Status and Occurrence of Scripps’s Murrelet (Synthliboramphus scrippsi) in British Columbia
by Rick Toochin
Introduction and Distribution
The Scripps’s Murrelet (Synthliboramphus scrippsi) is a small alcid species that breeds on islands off the coast of southern California from the Channel Islands and along the coast of western Mexico on islands off the west coast of Baja California at least as far south as Islas San Benito (Drost and Lewis 1995). Santa Barbara Island supports the greatest majority of nesting birds in southern California (Drost and Lewis 1995). The Scripps’s Murrelet has a lengthy nesting season that lasts from February to June (Drost and Lewis 1995). During this time the species’ distribution is closely centered around its nesting islands with the highest numbers being found around Santa Barbara Island (Briggs et al. 1987). The fledging period peaks in April or in some years in May, throughout southern California, from near San Diego to Rodriguez Dome, 90–100 km west-southwest of Point Conception (Drost and Lewis 1995). As family groups disperse from the nesting grounds in midsummer, there are high numbers found away from the nesting islands (Unitt 1984, Briggs et al. 1987). Most records of Scripps's Murrelet’s in Baja California waters are also from around breeding islands. Islands with definite breeding records are Islas Los Coronados, Islas Todos Santos, Isla San Martin, Isla San Geronimo, and Islas San Benito (Kaeding 1905, Bent 1919, Jehl and Bond 1975) with the southernmost confirmed nesting location found on the Islas San Benito (Boswall 1978).
After the breeding season when Scripps’s Murrelets are not at the breeding colonies, individuals occur along the Pacific Coast from at least the southern tip of Baja California to Washington State (Drost and Lewis 1995). There is little known about the occurrence of this species in offshore waters of Baja California, except in vicinity of the breeding islands (Drost and Lewis 1995). From August through October, a few Scripps’s Murrelets occur in California waters south of Point Conception and San Miguel Island (Drost and Lewis 1995). The highest numbers during this time are found from Point Conception to Monterey Bay and Point Año Nuevo, mostly 20–100 km offshore (Briggs et al. 1987). Numbers in the wintering areas decrease after November, but a few Scripps's Murrelets have been recorded off central California as late as February and March (Briggs et al. 1987). There are relatively few winter records for the distribution of this species between the months of November and December (Drost and Lewis 1995). The birds reported in April may be early post-breeding wanderers, or non-breeders (Drost and Lewis 1995).
This species is reported as rare but annual off Oregon where there are over 20 accepted records by the Oregon Bird Records Committee and is no longer a review species for the state (OFO 2012). The Scripps’s Murrelet is also a rare, but annual off Washington State where there are 7 accepted records for the newly split Scripps’s Murrelet, but over 40 accepted records under the species old name, the “Xantus’s” Murrelet, by the Washington Bird Records Committee (Wahl et al. 2005, WBRC 2013). In British Columbia, the Scripps’s Murrelet is a casual to possibly a very rare potentially annual occurring species in the pelagic waters of the Province with over 30 records (Toochin et al. 2014, see Table 1 and 2). The Scripps’s Murrelet has not been recorded in Alaska (Gibson et al. 2013).
The Scripps’s Murrelet and its sister species the Guadalupe Murrelet (Synthliboramphus hypoleucus) were formerly lumped together as one species that was called the Xantus’s Murrelet (Chesser et al. 2012). The Xantus’s Murrelet was officially split into the two new species by the American Ornithologist’s Union in 2012 (Chesser et al. 2012). The Guadalupe Murrelet has a more southerly range than the Scripps’s Murrelet and is uncommon north of Baja Mexico along the west coast of North America from southern California to Washington State (Drost and Lewis 1995, Howell and Web 2010). The status of this new species is not yet clear in British Columbia, but it has been recorded for certain once in Provincial pelagic waters on August 2, 1994, 15 Nautical Miles west of Moresby Island, in the Queen Charlotte Islands, coordinates (52°23.2'N, 132°29.2'W)(M. Force pers. comm.).
Occurrence and Documentation
The Scripps’s Murrelet is a casual to possibly very rare annual occurring species in pelagic waters off British Columbia with 34 records (Toochin et al. 2014, see Table 1 and 2). All have been found in pelagic waters from near shore to well offshore on the continental shelf (Toochin et al. 2014, see Table 1). This species leaves its breeding islands in May and birds tend to disperse northward in June and July (Drost and Lewis 1995). Records in British Columbia show a definite spike in August with 11 records and September having 13 records (Toochin et al. 2014, see Table 2). There are single records for the months of April and June (Toochin et al. 2014, see Table 2). There are 4 records for the months of July and October (Toochin et al. 2014, see Table 2). The majority of records come from the west coast of Vancouver Island with 23 records (Toochin et al. 2014, see Table 1 and 2). There are 11 records from the waters around the Queen Charlotte Islands (Toochin et al. 2014, see Table 1 and 2). This species prefers warmer water to feed on fish and small invertebrates (Drost and Lewis 1995). The pattern of occurrence in British Columbia is the same as in Washington State and Oregon (Wahl et al. 2005, OFO 2012). In Washington State, records of the Scripps’s Murrelet are concentrated in early August through early October (Wahl et al. 2005). What isn’t clear is if the warm water conditions of El Nino, where the ocean temperature is 16’C or higher, pushes this species north in greater numbers than in a year where the ocean temperatures are cooler (Wahl et al. 2005). In Washington State prior to the early 1970s, the Scripps’s Murrelet had been collected a couple of times, but was essentially unknown in Washington pelagic waters until the 1970’s when regular pelagic trips started to go well offshore and observers began to encounter this species (Wahl et al. 2005). This species is difficult to gauge in its overall occurrence in British Columbia because there are so few pelagic trips undertaken and most trips do not ever go as far as the continental shelf break. The vast majority of records come from research vessels that are able to go far offshore and spend extended periods in this area. Another consideration to the lack of sightings from the few pelagic trips undertaken in British Columbia is that they are organized far too late in the fall to have a good chance to find this species. These trips are run to maximize species diversity for the participants and this is totally understandable. However trips going offshore in late July through August and early September would likely yield a higher probability of success in detecting Scripps’s Murrelet in Provincial waters. There are at least five records for the inner mouth of the Juan de Fuca Strait on both sides of the border (Wahl et al. 2005, Toochin 2012). It is possible that further investigations by observers into this area could yield this species with greater frequency in the future. As with any alcid, the Scripps’s Murrelet is a species that is most likely to be found well offshore, but can be encountered close to shore and observers should always be on the lookout for this elusive seabird. It is likely, given the frequency that this species is encountered in nearby Washington State, there will be future records of Scripps’s Murrelet in British Columbia.
