Complex sentence: During the breeding season, males call while floating in the water, with a deep growl that has been described as a four-part "craw-awk, crawk, crok crok"--likened to the sound of a motorbike changing gears.
Split into simpler sentences: During the breeding season, males call while floating in the water. The call is a deep growl which has been described as a four-part "craw-awk, crawk, crok crok" likened to the sound of a motorbike changing gears.