Variation in the acoustic behavior of right whale mother-calf pairs

Abstract

North Atlantic right whale mother-calf pairs are a critical segment of the population for recovery of this endangered species and therefore their protection is paramount. Passive acoustics, including the development of real-time buoys, has increasingly played a role in the detection of right whale presence in high vessel traffic areas. The vocal behavior of North Atlantic right whale mothers and their young calves has not been well described and may not be well represented by calls produced by other individuals in the population that are commonly utilized for passive acoustic monitoring. Therefore, it is critical to determine the call types and rates of sound production by mother-calf pairs to assess the efficacy of passive acoustic monitoring for their detection. We conducted behavioral focal follows coupled with acoustic recording of right whale mother calf pairs off the coast of Florida and Georgia in January–March, Cape Cod Bay in April, and the Bay of Fundy in August–September from 2011 to 2014. Results show modifications in both call structure and call rate with increasing calf maturity and independence. These data are necessary to better utilize passive acoustic monitoring for management purposes in this species.