TY - JOUR
T1 - Did hybridization save the Norfolk Island boobook owl Ninox novaeseelandiae undulata?
AU - Garnett, Stephen T.
AU - Olsen, Penny
AU - Butchart, Stuart H.M.
AU - Hoffmann, Ary A.
PY - 2011/10
Y1 - 2011/10
N2 - The population of the Norfolk Island boobook owl Ninox novaeseelandiae undulata, a nocturnal bird restricted to the Australian territory of Norfolk Island, was reduced to a single female in 1986. Deliberate introduction of two males of its nearest relative, the New Zealand boobook N. n. novaeseelandiae, as a conservation intervention has allowed the taxon to persist on Norfolk Island, albeit in hybrid form. Although declared Extinct in 2000, a re-examination of this unique situation has concluded there is a strong argument that the taxon should be categorized as Critically Endangered because, on average, approximately half the nuclear genome of the original taxon and all the mitochondrial DNA is conserved in all living owls on the island. This thus represents a special case in which the taxon can be considered to be extant, in hybrid form, even though no pure-bred individuals survive. More generally, we suggest that, in exceptional cases, hybridization may not be a threat to highly threatened species and that guidelines are needed to determine when to consider hybrid populations as extant forms of the original taxon, and when to declare extinction through hybridization.
AB - The population of the Norfolk Island boobook owl Ninox novaeseelandiae undulata, a nocturnal bird restricted to the Australian territory of Norfolk Island, was reduced to a single female in 1986. Deliberate introduction of two males of its nearest relative, the New Zealand boobook N. n. novaeseelandiae, as a conservation intervention has allowed the taxon to persist on Norfolk Island, albeit in hybrid form. Although declared Extinct in 2000, a re-examination of this unique situation has concluded there is a strong argument that the taxon should be categorized as Critically Endangered because, on average, approximately half the nuclear genome of the original taxon and all the mitochondrial DNA is conserved in all living owls on the island. This thus represents a special case in which the taxon can be considered to be extant, in hybrid form, even though no pure-bred individuals survive. More generally, we suggest that, in exceptional cases, hybridization may not be a threat to highly threatened species and that guidelines are needed to determine when to consider hybrid populations as extant forms of the original taxon, and when to declare extinction through hybridization.
KW - Extinction
KW - IUCN Red List criteria
KW - Ninox novaeseelandiae undulata
KW - Norfolk Island
KW - hybridization
KW - owl
UR - http://www.scopus.com/inward/record.url?scp=80955126800&partnerID=8YFLogxK
U2 - 10.1017/S0030605311000871
DO - 10.1017/S0030605311000871
M3 - Article
SN - 0030-6053
VL - 45
SP - 500
EP - 504
JO - Oryx
JF - Oryx
IS - 4
ER -