Norfolk boobook
| Norfolk Island Boobook | |
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| Subspecies: | N. n. undulata
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| Trinomial name | |
| Ninox novaeseelandiae undulata (Latham, 1802)
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The Norfolk Island Boobook (Ninox novaeseelandiae undulata), also known as the Norfolk Island Owl, was a bird in the true owl family endemic to Norfolk Island, an Australian territory in the Tasman Sea. It is an extinct subspecies of the Southern Boobook (Ninox novaeseelandiae).
Description
The Norfolk Island Boobook was very similar in appearance to other subspecies of the Southern Boobook, being a small brown hawk owl with mottled plumage. It was smaller and darker than the Australian subspecies, with much spotting.[1] However, it was slightly larger than the nominate subspecies from New Zealand; female boobooks are 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.[2]
Habitat
The owl inhabited the island’s subtropical rainforest, which was largely cleared in the 19th century following human settlement. Most of the remaining forest lies within the small (4.60 km²) Mt Pitt section of the Norfolk Island National Park.
Behaviour
Breeding
Boobooks breed in tree hollows. Recorded clutch sizes from Norfolk Island range from one to three eggs, with two being usual.[3]
Feeding
Boobooks feed on small vertebrates, especially birds and mammals, as well as invertebrates.
Status and conservation
The population of the Norfolk Island Boobook declined with the clearance and modification of its forest habitat, especially the felling of large trees with suitable hollows for nesting in. There was also competition for nest hollows with feral honey bees and introduced Crimson Rosellas.[4] By 1986 the population had been reduced to a single female bird. As part of a program to attempt to conserve at least some of the genes of the insular subspecies, two male Southern Boobooks (Moreporks) of the nominate New Zealand subspecies, Ninox novaeseelandiae novaeseelandiae, were introduced to the island as mates for the female. The males were sourced from the New Zealand subspecies rather than one of the Australian subspecies as it was discovered that it was more closely related to the Norfolk Island taxon.[5][6] Nest boxes were also provided]]. One of the introduced males disappeared shortly after introduction but the other successfully mated with the female producing fledged chicks in 1989 and 1990. The original female disappeared in 1996 but, by then, there was a small hybrid population of about a dozen birds. These birds and their descendants continue to exist on the island.
Notes
References
- Double, Michael; & Olsen, Penny. (1997). Simplified polymerase chain reaction (PCR)-based sexing assists conservation of an endangered owl, the Norfolk Island Boobook Ninox novaeseelandiae undulata. Bird Conservation International 7: 283-286.
- Garnett, Stephen T.; & Crowley, Gabriel M. (2000). The Action Plan for Australian Birds 2000. Environment Australia: Canberra. ISBN 0-642-54683-5[1]
- Higgins, P.J. (ed). (1999). Handbook of Australian, New Zealand and Antarctic Birds. Volume 4: Parrots to Dollarbird. Oxford University Press: Melbourne. ISBN 0-19-553071-3
- Norman, Janette; Olsen, Penny; & Christidis, Les. (1998). Molecular genetics confirms taxonomic affinities of the endangered Norfolk Island Bookbook Owl Ninox novaeseelandiae undulata. Biological Conservation 86(1): 33-36.
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