David Geering wrote:
>What is likely to happen to these birds, and the many Little Eagles, when,
>and if, the rabbit numbers crash in this valley. Their traditional small
>mammalian prey is long extinct.
Will Steele, our Bird of Prey (BOP) Watch Coordinator, reports that an
initial analysis of BOP Watch data from 1996 to 1998 shows declines in
populations of Brown Falcons and Little Eagles in areas where the spread of
Rabbit Calicivirus Disease (RCD) has caused declines in rabbit numbers.
However, this second phase of the BOP Watch project is looking only at
diurnal raptors, and will not pick up declines in populations of owls that
prey on rabbits. It may be desirable, in the course of the second Atlas of
Australian Birds project (starting Saturday 1st August) to make a special
effort to determine the distribution of owls. If we pick up declines it
will make a stronger case for habitat protection.
Rabbit populations (and the raptors that prey on them) may reach some kind
of equilibrium with RCD. There will probably be, as Lawrie suggests, some
prey switching. Maybe breeding territory sizes will increase to accommodate
this. Maybe Barking or Masked Owls will disappear from places where the
habitat is already marginal. These are lots of 'maybes', but the more aware
we are about what is happening, the more hope we have of responding.
Birds Australia Conservation & Liaison,
Australian Bird Research Centre,
415 Riversdale Road,
Hawthorn East, VIC 3123, Australia.
Tel: (03) 9882 2622. Fax: (03) 9882 2677.
O/s: +61 3 9882 2622. Fax: +61 3 9882 2677.
Web Homepage: http://www.vicnet.net.au/~birdsaus/