Dear All,
Narganes Homfeldt, Tamara; Risch, Denise; Stevenson, Andrew and Henry, Lea-Anne
"Seasonal and diel patterns in singing activity of humpback whales migrating through Bermuda"
Abstract
Humpback whales (Megaptera novaeangliae) produce song and
non-song vocalisations, which allows their presence to be detected
through passive acoustic monitoring. To determine the seasonal and diel
acoustic presence and acoustic behaviour of humpback whales at the
migratory stopover site off Bermuda, three hydrophones were deployed
between March 2018 and April 2019 on Challenger Bank and the Bermuda
platform. Song was the predominant vocalisation type encountered, with
65% of song recordings containing whale chorus and a clear seasonal
trend of humpback whale occurrence in the spring and winter months from
late December to mid-May. A strong diel pattern in singing activity was
detected. Singing activity significantly increased at night relative to
the daytime (p<0.01), whilst twilight periods were characterised by
intermediate levels of singing. The song structure encountered in spring
2018 consisted of 18 units, 6 themes and 5 transitional phrases. The
high occurrence of whale chorus and the strong seasonal and diel
patterns of male humpback whale singing activity highlights the
importance of Bermuda not just on their northward migration during
spring, as described historically, but also on their southward migration
during winter. Bermuda therefore constitutes a two-way migratory
stopover site for humpback whales. The present study also provides
Bermuda’s planning authorities with better constraints on the duration
and intensity of anthropogenic activities in these waters.
The article is open access and can be downloaded following the link below:
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All the best,
Denise