The Status and Occurrence of Snowy Egret (Egretta thula) in British Columbia
by Rick Toochin and Jamie Fenneman
Read the full text with photos and tables here.
Introduction and Distribution
The Snowy Egret (Egretta thula) breeds along the Atlantic coast of the United States, north to Maine as well as throughout much of the southeastern and western states, north to eastern Oregon and southern Idaho (Dunn and Alderfer 2011). It is a local breeder in the Midwestern states, and north to North Dakota (Dunn and Alderfer 2011). It regularly disperses north in the late summer and fall into southern Canada, particularly in the Prairie Provinces, southern Ontario, and the Maritimes (Godfrey 1986, Sibley 2000). It withdraws from most interior regions of the continent in winter, moving to the Gulf and southern Atlantic coasts of the U.S. as well as to southern and coastal California and southern Arizona (Dunn and Alderfer 2011). South of the United States, the species is found throughout Mexico, Central America, the Caribbean, and most of South America (Howell and Webb 2010). It is generally present either year-round or in parts of Mexico and northern Central America as a wintering species in areas south of the United States (Howell and Webb 2010).
Although the species has a very large population and a distribution stretching from the northern United States to southern South America, populations often experience considerable flux (Parsons and Master 2000). Like other plumed egrets, the Snowy Egret was heavily hunted in the 19th and early 20th centuries and, as a result, populations in many areas of the U.S. plummeted (Parsons and Master 2000). Following cessation of this hunting, however, the species rapidly recolonized former breeding areas along the Atlantic coast of the United States, and even spread into new breeding areas in the northeastern states (Parsons and Master 2000). Populations in many areas subsequently declined, however, with the mid-Atlantic population dropping by c. 39% between the mid-1970s and mid-1990s (Parsons and Master 2000). Breeding populations in western North America appear relatively stable, although the species is apparently declining in the Salton Sea area of California, likely due to competition with the increasingly abundant Cattle Egret (Bubulcus ibis) (Parsons and Master 2000). This is a regular breeding species in California, Oregon, and Idaho, with breeding birds typically arriving in northern portions of its range (Oregon, Idaho) in late April or early May and departing primarily in September (Wahl et al. 2005). It is a rare vagrant to Washington (32 records), where it occurs primarily in spring (May) and fall (August-November) in both eastern and western portions of the state (Wahl et al. 2005, WBRC 2011). It is a very rare vagrant to Alberta, primarily in the late summer and fall (Hudon et al. 2009), but has not yet been recorded in either the Yukon (Sinclair et al. 2003) or Alaska (Gibson et al. 2013). The Snowy Egret is a casual vagrant to British Columbia with over twenty records scattered from all over the Province (Toochin et al. 2013a, see Table 1).
Occurrence and Documentation
The Snowy Egret is a casual to very rare vagrant to the south coast of British Columbia and is casual in the southern interior (Toochin et al. 2013, Please see Table 1). It has been recorded in the province on 24 occasions through to 2014, with an additional record that has been excluded because of questions regarding the validity of the sighting. The earliest account of this species in the province is from Fannin (1891) who states that two specimens were taken at Burrard Inlet, near Vancouver, in May 1879. One of these specimens, however, apparently pertains to a specimen of Intermediate Egret that was housed at the provincial museum (Kermode 1923, Brooks 1923); the location of the second specimen is unknown. As a result of the confusion regarding this record and the specimens to which it apparently refers, it has been excluded from further consideration here. Other authors (e.g., Brooks and Swarth 1925, Munro and Cowan 1947, Campbell et al. 1990) have treated the record similarly. The second report of the species in British Columbia was of a single bird observed at Crescent Beach, White Rock in 1946 by M.W. Holdom (Holdom 1948). Although Holdom (1948) published the record as pertaining to a Snowy Egret, some of the published details did not appear consistent with that identification. Specifically, Holdom states that the “legs and feet were light orange” and “there was no black visible.” These characteristics suggest that the species of egret that was being observed may not have been a Snowy Egret, which has characteristically blackish legs with contrasting yellow feet (or, in immatures and winter adults, yellow feet and a yellow stripe up the back of the otherwise black legs) as well as a black bill. Holdom did send more detailed notes to W.E. Godfrey at the National Museum of Canada, who supported the identification as a Snowy Egret (Campbell et al. 1990). Given that further information was provided to Godfrey and the record was accepted in Campbell et al. (1990), the record is included in this account.
The first unequivocal sighting of Snowy Egret in British Columbia is of an adult bird that was photographed near Pitt Meadows in the lower Fraser Valley on May 23, 1972 (Campbell et al. 1974). This record was quickly followed by another bird at Esquimalt Lagoon, near Victoria, from August 23-28 of that same year (Tatum 1973). Although Campbell et al. (1974) questioned whether these may have been the same individual, it is more likely that two separate birds were involved, given the time span between the records and the ages of the birds involved. The species was reported sporadically throughout the 1970s and 1980s, but the frequency of sightings increased noticeably through the 1990s and 2000s with 14 of 21 records have occurred since 1990 (Toochin et al. 2013, see Table 1). The years 1994 and 1999 were particularly productive for this species in British Columbia with three and four records respectively (although some of these records in each year may refer to a single individual moving around the province). The most recent coastal report is of an adult bird observed in Victoria on the southern tip of Vancouver Island from May 25-June 1, 2012 (Toochin et al. 2013, Please see Table 1). Records of Snowy Egret in British Columbia are primarily from the south coast, especially the lower Fraser Valley east to Chilliwack with eight records and extreme southeast Vancouver Island from Ladysmith south to Victoria with seven records (Toochin et al. 2013, see Table 1). The species has been recorded in the southern interior on only six occasions, two of which have been from the productive littoral habitats at Salmon Arm on the southern shore of Shuswap Lake (Toochin et al. 2013, see Table 1). The northernmost interior record, and indeed the northernmost record for the province, is of an individual at Williams Lake from July 30-31, 1999 (Toochin et al. 2013, see Table 1). The most recent interior record is of an adult bird found at Roberts Lake in Kelowna from June 3-5, 2014 (D. Cecile pers. comm. Please Figure 2-4). Peak occurrence of the species in British Columbia is during May, although some birds have occurred during the summer months (early July to early August) or during post-breeding dispersal in the fall (late August to mid-November) (Toochin et al. 2013, Please see Table 1 & 2). The earliest record for the province is 17 April and the latest is 19 November (Toochin et al. 2013, Please see Table 1 & 2).
Like several other vagrant herons and egrets, Snowy Egrets in British Columbia are closely associated with shallow water habitats, both freshwater and marine, where they can wade and feed (Sibley 2000, Dunn and Alderfer 2011). This includes both heavily vegetated habitats, such as sloughs and marshes, as well as more open habitats such as coastal lagoons, mudflats, harbours, marine shorelines, estuaries, lakeshores, and riverbanks (Parsons and Master 2000). They generally occur alone rather than in the company of other waders, although they may frequent the same habitats as those used by Great Blue Herons (Ardea herodias) or Green Herons (Butorides virescens) (Parsons and Master 2000).