Systematics

Taxonomy, as well as relationships to other Pterodroma species, is discussed extensively in Simons et al. (5 Simons, T. R., D. S. Lee, and J. C. Haney (2013). Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel. Marine Ornithology 41:S3–S43. Close ). The taxonomy of Black-capped Petrel is complex, with great variation between types (see Plumages), causing Howell and Zufelt (17 Howell, S. N. G., and K. Zufelt (2019). Oceanic Birds of the World. Princeton University Press, Princeton, NJ, USA. Close ) to describe it as “vexed.” Here we provide a summary of Simons et al. (5 Simons, T. R., D. S. Lee, and J. C. Haney (2013). Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel. Marine Ornithology 41:S3–S43. Close ) and other relevant information. Note that phenotypes in Black-capped Petrel have been referred to as “dark-faced,” “black-faced,” or “dark morph,” and “light-faced,” “white-faced,” or “light morph”. Since there is genetic evidence that these types diverged from a common ancestor (with intermediate types grouped with the light type; 18 Manly, B., B. S. Arbogast, D. S. Lee, and M. van Tuinen (2013). Mitochondrial DNA analysis reveals substantial population structure within the endangered Black-capped Petrel (Pterodroma hasitata). Waterbirds 36(2):228–233. Close ), we chose to use the term “form” until the taxonomy can be better resolved.

Before the 1800s, Black-capped Petrel was placed in the genus Procellaria with other gadfly petrels. In 1856, Bonaparte proposed the genus Pterodroma for all dark species, and the genus Aestrelata for some of species that had white underparts, including theBlack-capped Petrel; Coues (19 Coues, E. (1866). Critical review of the family Procellariidae;—Part V; embracing the Diomedeinae and the Halodrominae. With a general supplement. Proceedings of the Academy of Natural Sciences of Philadelphia 18:172–197. Close ) designated hasitata as the type for this genus. Black-capped Petrel has been placed in the genus Pterodroma since Loomis (20 Loomis, L. M. (1918). A review of the albatrosses, petrels and diving petrels. Proceedings of the California Academy of Sciences (4th Series) 2:1–187. Close ).

In addition to confusion over the status of dark and light-form birds, there is also disagreement on the status of the all-dark taxon caribbaea; it has variably been treated as a subspecies of Black-capped Petrel or treated as a distinct species, Jamaican Petrel (Pterodroma caribbaea), as we do here (see also Subspecies).

No clear geographic variation has been described in breeding Black-capped Petrels. At known nesting sites on Hispaniola, most petrels captured or photographed by camera traps have been of the dark form (International Black-capped Petrel Conservation Group, unpublished data). In Haiti and the southern Dominican Republic, most individuals are of the dark form and only a few individuals (notably one petrel opportunistically captured by Wingate upon his rediscovery of breeding activity in Haiti; 21 Wingate, D. B. (1964). Discovery of breeding Black-capped Petrels on Hispaniola. Auk 81(2):147–159. Close ) have been of the light and intermediate forms. In the central Dominican Republic, only a small number of nests has been located but most of them are those of light form individuals (E. Rupp, unpublished data). Stranded petrels recovered in Dominica in 2007 and 2010 were of the light form (International Black-capped Petrel Conservation Group, unpublished data).

At sea, based on the limited data available, ranges for both forms appear to overlap spatially (but not temporally) in Gulf Stream waters off the eastern coast of the US (7 Howell, S. N. G., and J. B. Patteson (2008). Variation in the Black-capped Petrel – one species or more? Alula 14(2):70–83. Close , 5 Simons, T. R., D. S. Lee, and J. C. Haney (2013). Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel. Marine Ornithology 41:S3–S43. Close ), though opportunistic observations (22 eBird (2021). eBird: An online database of bird distribution and abundance. Cornell Lab of Ornithology, Ithaca, NY, USA. Close ) and satellite tracking (12 Satgé, Y. G., B. S. Keitt, C. P. Gaskin, J. B. Patteson, and P. G. R. Jodice (2023). Spatial segregation between phenotypes of the diablotin black-capped petrel Pterodroma hasitata during the non-breeding period. Endangered Species Research 51:183-201. Close ) suggest that light forms may commonly use more northerly areas. Both forms have been recorded in the northern Gulf of Mexico (23 Jodice P. G. R., P. E. Michael, J. S. Gleason, J. C. Haney, and Y. G. Satgé (2021). Revising the marine range of the endangered black capped petrel Pterodroma hasitata: occurrence in the northern Gulf of Mexico and exposure to conservation threats. Endangered Species Research 46:49–65. Close ). Dark forms tracked by satellite from breeding grounds on Hispaniola used the central Caribbean Sea intensively (24 Jodice, P. G. R, R. A. Ronconi, E. Rupp, G. E. Wallace, and Y. Satgé (2015). First satellite tracks of the Endangered black-capped petrel. Endangered Species Research 26:23–33. Close ), and there is no reason to think that light forms would not also use these productive waters as well. Both forms have been recorded as vagrants in the Western Palearctic, but light and intermediate forms seem to be more commonly seen (see Table 1).

Two subspecies have historically been recognized: nominate Pterodroma hasitata hasitata and Pterodroma hasitata caribbaea (for the all-dark form that is now probably extinct; 5 Simons, T. R., D. S. Lee, and J. C. Haney (2013). Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel. Marine Ornithology 41:S3–S43. Close , 25 Dickinson, E. C., and J. V. Remsen, Editors (2013). The Howard and Moore Complete Checklist of the Birds of the World. Fourth edition. Volume 1. Aves Press, Eastbourne, UK. Close , 26 Clements, J. F., T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, S. M. Billerman, B. L. Sullivan, and C. L. Wood (2022). The eBird/Clements checklist of Birds of the World: v2022. Cornell Laboratory of Ornithology, Ithaca, NY, USA. Close ). Some authors, however, consider caribbaea to be a separate species, the Jamaican Petrel (Pterodroma caribbaea) (e.g., 27 Brooke, M. (2004). Albatrosses and Petrels Across the World. Oxford University Press, Oxford, UK. Close , 28 del Hoyo, J., and N. J. Collar (2014). HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1. Non-passerines. Lynx Edicions, Barcelona, Spain. Close , 29 Gill, F., D. Donsker, and P. Rasmussen, Editors (2022). IOC World Bird List (v 12.2). doi 10.14344/IOC.ML.12.2. http://www.worldbirdnames.org/ Close , 30 Clements, J. F., P. C. Rasmussen, T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, S. M. Billerman, B. L. Sullivan, and C. L. Wood (2023). The eBird/Clements checklist of Birds of the World: v2023. Cornell Laboratory of Ornithology, Ithaca, NY, USA. Close ).

Within hasitata, two color forms have been described (dark and light, with intermediate forms; see Plumages), with strong variations in plumage and measurements (light-form petrels are generally heavier and bulkier). To elucidate any genetic differences among these different phenotypes, Manly et al. (18 Manly, B., B. S. Arbogast, D. S. Lee, and M. van Tuinen (2013). Mitochondrial DNA analysis reveals substantial population structure within the endangered Black-capped Petrel (Pterodroma hasitata). Waterbirds 36(2):228–233. Close ) amplified mitochondrial cytochrome oxidase 1 (CO1) and found a fixed genetic difference between the dark and light forms; individuals classified as intermediate all grouped phylogenetically with the light form. Manly et al. (18 Manly, B., B. S. Arbogast, D. S. Lee, and M. van Tuinen (2013). Mitochondrial DNA analysis reveals substantial population structure within the endangered Black-capped Petrel (Pterodroma hasitata). Waterbirds 36(2):228–233. Close ) therefore suggested that some temporal or spatial breeding isolation led to the differentiation of the two color forms. In addition to phylogenetics, the notable differences in the timing of molt (light forms molt earlier; 7 Howell, S. N. G., and J. B. Patteson (2008). Variation in the Black-capped Petrel – one species or more? Alula 14(2):70–83. Close ), breeding (tracking data suggests that light forms breed earlier; 12 Satgé, Y. G., B. S. Keitt, C. P. Gaskin, J. B. Patteson, and P. G. R. Jodice (2023). Spatial segregation between phenotypes of the diablotin black-capped petrel Pterodroma hasitata during the non-breeding period. Endangered Species Research 51:183-201. Close ), and of the use of Gulf Stream foraging areas (dark forms are more common in the late summer and early fall, and light forms in April–June; 7 Howell, S. N. G., and J. B. Patteson (2008). Variation in the Black-capped Petrel – one species or more? Alula 14(2):70–83. Close ), suggest that subspecies status may have some relevance. Dark and light forms also appear to use different non-breeding areas in the western North Atlantic (12 Satgé, Y. G., B. S. Keitt, C. P. Gaskin, J. B. Patteson, and P. G. R. Jodice (2023). Spatial segregation between phenotypes of the diablotin black-capped petrel Pterodroma hasitata during the non-breeding period. Endangered Species Research 51:183-201. Close ). However, Manly et al. (18 Manly, B., B. S. Arbogast, D. S. Lee, and M. van Tuinen (2013). Mitochondrial DNA analysis reveals substantial population structure within the endangered Black-capped Petrel (Pterodroma hasitata). Waterbirds 36(2):228–233. Close ) cautioned that “whether these populations should be considered distinct subspecies or distinct species remains unclear at this time and cannot be resolved in the absence of population and behavioral data from breeding sites and analysis of nuclear DNA (microsatellites).” Better information on the genetic diversity of Black-capped Petrels from known nesting colonies is therefore necessary to draw further conclusions.

Within the genus Pterodroma, Black-capped Petrel appears to be sister to a clade of other Atlantic gadfly petrels, including Bermuda Petrel (Pterodroma cahow), Fea's Petrel (Pterodroma feae), Zino's Petrel (Pterodroma madeira), and the extinct Large St. Helena Petrel (Pterodroma rupinarum) based on mitochondrial DNA sequence data (31 Penhallurick, J., and M. Wink (2004). Analysis of the taxonomy and nomenclature of the Procellariiformes based on complete nucleotide sequences of the mitochondrial cytochrome b gene. Emu 104(2):125–147. Close , 32 Jesus, J., D. Menezes, S. Gomes, P. Oliveira, M. Nogales, and A. Brehm (2009). Phylogenetic relationships of gadfly petrels Pterodroma spp. from the Northeastern Atlantic Ocean: molecular evidence for specific status of Bugio and Cape Verde petrels and implications for conservation. Bird Conservation International 19(3):199-214. Close , 33 Welch, A. J., S. L. Olson, and R. C. Fleischer (2014). Phylogenetic relationships of the extinct St Helena Petrel, Pterodroma rupinarum Olson, 1975 (Procellariiformes: Procellariidae), based on ancient DNA. Zoological Journal of the Linnean Society 170:494–505. Close , 34 Tennyson, A. J. D., J. H. Cooper, and L. D. Shepherd (2015). A new species of extinct Pterodroma petrel (Procellariiformes: Procellariidae) from the Chatham Islands, New Zealand. Bulletin of the British Ornithologists’ Club 135:267–277. Close ). These results largely agree with those of Imber (35 Imber, M. J. (1985) Origins, phylogeny and taxonomy of the gadfly petrels Pterodroma spp. Ibis 127(2):197–229. Close ), who placed Black-capped Petrel in a large group with Bermuda Petrel, Fea's Petrel, and Zino's Petrel, as well as other gadfly petrels from the South Atlantic, South Pacific, and southern Indian Ocean, based on morphological characters. Jamaican Petrel has not been included in phylogenetic studies, but it is assumed to be closely related to Black-capped Petrel and part of the same clade with Bermuda Petrel, Fea's Petrel, and Zino's Petrel (33 Welch, A. J., S. L. Olson, and R. C. Fleischer (2014). Phylogenetic relationships of the extinct St Helena Petrel, Pterodroma rupinarum Olson, 1975 (Procellariiformes: Procellariidae), based on ancient DNA. Zoological Journal of the Linnean Society 170:494–505. Close ).

Together with the other members of this strongly supported clade of Atlantic gadlfy petrels, Black-capped Petrel appears to be closely related to another clade that includes Atlantic Petrel (Pterodroma incerta), White-headed Petrel (Pterodroma lessonii), Great-winged Petrel (Pterodroma macroptera), and Magenta Petrel (Pterodroma magentae) (33 Welch, A. J., S. L. Olson, and R. C. Fleischer (2014). Phylogenetic relationships of the extinct St Helena Petrel, Pterodroma rupinarum Olson, 1975 (Procellariiformes: Procellariidae), based on ancient DNA. Zoological Journal of the Linnean Society 170:494–505. Close ).

Not known (36 McCarthy, E. M. (2006). Handbook of Avian Hybrids of the World. Oxford University Press, Oxford, United Kingdom. Close ).

The origin of hasitata comes from the Latin “haesito,” root to the English word "hesitate," indicating the uncertainty Kuhl (37 Kuhl, H. (1820). Beiträge zur Zoologie und vergleichenden Anatomie. Verlag der Harmannschen Buchhandlung, Frankfurt, Germany Close ) had concerning the recognition of this species (5 Simons, T. R., D. S. Lee, and J. C. Haney (2013). Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel. Marine Ornithology 41:S3–S43. Close ).

Black-capped Petrel is known by several names throughout the Caribbean. In North America and in the English language it is also known as “Capped Petrel” and “West Indian Petrel.” In the Spanish- and French-speaking islands, the petrel is usually referred to as “Diablotin” or “Petrel Diablotin.” Diablotin means "little devil," descriptive of the species’ nocturnal habits and the odd-sounding vocalizations, which likely suggested to locals the presence of evil spirits. A mountain peak where it formerly bred in Haiti is named Morne Diablotin; in Dominica, Morne Diablotins is the highest peak on the island. Other names include “Pájaro de la Bruja” in Cuba (“bruja” is Spanish for “witch”), and “chat-huant/chawan” in Haiti and possibly other French-speaking islands (a generic term for nocturnal calling birds).

As noted by Simons et al. (5 Simons, T. R., D. S. Lee, and J. C. Haney (2013). Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel. Marine Ornithology 41:S3–S43. Close ), Zonfrillo (38 Zonfrillo, B. (1987). Names of petrels. British Birds 80:286. Close ) clearly explains why we should seek to call Pterodroma hasitata by its local name, Diablotin: “[T]he local name of the bird, Diablotin, appears to be as much in danger of dying out as the species itself. Where birds such as petrels feature in the economic or historical context of islands, or human populations on islands, it is surely not asking a lot to preserve the local name and incorporate it into modern usage? ‘Capped Petrel’, or ‘Black-capped Petrel’ as the bird is now referred to in the USA, are names which tell little about the bird or its history. There are several species of Pterodroma and shearwaters that have caps or a capped appearance. Along with the endangered Cahow Pterodroma cahow of Bermuda, the Gon-Gon Pterodroma feae of the Deserta & Cape Verde Islands, and the virtually extinct Friera Pterodroma madeira of Madeira, the local names are more quaint and evocative than their rather bland English equivalents. The Diablotin, the ‘devil-bird’, should not be allowed to fade away.”

Sub-fossil remains of Pterodroma, confirmed or suspected to represent hasitata, are known from several sites in Haiti (5 Simons, T. R., D. S. Lee, and J. C. Haney (2013). Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel. Marine Ornithology 41:S3–S43. Close , 39 Steadman, D. W., and O. M. Takano (2013). A late-Holocene bird community from Hispaniola: refining the chronology of vertebrate extinction in the West Indies. The Holocene 23:936–944. Close ). Remains found in middens in Martinique (40 Wetmore, A. (1952). A record for the Black-capped Petrel, Pterodroma hasitata, in Martinique. Auk 69:460. Close ), St. Croix (US Virgin Islands; 41 Wetmore, A. (1918). Bones of birds collected by Theodore de Booy from kitchen midden deposits in the islands of St. Thomas and St. Croix. Proceedings of the US National Museum 54:513–523. Close ), and Crooked Island (The Bahamas; 42 Olson, S. L., and W. B. Hilgartner (1982). Fossil and subfossil birds from the Bahamas. In Fossil Vertebrates from the Bahamas (S. L. Olson, Editor). Smithsonian Contributions to Paleobiology 48. pp. 22–56 Close ) are considered to be from harvested specimens and, in the case of The Bahamas, outside the accepted prehistorical breeding range for the species (42 Olson, S. L., and W. B. Hilgartner (1982). Fossil and subfossil birds from the Bahamas. In Fossil Vertebrates from the Bahamas (S. L. Olson, Editor). Smithsonian Contributions to Paleobiology 48. pp. 22–56 Close ). None of this material has been dated, although samples from Haiti are believed to be from the late Pleistocene to Holocene (5 Simons, T. R., D. S. Lee, and J. C. Haney (2013). Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel. Marine Ornithology 41:S3–S43. Close , 39 Steadman, D. W., and O. M. Takano (2013). A late-Holocene bird community from Hispaniola: refining the chronology of vertebrate extinction in the West Indies. The Holocene 23:936–944. Close ).