 The kakapo is a large , rotund parrot ; the adult can measure from 58 to 64 cm ( 23 to 25 in ) in length , and weight can vary from 0 @.@ 95 to 4 kg ( 2 to 9 lb ) at maturity . Males are larger than females . Twenty @-@ eight males were found to average 2 kg ( 4 @.@ 4 lb ) in one study , and 39 males were found to average 2 @.@ 06 kg ( 4 @.@ 5 lb ) in another . In the same studies , 28 females were found to average 1 @.@ 5 kg ( 3 @.@ 3 lb ) and 18 females averaged 1 @.@ 28 kg ( 2 @.@ 8 lb ) . However , one source states that females will not breed until they attain a threshold weight of 1 @.@ 5 kg ( 3 @.@ 3 lb ) . They are the heaviest living species of parrot ; while the largest males attain much heavier weights than any other extant parrot , kakapos average about 400 g ( 14 oz ) more than a hyacinth macaw . The kakapo cannot fly , having short wings for its size and lacking the pronounced keel bone ( sternum ) that anchors the flight muscles of other birds . It uses its wings for balance , support , and to break its fall when leaping from trees . Unlike other land birds , the kakapo can accumulate large amounts of body fat to store energy , making it the heaviest parrot . 
 The kakapo is a large , rotund parrot ; the adult can measure from 58 to 64 cm ( 23 to 25 in ) in length , and weight can vary from 0 @.@ 95 to 4 kg ( 2 to 9 lb ) at maturity . Males <a href='drop_aux' title='1'><mark>are</mark></a>larger than females . Twenty @-@ eight males <a href='uninflect' title='2'><mark>were</mark></a> found to average 2 kg ( 4 @.@ 4 lb ) in one study , and 39 males <a href='uninflect' title='3'><mark>were</mark></a> found to average 2 @.@ 06 kg ( 4 @.@ 5 lb ) in another . In the same studies , 28 females <a href='uninflect' title='4'><mark>were</mark></a> found to average 1 @.@ 5 kg ( 3 @.@ 3 lb ) and 18 females averaged 1 @.@ 28 kg ( 2 @.@ 8 lb ) . However , one source <a href='uninflect' title='5'><mark>states</mark></a> that females will not breed until they attain a threshold weight of 1 @.@ 5 kg ( 3 @.@ 3 lb ) . They <a href='drop_aux' title='6'><mark>are</mark></a>the heaviest living species of parrot ; while the largest males attain much heavier weights than any other extant parrot , kakapos average about 400 g ( 14 oz ) more than a hyacinth macaw . The kakapo cannot fly , having short wings for its size and lacking the pronounced keel bone ( sternum ) <a href='null_relcl' title='7'><mark>that</mark></a><a href='uninflect' title='8'><mark>anchors</mark></a> the flight muscles of other birds . It <a href='uninflect' title='9'><mark>uses</mark></a> its wings for balance , support , and to break its fall when leaping from trees . Unlike other land birds , the kakapo can accumulate large amounts of body fat to store energy , making it the heaviest parrot . 
The kakapo is a large , rotund parrot ; the adult can measure from 58 to 64 cm ( 23 to 25 in ) in length , and weight can vary from 0 @.@ 95 to 4 kg ( 2 to 9 lb ) at maturity . Males larger than females . Twenty @-@ eight males was found to average 2 kg ( 4 @.@ 4 lb ) in one study , and 39 males was found to average 2 @.@ 06 kg ( 4 @.@ 5 lb ) in anotha . In the same studies , 28 females was found to average 1 @.@ 5 kg ( 3 @.@ 3 lb ) and 18 females averaged 1 @.@ 28 kg ( 2 @.@ 8 lb ) . However , one source state that females gon not breed til they attain a threshold weight of 1 @.@ 5 kg ( 3 @.@ 3 lb ) . They da heaviest living species of parrot ; while the largest males attain much heavier weights than any other extant parrot , kakapos average about 400 g ( 14 oz ) more than a hyacinth macaw . The kakapo cannot fly , havin short wings fa its size and lacking the pronounced keel bone ( sternum ) anchor the flight muscles of other birds . It use its wings for balance , support , and to break its fall when leaping from trees . Unlike other land birds , the kakapo can accumulate bigass amounts of body fat to store energy , making it tdaheaviest parrot .