NORRIS ET AL.: BEHAVIOR OF CALIFORNIA GRAY WHALE 



pair swam off together. Because of the distance 

 involved at reentry of the calf and the rapid 

 reunion, we assume acoustic communication was 

 involved, perhaps the pulses mentioned above. 



The sharp clicks were made by two male calves, 

 on 2 and 5 February 1975, as they lay stranded at 

 Puerto San Carlos, upper Magdalena Bay. Prior to 

 click production the blowholes were pursed, giving 

 the impression the animal was about to blow, but 

 it did not, and no air was released. Instead it tossed 

 its head slightly upward causing the slightly 

 opened jaws to clap closed quickly (movement of 

 the throat also seemed involved), at which point 

 the click was produced. These signals were very 

 intense and could be heard for long distances 

 underwater; Bartley Gordon, who recorded the 

 sounds for us, could hear them very clearly at least 

 500 m from the stranded animal. In each case, as 

 the calf was released, clicks were heard before the 

 mother and calf rejoined. Low pulses or grunts 

 were also recorded from one animal. 



In the 5 February release, the mother whale 

 swam approximately 500 m southwest of the point 

 at which the young was released. The baby swam 

 resolutely down channel and the mother was 

 noted taking up a collision course. Until the 

 moment of contact sharp clicks were recorded, and 

 then, as the whales met in a flurry of lunges 

 partway out of water, the clicks ceased altogether. 



These clicks vary from those recorded by Fish et 

 al. (1974) in that we noted no long trains of closely 

 spaced clicks, but instead sporadic signals given at 

 a maximum rate of 2/s, but more often alone. The 

 signals we recorded seemed to be of much higher 

 intensity and of much broader band character 

 than those noted by Fish and his colleagues. 

 Further, their duration was about 0.25 s as op- 

 posed to 1-2 ms. In the sound spectrogram shown 

 in Figure 7, a very intense broad band signal is 

 portrayed, perhaps of frequency range extending 

 well above the flat response band of our in- 

 strumental system (0.1-20 kHz). One wonders if 

 these clicks bear any relation to the "earth- 

 quaking" reported by Ray and Schevill (1974). 



ACKNOWLEDGMENTS 



Work such as this requires many hands and 

 many minds. We cannot thank everyone who 

 participated but special thanks are due to our 

 hardworking and skillful field teams who helped 



KHz 



3*i 





I 23456789 10 



Time (ir '/ P0 sec) 



FIGURE 7. — Intense broad band "clack" emitted by a stranded 

 gray whale calf at Puerto San Carlos, Baja California Sur, 

 Mexico, on 5 February 1975. Effective analyzing filter band 

 width is 45 Hz. Due to the limits of the recording system (about 

 1-20 kHz flat response) the signal recorded above 20 kHz indi- 

 cates only some energy in that region, not its amount. 



to capture, harness, and track the whales. We 

 thank Captains Tim Houshar, Robert Newbegin, 

 Peter Zimmerman, and their crews; Thomas Dohl, 

 Paul Sebesta, Richard Pierce, Roger Gentry, Jose 

 Castello, Phyllis Norris, Candace Calloway 

 Hobbs, Sigmund Rich, Bartley Gordon, Jerry 

 Kooyman and his associates, and James Knipe 

 and his associates. 



We were helped with many logistical and official 

 details ashore by Senor S. Serrano of the cannery 

 at Lopez Mateos, Felix Armas Ortiz, Port Captain 

 of Puerto San Carlos, and Carlos Martinez 

 Toscano, ofConasupo, San Carlos, deserve special 

 mention. Our work would have been very difficult 

 without their assistance. 



Our support for which we are grateful has come 

 from grants from the Janss Foundation, the 

 National Aeronautics and Space Administration, 

 the U.S. Marine Mammal Commission, and the 

 National Oceanographic and Atmosphere Ad- 

 ministration, the National Geographic Society, 

 and by provision of ship support through the 

 Scripps Institution of Oceanography, La Jolla. 



Frank Brocato has helped us with advice and 

 equipment for capture and handling the calf 

 whales. 



George Rees of the American Embassy, Mexico 

 City, gave endless help in liaison with the Mexi- 

 can government. 



To all these people and organizations, our 

 thanks. 



171 



