BEHAVIOR OF CALIFORNIA GRAY WHALE, ESCHRICHTWS ROBUSTUS, 

 IN SOUTHERN BAJA CALIFORNIA, MEXICO 



Kenneth S. Norms, 1 Robert M. Goodman, 2 Bernardo Villa-Ramirez, 3 and Larry Hobbs 1 



ABSTRACT 



Mother-young pairs of the California gray whale, Eschrichtius robustus, have been studied by a variety 

 of means, including direct observation in calving lagoons from shore and ship, from aircraft, and by 

 attachment of jettisonable instrument packages to calves. Instrumented whale pairs were tracked 

 inside the lagoon, and one pair was followed for 63 h as the animals left Magdalena Bay and moved 

 southward along the Baja California coast 213 km at a traverse rate of 3.4 km/h. 



Mother-young pairs far back in the calving lagoon were found to move toward the deepest nearby 

 water available on the outgoing tide, returning again after low water had passed. Aerial behavior 

 consisted of breaching and spying out. In a breach the leaping animal rose two-thirds or more of its 

 length from the water, falling back on its side. In our observations breaching seemed associated with 

 the presence of males. Spying out was much more leisurely and often seemed to involve an animal with 

 its flukes on the bottom, forcing its head out of the water. Contact between mothers and calves was very 

 common; the calf often slid over the body of the mother and was lifted by the mother in conditions of 

 stress. Floating whales seemed to be supported by inflated lungs which spread the loose rib cage apart 

 producing a very flat cross-sectional profile. The spout was of seawater and it is speculated that part of 

 its volume comes from water entering the nostrils as they open. Whales were observed grubbing in the 

 bottom both in and out of calving lagoons, but feeding was not definitely confirmed. Mating was 

 concentrated at lagoon mouths but some sexual behavior was noted inside lagoons. Female whales 

 were found to be aggressive when their calves were disturbed, thrashing sideways with flukes at 

 intruders, or attempting to hit a vessel with the flat of the flukes. Resonant clicks and loud broad band 

 claps were recorded from calves as they were released to their mothers. 



Pacific Mexican lagoons frequented by calving and 

 breeding California gray whales, Eschrichtius 

 robustus (Lilljeborg), are easily accessible by road 

 and ship. Even so, information regarding the 

 behavior of adults and young in these lagoons 

 remains fragmentary. This paper describes be- 

 havior studies performed in January-February 

 1974 and 1975. Several methods were used. 

 Observations of undisturbed whales were made 

 from shipboard and skiff. Behavior was noted 

 during capture sequences of nine young whales. 

 Aircraft surveys were made. A set of sequential 

 observations, principally of mother-young pairs, 

 was made from a large dune (Colina Coyote) set on 

 the edge of a major nursery channel. Finally, 

 behavior of mother-young pairs was observed 

 during radio tracking sequences on three animals. 

 Data on diving depths and profiles, and water 

 temperature, were also gathered during these 

 tracks. 



'Department of Biology, University of California, Santa Cruz, 

 CA 95064. 



2 Franklin Institute Research Laboratory, Philadelphia, Pa. 

 3 Universidad Nacional de Mexico, Mexico City D. F., Mexico. 



Manuscript accepted May 1976. 



FISHERY BULLETIN: VOL. 75, NO. 1, 1977. 



Captain Scammon's initial forays into Laguna 

 Ojo de Liebre (Scammon's Lagoon) to capture 

 whales resulted in the first record of the California 

 gray whale from these lagoons, though the nature 

 of his work certainly imposed disturbances that 

 masked much behavior. Little was added for 

 nearly a hundred years. Initial population counts 

 were begun for the entire eastern Pacific popula- 

 tion by Hubbs (1959), extended by Gilmore and 

 Ewing (1954), Gilmore (1960a, b), Hubbs and 

 Hubbs (1967), and Rice and Wolman (1971) and 

 finally by Henderson (1972) and Gard (1974). 

 Gilmore et al. (1967) added information about 

 calving along the Sonora coast. 



These studies revealed information regarding 

 distribution of age-classes in the calving lagoons 

 and features of behavior such as respiration, 

 diving, swimming speeds, and aerial behavior. 



Other studies have touched on several aspects of 

 gray whale life. Huey (1928) and Wyrick (1954) 

 gave field descriptions of behavior. Acoustic 

 studies in Laguna Ojo de Liebre have been made 

 by Eberhardt and Evans (1962), Poulter (1968), 

 and Spencer (1973), while more general studies of 

 mother-calf behavior have been made by Walker 



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