. The Canadian field-naturalist. Natural history. 1997 Reeves and Whitehead: Status of the Sperm Whale 301. Figure 2. Grouped Sperm Whales at surface, Galapagos Islands, 1985. luminescent animals must be actively chased using sonar (see below). Sperm Whales apparently feed at all times of day, year-round (Rice 1989). Lockyer (1981) developed an energy budget for Sperm Whales. She concluded, judging mainly from an analysis of stomach capaci- ties and assuming a diet of squid providing 800 kcal/kg, that Sperm Whales weighing less than 15 metric tons consume about 3 percent of their body mass dai
. The Canadian field-naturalist. Natural history. 1997 Reeves and Whitehead: Status of the Sperm Whale 301. Figure 2. Grouped Sperm Whales at surface, Galapagos Islands, 1985. luminescent animals must be actively chased using sonar (see below). Sperm Whales apparently feed at all times of day, year-round (Rice 1989). Lockyer (1981) developed an energy budget for Sperm Whales. She concluded, judging mainly from an analysis of stomach capaci- ties and assuming a diet of squid providing 800 kcal/kg, that Sperm Whales weighing less than 15 metric tons consume about 3 percent of their body mass daily. This rate probably increases to about percent for the 30- to 50-ton males. Acoustics The principal vocalization of the Sperm Whale is a loud (source level IVldB re l|nPa), broad-band (ca. to 20kHz) click (Worthington and Schevill 1957; Backus and Schevill 1966; Watkins 1980; Weilgart 1990; Goold and Jones 1995). These clicks are used in a number of ways. During deep foraging dives, the clicks are heard in long trains with inter-click intervals of about s for males and s for females (Mullins, Whitehead, and Weilgart 1988; Whitehead and Weilgart 1990; Goold and Jones 1995). Most authors (, Norris and Harvey 1972; Gordon 1987a; Weilgart 1990; Goold and Jones 1995) believe that these clicks are a form of echolocation, allowing the whales to detect prey at ranges of several hundred metres. During social periods Sperm Whales produce codas, consisting of from two to about 20 clicks 'arranged into a patterned series (Watkins and Schevill 1977). Codas are often heard as exchanges, and they seem to function as communication (Watkins and Schevill 1977; Weilgart and Whitehead 1993). Other click-based vocalizations include creaks (click trains with high repetition rates) heard during both foraging and social periods (Gordon 1987a; Whitehead and Weilgart 1991), and slow clicks: loud, reverberant clicks with an inter-click interval of about 6 s heard principally from m
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