20 Common Raven Nesting in the Greater Area

Thea Hofmann

On 6 June 2003, while riding her adult Common Ravens (c. corax) horse in the North Tract of the York near the now empty nest. She won­ Forest, Allison Hegarty dered whether the supposed observed a large nest (Figure 1) in a American Crow nest could in fact Red Pine (Pinus resinosa) tree be the nest of the Common Ravens located at 17T 635276 4882134 which she had heard nearby. (North American Datum 1983). On 2 July 2003, Christel and I The nest contained two young visited the nest, which we estimated black "squawking" birds which she was at a height of about 15 m. It assumed were young American appeared to be at least 1 m in diam­ Crows (Corvus brachyrhynchos). eter, which I thought was rather She did mention the nest to anoth­ large for crows. We searched on the er rider, Christel von Richter, and ground around the nest and found a on 24 June Christel heard two skeleton of a black bird which was

Figure 1: Common Raven nest in the North Tract ofthe York Region Forest in 2003. Photo by Winnie Poon. o TARIQ BIRDS APRIL 2005 21 still mostly covered with skin and exposed site (Figure 3). That this feathers but missing the flesh. The nest was also that of Common bird appeared to be a juvenile since Raven was indicated by the agitat­ the feathers were not sufficiently ed behaviour of two ravens which developed for flight. The body was were calling and circling above us close to 45 cm long, which is rather during a visit to the site on 3 June long even for an adult American 2004. Crow and suggested that it might be a juvenile Common Raven. Discussion I took the bird to the Royal There are several casual observa­ Museum where Mark Peck tions of Common Raven, suggest­ and I were able to compare it with ing possible breeding, in the the skins of an adult American Toronto Ornithological Club Crow, and both a juvenile and an Database (TOC) since 1994. The adult Common Raven. Comparison first was by Gordon Cameron who of the nature and length of the cul­ on 4 June 1994 observed a men (6.0 cm), the nature of the cov­ Common Raven carrying food in ering of the tarsus and its length the Palgrave Conservation Area. (6.1 cm) and the length of the wings From the year 2000 onwards, there (35 cm) agreed well with those of were repeated sightings of the juvenile Common Raven and Common Raven from the Palgrave differed sufficiently from those of Area, including Duffy's Lane, dur­ the adult American Crow and the ing January and February and dur­ adult raven that we were confident ing the breeding season from that the skeleton was that of an March to July, although so far no immature Common Raven. stronger breeding evidence has Apparently, this young raven had been obtained. fallen out of the nest some consid­ Apart from a Common Raven erable time before we found it. that paired with an American Crow Common Ravens were present and built a nest (see below), the in the North Tract throughout the York Region occurrence reported autumn of 2003 and the following here is the first documented nest of winter. In 2004, the nest found in Common Raven in the GTA 2003 was abandoned. A new nest (, consisting had been built, located at 17T of the Regional Municipalities of 635188 4881947 (North American Halton, Peel, York, and Durham, Datum 1983), at a height of about and City of Toronto) in probably 10 m in a Red Pine, about 200 m over 150 years. from the 2003 nest. The new nest There is evidence that at least was in dense foliage and was diffi­ three other pairs bred in the GTA in cult to see (Figure 2), unlike the 2002, 2003 and 2004, but no nests 2003 nest which was in a more were found. On 7 July 2002, Dennis VOLUME 23 NUMBER 1 22

Figure 2: Common Raven nest in the North Tract of the York Region Forest in 2004. Photo by Theo Hofmann.

Figure 3: Common Raven nest in the North Tract ofthe York Region Forest in 2003, showing the open environment. Photo by Winnie Poon. ONTARIO BIRDS APRIL 2005 23

Barry. Ed Poropat and two other birders heard juvenile Common Ravens clamouring from the north side of Ravenshoe Road where it crosses Zephyr Creek, about 6.5 km west of Udora (D. Barry, pers. comm.). During their half-hour stay they also saw adult ravens flying back and forth across the road. Although the observers could not birdwatch find a nest because the area is very unique birding & nature products swampy and very difficult to access, 1907 Avenue Road the fact that the young ravens called Toronto, M5M 3Z9 (1 km. south of IIwy. 401) constantly from the same area sug­ gested that they were still on or near Phone (416) 785-9222 Fax (416) 785-3125 a nest, although this late in the sea­ toll free 1-877-785-9222 son the observers thought that it had [email protected] to be assumed that the young would www.birdwatchcanada.com have fledged. In 2003, Dave Shepherd (pers. comm.) obtained David Renaud suggestive evidence for breeding of a pair of Common Ravens in the ed with the southern boundary of the Milton Quarry, Halton Region, and . However, histori­ he confirmed breeding there in 2004. cally, the species was apparently Lastly, on 5 June 2004, Rayfield Pye once common in southern Ontario. saw two adult and three recently Alexander Wilson (1814) wrote fledged young ravens while he was the following about the occurrence atlassing in the Durham Regional of Common Ravens: "On the lakes, Forest Main Tract. The five birds and particularly in the neighbor­ were sitting in a large dead tree on hood of the Falls of the river Riggin Lane, east of Concession 7, Niagara, they are numerous; and it is Durham (TOC). a remarkable fact that where they so abound, the Common [American] Historical Record Crow, seldom makes its appear­ The southward expansion of breed­ ance"; and further on in the same ing Common Ravens into the GTA paragraph he mentioned a journey is interesting in itself, but especially during the months of August and so in a historical context. During the September in 1806 along the lakes first Ontario Breeding Bird Atlas Erie and Ontario and commented: project, Blomme (1987) concluded "The Ravens were seen every day, that the southern range limit of the prowling about for dead fish ... but I Common Raven in Ontario coincid- did not see or hear a single Crow VOLUME 23 NUMBER 1 24 within several miles of the lakes". event took place in Toronto which Black (1934) cited Charles is described and discussed exten­ Fothergill as having observed sively in three papers by Jefferson Common Ravens in courtship dis­ (1989, 1991,1994). It is very briefly play on 21 March 1821 at Rice Lake. summarized as follows. A Common Fleming (1907) quoted a letter Raven which was first observed in which mentioned that Common Etobicoke, City of Toronto, in 1985 Ravens were present in Port Hope (Jefferson 1989), built two nests in in 1820. Fleming also quoted Rev. the area of the former Lake Shore John Doel as remarking that the last Psychiatric Hospital in 1987, paired Common Raven pair in the Toronto with an American Crow in 1990 area was killed in Queen's Park (Jefferson 1991), and produced two about 1848. hybrid offspring in 1993 (Jefferson This was during a period when 1994). settlers moved into southern Ontario and caused the extirpation Conclusion of the Common Ravens by direct The reasons for the southward range persecution, by forest clearing for expansion by the Common Raven in agriculture which removed their recent years are not immediately habitat, and by eliminating large obvious. In contrast, preliminary predatory mammals by poison results from the current Ontario which in turn killed the Common Breeding Bird Atlas show a clear Ravens which scavenged on the poi­ northward expansion of several soned carcasses. In his book that was species, which can be attributed in "apparently based primarily on part at least to climate change due to material from and Toronto" global warming. Two possible con­ (McNicholl 1994), Alexander Ross tributing factors for the southward stated in 1871 that Common Ravens expansion of Common Ravens in had become very rare (Ross 1871). Ontario come to mind. One is that The extirpation of the Common they have been so successful on the Raven in southern Ontario extend­ Canadian Shield that the available ed northward into some areas on the territories are saturated and this has Shield as well. MacLulich (1938) forced the birds southward. The noted that even in the wilder parts of other is that the return of many pre­ Algonquin Provincial Park, viously farmed areas to forested con­ Common Ravens were rare due to ditions is offering a more suitable poisoned baits put out by the habitat south of the Shield. More rangers to kill wolves. study is required. Although no significant expan­ sion by Common Ravens toward Acknowledgements the south seems to have occurred I wish to thank above all Allison until the last few years, an unusual Hegarty and Christel von Richter for ONTARIO BIRDS APRIL 2005 25 alerting me to the presence of the the records for Common Raven Common Raven nests in the North from the TOC Database; to Glenn Tract of the York Regional Forest. I Coady for suggesting this note and am also indebted to Christel for the providing various references; to ongoing updates on the Common Winnie Poon for providing the pho­ Ravens in the North Tract. I am most tographs for Figures 1 and 3; to Mark grateful to Mark Peck for providing Peck, Glenn Coady and Ron Tozer the skins and for his invaluable help for their critical reviews of an earlier in the identification of the skeleton draft; and to Dave Shepherd for the of the young raven. I also owe my information on the Common Raven gratitude to Roy Smith for providing in a quarry near Milton.

Information Source (TOC): Database of the Toronto Ornithological Club.

Literature Cited Black, R.D. 1934. Charles Fothergill's notes Jefferson, E.A. 1994. Successful hybridiza­ on the natural history of eastern Canada, tion of Common Raven and American 1816-1837. Transactions of the Royal Crow. Ontario Birds 12: 32-35. Canadian Institute 20: 141-168. MacLulich, D.A. 1938. Birds of Algonquin Blomme, C. 1987. Common Raven (Corvus Provincial Park, Ontario. Royal Ontario corax). Pp. 290-291 in Atlas of the Museum of Zoology Contributions 13: Breeding Birds of Ontario (M.D. Cadman, 1-47. P.EJ. Eagles, and EM. Helleiner, compil­ McNicholl, M.K. 1994. Brief biographies of ers). Press, Ontario ornithologists. Pp. 315-394 in Waterloo Ontario. Ornithology in Ontario (M.K, McNicholl Fleming, J.H. 1907. Birds of Toronto, and J.L. Cranmer-Byng, editors). Ontario Canada. Part II, Land Birds. Auk 24: Field Ornithologists Special Publication No. 71-89. 1, Hawk Owl Publishing, Whitby, Ontario. Jefferson, B. 1989. Observations of Common Ross, A.M. 1871. The Birds of Canada. Raven in Metropolitan Toronto. Ontario Rowsell and Hutchinson, Toronto. Birds 7: 15-20. Wilson, A. 1814. American Ornithology; or, Jefferson, B. 1991. Evidence of pair bonding The Natural History of the Birds of the between Common Raven (Corvus corax) United States. Volume 9. Bradford and and American Crow (Corvus brachyrhyn­ Inskeep, Philadelphia, . chos). Ontario Birds 9: 45-48.

Theo Hofmann, 199 Arnold Avenue, Thornhill, Ontario L4J 1C1

VOLUME 23 NUMBER 1