counts, and estimates based on them, 

 of total southward migration, indicate 

 that over 90 percent of the northeast 

 Pacific migratory population are in 

 the aerial-census area at this time. 

 Air censuses in the first three weeks 

 of February appear to have been the 

 most successful. The most favorable 

 meteorological conditions for flight 

 census were a strong, high-pressure 

 area over the western United States 

 which brought an easterly, or land 

 breeze, from the interior to the coast 

 of southern California and Baja Cali- 

 fornia. This wind, locally called a 

 "Santa Ana," pushed away the usual 

 coastal fog and smoothed the water 

 surface by counteracting the prevailing 

 northwest wind. The best time of day 

 for air surveys was morning when air 

 was clearest, wind weakest, and sur- 

 face visibility best. The position of 

 the s\ui influenced visibility, but the 

 plane could often be maneuvered to 

 the sun-side of the migration path or 

 lagoon. 



The first air survey was carried 

 out from a Cessna 170. Later a Cessna 

 180, or Piper Supercub with floats, 

 and finally a Grumman Widgeon, a 

 five -passenger amphibian, were used. 

 The success of all flights can be 

 attributed, in part, to the efforts of 

 Dr. Gifford C. Ewing, owner and pilot 

 of the aircraft. 



The course of the aircraft in flight 

 along the coast was one to three miles 

 offshore, depending on the contour of 

 the coast. It was closer to the head- 

 lands, farther out across the open bays 

 and bights. The aircraft flew at about 

 90-knot speed at an elevation of 1,000 

 to 1,500 feet over the coastal waters. 

 This altitude over the ocean gave fair 

 coverage of a half mile or so on each 

 side and allowed quick recognition of 

 any whale below. When time pressed, 

 speed was increased to 110 or 120 

 knots, and the altitude to 2,000 feet, 

 without substantial loss of accuracy. 



Over lagoons, the plane dropped to 

 500 or 750 feet. The lower altitude 

 was high enough for lateral coverage 

 because the channels were narrow, 

 and yet was low enough for recognition 



of calves. Despite the low elevation, 

 however, a certain number of calves 

 were undoubtedly missed, even when 

 their mothers were in full view at the 

 surface. Rough water was particularly 

 disadvantageous for spotting calves. 

 Very young calves stayed close to the 

 mother's side and, when nursing, were 

 sometimes observed to be partially 

 hidden by her. It is assumed that a 

 few must have been entirely hidden. 



In the lagoons, the period of time 

 spent by a gray whale under the sur- 

 face is extremely variable. A whale 

 averages about four minutes below 

 the surface, when it cannot be seen. 

 It spends about a minute at or near 

 the surface, blowing from two to four 

 times. About one -fourth of the whales 

 beneath the plane could perhaps be 

 seen by the observers at any time. 



RESULTS 



Survey of 1952 



An air survey was made in 1952, 

 February 16-20, by Dr. Carl L. Hubbs 

 and Dr. Gifford C. Ewing. As it was 

 similar to later censuses, it has been 

 included here (table 5) with the kind 

 permission of Hubbs and Ewing. The 

 entire west coast of Baja California 

 was covered, including the principal 

 lagoons and the Gulf coast from Santa 

 Rosalia southward, although no gray 

 whales were seen in the Gulf of Cali- 

 fornia. 



Survey of 1953 



Two aerial surveys were made dur- 

 ing the 1952-53 season. The first was 

 made from January 31 through Feb- 

 ruary 3, 1953, Although the season 

 was early, the weather was excellent 

 and the results were good. The flight 

 was made in a Cessna 170. The entire 

 west coast of Baja California was 

 covered, except for the section from 

 Laguna Scammon to Laguna San Ignacio 

 and a small portion from Boca Las 

 Animas to Boca Soledad, north of 

 Bahia Magdalena. 



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