Kakapo the "booms" (see below for a recording) and "chings" of their mating calls, they will often loudly "skraark". The kakapo has a well-developed sense of smell, which complements its nocturnal lifestyle. It can distinguish between odours while foraging, a behaviour reported in only one other parrot species. The kakapo has a large olfactory bulb ratio (longest diameter of the olfactory bulb/longest diameter of the brain) indicating that it does, indeed, have a more developed sense of smell than other parrots. One of the most striking characteristics of the kakapo is its distinct musty-sweet odour. The smell often alerts predators to
Flightless bird free to increase in abundance until the population was limited by food and territory. A study looking at energy conservation and the evolution of flightlessness hypothesized intraspecific competition selected for a reduced individual energy expenditure, which is achieved by the loss of flight. Some flightless varieties of island birds are closely related to flying varieties, implying flight is a significant biological cost. Flight is the most costly type of locomotion exemplified in the natural world. The energy expenditure required for flight increases proportionally with body size, which is often why flightlessness coincides with body mass. By reducing large pectoral muscles