Use of glacial fronts by narwhals (Monodon monoceros) in West Greenland

• Published in: Biology Letters
• Main Authors: Laidre, Kristin L., Moon, Twila, Hauser, Donna D. W., McGovern, Richard, Heide-Jørgensen, Mads Peter, Dietz, Rune, Hudson, Ben
• Format: Text
• Language: English
• Published: The Royal Society 2016
• Subjects: Special Feature; Arctic; Greenland; glacier; Iceberg*; Monodon monoceros; narwhal*
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5095189/; http://www.ncbi.nlm.nih.gov/pubmed/27784729; https://doi.org/10.1098/rsbl.2016.0457

Glacial fronts are important summer habitat for narwhals (Monodon monoceros); however, no studies have quantified which glacial properties attract whales. We investigated the importance of glacial habitats using telemetry data from n = 15 whales tagged in September of 1993, 1994, 2006 and 2007 in Melville Bay, West Greenland. For 41 marine-terminating glaciers, we estimated (i) narwhal presence/absence, (ii) number of 24 h periods spent at glaciers and (iii) the fraction of narwhals that visited each glacier (at 5, 7 and 10 km) in autumn. We also compiled data on glacier width, ice thickness, ice velocity, front advance/retreat, area and extent of iceberg discharge, bathymetry, subglacial freshwater run-off and sediment flux. Narwhal use of glacial habitats expanded in the 2000s probably due to reduced summer fast ice and later autumn freeze-up. Using a generalized multivariate framework, glacier ice front thickness (vertical height in the water column) was a significant covariate in all models. A negative relationship with glacier velocity was included in several models and glacier front width was a significant predictor in the 2000s. Results suggest narwhals prefer glaciers with potential for higher ambient freshwater melt over glaciers with silt-laden discharge. This may represent a preference for summer freshwater habitat, similar to other Arctic monodontids.