Stereotyped Calling Patterns of a Male Weddell Seal (<I>Leptonychotes weddellii</I>)

Abstract

Underwater calling behaviour between breathing bouts of a single adult male Weddell seal (Leptonychotes weddellii) was examined with respect to call type and timing late in the breeding season at Davis Station, Antarctica. Underwater calls and breathing sounds were recorded on 1 and 8 December 1997. Thirty-seven sequences of calls prior to surfacing to breathe and 36 post-submerging sets of calls were analyzed with respect to probability of call type occurrence and timing. Dives were 461 ± 259 s (mean ± S.D.). The seal called every 29.7 ± 56.2 s throughout a dive. The first call after submerging was usually (n = 29 of 36) a low frequency (< 0.8 kHz) growl. Three patterns of three- to five-call type sequences were made following 28 of 36 breathing bouts. Call type patterns after submerging exhibited fewer different sequences than those before surfacing (χ 2 = 61.42, DF = 4, p < 0.000001). The call usage patterns before surfacing were diverse and did not indicate when the seal was going to surface, a time when he would be vulnerable to attack from below. Our findings suggest the hypotheses that territorial male Weddell seals call throughout each dive and use stereotyped call patterns to identify themselves while vocally asserting dominance.