Off Kaikoura, New Zealand, we recorded individually identified male sperm whales (Physeter macrocephalus) for entire dive cycles in order to investigate vocal behavior of individual whales and to examine possible functions of sperm whale clicks. In our study, sperm whales were almost always silent at the surface. They consistently started clicking within 25 s after fluking-up and diving. During the first 10 s of clicking, interclick intervals were significantly correlated with water depths at the location of fluke-up. The first "creak" was produced on average 7.5 min into a dive. Interclick intervals usually decreased substantially before clicks turned into "creaks." The highest click rate recorded in this study was 90.9 click/s, and clicks-within-creaks were much shorter than "usual clicks" (mean of 3.6 ms versus 17 to 30 ms). The number of creaks per minute of dive and the length of a dive were significantly correlated. On average, sperm whales were silent for the last 3.6 min before surfacing. Short sequences of "surface clicks" (3 to 8 metallic clicks with mean interclick interval of 5.5 s) were often produced at the end of a dive (in 57% of the dives), but their function remains puzzling. The results of this study suggest that usual clicks and creaks are both used for echolocation purposes, the former to gather information about acoustically reflective features and the latter to detect prey.

Knowledge of whale length is important to ecological studies. However, photographic techniques to measure sperm whales traditionally require high vantage points or a complicated stereo system. Furthermore, these traditional techniques require an alongside approach that often prevents individual identification. For simple and fast size measurements at sea, I used a laser range finder alongside a digital camera to obtain distance to the fluke at the same time as photo-identification. The camera/lens and laser range finder were calibrated on objects of known lengths. The coefficient of variation (CV) for test objects was low (CV = 0.21%). Forty-seven individually identified sperm whales were measured repetitively on up to 12 different occasions, and the CV was lower (CV = 1.3%) than for other photogrammetric techniques (CV = 4.4%-5.1%). A regression of log fluke span to log total length from whaling and stranding data yielded an r 2 of 0.87 (CV of residuals = 6.7%). Thirty-eight female/immature sperm whales were measured in the Gulf of Mexico (median = 9.3 m, range = 7.1-12.3 m), 167 in the Gulf of California (median = 10.7 m, range = 8.4-13.1 m) and 13 bachelor males off Kaikoura, New Zealand (median = 14.2, range = 11.7-15.8 m). The results were within known sperm whale size and suggested that the population in the Gulf of Mexico was made up of smaller animals than that of the Gulf of California. This technique is easy to implement and allows the measurement of identified individuals.

Male sperm whales (Physeter macrocephalus) were the preferred target of the whaling industry between 1950 and 1985, but despite hundreds of thousands of kills, very little is known about their ecology. To partially redress this, we present data on residency, seasonal distribution, and diving behaviour of individually identified sperm whales off Kaikoura, South Island, New Zealand, gathered during 15 field seasons over 8 years. One hundred and thirty-six sperm whales were identified within the study area. A lack of statistically significant differences in the abundance of sperm whales between summer and winter, and among the 15 seasons of fieldwork, suggests an adequate food supply year-round. Significant differences in distribution between summer and winter suggest that off Kaikoura, male sperm whales may change their diet in response to fluctuations in prey biomass. Diving behaviour was also significantly different between summer and winter: sperm whales dived for longer, stayed longer at the surface, and travelled farther between consecutive fluke-ups in summer than in winter. Unlike female sperm whales, males at Kaikoura spent little time at the surface; they spent about 83% of their total time under water. This paper represent the most extensive non-invasive study of male sperm whales and provides new insights into their ecology.

The movements of female and immature sperm whales Physeter macrocephalus in the tropical Pacific Ocean and adjacent waters are described using photoidentifications over time scales of 3 d to 15 yr and the tracks of followed groups over scales of 1 to 48 h. The female/immature whales frequently made movements of less than 2000 km and occasionally made movements of about 4000 km. There were no recorded movements of greater than 5000 km (for instance, between the eastern and western Pacific). On average, displacements for female/immature whales were about 4 km after 1 h of movement, 50 km after 1 d, 200 km after 3 d, and 1000 km after periods of 1 yr or more. Members of the 2 principal cultural clans of female and immature sperm whales that use waters near the Galápagos had distinctive movement patterns over all time scales greater than 3 h, with 1 clan's displacements about 50% greater than the displacements of the other. Displacements were greater than predicted by the correlated random walk over scales of 12 to 48 h because of autocorrelation in displacement, approximately as predicted by the correlated random walk over periods of days to weeks, but less than predicted by the correlated random walk over scales of years because of boundaries of home ranges. The adaptive movement of sperm whales over large spatial and temporal scales likely contributes to their substantial trophic impact, and reduces geographic population structure. These movements, together with cultural heterogeneity, complicate the management of the species, including the designation of management stocks.KEY WORDS: Sperm whale · Movement · Culture · Density-dependent habitat selection · Population structure Resale or republication not permitted without written consent of the publisher

Sperm whales occur worldwide and feed largely on meso-and bathypelagic squid, but little is known about the behavioral ecology of this predator and its prey. In the Gulf of California, sperm whales are thought to feed on the abundant jumbo (Humboldt) squid, an ecologically and commercially important species. In this study, we attached satellite-linked dive recorders to 5 sperm whales and pop-up archival transmitting tags to 3 jumbo squid in the same area and time period in order to record their diving behavior and movements. Most (91%) deep dives by whales ranged from 100 to 500 m (average 418 ± 216.0 m) and lasted 15 to 35 min (average 27 ± 9.1 min). During daytime hours, jumbo squid spent about 75% of the time in the 200 to 400 m depth range, and sperm whales showed a similar dive-depth preference. The vertical distribution pattern of squid changed during the night, with squid spending about half the time at depths of < 200 m and the remainder at 200 to 400 m. Although the whales shifted their nighttime diving to somewhat shallower depths, about 75% of dives remained in the 200 to 400 m depth range. Analysis of squid nighttime diving behavior, based on archival time-series data, showed that excursions into warm surface waters were often terminated by deep dives to typical daytime depths, after which the squid appeared to be relatively quiescent. Diving behavior by whales is thus consistent with the idea that they feed on jumbo squid at depth during the day, and we suggest that deep nighttime foraging may target squid that are recovering from stress after recent surface activity and are therefore more susceptible to predation.