AFTER-HATCHING-YEAR SUBADULT COMMON LOONS IN MANITOBA GORD HAMMELL, Erickson, MB, R0J0P0; Email: [email protected] The common loon (Gavia immer) is 29-June 2, and June 6-10) produced familiar to most Canadians, breeding respectively, zero, five, and four adult across Canada in suitable lakes and individuals in breeding plumage. No rivers and in most cases, migrating south chicks were seen on the study area but to coastal waters in winter.1,2 Population were observed on lakes within 400 m of trends from the annual Breeding Bird the boundary. Survey (1970-2009)3 suggest increasing populations for Canada and Manitoba While conducting waterfowl brood but a slight decrease for Prairie Potholes counts in the early morning on June Bird Conservation Region (Fig.1). The 29, 2011, I observed a large white- area south of Riding Mountain National looking bird on a 16 ha lake (50.43083, Park in southwestern Manitoba is -99.724717) ~ 11km southeast of “pothole” country within this Region Erickson. I initially assumed that it was and the topography is rolling with a gull because it appeared so white. numerous lakes and ponds interspersed The bird was at ~ 100m distance and

Figure 1. Annual indices of population change for the Common Loon in Manitoba based on Breeding Bird Survey data (1973 - 2009). Trend +15.5 with agricultural lands. I have been upon closer examination with a 20-60x conducting waterfowl surveys in this spotting scope, I realized that the bird area near Erickson (Fig 2) for several was facing me and was a loon. No other years and have regularly seen common loons were on the lake. The observed loons (hereafter loon) occupying and whitish glow was from its white breast, successfully raising young in the area. neck and throat. The back of the bird For example, in 2011 on a 22.km2 ( ~9 was greyish. I immediately assumed sq miles) study area, counts conducted that this was a juvenile bird from the over three time periods (May 23-25, May previous year but was surprised to see

70 (4) December 2012 263 Figure 2. Location of common loon sighting near Erickson, MB it as I could not remember seeing a with some young-of-the-year later in the juvenile of this size and colour except summer). in the late summer and early fall. Loon chicks in late June in this area are My interest was aroused so I downy and much smaller. I returned to contacted several experienced my birding books and discovered that birders in Manitoba, Saskatchewan this bird was most likely a subadult ; and Ontario and asked if they had ie: a juvenile from a previous year in observed these birds in spring or early basic plumage. If a subadult, then this summer. In Manitoba, one observer bird should be on or near salt water for recorded five May-July sightings since several years (usually three to five)4,5,(C. 1977 in Pinawa area (P. Taylor, Fig.

Walcott, pers.comm.) before returning to 3) and another recorded one sighting breeding areas in breeding (alternate) in Riding Mountain National Park in plumage. I revisited the lake the next May, 1984 (C. Cuthbert). Another morning, found the bird still in the same from southwestern Manitoba has not spot and examined it more carefully. I seen loons in basic plumage in spring noted a white partial triangular collar or early summer (K. Kingdon). For on the sides of the neck, a diagnostic Saskatchewan, I was unable to find characteristic of basic- plumaged birds anyone who had seen one of these and a mottled back of brown, black, and birds (S. Houston, T.Stene, R.Wilson). white, giving a greyish appearance. It Although far from a comprehensive lacked all of the plumage characteristics survey, the scarcity of sightings of an adult in breeding plumage. suggests that basic-plumaged birds I returned to the lake in one week are infrequent (but perhaps regular?) and the bird was gone and was not visitors to Manitoba inland breeding knowingly seen by me again in the area grounds in spring and summer. (this bird might have been confused Discussions with these observers

264 Blue Jay suggest that the abundance, distribution Wisconsin.10 Researchers there found and movements of these birds are that of the hundreds of loons seen each largely unknown. In Ontario in summer, summer, only one or two would be in these basic- plumaged loons are known basic plumage (J. Mager, pers. comm.). to occur in small numbers on large Usually they remain on large lakes used inland lakes (e.g., the Great Lakes)4,6,7,8 only for foraging, not for breeding. This but the authors imply that they do not behaviour of breeding lake avoidance continue on to breeding lakes. During might be expected as territorial pairs autumn migration, loons stage on are very aggressive towards intruders.10 the lower Great Lakes mainly from Although hundreds of adults and chicks August to December, a few lingering have been banded in the Wisconsin into January. They are known to over- study area over two decades, a banded winter on the Great Lakes extremely loon in basic plumage has not been infrequently and in very small numbers seen in early summer; these authors (usually< 10 on Lake Ontario Mid- suggest that these loons could be winter Waterfowl Count, Kingston to “prebreeders” but without marked Niagara).9,(D.Tozur, pers. comm.) Therefore, individuals, one can only speculate as there exists the possibility that basic- to the age and identity of these birds. plumaged birds seen in Manitoba in

Figure 3 Loons - sub-adult left adult right - Gervase Orton spring and summer over-wintered I suspect that few birders in Manitoba on the Great Lakes. Although this and in other areas are aware that all possibility cannot be ruled out, this or almost all loons seen in breeding seems unlikely given the small number plumage in summer are adults at observed over-wintering. It seems most least 3 years of age. The subadult likely that the basic-plumaged birds reported here and the other referenced seen in summer in the breeding range sightings of a basic-plumaged loon over-wintered in the regular (salt water) in early summer in Manitoba are to wintering grounds and returned the my knowledge the only ones reported following spring (D.Tozur, pers. comm.). for Manitoba. A more comprehensive survey would undoubtedly reveal more. I gathered additional insight on In the future, I (and I hope others) will loon behavior from results of a appreciate more fully observations of comprehensive study with a large this species and will be on the lookout banded population of loons in for early summer basic-plumaged birds

70 (4) December 2012 265 so that we might be able to monitor from the Birds of North America Online: spacial and temporal changes to this http://bna.birds.cornell.edu.cat1.lib. segment of the loon population . trentu.ca:8080/bna/species/313 doi:10.2173/bna.313 Acknowledgements My thanks go out to all those 5. Evers D, Kaplan JD, Reaman individuals who, by their assistance PS, Paruk JD, Phifer P (2000) A in the writing of this note, have made demographic characterization of the loons more interesting than they already Common Loon in the upper Great were. They include Cal Cuthbert Lakes. Pages 78-90 in Loons: Old (Ducks Unlimited, Brandon), Stuart history and new findings. Proceedings Houston (Saskatchewan), Kathy Jones of a Symposium from the 1997 (Canadian Lakes Loon Survey, Birds meeting of the American Ornithologists’ Studies Canada), Ken Kingdon (Parks Union (McIntyre J W and D Evers, Canada, Manitoba), Jay Mager (Ohio Eds.), North American Loon Fund, Northern University), Walter Piper Holderness, NH. (Chapman University),Theresa Stene (Parks Canada, Saskatchewan), Peter 6. Palmer RS (1962) Handbook of Taylor (Pinawa, Manitoba), Doug Tozer North American Birds. Vol. 1. Loons (Bird Studies Canada), Charles Walcott through Flamingos. Yale University (Cornell University), and Rob Wilson Press, New Haven, Connecticut. (Saskatchewan). Thanks also to Marg Hammell for reviewing this document 7. Black JE, Roy KJ (2010) Niagara and Bruce McLavy for helping with Birds: a compendium of articles and map-making. species accounts of the birds of the Niagara Region in Ontario. Brock 1. Manitoba Avian Research University Printing and Digital Services, Committee (2003) The birds of St. Catherines, ON. Manitoba. Manitoba Naturalists Society, Winnipeg MB. 8. Curry R (2006) Birds of Hamilton and surrounding areas. Hamilton 2. Godfrey WE (1966) The birds of Naturalists Club, Hamilton, ON. Canada. National Museums of Canada Bulletin No 203. Biological Series No 9. Sandilands AP (2005) The Birds 73. Ottawa ON. of Ontario: habitat requirements, limiting factors and status. UBC Press, 3. Trends from the Breeding Bird Vancouver. Survey in Canada: Common Loon. (2009) Migratory Birds Conservation 10. Walcott C (2010) Loon Behaviour Moitoring and Reporting. Canadian and Calls. In: BirdWatch Canada No Wildlife Service, Environment Canada, 50. Bird Studies Canada, Port Rowan, Ottawa. ON. 4. Evers DC, Paruk JD, Mcintyre JW, and Barr JF (2010) Common Loon (Gavia immer), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved

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