[6] However, it was slightly larger than the nominate subspecies from New Zealand; female boobooks were larger than the males, with New Zealand females comparable in size to Norfolk Island males, a factor which gave rise to sexing difficulties with hybrid birds in the conservation management program.

Most of the remaining forest lies within the small (4.65 km²) Mt Pitt section of the Norfolk Island National Park.

The population of the Norfolk boobook declined with the clearance and modification of its forest habitat, especially the felling of large trees with suitable hollows for nesting in.

One of the introduced males disappeared a year after introduction but the other successfully mated with the female with the pair producing fledged chicks in 1989 and 1990.

[13] The New Zealand Moreporks and Norfolk island boobooks are considered to be very closely related, with some debate over whether it should even be recognized as a separate taxon; they can only be distinguished by their physical features.

Genetic analysis indicates that half the nuclear genome and all the mtDNA of the original Norfolk boobook persists in the modern birds, marking it a special case of a taxon that can still be considered extant in a hybrid form.