Habitat Critical to Survival

Habitat Critical to Survival

All four nests recorded for this species, three in Marginal Rainforest and one in Primary Rainforest, have been in tree hollows in Syzygium nervosum (Hill & Young 1995) and all nest sites are likely to be in tree hollows (Hill & Young 1995). Syzygium nervosum is a common emergent tree particularly in Primary Rainforest where it forms approximately 18% of the forest canopy and 30% of the emergent species (Du Puy 1993). It is commonly greater than 35m high, has abundant tree hollows, unlike most other tree species in Primary Rainforest. Syzygium nervosum is, therefore, a very important tree species for Christmas Island Hawk-Owls and if its abundance was to change in the future, this might lead to a shortage of nest sites. Marginal Rainforest appears to have more species of trees with hollows and may have more potential nest sites for Christmas Island Hawk-Owls. Additional monitoring may show that owls can nest in a number of tree species.

Based on the available information and applying the EPBC Act criteria, habitat critical to the survival of the Christmas Island Hawk-Owl is defined as all Primary and Marginal rainforest, and all secondary growth rainforest that provides suitable habitat. The boundaries of Primary and Marginal rainforest are mapped and provided in Figure 1. Secondary growth rainforest suitable for Christmas Island Hawk-Owls has not been mapped, as there is currently insufficient data on this.