Potential Breeding Species and Hybrids
Authors: R. F. Koes and P. Taylor
This appendix provides brief accounts of species that did not reach the minimum "possible breeding" criteria for the atlas, but for which other records indicate that rare breeding is plausible or has occurred. Species that are long extinct (e.g. Passenger Pigeon, Ectopistes migratorius) or extirpated (e.g. Greater Prairie-Chicken, Tympanuchus cupido are excluded, as are birds of obviously recent captive or domestic origin (e.g. Chukar, Alectoris chukar and Indian Peafowl, Pavo cristatus).
There is inevitably a grey area involving late migrants and lingering summer individuals; in general, the appendix excludes both outright vagrants and regular migrants with breeding ranges far beyond Manitoba's borders. Some Arctic breeders with a history of summer lingering on the Hudson Bay coast are included, as are a few southern species for which increasing records suggest a potential for breeding in Manitoba.
Harlequin Duck Histrionicus histrionicus
This small diving duck is associated with fast-flowing streams during the nesting season and rocky tidal waters in winter. Males are boldly marked in blue-grey, chestnut and white, while females are brown with white head-markings reminiscent of female Surf Scoters. In North America there are two disjunct breeding areas: one in the western mountains from Alaska to the northwestern U.S.A. and a smaller population in the east from Baffin Island to northern Québec (Robertson and Goudie 1999). Corresponding winter areas are mainly along the Pacific and Atlantic coasts, respectively. Eastern and western birds are indistinguishable in the field, though subtle plumage differences have been claimed. The Harlequin Duck also breeds in Greenland, Iceland, and eastern Russia.
While no Harlequin Ducks were recorded as potential breeders during the atlas years, there remains a slim possibility of a small breeding population on remote rivers in Manitoba. Past sightings suggestive of breeding were at Clearwater Lake in June 1994 (Koes and Taylor 1994) and in 1998 (fide K. Ottenbreit) and at Goose Creek near Churchill in 2004 (Koes and Taylor 2004). Lone moulting males have summered twice (1988 and 2006) at Seven Sisters Falls. Small numbers annually visit Cape Merry, Churchill, but appear to be post-breeding birds and/or failed breeders of unknown provenance. In Manitoba, Harlequin Ducks are most often seen in rough water along rocky shores; e.g., at Cape Merry or inland on large water bodies, especially Lake Winnipeg and the Winnipeg River (Taylor and Thompson 1990, and subsequent records).
Globally, Harlequin Duck is listed as Least Concern, but the eastern North American population is classified as Special Concern in Canada.
Rock Ptarmigan Lagopus muta
This Arctic grouse is marginally smaller than the Willow Ptarmigan, with a smaller bill and generally darker (less rufous) breeding plumage. The North America breeding range stretches from Alaska to Greenland, north of the treeline, with isolated populations in the Rocky Mountains of British Columbia. The nearest breeding to Manitoba is about 200 km north of the Nunavut land border (Montgomerie and Holder 2008). Other populations occur in Arctic and montane regions of Eurasia. Some birds move south during winter into the northernmost forested areas of North America, including far-northern Manitoba (Larche and Sealy 1977).
During the atlas period there was an intriguing record of a female Rock Ptarmigan in the Churchill area, seen and photographed on 13 and 16 July, 2013 (Koes and Taylor 2013). Although present during the breeding period, it was considered a non-breeding lingerer. There have been occasional summer sightings in the past, but breeding has never been recorded.
Nesting habitat consists of tundra areas, often hilly and rocky; such habitat is scarce in Manitoba, making future breeding unlikely.
Pectoral Sandpiper Calidris melanotos
One of the larger "peeps" (small sandpipers), the Pectoral Sandpiper can be recognized by a sharp demarcation between the streaked breast and white abdomen, and by its yellow legs. It breeds on wet tundra in the High Arctic from northeastern Siberia eastward to Nunavut, and winters primarily on the pampas of south-central and southern South America (Farmer et al. 2013). The species is a common migrant in southern Manitoba, especially during the late-fall movement of juveniles.
There were nine atlas records in northern Manitoba, ranging in date from 7 June to 21 July, with 1 – 7 birds observed, which the review committee chose to treat as "observed only", because details pertaining to the birds' behaviour did not strongly suggest local breeding. Two of these records were well inland and the rest were within 30 km of Hudson Bay. Jehl (2004) noted breeding attempts and/or lekking behaviour in the Churchill and Cape Churchill regions in 1983, 1984, 1987, and 1992. None of these attempts were successful. Jehl further states: "The breeding of this species at Cape Henrietta Maria, Ontario, is based on a single occurrence (Cadman et al. 1998) and, as at Churchill, is evidently a cold-year phenomenon."
Red Phalarope Phalaropus fulicarius
The Red Phalarope is a small shorebird with largely reddish underparts, a white cheek patch, and black-tipped yellow bill in breeding plumage. As with other phalaropes, males are duller in colouration than females and they perform all incubation duties. Within its circumpolar, Arctic breeding distribution, this species nests most commonly at coastal tundra ponds and seldom far inland. During migration and winter, it is highly pelagic, occurring on both the Atlantic and Pacific Oceans; it is rarely found in the centre of the continent (Tracy et al. 2002). In cold springs or when inclement weather forces birds to shore, hundreds or even thousands of Red Phalaropes may occur along the Hudson Bay coast near Churchill, where some may linger well into July. Diligent nest searches have been unsuccessful, even though the species breeds commonly at McConnell River, Nunavut, less than 100 km north of the Manitoba land border (Jehl 2004).
The cold spring of 1992, following the eruption of Mount Pinatubo in 1991, saw exceptionally high numbers at Churchill, including a peak count of 604 birds on 15 June (Bob Ake), with at least 20 still present in July (Koes and Taylor 1992). Modest high counts in subsequent years in the Churchill area were in 2007 (29 birds on 10 June) and in 2009 (20 present in early June, R. Koes). During the atlas period, at least four Red Phalaropes were observed at Churchill in early June, 2011 (R. Koes, many observers) but with no evidence of local breeding.
Black Guillemot Cepphus grylle
The only alcid to appear regularly in Manitoba is the Black Guillemot, a teal-sized bird with black breeding plumage offset by bold white wing-patches. It breeds at scattered locations in inshore waters throughout the Arctic, and also along both sides of the Atlantic (south to Maine and Ireland) and in Hudson Bay south to the Nunavut/Manitoba border (Butler and Buckley 2002). A large portion of the Hudson Bay population winters at open leads in the bay ice (Jehl 2004). In general, the species seems to winter as close to breeding areas as sea-ice conditions permit (Butler and Buckley 2002), making a November, 1966 specimen record for Morris, Manitoba all the more extraordinary.
A few Black Guillemots are currently seen annually during summer in seemingly appropriate nesting habitat at Eskimo Point, across the river from Churchill (R. F. Koes, pers. obs.). Breeding has been rumoured at Cape Churchill, but there is no suitable nesting habitat there (Jehl 2004). All records during the atlas period, including one in Hudson Bay east of the mouth of the Seal River in July, 2012 (B. Chartier) and two east of Hubbard Point (late July, 2010, D. Fast, and late June 2014, C. Artuso, K. Kingdon), were on the water with no suggestion of nesting.
Sabine's Gull Xema sabini
With its striking black, grey, and white upper parts, black-rimmed grey hood, yellow-tipped black bill, and slightly forked tail, an adult Sabine's Gull in breeding plumage is unmistakable. A long-distance migrant, this gull breeds (occasionally semi-colonially) at marshes, ponds, and lakes throughout much of the High Arctic of North America and Eurasia. Eastern and western Canadian breeders are divided between primary wintering areas at sea off west Africa and between Mexico and Peru, respectively (Day et al. 2001). The species migrates through the Churchill area in varying numbers, with a peak in the first half of June. Jehl (2004) gives 8 July as the latest recorded date; late June and early July dates coincide with cold springs, and there is no evidence of lingerers remaining to breed. The nearest known regular breeding locality is Southampton Island, about 600 km northeast of Churchill. Sightings at Churchill during the atlas period were annual, involved as many as a dozen birds, and were all in early June and not suggestive of nesting.
Red-shouldered Hawk Buteo lineata
Intermediate in size between the Red-tailed and Broad-winged Hawks, the Red-shouldered Hawk is distinguished by its black-and-white multi-banded tail and reddish underparts and forewings. The breeding range stretches from Minnesota east through southern Ontario to New Brunswick and south to Texas, Florida, and Cuba, with a disjunct population in coastal California and Baja California (Dykstra et al. 2008). Northernmost breeders migrate south, and there is some wintering movement into northern Mexico.
Nearly half (19 of 43) Red-shouldered Hawk records in Manitoba to date have involved spring migrants passing the well-known St. Adolphe and the Pembina River valley (Windygates) hawk-watch locations. For example, during the atlas period, there were sightings at St. Adolphe on 16 March, 2012 (Koes and Taylor 2013) and 2 April, 2013 (Koes and Taylor 2014a). Though likely just spring overshoots, such birds could represent a small breeding population to the north or northwest. There is an undocumented breeding report from southeastern Manitoba in 1932 (The Birds of Manitoba). More recent evidence has been limited to tantalizing glimpses, often too brief for certain identification. The preferred breeding habitat is mature mixed woodland, especially riparian areas and deciduous swamps, and prey consists largely of small mammals and amphibians (Dykstra et al. 2008).
This species is stable to increasing in eastern Canada (BBS data) and is no longer considered at risk (COSEWIC 2006). Given the proximity of breeding populations in Minnesota, climate change could lead to expansion of the breeding range into Manitoba.
Barn Owl Tyto alba
The pale and long-legged Barn Owl, with its distinctive heart-shaped facial disc, is classified in a separate family (Tytonidae) from "typical" owls (Strigidae). Though widespread on five continents (split in some taxonomies into three or more species), including much of the conterminous U.S.A., it cannot withstand extreme cold, and its regular Canadian range is limited to small portions of southern Ontario (now all but extirpated) and southern British Columbia. Its closest normal approach to Manitoba is in southern North Dakota (Marti et al. 2005). Despite the Barn Owl's distinctive appearance, other owls are sometimes misidentified as this species, especially if occupying farm buildings. Nevertheless, there are about a dozen confirmed or plausible records for Manitoba (The Birds of Manitoba). The only record during the atlas period, and the first evidence of the species in the province since 1995, involved an emaciated hatch-year female found recently dead at a farm near Elie in early December 2012 (Mooi 2013). The sole Manitoba breeding record was near Springstein in 1994, when a nest in the attic of a private house contained eight eggs on 9 June, but they proved infertile (Nero 1995). Most Manitoba occurrences, including that in 2012, likely arise from long-range post-breeding dispersal, rather than local provenance, of this normally non-migratory species. Eastern and western Canadian populations are respectively Endangered and Threatened (COSEWIC 2010); regular breeding in the province is not expected in the near future.
Gyrfalcon Falco rusticolus
The Gyrfalcon is the world’s largest falcon, with individual plumages (morphs) ranging from almost pure white to grey and dark brown. In Manitoba, the grey morph is most frequently seen. The species' breeding range is circumpolar in Arctic and subarctic regions above the treeline, where it typically seeks exposed rocky ledges to nest. Though only partly migratory, the species occurs throughout Canada into the northern U.S.A. in winter. The breeding range is remarkably similar to that of the Rock Ptarmigan; indeed, ptarmigans are its staple prey, though many other birds and mammals are taken (Booms et al. 2008). As with the Rock Ptarmigan, the nearest Gyrfalcon breeding area to Manitoba is in coastal Nunavut about 200 km to the north.
The only potential nesting habitat in Manitoba is in the Churchill area, where birds have occasionally lingered for some time around the port's grain elevators, but there is no evidence of breeding there. Sightings in northern Manitoba during the atlas period in late August and September were considered to be of dispersing rather than local breeding birds. With ongoing climate change, future range-limit changes are likely to be northward, away from Manitoba.
Prairie Falcon Falco mexicanus
Easily mistaken for the similar-sized Peregrine Falcon, the Prairie Falcon can be recognized by its paler plumage overall, with contrasting dark axillaries evident in flight. It is a bird of western mountains and prairies, breeding from British Columbia, southern Alberta and southern Saskatchewan south to northern Mexico (Steenhof 2013). In fall and winter, it frequently disperses east and south of the breeding range. Most Manitoba records have been in the south between August and October, and have sometimes involved family groups, leading to speculation about local breeding (The Birds of Manitoba). However, there is no evidence that this has taken place and it is likely that most of these birds originate in northwestern U.S.A., the closest known breeding areas being in central-western North Dakota (Steenhof 2013). There is very little, if any, suitable nesting habitat, in the form of cliffs or ledges, in Manitoba, though wintering birds have occasionally selected roosting sites on tall buildings.
Blue-gray Gnatcatcher Polioptila caerulea
Comparable in mass to a kinglet, the well-named Blue-gray Gnatcatcher has a white eye-ring and long, white-edged black tail. It breeds across much of the conterminous U.S.A. (excluding Maine, the northern Great Plains, and the Pacific Northwest), south to Belize and Guatemala, and winters from the southern rim of the U.S.A. to Honduras and Cuba. Regular breeding in Canada is limited to southern Ontario and Québec, and the closest breeding area to Manitoba is southern Minnesota (Kershner and Ellison 2012). Preferred habitats range from deciduous forest (especially forest edges) to dry, shrubby areas.
Eight Manitoba sightings between 1977 and 2014 comprise three between late May and mid-June, one in late August, and four between the second half of October and mid-November. This suggests a combination of spring overshooting, post-breeding dispersal, and misdirected fall migration. Records during the atlas period were at Winnipeg on 26-27 May, 2013 (Koes and Taylor 2014a) and Grand Beach on 2 November, 2014 (Koes and Taylor 2015). The species is included here on the strength of an apparently unpaired female that built a nest in Assiniboine Forest, Winnipeg in June 1998 (The Birds of Manitoba). Continuation of this species' northward range expansion during the 20th Century (Kershner and Ellison 2012) may eventually bring it to Manitoba on a more regular basis.
Snow Bunting Plectrophenax nivalis
With its immaculate black-and-white pattern, a male Snow Bunting in summer is a striking bird. Females and birds in winter plumage have more brown and buffy tones (the brown feather tips wear away by spring to reveal the breeding "plumage"). This is one of only a handful of passerine species found breeding in the High Arctic, both in North America and Eurasia. Large flocks winter or migrate through Manitoba, with occasional birds lingering in summer along the Hudson Bay coast. There is one apparent breeding record: a stub-tailed young that had difficulty flying was seen near Churchill on 24 July, 1968 (Jehl 2004). There were atlas records in five squares within Wapusk National Park, some involving multiple birds, ranging in date from 26 May to 21 June (2010 and 2012 only). The most convincing of these was a pair seen near Cape Churchill on 21 June, 2012 (M. Scott); however, even though there is some rocky habitat in this area, these birds may still have been moving north following that cold spring with snow packs present well into June.
Summer Tanager Piranga rubra
Uniformly rose or orange-red with duller wings and tail, the breeding male Summer Tanager is easily distinguished from its Scarlet and Western cousins, while differences among the other, less colourful plumages are more subtle. The nominate subspecies breeds in deciduous forests of the eastern U.S.A., northward to about 40°N, while a southwestern form has a more restricted range between California, west Texas, and northern Mexico (Robinson 2012). Winter range extends from central Mexico to Northern Bolivia and western Brazil.
Since the first provincial sighting in 1953, there are now at least 65 Manitoba records of the Summer Tanager, mostly clustered from mid-May to mid-June and in October and November. Since the closest regular breeding locality is in Iowa, these are best categorized as spring overshoots and misoriented fall migrants. The only atlas-period record suggestive of breeding, albeit most likely a lone wanderer, was a singing male near Sandilands on 1-2 July, 2012.
Though hybridization is generally rare in wild birds, it is rather frequent (a) with some closely related waterfowl and gull species pairs, (b) within the contact zones (usually narrow) of some species pairs of passerines and other orders, and (c) occasionally when an individual of one species strays into the breeding range of a close relative. Sometimes, when an expanding species advances into a relative's range, "genetic swamping" by hybridization may be a factor in the invaded species’ demise. Historically, hybridization with Sharp-tailed Grouse (Tympanuchus phasianellus) may have been a factor in the final extirpation of the Greater Prairie-Chicken (T. cupido) in Canada, considering that some of the last sightings, including in Saskatchewan in the 1980s, involved hybrids (COSEWIC 2000). Current concerns with genetic swamping, relevant to Manitoba, include declines and shrinking ranges of American Black Duck (Anas rubripes) and Golden-winged Warbler (Vermivora chrysoptera) due to hybridization with Mallard A. platyrhynchos) and Blue-winged Warbler (V. cyanoptera), respectively. Hybrid zones for many other species pairs are fortunately more stable, and rarer hybridization events, involving more distantly related species, are unlikely to influence parent species' abundance.
Identification of the parent species of hybrids is not always straightforward, and the risk of error is high for unsubstantiated sight records. Detection of mixed pairs during the breeding season is generally less frequent than observation of hybrid progeny at other seasons or in other contexts, e.g. gull and waterfowl concentrations. Thus, there were few records of hybrids by atlas observers, even for frequent pairings such as Snow Goose (Chen caerulescens) x Ross’s Goose (C. rossii). The following records occurred during or shortly after the atlas period. Various hybrid gulls such as "Nelson's Gull" (Glaucous Gull x Herring Gull) have been reported in Manitoba, though generally not at nesting sites. In addition, potential for hybridization in Manitoba exists for, among others, Plegadis ibises, Sturnella meadowlarks, Passerina buntings, Spizella sparrows, and Pheucticus grosbeaks, as well as various waterfowl combinations and less-closely related warbler and sparrow pairings.
Blue-winged x Cinnamon Teal Spatula discors x cyanoptera
A hybrid male was photographed at Whitewater Lake on 16 April, 2017 (C. Blyth, G. Richards). A male Cinnamon Teal was present at another part of the lake in June of the same year (C. Blyth, C. Artuso). Given the difficulty of identifying females and eclipse males, hybrid pairings may be more common in Manitoba than the record suggests.
Mallard x American Black Duck Anas platyrhynchos x rubripes
This hybrid is probably scarcer in Manitoba now than in the past, with declining numbers of American Black Duck, especially in the south. During the atlas period, the only hybrid reported during the nesting season was a male near Cape Churchill in June, 2012 (M. Scott).
"Brewster's" (Golden-winged x Blue-winged) Warbler Vermivora chrysoptera x cyanoptera
A male Brewster's Warbler was identified by Christian Artuso 3.5 km southeast of Trentham on 7 June, 2008, furnishing just the second record of this hybrid for Manitoba (first in 1932), and the first to be photographed. This hybrid male was on the same territory well into July, when an unsuccessful effort to mist net this bird for a genetic sample was made. Although the genetics could not be determined, this male showed a phenotype associated with hybrids (possibly back-crossed to the Golden-winged Warbler parent type). Of 205 Golden-winged Warblers genetically tested from southeastern Manitoba (broadly from Ste. Geneviève to Richer), from 2010 to 2014, only 10 (4.9%, all found in 2012) were hybrids. Eight of these 10 were "cryptic hybrids", i.e., they showed no visible features of hybridization but had the mitochondrial DNA of the Blue-winged Warbler, indicating a hybridization event at some point in their lineage (Moulton et al., 2017).
Range expansion of the Blue-winged Warbler has not yet reached Manitoba, giving special importance to the province's Golden-winged Warbler population (see the Golden-winged Warbler species account for further context). There is as yet just one confirmed Blue-winged Warbler record, a misoriented fall migrant at Delta on November 7-8, 1987.
Spotted x Eastern Towhee Pipilo maculatus x erythrophthalmus
A singing male hybrid towhee was found and photographed by Garry Budyk in the Portage Sand Hills on 17 and 24 May 2012 (Koes and Taylor 2013). In the post-atlas period, a hybrid male was seen by Christian Artuso, in proximity to a male Spotted Towhee, in the Spy Hill-Ellice Community Pasture in the Qu'appelle River valley west of St-Lazare on 24 July, 2017 (see Spotted Towhee account), and a possible hybrid near Winkler on 12 May, 2018 (B. Ginter). Both parent species occur in Manitoba, though the Spotted Towhee is rare, and the main contact zone is south and west of the province.