[3] The sound is mainly present during austral winter in the southern ocean, detected off Western Australia and the Antarctic waters.
[1][7] During austral summer of 2013, a research team led by Denise Risch attached suction cupped recording devices to two Antarctic minke whales.
The devices were attached directly from a boat using a pole and it collected sound, temperature, pressure, acceleration and magnetic fields.
[3] Additionally, low frequency down sweeps, a sound previously associated with the Antarctic minke whales were also sampled from the tags.
[8] The researchers concluded that month of the year was the most prominent variable, followed by distance from sea ice and lastly, time of the day.
Another research came to a similar conclusion, determining that there is positive correlation between Antarctic minke whales time spent calling and sea ice presence.
However, the period with highest vocal activity was also detected during time of minimal irradiance, suggesting that the pattern is not caused by the animals reacting to the sun.
Instead, the vocal frequency matched the diel vertical migration of krill, a main diet of the Antarctic minke whales.
[5] Additionally, the bio-duck sound shared similar acoustic properties to a "pulse train" which is another call by minke whales believed to serve reproductive functions.
Combining this fact with research from 1995 which noted that breeding grounds of Antarctic minke whales in lower latitude areas are less concentrated compared to other cetaceans which favor shore waters,[9] Diego hypothesized that the repetitive properties of the bio-duck sound are for attracting mates over longer distances.
[3] From acoustic data collected at Perth Canyon between 14 October 2002 to 20 December 2002, Matthews and his research team initially noted three-types of bio duck sounds and classified them into two major types, with one being a variant of another.