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

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 in September 1993-1994 and 2006-2007 in Melville Bay, West Greenland. For 41 marine-terminating glaciers, we estimated 1) narwhal presence/absence, 2) number of 24 h periods spent at glaciers, and 3) 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 runoff, and sediment flux. Narwhal use of glacial habitats expanded in the 2000s likely due to reduced summer fast ice and later fall 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.

独角鲸（narwhal，Monodon monoceros）的重要夏季栖息地为冰川前缘，但目前尚无研究量化哪些冰川属性会吸引这类鲸类。本研究借助1993-1994年及2006-2007年9月间，西格陵兰梅尔维尔湾（Melville Bay）15头独角鲸的遥测数据，探究了冰川栖息地的重要性。针对41座入海冰川（marine-terminating glaciers），我们估算了三项秋季时段内的指标：1）独角鲸在冰川区域的出现与否；2）在冰川区域停留的24小时时段总数；3）在5、7、10公里范围内到访各冰川的独角鲸占比。我们还收集了以下冰川相关数据：冰川宽度、冰厚、冰流速、冰川前缘进退情况、冰山排放的面积与规模、水深测深数据、冰下淡水径流量以及沉积物通量。21世纪00年代，独角鲸对冰川栖息地的利用范围有所扩大，这可能与夏季固定海冰（fast ice）减少以及秋季封冻延后有关。借助广义多元建模框架（generalized multivariate framework），冰川冰前缘厚度（水柱中的垂直高度）在所有模型中均为显著协变量。部分模型中纳入了与冰流速呈负相关的变量，而在2000年代的模型中，冰川前缘宽度是显著的预测因子。研究结果表明，相较于携带沉积物负载的冰川，独角鲸更倾向于选择具备更高环境淡水融解潜力的冰川。这一偏好或许与其他北极单齿鲸类（monodontids）对夏季淡水栖息地的偏好一致。