Distribution, demography, and behavior of North Atlantic right whales (Eubalaena glacialis) in Cape Cod Bay, Massachusetts, 1998-2013

The occurrence of North Atlantic right whales (Eubalaena glacialis) in Cape Cod Bay was documented during aerial surveys between 1998 and 2013. The seasonal occurrence remained relatively unchanged during the study, spanning the January through mid-May timeframe. The number of individual whales visiting the Bay was positively correlated with the increasing Best Cataloged Estimate (BCE), the number of photographed whales alive, with a maximum in 2011 of 56.9% (n=277) of BCE. However, the rate of increase in number of individuals during the study was significantly greater than that of the BCE (difference in slope: 12.72; P< 0.01) suggesting that increased visitation to the Bay was due in part to a change in habitat preference. Although the demographic composition of whales observed during the study differed little from that of the cataloged whales, the proportion of calves born in the North Atlantic that were documented in the Bay increased significantly (P<0.01). Models of random visitation demonstrated an individual preference for or rejection of the Bay by the right whales of the North Atlantic population.