. The Canadian field-naturalist. 318 The Canadian Field-Naturalist Vol. 102 Table 1. Percentage of days during each month when Steller Sea Lions were seen on rookeries, year-round haulouts, and exposed winter haulouts in British Columbia during 1956-82. Site Month M M O N D Rookeries % (n) Year-round % Haulouts'' (n) Winter % Haulouts'' (n) 100 100 100 100 100 100 100 100 100 100 (6) (3) (4) (10) (27) (52) (20) (11) (7) - - (12) 100 100 100 100 95 95 100 85 100 100 100 83 (7) (8) (8) (14) (39) (91) (49) (27) (11) (2) (2) (23) 93 95 86 100 88 26 36 82 75 77 100 96 (15) (22) (14) (10) (9) (61) (
. The Canadian field-naturalist. 318 The Canadian Field-Naturalist Vol. 102 Table 1. Percentage of days during each month when Steller Sea Lions were seen on rookeries, year-round haulouts, and exposed winter haulouts in British Columbia during 1956-82. Site Month M M O N D Rookeries % (n) Year-round % Haulouts'' (n) Winter % Haulouts'' (n) 100 100 100 100 100 100 100 100 100 100 (6) (3) (4) (10) (27) (52) (20) (11) (7) - - (12) 100 100 100 100 95 95 100 85 100 100 100 83 (7) (8) (8) (14) (39) (91) (49) (27) (11) (2) (2) (23) 93 95 86 100 88 26 36 82 75 77 100 96 (15) (22) (14) (10) (9) (61) (14) (17) (16) (4) (6) (28) ^For sites listed in Table 5. ''For sites listed in Table 7 except Miller Group, Ashdown Island, sites with less than 50 animals usually present, and sites off southern Vancouver Island between Carmanah Pt. and Denman Island. mid-July in Alaska. Evermann and Hanna (1925) and Bartholomew and Boolootian(1960) observed that the seasonal timing of births was the same throughout the range. In British Columbia, as elsewhere, births take place from late May to mid- July (Pike and Maxwell 1958; Edie 1977). Figure 3 shows the remarkable similarity in the sequence of pupping on seven rookeries located between California and Alaska. The number of pups born by date was taken from studies by Mathisen et al. (1962), Gentry (1968), Sandegren (1970), Edie. 21 31 10 20 30 10 May June July Figure 3. The mean and range for the cumulative percentage of Steller Sea Lion pups born, at 5-day intervals, on seven rookeries between California and Alaska. (1977) and Calkins and Pitcher (1982). On average, 99% of births were completed by July 5. The total number of animals of all ages seen on rookeries begins to increase at the start of the birth season and to decline after the mating season. The number of bulls reaches a peak in early to mid- June, while the peak for juvenile males is late June, and that for cows and younger females mid- to late June (Gentry 1968; Edie 1977). T
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