NOTES 



MIGRANT GRAY WHALES WITH CALVES 



AND SEXUAL BEHAVIOR OF 



GRAY WHALES IN THE MONTEREY AREA 



OF CENTRAL CALIFORNIA, 1967-73 



This paper presents evidence modifying two state- 

 ments in the monographic study of the gray whale, 

 Eschrichtius robustus , by Rice and Wolman 

 (1971): 



1. "The route taken by females with calves 

 during the spring [northward] migration is 

 unknown [page 14]." They arrived at this 

 conclusion after being able to cite only three 

 records of cows with calves over a 10-yr 

 survey period inshore and offshore, at San 

 Francisco and on aerial censuses from San 

 Francisco, Cahf., to Cape Flattery, Wash. 



2. "Non-pregnant adult females regularly ovu- 

 late in late November and early December . . . 

 while still north of central California on the 

 southward migration [page 61]." and 

 "Almost all of the adult females (except those 

 carrying near-term fetuses) taken during 

 southward migration [end of page 73] prob- 

 ably had already conceived, although none 

 was visibly pregnant. . . . The mean concep- 

 tion date calculated from the fetal growth 

 curve ... is 5 December. . . . The calculated 

 conception dates fall between 27 November 

 and 13 December, except for one on 22 De- 

 cember and one on 5 January [pages 73-74]." 



Whales with Calves on Northward Migration 



The known breeding grounds of the north- 

 eastern Pacific Ocean population of gray whales 

 were described in detail by Gilmore (1960). Rice 

 and Wolman (1971) reviewed in their monograph 

 the seasonal migratory cycle of this species. 

 Leatherwood (1973)^ reported 23 observations of 

 northbound females with calves sighted during 

 aerial censusing from 1969 to 1972, off southern 

 California. The majority were "well inshore." 



'Leatherwood, J. S. 1973. Aerial observations of migrating 

 gray whales, Eschrichtius robustus, off southern California 

 (1969-1972). California Gray Whale Workshop, 21-22 Aug. 

 1972. (Unpubl. manuscr.) 



At 1400 h on 12 May 1967, at Point Lobos 

 State Reserve near Carmel, Calif., a group of six 

 or seven killer whales, Orcinus orca, attacked a 

 gray whale and its 6-m calf, killing the latter 

 as it took refuge in beds of giant kelp, Macro- 

 cystis pyrifera, (Baldridge, 1972). This was con- 

 sidered to be the same group of killer whales 

 that unsuccessfully attacked two adult gray 

 whales and a calf just outside the surf at Moss 

 Landing, Monterey County on 2 May 1967 (More- 

 john, 1968). 



At 1350 h on 27 March 1970, at Lucia, 

 Monterey County, 70 km south of Carmel, 

 together with W. B. Gladfelter, I observed an 

 adult and calf, with a second adult in close 

 attendance. All were resting at the surface in 

 open water on a day of remarkable calm. One 

 adult frequently rolled on its side, raising a flipper 

 and half of the tail flukes above the surface. The 

 distance from the point of observation was too 

 great to confirm whether or not the calf nursed. 

 They remained in the same location for 30 min and 

 were still there when observation was terminated. 



From 0715 to 0800 h on 16 April 1970, two 

 adults accompanied by their calves with an 

 estimated length of 6-7 m remained in a sheltered 

 cove at Hopkins Marine Station in Pacific Grove, 

 Monterey County, where the water depth is 12 m. 

 Both calves appeared to nurse when the adults 

 rolled on their longitudinal axes, each with a 

 flipper and half fluke raised. Although the calves 

 were mottled in pigmentation, no barnacle in- 

 crustations could be seen on the dorsal areas. 

 Upon completion of the nursing behavior the 

 adults, very closely accompanied by their calves, 

 swam off on a course following the shore of 

 Monterey Bay. Northbound whales unaccom- 

 panied by calves for the most part follow a direct 

 course from the vicinity of Point Pinos, Monterey 

 County, toward Davenport, Santa Cruz County, 

 48 km to the north. 



At 0900 h on 15 May 1971, at Julia Pfeiffer 

 Burns State Park, 40 km south of Carmel, 

 Judson E. Vandevere and I observed two adults, 

 one very closely accompanied by a half-grown 

 calf. They swam steadily north very close to, 

 and in some instances through, the outer edges 

 of the kelp beds. 



615 



