Common Black Hawk, Buteogallus anthracinus predating Oilbird, Steatornis caripensis at Cumaca Cave, Trinidad and Tobago

Cumaca Cave, or Oropuche Cave as it is also referred to, is located in the eastern Northern Range, Trinidad and is home to a large colony of Oilbirds Steatornis caripensis. The cave has a narrow entrance out of which flows a small river and is surrounded by secondary forest (Comeau, Potter, and Roberts 2006)

On 28 March 2016 at approximately 1100h a Common Black Hawk, Buteogallus anthracinus was seen next to the mouth of Cumaca Cave with a dead oilbird chick clutched in its talons. My appearance startled the hawk and caused it to fly off dropping the chick to the ground. The hawk had not had time to start consuming the chick beyond tearing open the lower abdomen and pulling out a length of intestine.

I have been unable to find any references on predation on oilbird chicks by hawks so this is possibly a first record.

 

Fig. 1. Dead Oilbird Chick, preyed upon by Common Black Hawk. Cumaca Cave, 28 March 2016.

 

The possibility that the hawk had scavenged the chick is unlikely, when recovered from the ground the body was still warm and flexible suggesting it had been recently killed. If the chick had fallen out of its nest it would have fallen into the stream and would have been wet and cold when found. On further investigation of the cave several occupied nests were found close to the entrance with some no more than 2m above the level of the stream. The nests were easily observable in daylight thus the hawk would not have had to enter the dark parts of the cave to grab a chick.

In Trinidad Common Black Hawks are thought to feed almost exclusively on crabs (ffrench 2012) but dietary accounts from throughout their range (Schnell 1994) show that they are opportunistic and will feed on a wide range of vertebrates and invertebrates.

The chick weighed 180g and was approximately 21 days old (Thomas, Bosque, and Arends 1993) but its downy feathers had not yet erupted (Fig. 1). The specimen has been preserved in the University of the West Indies Zoology Museum (accession number UWIZM.2016.11).

 

REFERENCES

Comeau, P., Potter, R. and Roberts, P. 2006. The Trinidad and Tobago Field Naturalists’ Club Trail Guide (2nd ed.). Port of Spain, Republic of Trinidad and Tobago: Trinidad and Tobago Field Naturalist’s Club

ffrench, R. 2012. A Guide to the Birds of Trinidad & Tobago (3rd ed.). Cornell University Press, London.

Schnell, J.H. 1994. Common Black Hawk (Buteogallus anthracinus), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology. [Online]. Available at https://birdsna.org/Species-Account/bna/species/comblh1 (Accessed July 2016)

Thomas, D.W., Bosque, C. and Arends, A. 1993. Development of Thermoregulation and the Energetics of Nestling Oilbirds (Steatornis caripensis). Physiological Zoology, 66(3), 322-348.

 

Mike G. Rutherford

The University of the West Indies Zoology Museum, Department of Life Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago.

mike.rutherford@sta.uwi.edu

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