First acoustic recordings of narwhals (Monodon monoceros) in winter

Abstract

Among the arctic top predators that inhabit the Baffin Bay pack ice, the narwhal (Monodon monoceros) is perhaps the most conspicuous. The largest abundance of narwhals is found in the eastern Canadian High Arctic and in West Greenland (Heide-Jorgensen et al. 2010, Richard et al. 2010). In summer, narwhals spend approximately 2 mo between June and September in High Arctic ice-free shallow bays and fjords (Dietz et al. 2008). The winter period between November and March is spent in offshore, deep, ice-covered habitats along the continental slope in Baffin Bay and Davis Strait (Heide-Jorgensen and Dietz 1995). These disjunct seasonal distributions are connected by extensive annual migrations (over 1,000 km), which last approximately 2 mo (Heide-Jorgensen et al. 2002, 2003). Narwhals arrive at offshore wintering grounds in Baffin Bay and Davis Strait, where an abundance of >80,000 whales occupy dense pack ice (Koski and Davis 1994, Heide-Jorgensen et al. 2002, Innes et al. 2002). Satellite tracking studies show that narwhals have high site fidelity to discrete wintering grounds (Heide-Jorgensen et al. 2002). These wintering groundsmay be themost critically important habitat for narwhals (Laidre et al. 2004a, b). Intense benthic feeding behavior has been documented between November andMarch for narwhals from northern Canada andWest Greenland (Laidre et al. 2003, Laidre and Heide-Jorgensen 2005) and is in contrast to low feeding activity observed during the summer period (Laidre and Heide-Jorgensen 2005).