Justification of Red List Category
Even though the population size of this species is very large, it breeds only in a small number of relatively small colonies, which are threatened by habitat degradation. The population is considered to be in decline due to various threats, but the rate of decline is not known. The species is therefore classified as Near Threatened.
A minimum of 2,305 pairs were present on the Paracas peninsula in 1992 (Tobias et al. 2006). Following the recent discovery of several large breeding colonies in the Atacama Desert (Schmitt et al. 2015, Barros et al. 2019), the global population was estimated to number c.50,000-60,000 breeding pairs (Schmitt et al. 2015, Barros et al. 2019, Medrano et al. 2019). This equates to 100,000-120,000 mature individuals, or 150,000-180,000 individuals in total.
The population trend of Markham’s Storm-petrel has not been estimated directly. However, it has been suggested that each year, about 20,000 fledglings of the colonies in the Atacama Desert die after light-induced grounding, which potentially represent about 1/3 of the entire cohort (Barros et al. 2019, F. Medrano in litt. 2019). Based on this, it is assumed that the population is in decline. The rate of decline cannot be assessed based on the available information though, as population decline is measured as the decline in mature individuals. Juvenile seabirds generally have a high mortality for various reasons, which is dependent on age, sex and environmental parameters (Fay et al. 2015). It is not clear how many juveniles of Markham’s Storm-petrel die of natural causes each year, or if the reduced population density may even enhance the survival of the remaining fledglings, as has been shown in other seabirds (Fay et al. 2015). As such, it is unclear to which extent the light-induced mortality of juveniles affects the recruitment and the population size of Markham’s Storm-petrels.
Markham’s Storm-petrel (Hydrobates markhami) occurs in the tropical zone of the eastern Pacific Ocean. Between July and September, it is found over warm, equatorial waters, while between January and July it moves to cooler waters of the Peru Current and further west (Pyle 1993, Spear and Ainley 2007). It breeds on the Paracas peninsula on the coast of central Peru and in the Atacama Desert of southern Peru and northern Chile (Carboneras 1992, Barros et al. 2019). In Paracas, the species forms six breeding colonies (Medrano et al. 2019), which were estimated at a minimum of c.2,300 pairs in 1992 (Tobias et al. 2006). In Chile, several colonies have been discovered recently: near Arica, the species breeds in five colonies, of which two colonies hold fewer than 10 pairs (Pampa Tana, Pampa La Higuera), one colony holds 90 pairs (Pampa Chuño), another colony around 10,000 pairs (Pampa Camarones), and the largest colony around 25,000 pairs (Pampa Chaca; Barros et al. 2019, Medrano et al. 2019). Further colonies were located in Tarapacá and Antofagasta regions: The colony in Salar de Quiuña is estimated at c.400 breeding pairs, the colony in Pampa La Perdiz at c.600 pairs, the colony in Salar Grande at 20,000 pairs and a smaller colony further south in Salar de Navidad at fewer than 10 pairs (Barros et al. 2019, Medrano et al. 2019). It is assumed that several more breeding colonies could be located around the border of Chile and Peru, and in Mejillones and Antofagasta (Barros et al. 2019).
Markham’s Storm-petrel breeds in dispersed colonies in saline areas, using fissures and holes created by saltpetre deposits for nesting (Tobias et al. 2006, Schmitt et al. 2015, Barros et al. 2019). In Paracas, the species breeds in small, dispersed colonies up to 5 km from the sea on sloping ground (Tobias et al. 2006). The colonies in Chile are located on the east of the Cordillera de la Costa mountain range at up to 50 km distance from the sea (Barros et al. 2019, Medrano et al. 2019). In Chile, known colonies are located at 600-1,100 m a.s.l. (Medrano et al. 2019). Reproduction can be asynchronous within a colony (Barros et al. 2019). Nevertheless, in the northern colonies in Paracas, near Arica and in Salar de Quiuña, most pairs lay eggs between April and August, and are with chicks between July and January (Jahnke 1994, Barros et al. 2019, Medrano et al. 2019). Pairs breeding in the colonies of Pampa Perdiz, Salar Grande and Salar de Navidad further south lay eggs between November and January, while chicks hatch between January and April (Malinarich et al. 2018, Barros et al. 2019, Medrano et al. 2019). The species feeds opportunistically both inshore and offshore on fish, crustaceans and cephalopods (Garcia-Godos et al. 2002). Adults arrive at the colonies at least 45 min after sunset (Barros et al. 2019).
The principle threat faced by Markham’s Storm-petrel is the mining of saltpetre from the salt plain on which it nests (Torres-Mura and Lemus 2013, Barros et al. 2019). This has resulted in the loss of considerable amounts of breeding habitat, as it destroys the burrows and crevices in which nests are placed (Schmitt et al. 2015, Barros et al. 2019). Light pollution also represents a significant level of mortality, with 10-20 fresh corpses reported each morning next to a single light close to a breeding colony (Schmitt et al. 2015). It is assumed that fledglings are attracted to the lights of nearby cities during their first flights (Torres-Mura and Lemus 2013, Schmitt et al. 2015), and already few, strong light sources may affect large parts of a breeding colony (F. Medrano in litt. 2019). It has been estimated that each year around 20,000 fledglings die because of light pollution, representing 1/3 of the entire cohort (F. Medrano in litt. 2019). Light-pollution was found to be a severe threat to seabirds and Hydrobatidae in particular, which can potentially have a detrimental effect on the overall population size (Rodriguez et al. 2017). Further threats include infrastructure developments (roads, wind farms and power lines), military exercises and garbage (Barros et al. 2019). Overall, given the severity of the threats presented by mining and light pollution and their potentially detrimental impacts on the population size, the number of locations of occurrence (as defined by the most severe threat) is assumed to be relatively small.
Conservation Actions Underway
Surveys are being carried out to locate new breeding colonies and to estimate the population size (Barros et al. 2019, Medrano et al. 2019). Grounded fledglings are rescued and released by the Servicio Agricola y Ganadero.
Conservation Actions Proposed
Expand the search for new breeding colonies and estimate their population size. Monitor the known colonies. Study the species's ecological requirements, breeding biology, post-breeding movements, and the connectivity between colonies or breeding areas. Assess threats to the species and their impacts on the population size and trend. Protect the breeding colonies and flight paths to the sea (Barros et al. 2019). Reduce the impact of light pollution in northern Chile (Barros et al. 2019). Continue and expand the rescue and release programme for grounded fledglings.
Text account compilers
Martin, R., Stuart, A., Miller, E., Moreno, R., Benstead, P., Fjagesund, T., Sharpe, C.J., Calvert, R., Hermes, C.
Barros, R., Bretagnolle, V., Brooke, M., Medrano, F., Norambuena, H. & Silva, R.
BirdLife International (2020) Species factsheet: Hydrobates markhami. Downloaded from http://www.birdlife.org on 28/02/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 28/02/2020.