The Status and Occurrence of Slaty-backed Gull (Larus schistisagus) in British Columbia. By Rick Toochin and Don Cecile. Revised: June 20, 2023.

 

The Slaty-backed Gull (Larus schistisagus) is a large coastal species of gull that is found in northeast Asia from Koryakia, Kamchatka Peninsula, Sea Of Okhotsk, Shantar Island, Sakhalin Island, Hokkaido and northern Honshu Island in Japan (Brazil 2009). The species winters in ice-free regions from the Commander Islands, Hokkaido, south down the Sea of Japan to the Korean Peninsula, Bohai Gulf, and the Pacific Coast to Nansei Shoto, Taiwan and occasionally Southeast China (Brazil 2009). The Slaty-backed Gull has been recorded throughout the year in western Alaska, and has nested several times, including both pure pairs and mixed and hybrid pairs (McCaffery et al. 1997, Winker et al. 2002). The species is most regular in the Bering Sea Region of the State (Dunn and Alderfer 2011). The Slaty-backed Gull is rare, but regular in south and southeastern Alaska (West 2008). In British Columbia, the Slaty-backed Gull is a rare, but increasingly annual species, with over 75 Provincial records (Campbell et al. 1990b, Toochin et al. 2014a, see Table 1). In Washington State, the Slaty-backed Gull is a very rare winter visitor in the Northwest part of the State with 15 accepted records by the Washington Bird Records Committee (Wahl et al. 2005, WBRC 2013). In Oregon, the Slaty-backed Gull is an accidental species with 7 accepted records by the Oregon Bird Records Committee (OFO 2012). In California, the Slaty-backed Gull is a recent addition to the State’s checklist with the first accepted record occurring in 2001 (Hamilton et al. 2007). There are now 53 accepted state records by the California Bird Records Committee (Tietz and McCaskie 2014). The sudden increase in records all along the west coast likely reflects increased identification knowledge and awareness of gull identification (Olsen and Larsson 2004). It is unclear if the rapid increase in Slaty-backed Gull records across North America is due to the species expanding its range or due to better observer coverage (Hamilton et al. 2007). The Slaty-backed Gull is an accidental to casual visitor in the rest of Canada with records from almost every Province and Territory (Cormier and Savard 1994, Sinclair et al. 2003). The Slaty-backed Gull is also an accidental throughout the eastern United States with records as far south as Texas and Florida (Dunn and Alderfer 2011). The species is casual in Hawaii (Hamilton et al. 2007). The Slaty-backed Gull has been recently added to Europe with about 6 records from various countries (Birdguides 2011, Netfugl.dk 2014). 

 

The identification of the Slaty-backed Gull is covered in all standard North American Field Guides. The identification of gulls has gone through a huge transformation over the past 20 years with new identification guides and with the expansion of the internet. The Slaty-backed Gull is a large bird at 25 inches (64 cm) in length and a wingspan of 58 inches (147 cm) (Dunn and Alderfer 2011). The identification of adult birds can be straight-forward, but younger plumages and hybrids are hard to identify (Olsen and Larsson 2004). As with any identification dealing with younger plumages, it is important to use caution, obtain lots of photographs, and try and get confirmation from experienced observers whenever possible.

 

Adult Slaty-backed Gulls in breeding plumage hold this plumage from February/March to September (Olsen and Larsson 2004). These birds have white heads, a thin fairly straight yellow bill with a red spot on an almost minimal gonys-angle (Olsen and Larsson 2004). The eyes are pale yellow and the orbital ring is pinkish-red (Olsen and Larsson 2004). The neck is heavy and thick (Sibley 2000). The throat, chest, belly, flanks and undertail coverts are white (Dunn and Alderfer 2011). The legs are fleshy-pink (Sibley 2000). The mantle is slate-gray and appears almost black in certain lighting conditions (Dunn and Alderfer 2014). On sitting birds, the thick white trailing edge cuts across the black folded primaries, and, when seen from behind, the white training edge extends partially up the back (Olsen and Larsson 2004). There is also a large white patch on the back, giving the Slaty-backed Gull a very black and white look (Olsen and Larsson 2004). The folded wings are black with 5 large white mirrors; with the closest white mirror to the trailing edge partially obscured (Olsen and Larsson 2004). In flight, the upper wing is slate-gray with a thin white leading edge (Brazil 2009). The thick white trailing edge extends up the entire wing and continues into the primary shafts as a “string of pearls” (Olsen and Larsson 2004). The primary tips are black with the white mirrors at the tips of the feathers, followed by a black area, and then the white spots (Olsen and Larsson 2004). This white line created by the “String of pearls extends all the way towards the outermost primary feather or P10 (Olsen and Larsson 2004). The auxiliaries on the underside of the wing are white (Brazil 2009). The underside of the primaries is gray (Dunn and Alderfer 2011). The thick white trailing edge shows well from underneath on flying birds (Olsen and Larsson 2004). There is also a secondary dark line just inside from the trailing edge that extends up the entire wing and gives the underside of the primary feathers a dark appearance (Olsen and Larsson 2004). The white spots of the “string of pearls” are also found on the underside of the primary feathers (Dunn and Alderfer 2011). This makes the wing pattern a very important field mark for observers to see on any potential Slaty-backed Gull. Slaty-backed Gulls hold their winter plumage from September to March (Olsen and Larsson 2004). In winter plumage, the head of the adult birds normally has heavy brownish streaking on the crown that is even heavier on the back of the neck (Olsen and Larsson 2004). There is a dark line through the eye, giving adult birds in winter plumage an “evil eyed appearance” (Olsen and Larsson 2004). Birds in fourth winter are the same looking as adults, but will often have some dark on their otherwise yellow bill (Olsen and Larsson 2004).

 

Third cycle Slaty-backed Gulls hold this plumage from August to April (Olsen and Larsson 2004). These birds are similar looking to adult birds, but the mantle is only partially slate-gray, and the lesser, median and greater coverts are brown with some mottled slate-gray feathers (Olsen and Larsson 2004). The white trailing edge is defined and thick (Olsen and Larsson 2004). The folded primaries are black with white edges where the mirrors grow in later as adults (Olsen and Larsson 2004). In flight, the “string of pearls” is clearly visible along the primary shafts on both the upper side and underside of the wing (Olsen and Larsson 2004). The head in winter plumage is heavily streaked on the crown, nape, back of the neck, down the sides of the neck and onto the flanks (Olsen and Larsson 2004). The eyes are yellow with a dark line running through them giving birds an evil eyed look (Sibley 2000). The bill is yellow with a black band across the mid-section of the bill (Sibley 2000). The belly is white (Sibley 2000). The tail has a thick black band with white edges to the dark feathers (Olsen and Larsson 2004).

 

Second cycle Slaty-backed Gulls hold this plumage from August to April (Olsen and Larsson 2004). The overall look of these birds is highly variable depending on the time of year (Olsen and Larsson 2004). Most birds have a whitish head and body with strong spots or streaks on the neck, sides of the neck, across the breast and down the flanks on to the vent (Olsen and Larsson 2004). There are lighter streaks around the eye (Sibley 2000). Birds in the fall have dark eyes that change to light eyes by the early spring (Olsen and Larsson 2004). The bill is pale based with a dark band near the tip with the tip of the bill pale (Olsen and Larsson 2004). It is in this plumage that the dark slate-gray mantle feathers start to show (Olsen and Larsson 2004). Birds in the fall have gray feathers with dark thin brown centers to the feathers on the mantle (Olsen and Larsson 2004). These are replaced in the early spring with dark slate-gray feathers (Olsen and Larsson 2004). In the fall, the greater coverts are brown (Olsen and Larsson 2004). In the early spring the lesser, median and greater coverts are light whitish-brown (Olsen and Larsson 2004). The tertials are a darker brown with white edges (Dunn and Alderfer 2011). The folded primaries are blackish-brown with light brown edges where the mirrors will develop at an older age (Olsen and Larsson 2004). In flight, the trailing edge of the secondaries is dark brown with whitish edges that extend to the beginning of the primaries (Olsen and Larsson 2004). The inner primaries are pale creating a pale panel with the outer primaries from P10-P7 having dark webs with light areas near the feather bases and dark outer tips (Olsen and Larsson 2004). The rest of the upper wing is a whitish-brown colour (Olsen and Larsson 2004). The rump is white with a blackish tail (Dunn and Alderfer 2011). The legs are light pink (Grant 1986). 

 

First cycle Slaty-backed Gulls hold this plumage from September to April (Olsen and Larsson 2004). This is the most difficult plumage to accurately identify in the context of British Columbia. Birds are generally greyish-brown with a diluted covert pattern (Olsen and Larsson 2004). The mantle and scapulars are grey with dark shafts or sub terminal markings, appearing weak and unbarred (Olsen and Larsson 2004). The lesser, median and greater coverts are brownish-white (Olsen and Larsson 2004). The tertials are brown with light edges to the feathers (Olsen and Larsson 2004). The head is pale through wear (Olsen and Larsson 2004). The crown, nape, back of the neck, the sides of the neck down to the belly, the flanks and undertail coverts are streaked (Olsen and Larsson 2004). The folded primaries are blackish-brown with light brown edges where the white mirrors will develop as the bird matures to an adult (Olsen and Larsson 2004). In flight, the trailing edge is dark and extends to the beginning of the primary feathers (Olsen and Larsson 2004). The bases of the primary feathers from P1 – P5 are pale giving the wing almost a pale panel in flight (Olsen and Larsson 2004). The outer primaries from P10 – P6 have dark shafts with the inner edge of the feathers pale and the outer tips of the primaries dark (Olsen and Larsson 2004). The wrist area of the open wing on the upper surface is dark (Olsen and Larsson 2004). The rest of the open wing on the upper side of the wing is pale brownish-white (Olsen and Larsson 2004). The bill has a fleshy base and is otherwise black (Olsen and Larsson 2004). The eyes are dark (Sibley 2000). The legs are light pink (Grant 1986). The rump is pale white with light brown bars, and the tail is dark blackish-brown (Olsen and Larsson 2004).

 

There are a few North American gulls that could be confused with adult Slaty-backed Gull (see discussion below).  Any Asian gulls or possible hybrids or immature birds that could be similar looking to the Slaty-backed Gull are not discussed in this account. For further identification criteria it is recommended readers consult Olsen and Larson (2004), Gulls of North America, Europe, and Asia, or Howell and Dunn (2007) Gulls of the Americas, for more in depth details on other ages of possible similar species and potential problematic hybrids.

 

The adult Western Gull (Larus occidentalis) is a species that has a dark blue-gray mantle that is about the same size as a Slaty-backed Gull (Sibley 2000). This species is quite large measuring 25 inches (64 cm) in length with a wingspan of 58 inches (147 cm) (Dunn and Alderfer 2011). The head on pure birds is white in the summer and only lightly streaked in the winter (Olsen and Larsson 2004). They also have bright pink legs (Dunn and Alderfer 2011). The Western Gull has a heavy yellow bill that has a large gonys-angle which is different to the thin, fairly straight bill of the Slaty-backed Gull (Olsen and Larsson 2004). The trailing edge is thin white and doesn’t extend up the back when viewed from behind (Sibley 2000). In flight, the primaries are black, lacking the white spots or “string pearls” found on the Slaty-backed Gull (Olsen and Larsson 2004). The underside of the wing is black from the secondary edge all the way up to the primaries, and lacks the white spots in the primary shafts (Dunn and Alderfer 2011). Hybrid birds, such as Slaty-backed X Glaucous-winged Gull are variable, and could be confused with an adult Slaty-backed Gull by inexperienced observers. It is important to note that hybrids are lighter in colour on the mantle than pure birds and are never as black backed as pure Slaty-backed Gulls (Howell and Dunn 2007). The head streaks on hybrid Western X Glaucous-winged Gulls are large and billowy and not large defined streaks like those found on the adult winter- plumaged Slaty-backed Gull (Howell and Dunn 2007).

 

The Lesser Black-Backed Gull is a medium sized species measuring 21 inches (53 cm) in length with a 54 inches (137 cm) wingspan (Dunn and Alderfer 2011). This species is extremely tapered with very long tapered wings that extend well past the tail on sitting birds (Sibley 2000). The mantle is dark slate-gray with a thick white trailing edge or saddle that is similar in darkness and shade to the adult Slaty-backed Gull (Olsen and Larsson 2004). It is important to note that Lesser Black-backed Gull has bright yellow legs and feet (Dunn and Alderfer 2011). The smaller size should also help observers rule out the much larger and bulkier looking Slaty-backed Gull.

 

The Slaty-backed Gull has gone from being an accidental species in British Columbia, to being a rare almost annual species in the Province. There are 95 records for the Province (Campbell et al. 1990b, Toochin et al. 2014a). The vast majority of records come from coastal regions on British Columbia such as: Vancouver Island with 45 records; Haida Gwaii with 7 records; the Vancouver area with 28 records and the Fraser Valley with 16 records (Campbell et al. 1990b, Toochin et al. 2014a, see Table 1). Interior records are far fewer with only 5 records over the past 25 years (Campbell et al. 1990b, Toochin et al. 2014a, see Table 1). So far, the vast majority of records are of adult birds which are quite obvious to even the newest observers. It is likely that even more birds occur as 1st and 2nd cycle birds, but, due to the difficultly in identification, are likely overlooked completely (Roberson 1980). Due to the difficulty in separating 1st cycle Slaty-backed Gulls from problematic hybrid birds, such as Glaucous-winged X Herring Gull, all 1st cycle birds are placed into the hypothetical category (McKee et al. 2014, Toochin et al. 2014, see Table 1). It is possible in the future that the photographed birds can be properly sorted out as our understanding grows about this complicated identification problem (McKee et al. 2014). The number of Provincial records reflects the explosion of records of this species south of Alaska that began in the late 1980s and early 1990s. The time frame that birds generally turn up in British Columbia is from October to mid-April (Campbell et al. 1990b, Toochin et al. 2014a, see Table 1). Often this species is found by very keen observers that check through gull flocks in landfills, fish plants, or areas where gulls congregate. There are many records of wintering and returning birds in the Delta Landfill and surrounding area of the Lower Mainland (Toochin et al. 2014c). There is also a large push of Gulls into the eastern part of Vancouver Island from Parksville to Qualicum Beach between late February and early April that coincides with the Herring Spawn (Toochin et al. 2014a, see Table 1). The past 20 years has seen better scrutiny of this incredible spectacle of thousands of gulls packed into sometimes small regions (M. Ashbee Pers. Comm.). As a result Slaty-backed Gull has become almost annual during this period on Vancouver Island (Toochin et al. 2014a. See Table 1). Slaty-backed Gulls found in the Fraser Valley are often associated with the fields near the Chilliwack Landfill or the Abbotsford Recycling Depot (Toochin et al. 2014d). The Slaty-backed Gull records from the interior were all birds found in or near landfill sites (D. Cecile Pers. Comm.). Given that this species wanders inland in North America, there will be future interior records. The only summer record for British Columbia comes from the Queen Charlotte Islands at Rose Spit on August 1, 1997 (Toochin et al. 2014a, see Table 1). The chances of finding future summer records are possible in British Columbia. In Washington State one adult individual stayed for an entire year in the Tacoma area and was well photographed (Wahl et al. 2005, WBRC 2012). The lack of summer records likely reveals the fact that most observers do not bother to scrutinize gulls during the summer months so future records are a real possibility. Though currently the Slaty-backed Gull is only documented by 2 records for the Queen Charlotte Islands, this is likely due to low numbers of observers looking on the Islands and records should increase in the future as more people scrutinize gulls in that region (P. Hamel Pers. Comm.). The Slaty-backed Gull is possible anywhere in British Columbia and should be looked for by keen gull enthusiasts every year. With more and more observers buying digital and SLR cameras it is likely that this species will be documented from other regions of British Columbia in the future.

1.(1) adult breeding plumage March 1, 1974: Vic & Peggy Goodwill (RBCM Photo 340) Clover Pt., Victoria (Shepard 1974, Roberson 1980) 

2.(1) adult plumage October 20, 1986: : off West Coast Trail on research vessel (48.50°N, 124.68°W) (Kenyon et al. 2009)  

3.(1) adult winter plumage November 11-12, 1986: Michael Force, mobs (RBCM Photo 1138) Beaver Harbour, Port Hardy (Campbell 1987a, Campbell et al. 1990b)  

4.(1) adult winter plumage November 18, 1989-February 25, 1990: Michael Force, mobs (photo) 68th St. & River Rd., Delta (Weber and Cannings 1990, Weber 1992, Campbell et al. 1990b)

5.(1) adult winter plumage January 15, 1990: Rick Toochin: 72nd St. & 36th Ave, Delta (different individual) (Toochin et al. 2014c)

6.(1) adult winter plumage October 27, 1990-February 2, 1991: Bill Lamond, mobs: Vancouver Landfill & vicinity, Delta (Siddle 1991a, Dorsey 1996a, Toochin et al. 2014c)

7.(1) adult winter plumage November 12, 1992: Brian Self: 64th St. at 60th Ave., Delta (Toochin et al. 2014c)

8.(1) adult winter plumage October 17-18, 1993: Patrick Sullivan, mobs (photo) Revelstoke (Siddle 1994a, Davidson 1994, Toochin et al. 2014a)

9.(1) adult winter plumage November 11-13, 1993: Chris Siddle, B. Collins, PG, GD, mobs (photo) Vernon (Siddle 1994a, Davidson 1994, Toochin et al. 2014a)

10.(1) adult winter plumage December 21, 1993-March 15, 1994: AJa, RTo, mobs (photo) Vancouver Landfill (diff. indiv.), Delta (Bowling 1994a, Davidson 1994, Dorsey 1996b, Toochin et al. 2014c)

11.(1) adult breeding plumage February 15-20, 1994: Mike Bentley, mobs: 68th St. and River Rd. Delta (Toochin et al. 2014c)

12.(1) adult winter plumage February 19-March 11, 1995: Alvaro Jaramillo, mobs (photo) Hornby Dr., Delta (Bowling 1995b, Davidson 1995, Toochin et al. 2014c)

13.(1) adult winter plumage January 13- March 3, 1996: Carlo Giovanella, mobs: Highway 10 & Highway 99, Delta (Bowling 1996b, Davidson 1999, Toochin et al. 2014c)

14.(1) adult winter plumage January 2-March 6, 1997: Rick Toochin, mobs: Burns Drive, Delta (Bowling 1997b, Toochin et al. 2014c)

15.(1) adult breeding plumage August 1, 1997: Peter Hamel, mobs: Rose Spit, QCI (Bowling 1997c, Toochin et al. 2014a)

16.(1) adult winter plumage January 22-March 7, 1998: Dale A. Jensen, mobs: Burns Dr., Delta (Bowling 1998b, Bowling 1998c, Toochin et al. 2014c)

17.(1) 3rd winter plumage February 15-28, 1998: Derrick Marven, mobs (photo) Duncan (Bowling 1998b, Toochin et al. 2014b)

     (1) 3rd winter plumage April 12-15, 1998: Derrick Marven, mobs (photo) Duncan (Bowling 1998c, Toochin et al. 2014b)

18.(1) 2nd winter plumage November 28-30, 1998: Derrick Marven, mobs (photo) Duncan (Bowling 1998a, Toochin et al. 2014b)

19.(1) adult winter plumage  December 4, 1998: Rick Toochin: River Road, Delta (different individual) (Toochin et al. 2014c)

20.(1) adult winter plumage December 28, 1998-February 22, 1999: Rick Toochin, mobs: Burns Dr., Delta (Shepard 1998, Toochin et al. 2014c)

21.(1) adult winter plumage January 11-February 15, 2000: Tom Plath, mobs: Burns Dr., Delta (Toochin et al. 2014c)

22.(1) 3rd winter plumage October 23-24, 2000: Guy Monty: Tofino (Toochin et al. 2014b)

23.(1) adult winter plumage November 1, 2000: Denis Knopp (photo) Sardis Park, Chilliwack (Toochin et al. 2014d)

24.(1) adult winter plumage December 23, 2000-March 11, 2001: Rick Toochin, DM, Guy Monty, mobs (photo) Burns Dr., Delta (Cecile 2001a, Toochin et al. 2014c)

25.(1) 3rd winter plumage February 17, 2001: Rick Toochin, Jamie Fenneman: Iona Island South Jetty Tip, Richmond (Cecile 2001a, Toochin et al. 2014c)

26.(1) 2nd winter plumage  February 19, 2001: Rick Toochin, Jamie Fenneman: 72nd St., Delta (Toochin et al. 2014c)

27.(1) 3rd winter plumage November 10, 2001: Dennis Knopp (photo) near mouth of Chehalis River, Harrison Mills (Toochin et al. 2014d)

28.(1) adult winter plumage December 3-8, 2001: Rick Toochin: 72nd St., Delta (Toochin et al. 2014c)

29.(1) adult winter December 16, 2001: Jamie Fenneman: Guthrie Road, Comox (Toochin et al. 2014b)

30.(1) 3rd cycle plumage January 5 & 15 & February 3, 2002: Gary Davidson, mobs (photo) Kuskanax Creek, Nakusp (Cecile 2002b, Toochin et al. 2014a)
31.(1) adult transition to breeding plumage February 23-March 10, 2002: Mike Tabak, mobs: 96th St. & Hornby Dr., Delta (Toochin et al. 2014c)

32.(1) adult breeding plumage October 27, 2002: David Allinson: Combers Beach, PRNP (Toochin et al. 2014b)

33.(1) 2nd winter plumage October 30, 2002: Rick Toochin: 96th St. and Burns Drive, Delta (Toochin et al. 2014c)

34.(1) adult in transition November 3, 2002: Mitch Meredith, RTo, JO, mobs: Bailey Landfill, Chilliwack (Cecile 2003a, Toochin et al. 2014d)

35.(1) adult winter plumage December 5, 2002: Rick Toochin: Burns Drive, Delta (Cecile 2003b, Toochin et al. 2014c)

36.(1) adult winter plumage November 2-December 21, 2003: Rick Toochin, mobs (video/photo) Vancouver Landfill, Delta (Cecile 2004a, Toochin et al. 2014c)

37.(1) adult winter November 29, 2003-January 14, 2004: Jamie Fenneman, Nathan Hentze, AM, mobs: Cumberland (Cecile 2004a, Toochin et al. 2014b)

38.(1) adult winter December 28, 2003: Guy Monty, mobs:  Nanaimo (Toochin et al. 2014b)

39.(1) adult winter December 23, 2004: Guy Monty (shot dead by poacher) Nanaimo River Estuary (Toochin et al. 2014b)

40.(1) adult winter January 8, 2005: Rick Toochin, Corina Isaac: Burns Drive, Delta (Cecile 2005b, Toochin et al. 2014c)

41.(1) adult winter December 4-5, 2005: Guy Monty, John Brigton (photo) off Portuguese Joe’s on sandy spit, Comox Valley (Cecile 2006b, Toochin et al. 2014b)

42.(1) adult winter January 22-February 9, 2006: Gordie Gadsden, mobs (photo) Evans Road in Sardis, Chilliwack (Cecile 2006b, Toochin et al. 2014d)

43.(1) adult March 12, 2006: Jukka Jantunen (photo) Kye Bay, Comox (Cecile 2006c, Toochin et al. 2014b)

44.(1) adult winter March 14-19, 2006: Jonathan Simms, mobs (photo) near the old hovercraft base at Parksville Bay (Cecile 2006c, Toochin et al. 2014b)

45.(1) adult winter March 17, 2006: Jukka Jantunen (photo) Willow Point, Campbell River (Cecile 2006c, Toochin et al. 2014b)

46.(1) 3rd winter plumage March 22, 2006: Guy Monty (photo) the Little Qualicum Estuary, at east end of Surfside Dr. (Toochin et al. 2014b)

47.(1) adult winter plumage October 13, 2006: Chris Saunders, mobs (photo) Cattle Point, Victoria (Cecile 2007a, Toochin et al. 2014b)

48.(1) adult winter plumage October 14, 2006: Adrian Dorst, mobs (photo) 30 miles off Ucluelet (Cecile 2007a, Toochin et al. 2014b)
49.(1) adult winter plumage March 13-15, 2007: Art Martell, mobs (photo) Qualicum Bay, Qualicum (Cecile 2007c, Toochin et al. 2014b)

50.(1) 2nd winter plumage March 17, 2007: Rick Toochin: Qualicum Bay, Qualicum (Toochin et al. 2014b)

51.(1) adult winter plumage November 12, 2007: Rick Toochin: Sheringham Lighthouse, Shirley (Toochin et al. 2014b)

52.(1) adult winter plumage November 13-24, 2007: Peter Candido, mobs: field off Sandburg Road, Abbotsford (Toochin et al. 2014d)

53.(1) adult winter plumage December 16, 2007: Gary Davidson (photo) end of the lake, Okanagan Landing, Vernon (Toochin et al. 2014a)

54.(1) adult winter plumage December 23, 2007: Mike Tabak, John Tabak, John Kalman (photo) Vancouver Landfill, Delta (Cecile 2008a, Toochin et al. 2014c)

55.(1) adult winter plumage December 29, 2007: Gordie Gadsden, mobs (photo) Abbotsford Landfill, Abbotsford (Toochin et al. 2014d)

56.(1) 3rd winter plumage December 29, 2007: Mike Tabak (photo) 68th and River Road, Delta (Toochin et al. 2014c)

     (1) 3rd winter plumage January 31, 2008: Roger Foxall, Mike Newey (photo) Ladner Trunk between 72nd and 88th Street, Delta (Toochin et al. 2014c)    

57.(1) adult winter plumage January 6, 2008: Rick Toochin: Gordon’s Beach, Otter Point (Toochin et al. 2014b)

58.(1) adult winter plumage January 27, 2008: Mike and John Tabak (photo) 72nd Street, Delta (Cecile 2008a, Toochin et al. 2014c)

59.(1) 2nd winter plumage January 27-March 8, 2008: Rick Toochin, Louis Haviland, mobs (photo) Sooke River Estuary, Sooke (Cecile 2008a, Toochin et al. 2014b)

60.(1) 3rd winter plumage February 2, 2008: Rick Toochin, Louis Haviland (photo) Sooke River Estuary, Sooke (Toochin et al. 2014b)

61.(1) 2nd winter plumage February 24-Mar 8, 2008: Rick Toochin, Roger Taylor (photo) Goodridge Peninsula [different individual] (Toochin et al. 2014b)

62.(1) 2nd winter plumage March 3 - 19, 2008: Mike Tabak, mobs (photo) Qualicum Beach, Qualicum (Toochin et al. 2014b)

63.(1) adult winter plumage March 6, 2008: Jukka Jantunen, mobs (photo) Goose Spit, Comox (Toochin et al. 2014b)

64.(1) adult breeding plumage April 6, 2008: Mike Tabak, John Tabak (photo) Burns Drive and 88th Street, Delta (Toochin et al. 2014c)

65.(1) adult winter plumage November 23, 2008: Mike Ashbee (photo) Courtenay (Toochin et al. 2014b)

66.(1) adult winter plumage January 3- February 8, 2009: Gordie Gadsden, mobs (photo) Abbotsford Landfill, Abbotsford (Toochin et al. 2014d)

67.(1) adult winter plumage January 10-12, 2009: Mike Ashbee, mobs (photo) Lochside and Island View Beach Road, Saanich (Toochin et al. 2014b)

68.(1) adult breeding plumage March 8, 2009: Mike Ashbee (photo) Deep Bay (Toochin et al. 2014b)

69.(1) adult winter plumage March 17, 2009: Chris Saunders: Swan Lake, Victoria (Toochin et al. 2014b)

70.(1) adult winter plumage January 16, 2010: Mike Tabak, mobs (photo) Hornby Drive, Delta (Toochin et al. 2014b)

71.(1) adult winter plumage January 17, 2010: Rick Toochin: along McGuire Road, Chilliwack (Toochin et al. 2014d)

72.(1) 2nd –3rd cycle March 11, 2010: Mike Yip (photo) Qualicum Beach, Qualicum (Toochin et al. 2014b)

     (1) 2nd –3rd cycle March 20-24, 2010: Mike Yip, mobs (photo) Deep Bay (same bird as above)(Toochin et al. 2014b)

73.(1) adult near breeding plumage March 15-16, 2010: Mike Ashbee (photo) Columbia Beach (Toochin et al. 2014b)

74.(1) adult March 19, 2010: Mike Tabak (photo) French Creek, Parksville (Toochin et al. 2014b)

75.(1) adult January 18, 2012: Dave Aldcroft: Whiskey Point, Mill Bay (Toochin et al. 2014b)

76.(1) adult winter plumage December 17, 2012: Gord Gadsden (photo) along McGuire Road, Chilliwack (Toochin et al. 2014d)

77.(1) adult winter plumage December 20, 2012: Derrick Marven: Duncan (Toochin et al. 2014b)

78.(1) adult acquiring winter plumage October 11 & 17, 2014: Rick Toochin, Mitch Meredith & Peter Hamel (photo) Skonun Point, Masset (R. Toochin Pers. Comm.)

79.(1) adult winter plumage December 22, 2014: Rick Toochin (photo) Wells Line Road & Cole Road (R. Toochin Pers. Comm.)

80.(1) adult breeding plumage April 5, 2016: Peter Hamel: Sandspit Airport (P. Hamel Pers. Comm.)

81.(1) adult winter plumage October 24, 2016: Peter Hamel and Margo Hearne (photo) Skonun Point, Masset (P. Hamel Pers. Comm.)

82.(1) 3rd cycle November 27 – December 3, 2016: Liron Gerstman, mobs (photo) 72nd St., Boundary Bay, Delta (D. Cecile Pers. Comm.)

83.(1) 2nd cycle plumage February 7-21, 2017: Blair Duceck, mobs (photo) Nanaimo River  Estuary  (D. Cecile Pers. Comm.)

84.(1) adult acquiring breeding plumage February 27, 2018: Peter Hamel, Margo Hearne (photo) Skonun Pt., Haida Gwaii (P. Hamel Pers. Comm.)

85.(1) 3rd cycle September 16, 2018: Peter Lypkie, Mike Toochin, mobs (photo) foot of 96th St., Boundary Bay (D. Cecile Pers. Comm.)

86.(1) adult basic plumage October 2, 2018: Peter Hamel, mobs: Skidegate Inlet (P. Hamel Pers. Comm.)

87.(1) adult basic plumage November 6, 2018: Rick Toochin, Keelan Toochin (distant photo) Stirling Road (R. Toochin Pers. Comm.)

88.(1) 3rd cycle August 17, 2019: Liron Gertsman, mobs (photo) SE tip of Cleland Island (D. Cecile Pers. Comm.)

89.(1) adult winter plumage March 7, 2020: Liam Singh (photo) end of Amber Way near Spindrift Rd in Royston (D. Cecile Pers. Comm.)

90.(1) adult winter plumage November 4, 2020: Rick Toochin (photo) Marion Road, Sumas Prairie (R. Toochin Pers. Comm.)

91.(1) adult winter plumage December 30, 2020: Peter Hamel, Margo Hearne: southeast harbour near Tlell (P. Hamel Pers. Comm.)

92.(1) 3rd cycle March 18, 2021: Liam Singh, mobs (photo) Pt. Holmes, Comox (D. Cecile Pers. Comm.)

      (1) 3rd cycle March 23-25 & April 1, 2021: Liam Singh, mobs (photo) Qualicum Beach area (D. Cecile Pers. Comm.)

93.(1) adult molting into winter plumage September 28, 2021: Keith Matthieu (photo) Willow Point Estuary,  Campbell River (D. Cecile Pers. Comm.)

      (1) adult molting into winter plumage September 30, 2021: Jack Nindernagel, mobs (photo) Oyster Bay (D. Cecile Pers. Comm.)

94.(1) adult winter plumage January 19, 2022: Rick Toochin (photo) Fadden Road, Sumas Prairie (R. Toochin Pers. Comm.)

95.(1) adult winter plumage November 21-26, 2022: Tana Coetzer, mobs (photo) Kamloops River Trail, Kamloops (D. Cecile Pers. Comm.)

Hypothetical Records:

1.(1) 2nd winter plumage January 15, 1989: Brian M. Kautesk, Mike Darney: 72nd St., Boundary Bay (Toochin et al. 2014c)

2.(1) adult winter plumage  December 6, 1998: Libor Michalak: Vancouver Landfill (different individual)( Toochin et al. 2014c)

3.(1) adult winter plumage January 18, 1999: Libor Michalak: 72nd St., Delta (different individual) (Toochin et al. 2014c)

4.(1) 1st summer plumage March 20, 2004: Rick Toochin, Jamie Fenneman, GM, NH, PL (photo) Kye Bay, Comox (Cecile 2004c, Toochin et al. 2014b)

5.(1) 1st winter plumage March 24, 2007: Jonathan Simms: French Creek (Toochin et al. 2014b)

6.(1) 1st winter plumage January 24, 2008: Gordie Gadsden (photo) Chilliwack Landfill, Chilliwack (Toochin et al. 2014d)

7.(1) adult winter plumage March 15, 2008: Adrian Dorst: Tofino Harbour, Tofino (Toochin et al. 2014b)

8.(1) 1st summer May 2, 2009: Rick Toochin, Louis Haviland, Mike Ashbee (photo) Jordan River (Toochin et al. 2014b)

9.(1) adult August 19, 2012: Michael Lanzone, David La Puma: Amphitrite Point, Ucluelet (Toochin et al. 2014b)

10.(1) 1st winter plumage March 5-7, 2014: Rick Toochin, mobs (photo) Sumas Prairie, Abbotsford (R. Toochin Pers. Comm.)

11.(1) 1st winter plumage November 22, 2014: Rick Toochin, Al Russell, Paul & David Baker (photo) Campbell Road near Cole Road (R. Toochin Pers. Comm.)

 

We wish to thank Barbara McKee for editing the manuscript. We also wish to thank Michael Ashbee for the use of his many Slaty-backed Gull images from around Vancouver Island.  We also wish to thank Mike Yip for the use of his Slaty-backed Gull images from Qualicum Beach. We also wish to thank Steve Metz and Joh Kalman for the use of his Slaty-backed Gull images from the Delta Landfill. We also would like to thank Peter Hamel for details on all records for Haida Gwaii. We also wish to thank Daniel Bastaja for helping track down European records for this species. All photos are used with permission of the photographer and are fully protected by copyright law.

 

Birdguides. (March 2011). Slaty-backed Gull in London. [Online Website] Retrieved from http://www.birdwatch.co.uk/userfiles/file/1103%20highlights%20v3.pdf [Accessed March 8, 2015].

 

Bowling, J. 1995a. The fall migration – British Columbia/Yukon region. North American Field Notes 49: 87- 92.

 

Bowling, J. 1995b. The winter season – British Columbia/Yukon region. North American Field Notes 49: 184-189.

 

Bowling, J. 1996a. The fall migration – British Columbia/Yukon region. North American Field Notes 50: 99-105.

 

Bowling, J. 1996b. The winter season – British Columbia-Yukon region. North American Field Notes 50: 208-213.

 

Bowling, J. 1997a. Autumn migration- British Columbia/Yukon region. North American Field Notes 51: 105-108.

 

Bowling, J. 1997b. The winter season – British Columbia-Yukon region. North American Field Notes 51: 789-792.

 

Bowling, J. 1997c. Summer season - British Columbia/Yukon region. North American Field Notes 51: 1040-1043.

 

Bowling, J. 1998a. Autumn migration– British Columbia/Yukon region. North American Field Notes: 52: 111-113.

 

Bowling, J. 1998b. The winter season – British Columbia-Yukon region. North American Field Notes 52: 245-247.

 

Bowling, J. 1998c. Spring migration – British Columbia-Yukon region. North American Field Notes 52: 376-379.

 

Brazil, M. 2009. Birds of East Asia: China, Taiwan, Korea, Japan, and Russia. Princeton Field Guides. Princeton University Press, Princeton, New Jersey. 528pp.

 

Campbell, R. W. 1987a. British Columbia wildlife – winter report 1986-87. B.C. Naturalist 25(1): 6-7.

 

Campbell, R.W., N. K. Dawe, I. McTaggart-Cowan, J. M. Cooper, G. W. Kaiser, and M. C. E. McNall. 1990b. The Birds of British Columbia – Volume 2 (Nonpasserines [Diurnal Birds of Prey through Woodpeckers]). Victoria: Royal British Columbia Museum. 

 

Cecile, D. 2001a. Winter season – British Columbia-Yukon. North American Birds 55: 215-218.

 

Cecile, D.  2002b. Winter season– British Columbia-Yukon. North American Birds 56: 212-214.

 

Cecile, D. 2003a. Fall season – British Columbia & Yukon. North American Birds 57: 105-106.

 

Cecile, D. 2003b. Winter season – British Columbia & Yukon. North American Birds 57: 244-246.

 

Cecile, D. 2004a. Fall season – British Columbia & Yukon. North American Birds 58: 129-130.

 

Cecile, D. 2004b. Winter season – British Columbia & Yukon. North American Birds 58: 270-271.

 

Cecile, D. 2004c. Spring season – British Columbia. North American Birds 58: 421-422.

 

Cecile, D. 2005a. Fall season– British Columbia. North American Birds 59: 133-134.

 

Cecile, D. 2005b. Winter season – British Columbia. North American Birds 59: 311-312.

 

Cecile, D. 2006a. Fall season – British Columbia. North American Birds 60: 124-126.

 

Cecile, D. 2006b. Winter season – British Columbia. North American Birds. 60: 274-275.

 

Cecile, D. 2006c. Spring season - British Columbia. North American Birds 60: 424-425.

 

Cecile, D. 2007a. Fall season- British Columbia. North American Birds 61: 124-126.

 

Cecile, D. 2007b. Winter season- British Columbia. North American Birds 61: 314-315.

 

Cecile, D. 2007c. Spring season- British Columbia. North American Birds 61: 497-498.

 

Cecile, D. 2008a. Spring season- British Columbia. North American Birds 62: 93-95.

 

Cormier, C., and G. Savard. 1994. A Slaty-backed Gull at Saguenay/Lac St.-Jean: First record for Quebec. Birders Journal 3: 54-62.

 

Davidson, G. S. 1994. B.C. Field Ornithologists records committee annual report for 1993. British Columbia Birds 3: 18-20.

 

Davidson, G. S. 1995. B.C. Field Ornithologists records committee annual report for 1994-1995. British Columbia Birds 5: 2-22.

 

Davidson, G. S. 1999. B.C. Field Ornithologists Bird Records Committee report for 1996-1997. British Columbia Birds 9: 15-18.

 

Dorsey, J. 1996a. Vancouver Rare Bird Records Committee Report, 1990 and 1991. Vancouver Natural History Society Discovery 25: 16-22.

 

Dorsey, J. 1996b. Vancouver Rare Bird Records Committee Report 1992 and 1993. Vancouver Natural History Society Discovery 25: 66-70.

 

Dunn, J. L. and J. Alderfer. 2011. National Geographic Field Guide to the Birds of North America. National Geographic Society, Washington D.C. 574pp.

 

Gibson, D.D, L. H. DeCicco, R. E. Gill Jr., S. C. Heinl, A. J. Lang, T. G. Tobish Jr., and J. J. Withrow. 2013. Checklist of Alaska Birds. 19th Edition: 2013. [Online Resource] Retrieved from http://www.universityofalaskamuseumbirds.org/products/checklist.pdf [Accessed: December 16, 2013].

 

Grant, P. J. 1986. Gulls: An Identification Guide. Buteo Books, Vermillion, South Dakota. 352pp.

 

Hamilton, R. A., M. A. Patten and R. A. Erickson. (editors). 2007. Rare Birds of California: A work of the California Bird Records Committee. Western Field Ornithologists, Camarillo, California. 

 

Howell, S. N. G. and J. Dunn. 2007. Gulls of the Americas. Houghton Mifflin Co., New York. 516pp

 

Kenyon, J. K., K. H. Morgan, M. D. Bentley, L. A. McFarlane Tranquilla, and K. E. Moore. 2009. Atlas of Pelagic Seabirds off the west coast of Canada and adjacent areas. Technical Report Series No. 499. Canadian Wildlife Service Pacific and Yukon Region, British Columbia.

 

McCaffery, B. J., C. M. Harwood, and J. R. Morgart. 1997. First breeding records of Slaty-backed Gull (Larus schistisagus) for North America. Pacific Seabirds 24: 70.

 

McKee, T., P. Pyle, and N. Moores. 2014. Vagrancy and Identification of First Cycle Slaty-backed Gulls: North American Birders Face a Formative Identification Puzzle. Birding 46 (6)38-51.

 

Netfugl.dk Danish Birds. (March 2014). WP Observations: Slaty-backed Gull. [Online website] Retrieved from http://www.netfugl.dk/observations.php?id=wp&species_id=1075 [Accessed March 9, 2015].

 

OFO. 2012. Oregon Field Ornithologists - Records Committee. [Online resource] http://www. oregonbirds.org/index.html. [Accessed: December 14, 2013].

 

Olsen, K. M. and H. Larsson. 2004. Gulls of North America, Europe, and Asia. Princeton University Press, New Jersey.

 

Roberson, D. 1980. Rare Birds of the West Coast of North America. Pacific Grove: Woodcock Publications. 

 

Shepard, M. G.  1974. British Columbia birds – winter season 1973-1974. Vancouver Natural History Society Discovery 3: 4-11.

 

Shepard, M. G.  1998. The summer season – British Columbia – Yukon region. North America Birds 52: 493-494.

 

Sibley, D. A. 2000. The Sibley field guide to birds. Alfred A. Knopf, New York. 545pp.

 

Siddle, C.  1991a. The autumn migration – British Columbia/Yukon region. American Birds 45: 142-145.

 

Siddle, C. 1994a. Fall migration – British Columbia-Yukon region. American Birds, 48: 142-144.

 

Sinclair, P. E., W. A. Nixon, C. D. Eckert, and N. L. Hughes (eds). 2003. Birds of the Yukon Territory. University of British Columbia Press, Vancouver. 596pp.

 

Tietz, J. and G. McCaskie. 2014. Update to Rare Birds of California: 1 January 2004 – 4 February 2014. [Online Resource] Retrieved from      http://www.californiabirds.org/cbrc_book/update.pdf [Accessed: February 8, 2015].

 

Toochin, R., J. Fenneman and P. Levesque. 2014a. British Columbia Rare Bird List: Casual and Accidental Records: January 1, 2014: 3rd Edition. [Online resource] Retrieved from http://ibis.geog.ubc.ca/biodiversity/efauna/documents/BCRareBirdListVersionXZABC.pdf [Accessed: January 2, 2015].

 

Toochin, R., P. Levesque, and J. Fenneman. 2014b. Rare Birds of Vancouver Island. [Online resource] Retrieved from http://ibis.geog.ubc.ca/biodiversity/efauna/documents/RareBirdRecordsofVancouver%20IslandVersionXZAB.pdf [Accessed: January 2, 2015].

 

Toochin, R., P. Levesque and J. Fenneman 2014c. Checklist of the Rare Birds of the Vancouver Area: Casual and Accidental Records. January 1, 2014: 2nd Revised Edition. [Online resource] Retrieved from http://ibis.geog.ubc.ca/biodiversity/efauna/documents/BirdsRareVancouverXZAB.pdf [Accessed: January 2, 2015].

 

Toochin, R and J. Fenneman. 2014d. Rare Birds of the Upper Fraser Valley. January 1, 2014: 2nd Revised edition. [Online resource] Retrieved from http://ibis.geog.ubc.ca/biodiversity/efauna/documents/BirdsRareFraserValleyVersionXZAB.pdf [Accessed: January 5, 2015].

 

Wahl, T. R, B. Tweit, and S. Mlodinow. 2005. Birds of Washington: Status and Distribution. Oregon State University Press, Corvallis, Oregon. 436pp.

 

WBRC. 2012. Washington Bird Records Committee – Summary of Decisions. Washington Ornithological Society, Seattle, WA. [Online resource]  http://www.wos.org/wbrcsummaries.html. [Accessed: December 16, 2013].

 

Weber, W. C. 1992. Vancouver Bird Records Committee Report for 1989. Vancouver Natural History Society Discovery 21: 68-73.

 

Weber, W. C. and R. J. Cannings. 1990. Fall season: August 1 – November 30, 1989- British Columbia and Yukon Region. American Birds 44: 144-149

 

West, G.C. 2008. A Birder’s Guide to Alaska. American Birding Association, Colorado Springs, CO. 586 pp.

 

Winker, K., D. D. Gibson, A. L. Sowls, B. E. Lawhead, P. D, Martin, E. P. Hoberg, and D. Causey. 2002. The birds of St. Mathew Island, Bering Sea. Wilson Bulletin 114: 491-509.

 

Yip. M. (2008, March 19). Vancouver Island Birds: Journal 247 [Online Website] Retrieved from http://vancouverislandbirds.com/Journal247.html [Accessed March 1, 2014].