Temporal variation in the vocal behaviour of southern right whales in the Auckland Islands, New Zealand

Autonomous recorders are frequently utilised for examining vocal behaviour of animals, and are particularly effective in remote habitats. Southern right whales are known to have an extensive acoustic repertoire. A recorder was moored at the isolated sub-Antarctic Auckland Islands for a year to examine whether the acoustic behaviour of southern right whales differed seasonally and throughout the day at their main calving ground in New Zealand. Recordings were made in each month except June, and vocalisations were audible in all months with recordings except January. A total of 35,487 calls were detected, of which upcalls were the most common (11,623). Call rate peaked in August (288±5.9 [SE] calls/hour) and July (194±8.3). Vocal behaviour varied diurnally with highest call rates detected at dusk and night, consistent with the concept that upcalls function primarily as contact calls. Zero-inflated model results confirmed that seasonal variation was the most important factor for explaining...