Document ID: chunk:federal_register_of_legislation:F2007B00391:body:0:p2
Version: federal_register_of_legislation:F2007B00391
Segment Type: other
Provision Reference: 
Character Range: 2862–5808

species, monitoring the population, and educating the Christmas Island community about this small, unique owl.

Background Information

Conservation Status
The Christmas Island Hawk-Owl Ninox natalis is currently listed as Vulnerable under the EPBC Act due to its small population size. This was based on estimates provided by van Tets (1975) of 10 - 100 pairs and subsequently by Stokes (1988) of 100 pairs. Following the outbreak of Crazy Ant supercolonies, Garnett & Crowley (2000) recommended the Christmas Island Hawk-owl be upgraded to Critically Endangered.

Approximately 25% of the island's forests have been cleared since settlement and all but the small areas of regrowth vegetation are currently unsuitable and are unoccupied by Christmas Island Hawk-Owls. Hill & Lill (1998a) estimated that the island prior to settlement had a carrying capacity in the order of 740  135 owl territories. Between 1994-1996 Hill & Lill (1998a) estimated the population at 556  101 occupied owl territories in Primary Rainforest and 6  4 occupied owl territories in regrowth vegetation, and a total population size of 562105 occupied territories. The total Christmas Island Hawk-Owl population has probably decreased by at least 25% since settlement (Stokes 1988, Hill & Lill 1998a).

Taxonomic status
The Christmas Island Hawk-Owls is now considered a full species after Norman et al. (1998). Formerly a subspecies of N. squamipila, Norman et al. (1998) concluded, using molecular data, that the three subspecies for which material was available, including the Christmas Island Hawk-Owl, each represented separate species in the genus Ninox.

Distribution and location
The Christmas Island Hawk-Owl is restricted to Christmas Island in the Indian Ocean (10o0'S; 105o40' E), approximately 1400km northwest of Australia. The nearest land is Java in the Republic of Indonesia, 360km to the north. Christmas Island is 135km2 in area and 75% is covered with original vegetation. During 1994-1995, Christmas Island Hawk-Owls were widespread and occurred in all Primary, Marginal and secondary regrowth rainforests. The highest densities were found in Primary rainforests (Hill & Lill 1998a). Hill and Lill (1998a) concluded that the total population size was probably limited primarily by the area of remaining rainforest and that the observed owl densities within available habitat had probably not changed markedly since settlement (Hill & Lill 1998a). The lack of change in density of birds in the habitat available combined with the reduction in 25% of habitat area leads to the conclusion that the population has declined by 25%.

Using data from radio-tracking, territory mapping and census by playback of calls, Hill & Lill (1998a) found that owls were uniformly distributed throughout the two Primary and Marginal of rainforest at a density of 5.5  1.0 territories per square kilometre. They speculated that densities might be lower