Behavior

Walking, Running, Hopping, Climbing, etc.

Like most other Procellariiformes, the Black-capped Petrel presumably walks by shuffling on feet and tarsi (74 Warham, J. (1996). The Behaviour, Population Biology, and Physiology of the Petrels. Academic Press, San Diego, CA, USA. Close ). It is suspected that most locomotion on the ground is restricted to the vicinity of the nesting burrow. When birds depart their burrow during the breeding season, it is generally suspected that they take off from an elevated location such as rocky outcrops or tree stumps. Camera traps recorded adult petrels scrambling up rocks and trees using their feet and wings, presumably before taking off (Ernst Rupp, personal communication; see Figure 9.3 in [74 Warham, J. (1996). The Behaviour, Population Biology, and Physiology of the Petrels. Academic Press, San Diego, CA, USA. Close ]).

Flight

Black-capped Petrel employs flight patterns typical of gadfly petrels (Pterodroma sp.), using dynamic soaring with occasional flaps and high arcs above the wave surface to move rapidly over large distances. In winds greater than 18.5 km/h (10 knots), the species adopts a sinusoidal motion, one wing pointed at the water, the other at the sky. Petrels usually fly in rapid “roller coaster” flight on bowed and angled wings; this behavior results in a a distinctive rising-and-falling progression (15 Harrison, P. (1983). Seabirds. An Identification Guide. Croom Helm, Beckenham, UK. Close ). Haney (68 Haney, J. C. (1987). Aspects of the pelagic ecology and behaviour of the Black-capped Petrel (Pterodroma hasitata). Wilson Bulletin 99(1):153–168. Close ) reported on the marine habitat and behavior off Georgia:

Occasionally, they rose to 20–25 m above the sea at the peaks of the arcs. The extent of wing-flapping in this flight mode was inversely related to wind speed. At wind speeds ≤ 11.1 km/h (6 knots), petrels used a very slow and labored flight with many deep, rapid wing-beats, particularly when taking off from the ocean surface. Gull-like soaring on horizontal wings from 50–100 m above the ocean surface was observed very rarely during moderate wind conditions (11.1–77.8 km/h or 6–15 knots). In higher winds, Black-capped Petrel may spring directly into the air from the water surface (15 Harrison, P. (1983). Seabirds. An Identification Guide. Croom Helm, Beckenham, UK. Close ), whereas in low winds (<11.1 km/h or 6), they run along the ocean surface for 2–4 m before taking flight (75 Haney, J. C. (1983). Previously unrecorded and hypothetical species of seabirds on the continental shelf of Georgia. Oriole 48:1-32. Close ).

Swimming or Diving

Birds will swim on the surface of the water. While rare, they may also dive completely beneath the surface of the water in search of prey (KES, unpublished data; see Feeding).

Preening, Head-Scratching, Stretching, Sunbathing, Anting, etc.

Information needed.

Sleeping, Roosting

Information needed.

Daily Time Budget

It comes to land only at dusk and under the cover of darkness, to breed in remote, high-elevation locations. During the breeding season, adult petrels leave or approach nesting areas in the dark. After sunset, adults leave the sea and head over land towards breeding areas, often using watersheds as flight corridors. Upon arriving near the nesting site, adults crash-land through the forest canopy onto the soil surrounding their nest, and rapidly enter the burrow. Monitoring of nesting burrows by trail camera showed that chick-rearing adults arrived between 2213–0408 h (n = 9) and departed between 2200–0417 h (n = 36), and time at nest averaged 30.7 ± 8.9 min (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 ). Satellite-tracked adults and their breeding partners spent, on average, between 4.8–22.5 d at sea between nest visits (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 , 16 Satgé, Y. G., E. Rupp, and P. G. R. Jodice (2019). A preliminary report of ongoing research of the ecology of Black-capped Petrel (Pterodroma hasitata) in Sierra de Bahoruco, Dominican Republic – I: GPS tracking of breeding adults. Clemson, South Carolina, USA: South Carolina Cooperative Research Unit, Clemson University. Close ). During the egg incubation phase of breeding, it is believed that the mates switch once the inbound adult reaches the nest, with the second adult then flying overland to the sea, also at night. Upon exiting the burrow, adults may spend time near the burrow’s entrance, resting or preening (E. Rupp, personal communication).

At sea, Black-capped Petrel is active during the daytime, with peaks in activity from 0700–0900 h and 1700–1900 h (68 Haney, J. C. (1987). Aspects of the pelagic ecology and behaviour of the Black-capped Petrel (Pterodroma hasitata). Wilson Bulletin 99(1):153–168. Close ). The degree of activity during nighttime is not known.

Petrels commonly defend their burrow against other petrels. For instance, following the invasion of the Loma del Toro colony by dogs, two petrels (possibly a pair) were recorded inspecting a burrow before being fought and chased away by a third petrel (possibly the owner of this or a nearby burrow); this occurred two days in a row (E. Rupp, personal communication).

At sea when attending a chum slick, Black-capped Petrel may squabble over fish pieces and chase one another similar to other seabird species (YGS, personal observation). Nothing is known about agonistic behavior at sea under natural conditions.

Mating System and Operational Sex Ratio

Presumably monogamous.

Courtship, Copulation, and Pair Bond

Courtship behavior is suspected to be similar to that of other Pterodroma species, with the Black-capped Petrel performing nocturnal courtship flights and calls near breeding areas, during the early breeding period (from nest initiation to egg hatching). Records by camera traps suggest that mating and copulation occur outside the burrow (E. Rupp, personal communication).

Degree of Sociality

Social behavior is not well understood, but records by camera traps provide some clues into intraspecific interactions. For instance, during nest initiation, members of a pair cooperate to prepare the nest site; on one occasion, a petrel cleaned the entrance of its burrow while its partner was inside. Another time, both members of a pair were observed cleaning the path to their burrow in unison.

Radar studies on Hispaniola show that adults occasionally fly in overland flight corridors in small groups (3–5 individuals). Upon reaching the breeding areas, petrels are occasionally observed, via radar, flying back and forth, sometimes circling above the breeding area, before descending to a nesting burrow (AB, unpublished data).

At sea, the species occasionally forms rafts of tens of individuals. Presumably, concentrations in the tens of birds, as seen in the Gulf Stream and in Cuban waters, are regular occurrences (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 ). Although most resting rafts have been observed in offshore conditions, Rosenberg (eBird) observed rafting petrels within sight off the coast of Cuba. In two instances, birds tracked by GPS displayed a behavior consistent with coastal rafting (16 Satgé, Y. G., E. Rupp, and P. G. R. Jodice (2019). A preliminary report of ongoing research of the ecology of Black-capped Petrel (Pterodroma hasitata) in Sierra de Bahoruco, Dominican Republic – I: GPS tracking of breeding adults. Clemson, South Carolina, USA: South Carolina Cooperative Research Unit, Clemson University. Close ); tracked petrels rested close to shore, off southwest Haiti and off southern Cuba, in the proximity of known or suspected breeding colonies. Both birds arrived in the middle of the day and departed after sunset; the petrel rafting near Haiti subsequently flew back to its breeding colony.

Nonpredatory Interspecific Interactions

Black-capped Petrel occasionally forms small intraspecific rafts during the day. When foraging, it is also often associated with mixed species flocks (88% of occurrences, n = 25); it frequently associates with Cory's Shearwater, Great Shearwater, Audubon's Shearwater, and Pomarine Jaeger in summer, and Herring Gull and Black-legged Kittiwake (see Feeding for more detail; 68 Haney, J. C. (1987). Aspects of the pelagic ecology and behaviour of the Black-capped Petrel (Pterodroma hasitata). Wilson Bulletin 99(1):153–168. Close ).

Both Parasitic Jaeger (Stercorarius parasiticus) and Pomarine Jaeger have been recorded attempting to parasitize feeding petrels as they rested on the surface (68 Haney, J. C. (1987). Aspects of the pelagic ecology and behaviour of the Black-capped Petrel (Pterodroma hasitata). Wilson Bulletin 99(1):153–168. Close ). Offshore Hatteras, North Carolina, seabirding pelagic cruises regularly use chum and oil slick to attract birds to the boat, including jaegers and skuas. Black-capped Petrels are commonly observed pursuing individual jaegers or skuas, either singly or in groups of up to nine petrels; it appears that dark-morph jaegers are more often pursued than light-morph ones (KES, unpublished data). It is unclear why Black-capped Petrels pursue these kleptoparasitic species, but the pursuit behavior appears similar to mobbing, with petrels flying closely behind jaegers or skuas, almost brushing them as they fly past. Petrels have been observed flying just above or just below jaegers or skuas, before maneuvering closer and then flying away; photographs show that Black-capped Petrels are intently focused on jaegers or skuas, and this behavior has sometimes resulted in jaegers or skuas leaving the area (KES, unpublished data).

Lee (in 72 Haney, J. C., D. S. Lee, and R. D. Morris. 1999. Bridled Tern (Sterna anaethetus). In The Birds of North America, No. 468 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA. Close ) watched a Bridled Tern repeatedly attack a Black-capped Petrel that was trying to feed on the wing; the pursuit continued for some time with the petrel eventually leaving the area. This was the only such incidence observed during 15 years of study.

On land, the Hispaniolan hutia (Plagiodontia aedium) uses petrel burrows and, on one occasion, a petrel was observed fighting a hutia (E. Rupp, personal communication). However, most interspecific interactions recorded at nest sites have remained indirect. For instance, in June 2012 and May 2021, camera traps recorded Pine Warbler (Setophaga pinus) entering petrel burrows to collect breast feathers, supposedly for nest material (E. Rupp, personal communication). In April 2018, researchers found a caterpillar (Lepidoptera, family Tineidae) using Black-capped Petrel feathers to make a case (i.e., cocoon). Caterpillars of case-making moths are known to incorporate animal material into their cases to feed on them (YGS, unpublished data).

Mammals are frequent predators of eggs, chicks, and adults. It is not known if endemic mammals (most of which are extinct on on Hispaniola and other probable and suspected nesting areas) depredate Black-capped Petrels. However, introduced mammals known to prey on birds are present at all confirmed and suspected nesting sites within the Caribbean region (see Conservation and Management: Effects of Human Activity). These include, but are not limited to, rats (Rattus sp.), cats (Felis catus), dogs (Canis familiaris), Indian mongoose (Herpestes edwardsii), and feral pig (Sus scrofa).

It is unclear if Black-capped Petrel is also subject to predation by other avian species. On land, their nocturnal habits may prevent predation by birds of prey, as no large nocturnal raptors are present in the Caribbean. At sea, Brinkley (76 Brinkley, E. S. (1994). Evasive maneuvers of Black-capped Petrel (Pterodroma hasitata). Chat 58:18-22 Close ) reported evasive maneuvers by individuals pursued by South Polar Skua and Pomarine Jaeger, suggesting possible predation by these species. On at least two occasions, South Polar Skua was observed feeding on the carcass of a Black-capped Petrel, but the cause of death was unknown (76 Brinkley, E. S. (1994). Evasive maneuvers of Black-capped Petrel (Pterodroma hasitata). Chat 58:18-22 Close ; KES, unpublished data).