62

Common Raven Nesting in Eastern Ontario

by Bruce M. Di Labio and Paul R. Martin

In Ontario, the Common Raven 198Os, the winter population (Corvus corax), is considered a ranged from 10 to 40 birds, with common permanent resident most found at the Torbolton throughout the province, but rare Township Dump, and a few south ofAlgonquin Provincial Park remaining into the summer Games et aL 1976). Its status in the (B. M. D.). Ottawa District has changed InJune 1984 the first possible considerably over the pastdecades. breeding evidence in the Ottawa In 1911, the Common Raven was District was found. An adult raven found to be a rare resident, and two young were observed in a becoming common on the Quebec heavily wooded area consisting of side of the Ottawa District. In the eastern white cedar (Thuja immediate vicinity ofOttawa itwas occidentalis) and white pine (Pinus a rare winter visitor (Eifrig 1911). strobus) at the south end of H. Lloyd described this species as a Constance Lake, March Township "rare resident" in the Ottawa (B. M. D.). District, "formerly occurring in the During the five years ofthe city" (Uoyd 1944). In 1969, Ontario Breeding Bird Atlas project Pittaway referred to the Common (1981-85), no confirmation of Raven as a "scarce resident in [the] nesting was found in the Ottawa Gatineau; breeds. Very rare District or anywhere east ofOttawa elsewhere" (Pittaway 1969). Since (Blomme 1987). Itwas not until ~en, the number ofCommon 1987 that the first documented Raven sightings has increased on nesting ofCommon Raven was the Ontario side ofthe Ottawa established in the Regional District, primarily in the townships Municipality ofOttawa-Carleton. ofWest Carleton and Kanata. Surprisingly, this nest site occurred During the mid-1970s most ofthe east ofOttawa, rather than to the observations were made during the west where itwas expected. winter months, but by the late Since the early 19808 two or 19708 sightings ofCommon Ravens three Common Ravens have been were reported all year round. In the regularly observed around the

Bruce M. Di Labio, 62 Grange Avenue, Ottawa, Ontario K1YON9 Paul R. Martin, 25 Beechmont Crescent, Gloucester, Ontario KlB 4A7

ONTARIO BIRDS AUGU5f 1989 63

Figure 1: Common Raven nest (arrpw), Francon Gravel Pits, Gloucester, Regional Municipality of Ottawa-Carleton, Ontario, April 1987. Photo by Bruce M. Di Labio.

VOLUME 7 NUMBER 2 64

Green's Creek Sewage Lagoon, east the south-facing wall ofthe pit and ofOttawa. Breedingwas first was constructed mainly oflarge suspected in May 1986, when a sticks. Due to the inaccessibility of large abandoned nestwas found at the nest, a complete description of the Francon Gravel Pits along the the nest materials was impossible. north end ofBearbrook Road, near The Common Raven is normally Blackburn Hamlet, Gloucester wary ofhumans; however in some Township. circumstances they prove to adapt The gravel pitwas monitored well when suitable man-made the following year, beginning in habitat is present (Blomme 1987). February. Mter numerous visits, a This proved to be the case with this Common Raven was finally nesting, since the gravel pitwhere observed on 17 March. By 4 April the nest was located was active, with two Common Ravens were present, heavy machinery and dynamite with a large nest in the final stages actiyity presenL This demonstrates ofcompletion. From 5 April on, the adaptability ofCommon Ravens Common Ravens were observed in the selection ofnest sites when sharing the incubation duties. Due there is a lack ofnatural nesting to the remoteness of the nesting habitat. site, the authors were unable to This record represents an view inside the nest, making the eastern extension ofthe breeding exact hatching date impossible to range of the Common Raven in confirm. The nesting ofthe Ontario. It is also the first Common Ravens was later documented breeding record of confirmed on 20 April when at least the Common Raven in the Regional two and possibly three young were Municipality ofOttawa.carleton. observed sticking their heads above the walls ofthe nesL They left the Literature cited neston 15 May, and were later seen BlorIafu, C 1987. Common Raven. pp. less than 1km away from 'the 290-291. I,. Cadman, M. D., P. F. J. Eagles, and F. M. Helleiner (eds.). 1987. Adas of nesting site on 28 May. the Breeding Birds ofOntario. University The nest site was located on the ofWaterloo Pre_, Waterloo. side ofthe gravel pitwall, Eiftig, C W. G. 1911. The birds ofOttawa. The Ottawa Naturalist 24:152-16!, 176-187, approximately 20 to 25m above the 198-206, 222. floor of the quarry, and !m from }4fUS, R. D., P. L McL4".,., andJ C. B.low. the top. The nestwas situated in a 1976. Annotated Otecklist ofthe Birds of crevice with a large overhanging Ontario. Life Sciences Miscellaneous Publication, Royal Ontario Museum, rock protecting the nest from Toronto. weather and disturbance (Fig. 1). It LWJt4 H. 1944. The birds ofOttawa, 1944. is inr.eresting to noterhat the nest Culadian Field-Naturalist 58:14!-175. ~ R. 1969. The birds ofthe Ottawa site was atone ofthe highest Region. Trail and LandscaPe !:1~15. elevations in Ontario east of Ottawa. The nestwas situated on

ONTARIO BIRDS AUGUsr 1989