Sex

Kakapos, like many bird species, exhibit sexual dimorphism, meaning there are observable differences between males and females. Generally, male Kakapos tend to be larger and heavier than females, with males weighing between 2.0 to 4.0 kilograms (4.4 to 8.8 pounds) on average, while females typically weigh between 1.0 to 2.0 kilograms (2.2 to 4.4 pounds). This size dimorphism is believed to be an adaptation related to mating behavior and competition for mates.

Another characteristic that distinguishes male and female Kakapos is their behavior during the breeding season. Male Kakapos are known for their elaborate courtship displays, which they perform at traditional sites known as "lek sites" to attract females. These displays involve vocalizations, body movements, and visual displays designed to showcase the males' fitness and attractiveness to potential mates. In contrast, female Kakapos are more selective in choosing mates, typically selecting males based on the quality of their displays and the suitability of their territories for nesting.

Reproductive anatomy also differs between male and female Kakapos. Male Kakapos have a pair of testes located within their body cavity, which produce sperm during the breeding season.

Female Kakapos have a single functional oviduct, which serves as the passage for both eggs and sperm during mating.

During the breeding season, male Kakapos compete for access to females and breeding territories through aggressive displays and vocalizations. Females may visit multiple lek sites to assess potential mates before selecting a mate and establishing a nesting territory.

Once a male and female Kakapo have formed a pair bond, they engage in courtship behaviors such as mutual preening, allopreening, and bill rubbing. These behaviors strengthen the pair bond and facilitate copulation, which typically occurs at the female's chosen nesting site. After mating, the female Kakapo lays a clutch of one to four eggs, which she incubates for approximately 30 days until they hatch.

Parental care duties are shared between male and female Kakapos, with both parents contributing to incubation, brooding, and feeding of the chicks. Both parents provide regurgitated food to the chicks until they are old enough to feed themselves and fledge from the nest, which typically occurs around three to four months of age.

Sexual dimorphism in Kakapos extends beyond physical characteristics and behavior to include differences in vocalizations and communication. Male Kakapos are known for their loud "booming" calls, which they produce during the breeding season to attract females and establish territories. In contrast, female Kakapos may produce softer vocalizations and contact calls to communicate with their mates and offspring. These differences in vocalizations may play a role in mate attraction, pair bonding, and territorial defense among Kakapos in the wild.