Behaviour 142, 3
Eriksen, N, LA Miller, J Tougaard & DA Helweg (2005) Cultural change in the
songs of humpback whales (Megaptera novaeangliae) from Tonga. Behaviour 142:
305-328.
Some humpback whales migrate annually from Antarctic feeding grounds to the
seas around the Tongan Islands to give birth and mate. The Tongan humpbacks
are considered part of Southern Hemisphere Group V that splits during
migration, some swimming to Eastern Australia and others to various
Polynesian Islands. During this time long complex songs are produced. The
song is thought to be a male breeding display and may serve either as an
intra-sexual or an inter-sexual signal or both. It is in a constant state of
change that occurs every season. Since these changes are directional they
cannot be described by drift, and singers incorporate changes as they occur,
thus song must be shared through cultural transmission. This investigation
describes the cultural changes that occurred in 158 songs recorded from
Tongan humpbacks through the 1990s. The rate of change differed within
years, some themes were retained for as much as five years and others were
lost after only two years. The farther apart the years the less similar are
the songs, as in the humpback songs of the Northern Hemisphere. The largest
number of changes seems to have occurred in the early 1990s where all themes
seemed to have been lost and new ones originated. What initiates these
changes remains speculative, but we assess some hypotheses in relation to
humpback whale behaviour and cultural transmission in avian song.
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