish brown, and become almost :wikt:fuscous|fuscous with wear of the plumage. External edges of wing coverts in the bird become whitish with wear, but are normally brown; the whitening produces a broad grayish bar that generally extends closer to the wing's bend than what Robert Cushman Murphy observed as a somewhat similar mark in the black petrel Loomelania melania. Its iris is brown, its bill and feet are black, and its tail is deeply forked. Two female specimens taken from in August 1967, both with small gonads and unused oviducts, had heavy contour molt and light fat. Murphy described the species as difficult to distinguish in life from the black petrel, with the chief difference being a much shorter tarsus.
Adult males have a wingspan of compared to a wingspan of in adult females, and the tarsus is in adult males and in females. Tails are in adult males and in adult females. Sexes are alike. Eggs are described as pure white without gloss.
Ornithologists Larry B. Spear and David G. Ainley report that Markham's storm petrel has a more leisurely flight pattern than that of the black petrel, and states the Markham's storm petrel has a similar flight pattern to Leach's storm petrel. In 1980, Canadian author RGB Brown stated the birds tended to glide over two observations, with shallow and rapid wingbeats, though an observation by Rollo Beck described its wingbeats as slow, and slower than the more rapid wingbeats of Wilson's storm petrel Oceanites oceanicus and Elliot's storm petrel Oceanites gracilis. Markham's storm petrel typically flies greater than one meter over the ocean surface, compared to the black petrel.

Distribution and habitat

Markham's storm petrel inhabits waters in the Pacific Ocean around Ecuador, Peru, and Chile, though sightings have occurred on the equator west of the Galápagos Islands, within the Panama Bight, and off of Baja California. Sightings off of Baja California might mistake Markham's storm petrel for the black storm petrel due to difficulties of distinguishability in the field. Spear and Ainley observed Markham's storm petrel from to, which expanded its westward range from Crossin. Its presence is highly unlikely in the Atlantic Ocean outside of freak vagrancies, and in 2007, and Spear and Ainley classified the species as endemic to the Humboldt Current. Despite its range, Markham's storm petrel only nests in Peru and Chile.
An observation conducted by Spear and Ainley from 18°N to 30°S, west to 115°, found greatest densities of the bird during austral autumn, the non-breeding season, close to the coast near central Peru, while during spring densities bifurcated between southern Peru–northern Chile and an area roughly west thereto. Nesting colonies were unknown in 1931, though 1,144 nests, equal to a population of approximately 2,300 nesting pairs, were found in 1992 inland on Paracas Peninsula in Peru. After two separate discoveries in Chile in 2013, one of nesting sites south of the in Arica Province by a group of ornithologists and one of a recording of bird singing by a biologist working for a consulting company, and after further exploration in November 2013 based on the recording, in 2019, populations of 34,684 nests in Arica, 20,000 nests in Salar Grande, and 624 nests in Pampa de la Perdiz were found in the Atacama Desert of northern Chile, which translated to about 95% of the known breeding population at the time.

Behavior and ecology

Markham's storm petrel nests in natural cavities, holes, and interstices in saltpeter crusts, with saltpeter cavities reported in both Pampa de Camarones in northern Chile and Paracas Peninsula. In Peru, egg laying occurs from late June to August; in Chile, an analysis of three colonies in the Atacama Desert found a five-month reproductive cycle, from arrival at colonies to departure of fledglings, across all three colonies, though pairs could reproduce asynchronously, which could lead to an overall ten-month reproductive span. Pairs produce one egg per season, and adults in nests were found to vocalize when a conspecific recording of vocalizations was played at the entrance to the nest. Mean width of the widest part of openings to nest burrows in Chile was measured at with a standard deviation of ±, with the narrowest part measured at with a deviation of ±. The average depth of the burrows was greater than. After hatching, in Chile, the fledglings move towards the sea, with fledglings either attracted to or disoriented by artificial lights, an occurrence common to burrow nesters in the order Procellariiformes.
Among a study by Spear, Ainley and Walker of the diets of thirty different species of eastern tropical Pacific Ocean avifauna taken from 1983–1991, a sample of fifteen Markham's storm petrel and thirty prey samples found a diet of fish, Myctophidae, namely Diogenichthys laternatus, and the Photichthyidae Vinciguerria lucetia, among different food types, with a high diet diversity among small species of Procellariiformes. A 2002 study in Marine Ornathology that examined a total of 95 Markham's storm petrel, collectively, from Paracas Peninsula and La Vieja Island in central Peru found that its main diet by mass consisted of fish, namely the Peruvian anchovy Engraulis ringens, cephalopods, namely the octopus Japetella sp., and crustaceans, namely the pelagic squat lobster Pleuroncodes monodon, with about ten percent of analyzed stomach contents suggestive of scavenging. Based on large variations in the types of food it consumes, and its tendency to scavenge, García-Godos et al. concluded Markham's storm petrel was a forager which opportunistically finds food near the surface of the ocean. The proportion of birds that feed–rest, compared to flying in transit, was significantly higher in austral autumn than spring in Spear and Ainley's 2007 observation.
In 2018, Cerpa, Medrano and Peredo found the ectoparasite stick-tight flea Hectopsylla psittaci, in the family Hectopsyllidae, on two birds out of ten captured in Pampa de Chaca within the Arica y Parinacota Region, with both specimens found in the lorum on each bird; both fleas were neosomatic females, with legs chopped at the coxa, trochanter or femur. The turkey vulture Cathartes aura served as a possible source for the transition between hosts, as Cerpa, Medrano and Peredo observed the two nesting in the same colony.
The bird has been described as "one of the least known seabirds in the world".

Threats and conservation

The IUCN estimated the population of Markham's storm petrel in 2019 as between 150,000 and 180,000 individuals, with between 100,000 and 120,000 mature individuals, based on an estimate by Medrano et al., which combined a new colony description with previous findings by Barros et al., and estimated the global breeding population at 58,038 pairs. The IUCN estimated the population of Markham's storm petrel was in decline generally based on an estimate by Barros et al., who estimated up to 20,875 fledglings die each year, though the IUCN noted juvenile seabirds have a higher mortality rate in general based on environmental parameters, age, and sex. The IUCN could not give a specific estimate as to decline among mature individuals as tendencies for mature populations were unknown. Prior to 2019, no concrete population estimates for Markham's storm petrel existed, with a 2004 estimate by Brooke placing the population at likely in excess of 30,000 individuals, a 2007 estimate by Spear and Ainley placing the population between 806,500 in austral spring and 1,100,000 in austral autumn, and a 2012 IUCN estimate placing the population at 50,000 overall individuals.
Despite its "very large" population size, in 2019, the IUCN classified the conservation status of Markham's storm petrel as Near Threatened due to habitat loss on its nesting grounds. Since at least 2012, the bird has been classified as endangered in Chile, and, in 2018, the Chilean classified the bird as En Peligro de Extinción by its Reglamento de Clasificación de Especies. Conservation efforts have been undertaken by the SAG, a department of the of Chile. In April 2014, the SAG stated it "already... rescued" a "large amount" of juveniles who lost their way based on lighting in cities, a phenomenon that had been evident in the region for at least ten years prior. In 2018, the SAG reports it returned approximately 2,000 juvenile birds to their natural habitat after the birds fell on streets, the birds believing they had already reached the coast. Along with volunteers from a civil organization aimed at protecting the bird, the SAG handed out informational brochures to citizens in March 2019 which informed citizens about the start of the juvenile flight season and instructed citizens what to do if they found a grounded Markham's storm petrel.
Chief threats to Markham's storm petrel in Chile include garbage, roadways across nesting colonies, mining, new construction and development, and artificial lights. In 2013, Torres-Mura and Lemus report seeing bulldozer trails, dogs and an encampment of road construction workers near nesting areas. Other than habitat loss, salt mines in northern Chile may also provide a source of habitat disturbance through artificial lights; a salt mining company in Chile, for instance, reported over a three-month span that 3,300 fledglings had been grounded, due to their lights. In September 2019, the MMA produced a Recuperación, Conservación y Gestión de Especies plan which included Markham's storm petrel, and which sought to evaluate proposals such as updating a light pollution standard to mitigate the affects of artificial lights on the birds and designating a nesting site at Pampa de Chaca as a protected area.