evolution - Why is the Kakapo more attracted to humans than its own kind?

The male kakapo (Strigops habroptila) in that video is called Sirocco. Kakapo were (and still are) very close to extinction, so in the 1980s the Kakapo Recovery Programme was launched. As part of this programme, rangers monitor all known kakapo in the wild, visiting their nests and generally ensuring they are in good health. When Sirocco was a young chick, a ranger discovered him in his mothers nest with severe breathing problems. He was brought back to the Kakapo care hut and raised by humans. As a result of this, he imprinted on his carers (see his website!).

Imprinting is common in birds, and takes several different forms. The most well-known form is filial imprinting, where young birds (and some other animals) develop a strong fixated image of who their mother is. They then learn their behaviour almost exclusively from the animal they fixated on. This is well studied in geese, for example by Konrad Lorenz.

However, Sirocco was demonstrating sexual imprinting. This is where young animals (including humans, see e.g. Bereczkei et al., 2004) learn which characteristics are sexually desirable by fixing an image of their parent(s). In Sirocco's case, he imprinted on a human and subsequently saw humans as his species, and therefore potential mates.

The exact purpose of sexual imprinting has been widely discussed (e.g. see Immelmann, 1972). Lorenz suggested that it allowed animals to recognise their own species. However, some imprintable birds will show a preference toward individuals resembling the one they imprinted on, but when introduced to their own species will still recognise them as potential sexual partners. It may therefore be the case that imprinting allows a juvenile firstly to supplement a genetic predisposition toward its own species, but secondly to recognise closely related and less related individuals. Bateson (1978) suggested that this would enable a sexual strategy of choosing mates which are sufficiently unrelated so as not to cause inbreeding depression, but sufficiently related so as not to cause outbreeding depression, and he found an example which bore out the predicted behaviour in Japanese quails.

Sirocco seems not to have the genetic ability to recognise his own species, and according to his website does not associate with other birds.