Markham's Storm-petrel

Markham's storm petrel nests in burrows, natural cavities, and holes in saltpeter crusts. Nests in saltpeter cavities have been reported in Pampa de Camarones in northern Chile, and inland on 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. This could lead to an overall ten-month reproductive season. 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 10.3 centimetres (4.1 in) with a standard deviation of ± 3.1 centimetres (1.2 in), with the narrowest part measured at 6.8 centimetres (2.7 in) with a deviation of ± 1.9 centimetres (0.75 in). The average depth of the burrows was greater than 40 centimetres (16 in). After hatching, in Chile, the fledglings move towards the sea. Fledglings are either attracted to or disoriented by artificial lights, an occurrence common to burrow-nesting petrels. Among a study by Spear, Ainley and William A. Walker of the National Marine Mammal Laboratory which analyzed stomach contents of thirty different species of Pacific Ocean avifauna from 1983–1991, a sample of fifteen Markham's storm petrel had consumed namely the fish Diogenichthys laternatus and Vinciguerria lucetia, among other foods. Markham's storm petrel was found to have a lower dietary diversity than other small petrels, though dietary diversity was high generally among small petrels compared to other birds analyzed. A 2002 study in Marine Ornithology that examined a total of 95 Markham's storm petrels from Paracas Peninsula and La Vieja Island in central Peru, collectively, found 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, biologist Ignacio García-Godos concluded Markham's storm petrel was a forager which opportunistically found food near the surface of the ocean. The proportion of birds that feed or rest, compared to flying in transit, was significantly higher in austral autumn than spring in Spear and Ainley's 2007 study. In 2018, researchers Patrich Cerpa, Fernando Medrano and Ronny Peredo found the ectoparasite stick-tight flea Hectopsylla psittaci on two birds out of ten captured in Pampa de Chaca within the Arica y Parinacota Region. Both specimens were found in the lorum on each bird. 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. Researchers Rodrigo Barros et al. (2019) described the bird as "one of the least known seabirds in the world".

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 (2007) observed Markham's storm petrel from 29°54′S 118°01′W / 29.90°S 118.02°W / -29.90; -118.02 to 16°33′N 118°01′W / 16.55°N 118.02°W / 16.55; -118.02, which expanded its westward range from a compilation of sightings recorded by ornithologist Richard S. Crossin in 1974. Its presence is highly unlikely in the Atlantic Ocean outside of freak vagrancies, and in 2007, 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. A survey conducted by Spear and Ainley (2007) from 18°N to 30°S, west to 115°, found greatest densities of the bird during austral autumn (the non-breeding season) offshore between Guayaquil and Lima. During spring, the breeding population splits into two around southern Peru and northern Chile, stretching out 1,700 km (1,100 mi) offshore. Nesting colonies were first reported in the late 1980s to early 1990s. In 1992, 1,144 nests, equal to a population of approximately 2,300 nesting pairs, were found five kilometres (3.1 mi) inland on Paracas Peninsula in Peru. Two separate discoveries occurred in Chile in 2013: one of nesting sites south of the Acha valley [es] in Arica Province by a group of ornithologists and one of a recording of a bird singing by a biologist working for a consulting company. 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. This translated to about ninety-five percent of the known breeding population at the time.

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 researcher Fernando Medrano in 2019. Medrano combined a new colony description with previous findings by Barros in 2019, 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. (2019), 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 population trend for mature individuals because 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 Ministry of the Environment [es] (MMA) classified the bird as En Peligro de Extinción [in danger of extinction] by its Reglamento de Clasificación de Especies. Conservation efforts have been undertaken in Chile by the Servicio Agrícola y Ganadero [es] (SAG), a department of the Ministry of Agriculture [es] (Minagri). In April 2014, the SAG stated it already rescued a large amount of juveniles who lost their way likely due to lighting in cities, a phenomenon that had been evident in the Tarapacá Region for at least ten years prior. In 2018, the SAG reported 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. In a program headed by Fernando Chiffelle, a Ministerial Regional Secretary [es] (seremi) from the Minagri, and Sue Vera, a seremi from the SAG Tarapacá, officials from the civil organization Red de Voluntarios de Rescatistas de la Golondrina de Mar Negra and from the seremi MMA handed out informational brochures to citizens in March 2019 which informed citizens about the start of the juvenile flight season. The brochures instructed citizens what to do if they found a grounded Markham's storm petrel. Similarly, in 2015, the Peruvian Servicio Nacional Forestal y de Fauna Silvestre instructed citizens how to transport a fallen Markham's storm petrel if they should find one. In Ecuador, as of 2018, the species is classified as Near Endangered. 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, Juan C. Torres-Mura and Marina L. Lemus of the Unión de Ornitólogos de Chile reported seeing bulldozer trails, dogs and an encampment of road construction workers near nesting areas close to Arica. 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. Fallen birds were reported in Tacna, Peru, in November 2015, the birds having possibly fallen due to artificial lights. In September 2019, the Chilean MMA produced a Recuperación, Conservación y Gestión de Especies [Recovery, Conservation and Management of Species] plan which included Markham's storm petrel, and which sought to evaluate proposals such as updating a light pollution standard to mitigate the effects of artificial lights on the birds and designating a nesting site at Pampa de Chaca as a protected area.