106 Articles

The Great Gray Owl Irruption of 2004-2005: Numbers, Dates and Distribution

Colin D. Jones

Introduction to witness and photograph the spec­ The Great Gray Owl (Strix nebu­ tacle. The media and the general losa) occurs throughout the boreal public took great interest in the forest region of (Bull and irruption, with many local newspa­ Duncan 1993). During some win­ pers and television and radio sta­ ters, when rodent prey is scarce in tions running stories on the invasion the boreal forest, Great Gray Owls and many curious observers making move southward into southern trips specifically to look for owls. Canada and the northern United As in previous irruptions, States (generally referred to as unfortunately, many owls were "irruptions"), sometimes in consid­ found dead, most often as a result erable numbers, until they locate an of collisions with vehicles, and were area with sufficient food resources brought in to local Ontario Ministry (Bull and Duncan 1993). During of Natural Resources (OMNR) the winter of 2004-2005, such an offices where they were issued with irruption occurred in northeastern a "Certificate of Reporting". In North America, with record num­ addition, many injured birds were bers occurring in both southern captured and brought to rehabilita­ Quebec (Bannon et al. 2005) and tion centres, and some of these owls Minnesota (Granlund 2005). The subsequently died. More details on situation was similar in Ontario, mortality during this irruption can with a record number of Great be found in the article by Peck and Gray Owls reported. Murphy on page 122 in this issue of Regionally, many Ontario bird­ Ontario Birds. ers began accumulating records and This article summarizes the actively tracking observations. In number of owls involved in the some areas, coordinated one-day Ontario irruption, the timing of surveys were conducted. Birders movements in various areas, and the and photographers from other parts main distribution of over-wintering of Ontario, as well as from neigh­ birds. This summary is based on bouring states and beyond, travelled records from all of the above men­ to areas with concentrations of owls tioned sources as well as reports ONTARIO BIRDS DECEMBER 2005 107 sent to ONTBIRDS, the electronic comm.), further evidence that some mailing list service maintained by kind of movement might be occur­ the Ontario Field Ornithologists ring. Nearby in the Atikokan area that notifies birders of interesting (), a similar Ontario bird sightings. movement was observed, with birds Initially, I attempted to compile first being noted in late September and map all of Ontario's Great and increasing dramatically into Gray Owl records from the winter mid November (Dave Elder, pers. of 2004-2005. However, due to the comm.). sheer number of records, the fact Meanwhile, a similar situation that many reports had vague dates was happening in the Hearst area and locations, and the extreme diffi­ () where by mid culty in avoiding duplicate count­ September, Great Gray Owls were ing, I decided that I would examine noted moving out of their boreal patterns and trends in the timing of forest habitat into abandoned agri­ movements and focus in on summa­ cultural fields and roadsides (Marc rizing numbers for areas that had Johnson, pers. comm.). Numbers well-coordinated survey efforts. began building in the Hearst area and peaked in mid October (Marc Departure from Johnson, pers. comm.). The first hint that a movement of Back in the Thunder Bay area, Great Gray Owls might be occur­ peak numbers occurred in ring came during the summer of November, with a total of 44 2004. In the Thunder Bay area, reports (Nick Escott, pers. comm.). there were many more sightings of December was quieter, with only 14 Great Gray Owls than usual, from reports in total, including 24 Great the Canada-US border in the south­ Gray Owls on 12 December during west, to Caramat in the east, and a survey of rural areas around north to Armstrong (Nick Escott, Thunder Bay (Nick Escott, pers. pers. comm.). The first report was comm.). By mid December, most of on 19 April, with four reports in the owls present in the Atikokan May, eight in June and 13 in July. All area had left (Dave Elder, pers. were single birds except for two on comm.). By January, most birds had 15 July, and there was no evidence disappeared from the Thunder Bay of breeding (Nick Escott, pers. area, although a few were still being comm.). Interestingly, then there seen in January and February, most­ were no reports in the Thunder Bay ly within the Thunder Bay city lim­ area until mid September. From 20 its (Nick Escott, pers. comm.). A September to 29 October, there repeat of the 12 December survey were, however, 25 Great Gray Owl route on 6 March turned up no sightings in the Heron Bay area, Great Gray Owls (Nick Escott, near Marathon (Nick Escott, pers. pers. comm.). VOLUME 23 NUMBER 3 108

Figure 1: Great Gray Owl in typical scrubby field habitat in the Hearst area on 26 November 2004. Photo by Marc Johnson.

The above pattern of move­ the remainder of January, and only ment is also evident when examin­ one each in February and March ing the records of dead owls turned (OMNR 2005). By examining these in to local OMNR offices for Certificates of Reporting, therefore, Certificates of Reporting. In it seems quite possible to piece alone, a stag­ together relatively accurately the gering 63 dead Great Gray Owls timing of movements of Great Gray were reported to those offices Owls during these irruptions. between 29 October and 7 However, it should be noted that December, with only an additional although the date the bird was eight for the remainder of found is recorded on the December, four in January, and Certificates of Reporting, this date only one in each of February and can be erroneous if the person March (OMNR 2005). In Rainy reporting the bird does not provide River District, the pattern was sim­ accurate information. Even though ilar-the majority of their dead persons reporting a bird are birds (23 of 31) were reported required to do so within three days between 6 November and 6 of finding it, this is not always the January, with an additional four in case. Birds recorded as having died

ONTARIO BIRDS DECEMBER 2005 109

on a particular date may have actu­ (Marc Johnson, pers. comm.) and ally been found many days or even only one dead bird reported to local weeks earlier, and then kept in a OMNR offices in Cochrane District freezer until it was convenient to after December, one from the visit the local OMNR office. Lowther area on 27 February Therefore, the date of death some­ (OMNR 2005). times corresponds more closely to Farther southeast, in Algoma the reporting date (i.e., within three District, peak movements appeared days of the reporting date) rather to be between 13 November and 22 than the actual date of death. December, when 18 dead Great Although I received no reports Gray Owls were reported (OMNR of live Great Gray Owls from 2005). In the Massey area (Sudbury , the timing of the District), numbers increased sub­ movement there was probably very stantially from the end of October, similar to that experienced in when the first was reported, until Thunder Bay and Rainy River dis­ they peaked during mid to late tricts. There were 26 dead Great November, when it was estimated Gray Owls reported from Kenora by Erwin Meissner that at least 60 District between October 2004 and birds were present along Highway May 2005, the bulk of which (18) 17 between Thessalon, Algoma occurred between 22 October and 2 District and Nairn Centre, Sudbury January (OMNR 2005), which District (Lemon 2005). In contrast, probably corresponds with the peak in the area, only of the movement through that area. 80 km to the east of Massey, the first In Rainy River District, immediate­ bird was not noted until 9 ly south of Kenora District, the pat­ November and the peak did not tern was similar-the majority of occur until mid December (Lemon their dead birds (23 of 31) were 2005). On 14 December, 10 birds reported between 6 November and were found within sight of each 6 January (OMNR 2005). Like the other along a stretch of road west of Thunder Bay area, some birds obvi­ Sudbury, and appeared to be on the ously also stayed in Kenora and move as none were found in the Rainy River districts through the same area on the following day winter months as dead birds contin­ (Lemon 2005). Like Kenora, Rainy ued to be brought in to local River, and Thunder Bay districts, OMNR offices in January, February some birds appeared to be present and March. all winter long in Algoma and In contrast to Thunder Bay, Sudbury Districts, but the bulk Kenora and Rainy River districts, in appeared to have moved farther the Hearst area, virtually no birds southward. appeared to over-winter, with the On Manitoulin Island, the first last bird noted on 17 December Great Gray Owl was not reported VOLUME 23 NUMBER 3 110 until 15 November, with numbers A distinct movement of Great building through December and Gray Owls was noted through January, with a total of 27 sightings Algonquin Provincial Park, with a in January, although some of these total of 11 records between 1 were likely of the same bird or birds November and 7 January, all of (Lemon 2005). Numbers on which seemed to involve birds that Manitoulin Island remained con­ were present for a day only as they stant through February and March continued to move southward in (Lemon 2005). search of food (Ron Tozer, pers. comm.). Pattern in Central and Southern By late November, Great Gray Ontario Owls had reached other districts The first Great Gray Owl reported and counties in , in the southern portion of the including Parry Sound, Muskoka, province was a single bird at and Renfrew (Figure 2 and Table Midhurst, , on 27 1). Remarkably, single birds had October (Bob Bowles, pers. also reached areas as far south as comm.). The majority of owls, how­ the Charleston Lake area on 14 ever, arrived much later. November (Ron Weir, pers. comm.)

o SEPT - OCT 2004 _ NOV 2004

_ Post NOV 2004

Figure 2: Map of Ontario (excluding the far north) indicating the timing of the tirst Great Gray Owl record by county and district for the irruption of 2004-2005.

ONTARIO BIRDS DECEMBER 2005 111

Table 1: Date of the first Great Gray Owl record by area during the irruption of 2004-2005. The source of each record is indicated within brackets following the date. TOC = Ornithological Club Database. AREA DATE OF FIRST OCCURRENCE 4 January 2005 (TOC) Cochrane District mid September 2004 (M. Johnson) Durham Region 27 December 2004 (TOC) 20 December 2004 (TOC) Halton Region 2 February 2005 (TOC) Hamilton 2 January 2005 (TOC) 22 December 2004 (TOC) Kenora District 22 October 2004 (OMNR 2005) 6 January 2005 (OMNR 2005) Leeds & Grenville County 14 November 2004 (R. Weir) Lennox & Addington County 1 January 2005 (OMNR 2005) 15 November 2004 (Lemon 2005) Muskoka District 26 November 2004 (A. Sinclair) 1 November 2004 (R. Tozer) Northumberland County 26 November 2004 (TOC) 12 December 2004 (c. Lewis) 24 November 2004 (B. Bowles) Peel Region 29 December 2004 (TOC) 19 December 2004 (D. Monkman) Prescott & Russell County 11 December 2004 (c. Lewis) Rainy River District late September 2004 (D. Elder) 12 November 2004 (c. Michener) Simcoe County 27 October 2004 (B. Bowles) 27 October 2004 (Lemon 2005) Thunder Bay District 20 September 2004 (N. Escott) 26 November 2004 (ONTBIRDS) Toronto 27 December 2004 (TOC) Victoria County 17 December 2004 (TOC) York Region 29 December 2004 (TOC)

VOLUME 23 NUMBER 3 112

Table 2: Date ofthe last Great Gray Owl record by area during the irruption of2004­ 2005. The source of each record is indicated within brackets following the date. Caution is necessary when evaluating the dates of records associated with Certificates of Reporting (OMNR 2005), as noted on page 108. TOC =Toronto Ornithological Club Database. AREA DATE OF LAST OCCURRENCE Bruce County 9 June (J. Haselmayer); also 26 June (J. Miles) Durham Region 22 April 2005 (TOC) Frontenac County 30 April 2005 (R. Weir) 16 May 2005 (OMNR 2005) Halton Region 12 February 2005 (TOC) Hamilton 12 March 2005 (TOC) Hastings County 10 May 2005 (OMNR 2005); also one into the first week of July (T. Dyson) Lanark County 11 April 2005 (B. Di Labio) Leeds & Grenville County 23 March 2005 (M. Peck) Lennox & Addington County 11 March 2005 (TOC) Manitoulin District mid June (Lemon 2005) Muskoka District 9 April (A. Sinclair); also 18 April 2005 (OMNR 2005) Nipissing District 29 April 2005 (R. Tozer) Northumberland County 3 April 2005 (OMNR 2005) Ottawa 13 April (c. Lewis); also 17 May 2005 (OMNR 2005) Parry Sound District 18 April 2005 (M. Peck) Peel Region 21 February 2005 (TOC) Peterborough County 18 April (T. Dyson); 12 May 2005 (OMNR 2005) Prescott & Russell County 26 March 2005 (OMNR 2005) Prince Edward County 5 June 2005 (TOC) Renfrew County 12 April 2005 (c. Michener) Simcoe County 19 June 2005 (B. Bowles) Sudbury District 21 April 2005 (OMNR 2005) Thunder Bay District 7 May 2005 (N. Escott) Timiskaming District 5 May 2005 (OMNR 2005) Toronto 13 March 2005 (TOC) Victoria County 18 April 2005 (OMNR 2005) York Region 1 April 2005 (OMNR 2005)

ONTARIO BIRDS DECEMBER 2005 113 and Port Hope on 26 November present throughout southern (fide Margaret Bain, ONTBIRDS, Ontario during the winter of 2004­ 27 November 2004). 2005, some regional studies provide Through December, Great some insight into numbers. These Gray Owls began being reported regional accounts also provide from most of the counties in south­ some further insight into the timing ern Ontario, north of Lake Ontario and patterns of movement. (Figure 2). A summary of the first In Simcoe County, for example, known records for each county is one of the areas with a particularly provided in Table 1. Concentrations large concentration, Bob Bowles began to build through December actively tracked reports, and plot­ and into January, especially in agri­ ted movements on a map (attempt­ cultural areas immediately south of ing to keep track of duplicate the Canadian Shield from Simcoe records), as well as performing sev­ County east through southern eral one-day counts. Although the Peterborough County and across to first bird was reported on 27 Ottawa. By February, in many October, the next confirmed report areas, most birds seemed to have was not until 9 December (Bob settled in for the winter. There were Bowles, pers. comm.). On 22 fewer numbers over-wintering in December, Bowles felt that there areas north of the concentration were nine individual owls in Simcoe zone. For example, there were only County (Bob Bowles, ONTBIRDS, 27 records throughout the season 22 December 2004). In less than from Renfrew County (Chris two weeks, the number increased to Michener, pers. comm.) and 25 from at least 50 birds (Bob Bowles, ONT­ Muskoka District (Al Sinclair, pers. BIRDS, 4 January 2005) and by 12 comm.), several of which represent January to 130 (Bob Bowles, ONT­ birds passing through and not actu­ BIRDS, 12 January 2005). More ally over-wintering at these loca­ and more birds began arriving tions. By March, most areas in through the month of January and were reporting by the end of the winter, more than lower numbers or that birds were 400 Great Gray Owls were record­ becoming more active (i.e., moving ed in Simcoe County (Bob Bowles, around more) and it was obvious pers. comm.)! Single day counts in that birds had begun to fly north­ Simcoe County provided the fol­ ward again. By mid April, owls had lowing results: 59 on 28 January completely vacated most areas, (Bob Bowles); 35 on 5 February although a few birds lingered into (Bob Bowles and four others); 34 May and even June in some loca­ on February 11 (Bob Bowles and tions (see Table 2). friend); 82 on February 20 (10 While it is difficult to estimate teams of over 20 observers), as the number of Great Gray Owls reported by Bob Bowles (ONT- VOLUME 23 NUMBER 3 114

BIRDS, 21 February 2005). By 25 that many owls would not have March, numbers in Simcoe County been visible from the roads, the were still felt to be stable, although actual number of owls present must it was noted that they seemed to be have been significantly higher. moving around more than earlier in Tim Dyson invested a tremen­ the season (Bob Bowles, ONT­ dous amount of time studying the BIRDS, 25 March 2005). Numbers Great Gray Owls in a portion of continued to be stable until 29 southern Peterborough County and March, then they suddenly dropped adjacent Northumberland County, (Bob Bowles, ONTBIRDS, 2 April and his studies provide further 2005). By 9 April, there were still insight into the calculation of a 16-20 Great Gray Owls present in county-wide estimate. For example, Simcoe County (Bob Bowles, ONT­ in places where he would see only BIRDS, 9 April 2005). Five individ­ four or five from the road, a walk uals were reported up until the first through the property between the week of June (Bob Bowles, pers. roads would reveal that there were comm.) and another bird was pres­ actually 17 present (Tim Dyson, ent near Penetanguishene on 19 pers. comm.). At least 105 individ­ June (Andrew Promaine, Simcoe ual Great Gray Owls were present County Bird and Nature Board, 20 in his study area (bordered by June 2005). Lakefield in the northwest, Keene The southern half of in the southwest, Campbellford in Peterborough County (south of the the southeast and Round Lake in Canadian Shield) was also a noted the northeast), and based on this hotspot for over-wintering Great total, he estimated that over 500 Gray Owls, with significant num­ Great Gray Owls were present in bers building from about Christmas Peterborough County (Tim Dyson, time through January. I coordinated pers. comm.). As was the case in a one-day survey of the southern Simcoe County, numbers appeared half of the county on 9 January to be stable through February, but 2005. Twenty-two participants were in March the owls seemed to be involved in the survey and I esti­ moving around more (Tim Dyson, mate that 75-800/0 of the roads were pers. comm.). By mid April, virtual­ driven. At least 13 other people, ly all of the birds had left who were not involved in the for­ Peterborough County. Tim Dyson's mal survey, participated by submit­ last observation was, for example, a ting additional records from both single bird on 18 April (Tim Dyson, the 8th and 9th of January. In total, pers. comm.). However, a dead indi­ 96 individual Great Gray Owls vidual was reported to have been were reported and mapped (Figure hit by a vehicle on 12 May near 3). Considering that 20-25% of the Young's Point (OMNR 2005). road network was not covered, and The Ottawa area also was well ONTARIO BIRDS DECEMBER 2005 115

Woodview Stonyridge •Nogies Creek Big C;dar ~.s;;;;;I;;e\ (i r~ ~ .~) --B~' '~FI1I1t" ,Lui/an,.

Warkworth • .Norhem • Figure 3: Map of the southern half of Peterborough County indicating the location ofthe 96 Great Gray Owls recorded during an organized survey on 8-9 January 2005. known to have a large concentra­ Labio, ONTBIRDS, 9 March 2005), tion of Great Gray Owls. By the although on 23 March, significant end of February, within 50 km of numbers were once again observed Ottawa, at least 111 individuals in the same area (Bruce Di Labio, were present on the Ontario side, ONTBIRDS, 23 March 2005), per­ with an additional 90 on the haps indicating that a movement Quebec side (Bernie Ladouceur, was occurring. Most had left the pers. comm.). Bruce Di Labio tal­ Ottawa area, however, by the end of lied the highest one-day count in March, although a few were report­ the Ottawa area when, on 9 ed as late as 9 April (G. Gray, ONT­ January, he found 46 southwest of BIRDS, 9 April 2005). the city (Bruce Di Labio, ONT­ In Durham Region, three one­ BIRDS, 9 January 2005). As was the day counts of Great Gray Owls case in other areas, numbers were performed, with totals of 31 seemed to be more or less stable (16 January), 40 (13 February) and through February. By 9 March, a 32 (13 March) present (Rayfield definite drop in the number of Pye, pers. comm.). It was noted on Great Gray Owls present in the the last survey that many of the reg­ Ottawa area was noted (Bruce Di ular locations where owls were VOLUME 23 NUMBER 3 116 present all winter had none Prince Edward County, where at (Rayfield Pye, ONTBIRDS, 13 least nine birds were recorded, and March 2005). The owls seemed to Amherst Island, where one bird be concentrated in certain areas, spent the winter (Terry Sprague, and noticeably lacking in others. pers. comm.). The Kingston area For example, in central Durham reported that 100 birds had over­ Region, the area between Brooklyn wintered (Ron Weir, pers. comm.). and Sunderland did not have any Far fewer birds were reported from owls until March, despite persistent counties bordering the St. checking by local birders (Rayfield Lawrence River, especially the Pye, pers. comm.). The small mam­ United Counties of Stormont, mal population in that area was Dundas & Glengarry, where only presumably low. The highest con­ one dead bird was reported centration of Great Gray Owls in (OMNR 2005) and no records of Durham Region was on Halls living owls were received. Road, Whitby Gust north of Lake There were lower numbers Ontario) where up to 15 Great over-wintering in areas north of the Gray Owls spent the winter concentration zone, e.g., Renfrew (Rayfield Pye, pers. comm.). The County (Chris Michener, pers. last record in Durham was one on comm.) and Muskoka District (AI 22 April (Rayfield Pye, pers. Sinclair, pers. comm.). comm.). The southern limits of Great The Return Passage Gray Owl records in Ontario were As is usually the case with Great as follows. In Toronto, a few birds Gray Owl irruptions, the return pas­ were present through the winter, sage of birds northward in the mostly within parkland where small spring was nowhere near as notice­ mammals could be found. able as the movement south in the Southwest of Toronto, there were early winter. only three records: two from Halton It seems plausible, however, Region, both of which occurred in that the increased movement of February (Cheryl Edgecombe, owls witnessed in March in both ONTBIRDS, 10 and 17 February Peterborough and Simcoe counties, 2005); and, a single bird in as well as the shift in numbers Hamilton at the Dundas Valley noticed in Ottawa during the same Conservation Area, that was pres­ time period, may have correspond­ ent between at least 2 January and ed with birds moving back north­ 12 March (Cheryl Edgecombe, ward from over-wintering sites far­ ONTBIRDS, 3 January, 10 ther south. This is further support­ February, 10 and 17 March, 2005). ed by the absence of birds from Birds were present along the north sites in the south where they had shore of Lake Ontario east to been present in January and ONTARIO BIRDS DECEMBER 2005 117

February (e.g., Durham Region, as Lingering Birds well as in the Kingston area; Ron Although in most areas of Ontario, Weir, pers. comm.). The movement south of the usual breeding range of north, therefore, seems to have the Great Gray Owl, most of the begun sometime in March. In the birds that were present in signifi­ Hearst area (Cochrane District), cant numbers all winter were gone after being absent all winter, the by the end of April, a few lingered first returning bird was noted on 29 into May, June and even July. As March (Marc Johnson, pers. mentioned earlier, five lingered comm.). Birds apparently contin­ until the first week of June in ued to travel northward through Simcoe County, with another report the month of April as the records on 19 June near Penetanguishene. from Algonquin Provincial Park In Bruce County, two birds were and nearby would indicate. No present until the last week of May birds were thought to have spent (Ethan Meleg, pers. comm.), a sin­ the winter there, but there were 10 gle bird was seen on 9 June at Cove records between 2 and 29 April, Island (John Haselmayer, pers. with none thereafter (Ron Tozer, comm.), and one bird was found on pers. comm.). In the Thunder Bay the Crane Lake Road on 26 June area, a movement in April through during the OFO Bruce Weekend early May seems to have occurred. (John Miles, ONTBIRDS, 27 June Despite the fact that only three 2005). On Manitoulin Island, a bird reports of live birds were received was present near Sheguiandah on (one on 6 April from Pukaskwa 21 May (Lemon 2005). Also on National Park, six in Sleeping Manitoulin, a possible pair was Giant Provincial Park on 23 April present in Billings Township, but and one near Jellicoe on 7 May; one was hit by a car on 9 May, while Nick Escott, pers. comm.), there the other bird was regularly seen in were an additional four records of the area until mid June (Lemon dead birds in April and two more in 2005). It is possible that any of the early May from Thunder Bay above birds could have bred, as District (OMNR 2005). Interest­ breeding records in Ontario have ingly, unlike the situation in the occurred as far south as Algonquin summer of 2004, when there were Provincial Park (Forbes et al. 1992) more sightings of Great Gray Owls and Island, Manitoulin than usual in the Thunder Bay District (Whitelaw 1998). Perhaps area, no owls could be found in the the most noteworthy lingering bird summer of 2005 despite searching was one reported by a property several times (Nick Escott, pers. owner northeast of Belleville, comm.). Birds appeared to have Hastings County, into the first week returned to more remote sections of July (fide Tim Dyson, pers. of the boreal forest. comm.)! VOLUME 23 NUMBER 3 118

Total Number of Birds on the above information, there­ Although in this analysis, for the fore, the number of Great Gray reasons mentioned in the introduc­ Owls actually involved in the 2004­ tion, it was not practical to perform 2005 Ontario irruption must have an actual count of the number of numbered in the thousands. birds involved in the irruption of 2004-2005, it is possible to provide a Comparisons with Other Irruptions rough estimate, based on the sum­ Previously, the largest recorded maries and estimates from the few irruption of Great Gray Owls in areas highlighted above. We do Ontario took place during the win­ know, for example, that there were ter of 1995-1996, with a significantly over 400 Great Gray Owls recorded large "echo" flight the following from Simcoe County, an estimate of winter. Sadler (1998) reported more approximately 500 individuals from than 330 different Great Gray Owls Peterborough County, as well as at in 1995-1996 and 265 in 1996-1997, least 111 birds in the Ontario por­ from an area including all of tion of the Ottawa 50-km circle. We Peterborough County, west to Lake also know that based on records of Simcoe, the , and both living and dead owls in­ north and eastward into Haliburton between these three locations, and Hastings counties. A conserva­ Great Gray Owls were present tive estimate of the total number of (potentially in the same kind of Great Gray Owls present across concentrations) throughout the southern Ontario in March 1996 entire zone roughly corresponding was over 600 birds (Ridout 1997). to the marginal farmland along the It is difficult to directly compare southern edge, and immediately the irruption of 1995-1996 with that south of, the Canadian Shield. In of 2004-2005, since we do not have addition, significant numbers were numbers for each irruption from the present in certain areas south of same geographic areas. In addition, this zone, especially east of Toronto the estimate of over 600 birds in (e.g., Durham Region, Northumber­ 1995-1996 was a conservative one; land County, Prince Edward the actual numbers recorded might County, and the Kingston area). We have been much larger if more also have documentation for a total information had been readily avail­ of 501 dead Great Gray Owls able. With the age of the internet throughout Ontario, during the and electronic communicating and irruption of 2004-2005 (see the arti­ reporting (such as ONTBIRDS), it cle by Peck and Murphy on page has become much easier and quick­ 122). A significant number of owls er to collect and compile informa­ (double? triple?) must have met a tion. I think that it is safe to say that similar fate to the 501 dead birds the Great Gray Owl irruption of actually found and reported. Based 2004-2005 was at least equal to the ONTARIO BIRDS DECEMBER 2005 119 irruption of 1995-1996, and proba­ bly bigger. It will be interesting to see if a similar "echo" flight occurs again this winter. The timing of the advance southward in 2004-2005 was very NATURE STORE 636 Point Pelee Dr. Leamington ON N8H 3V4 similar to that witnessed in the 1983­ Birding • Nature • Optics • Books 1984 irruption, when birds in small Canada's Largest Selection of Binoculars and Scopes numbers were seen across northern All at Discount Prices! Ontario in October, followed by a • Swarovski • Kowa build-up in the Sudbury area in • Pentax November, with a few birds reach­ • Leica ing as far south as Simcoe County • Nikon • Swift (James 1989). In 2004-2005, most • Bushnell areas in the south did not receive • Zeiss their first owls until toward the sec­ • Brunton • Celestron ond half of December, similar to • Vortex/DLS both the 1978-1979 and 1983-1984 For fA5I Mail Order Delivery or Quote... irruptions. Unlike the 1983-1984 irruption, however, when the move­ www.peleewings.ca ment of owls seemed to come to a stop by early January (James 1989), timing from other irruptions in that the number of birds continued to the owls were present in southern build through to the end of the Ontario over a much longer time month in 2004-2005 and was then period, arriving relatively early and more or less stable through persisting relatively late. February. During the 1978-1979 As far as the distribution of irruption, the movement south con­ over-wintering owls is concerned, tinued through February, and in the the main concentrations were in 1995-1996 and 1996-1997 irruptions, areas where concentrations have most owls didn't appear to arrive occurred in the past (e.g., Simcoe until February, with reports building County, Peterborough County, and through March. In most of the pre­ the Ottawa area), specifically in vious irruptions, the owls quickly somewhat marginal farmland, inter­ retreated northward in early March spersed with forest, along the south­ (James 1989). The 2004-2005 irrup­ ern edge of the Canadian Shield. tion, however, was much like that of There was a significant movement 1995-1996 and 1996-1997, when south of this zone, however, during many birds lingered into April, with the irruption of 2004-2005, which a few even persisting into May and has not occurred in all past irrup­ June (Sadler 1998). Overall, the tions. This may have been related to 2004-2005 irruption differed in the the sheer number of owls involved VOLUME 23 NUMBER 3 120

(i.e., in order to avoid competition northern Ontario. By March, some for food, some individuals may kind of movement appeared to be have moved farther south where taking place, although slowly. there were fewer owls). In northern Numbers remained high through areas, including Rainy River, most of March but by the end of the Thunder Bay, Algoma, Sudbury and month and through April, most of Manitoulin districts, although a sig­ the birds returned northward. A few nificant movement was noticed in birds lingered in areas south of their the early winter, most owls moved normal breeding range into May, on to other areas with only a few June and even July, but no reports of actually over-wintering. breeding were received. In many ways, this irruption was similar to Summary that of 1995-1996, when the follow­ The Great Gray Owl irruption of ing year, an "echo" flight occurred 2004-2005 was undoubtedly one of that was nearly as large as the irrup­ the largest irruptions to have tion the previous year. Will we see a occurred in Ontario. A total of 501 similar echo flight of these beautiful documented cases of dead birds, and charismatic birds in 2005-2006 or combined with regional counts and will we have to wait a few years for estimates in the hundreds equate to the next irruption? an overall estimate numbering in the thousands. The movement was Acknowledgements detected early, when birds became Many individuals compiled records obvious in both Thunder Bay and on a regional basis during the winter Cochrane Districts in September. of 2004-2005 and submitted the Numbers began to build and move­ records or summaries from their area ment peaked in the northern districts to me for inclusion in this article, during November and December. By and/or commented on the summary the end of December, most counties that I had pieced together for their in southern Ontario had begun to area, including: Nick Escott (Thunder witness the irruption, with numbers Bay); Dave Elder (Atikokan), Marc gradually building in the south Johnson (Cochrane District); John through January. Numbers of over­ Lemon (Sudbury); Ron Tozer wintering birds became stable (Algonquin Park); Chris Michener, through February. The main area of Lauren Trute and Daryl Coulson concentration extended from Simcoe (Renfrew County); AI Sinclair and County, across the southern edge of the Muskoka Bird Board (Muskoka the Canadian Shield to Ottawa, with District); Christina Lewis, Bernie significant numbers also found in Ladouceur and Bruce Di Labio many areas to the south of this, south (Ottawa); Bob Bowles (Simcoe to Lake Ontario. Smaller numbers County); Ethan Meleg and John over-wintered in parts of central and Haselmayer (Bruce County); Tim ONTARIO BIRDS DECEMBER 2005 121

Dyson and the Peterborough Natural and these were made available to me History Listserv (Peterborough for the preparation of this article. County); Rayfield Pye (Durham Lorraine Norris of the Peterborough Region); Doug McRae (North­ District office of OMNR provided umberland County); and Ron Weir access to the provincial database con­ (Kingston area). Email messages sent taining the records of dead owls by numerous birders to ONTBIRDS, which were issued a Certificate of the Ontario Field Ornithologists' bird Reporting, while Julia Monkman sightings listserv coordinated by assisted with the retrieval of these Mark Cranford, provided extremely records. Mark Peck of the Royal valuable information on records. Ontario Museum provided numer­ Such records were even easier to sort ous records of dead owls not con­ and analyze since Roy Smith, who tained within the OMNR database. maintains the Toronto Ornithological Peter and Dawn Burke assisted by Club (TOC) Database, had been providing copies of several refer­ adding these records, in addition to ences. Simon Dodsworth of the many others from the Greater Natural Heritage Information Centre Toronto Area, to the TOC Database (OMNR) produced the maps.

Documents Cited Lemon, J.G. 2005. Summary of Great Gray [OMNR] Ontario Ministry of Natural Owl activity in the Sudbury area during Resources. 2005. Certificates of Reporting the winter of 2004-2005. Unpublished spanning 1 October 2004 through 7 June report. 2005. ELlS Database.

Literature Cited Bannon, P., S. Denault, Y. Aubry, and N. Granlund, J. 2005. Western Great Lakes. David. 2005. Quebec. North American North American Birds 59: 270-272. Birds 59: 234-235. James, R.D. 1989. The Ontario Great Gray Bull, E.L. and J.R. Duncan. 1993. Great Owl invasion of 1983-1984: Numbers, Gray Owl (Strix nebulosa). In The Birds of dates and distribution. Ontario Birds 7: North America, No. 41 (A. Poole and F. 5-15. Gill, editors). Academy of Natural Sadler, D. 1998. The 1995-1997 Great Gray Sciences, Philadelphia, Pennsylvania, and Owl invasions in the Peterborough area. American Ornithologists' Union, Ontario Birds 16: 81-87. Washington, D.C. Whitelaw, C.J. 1998. Northern owls in Forbes, G., M. Runtz, and R. Tozer. 1992. Sudbury and Manitoulin Districts: High New breedng record for Great Gray Owl: numbers, out of season occurrences and Most southerly in Canada. Ontario Birds breeding. Ontario Birds 16: 1-4. 10: 117-118.

Colin D. Jones, Box 182, Lakefield, Ontario KOL 2HO

VOLUME 23 NUMBER 3