Wednesday, November 12, 2014

Owls and Nestboxes

Troy O’Keefe, local raptor carer, and Dr Brendan Taylor, working in nest box monitoring, spoke at the Brunswick Valley Landcare sponsored Owl Event at the Mullumbimby Community Gardens on Saturday November 1.

Barking owl roosting in the daytime & keeping half an eye open for trouble,
photo sourced from free internet stock
Ten attendees made for a very informative afternoon, with everyone able to ask questions and have them answered in detail. And we learned wonderful detail about the lives of our native owls, and their care should they be found in an injured state.

The breeding up of mouse plagues cause barn owls to raise two nests per year of owlets. The young owls when first making their way in the world are the most vulnerable to being killed by cars. Perhaps their hunting skills haven’t developed yet to where they don’t need to scrounge by the side of the road. Perhaps the end of the mouse plague spells their doom, and they become part of nature’s natural attrition rates.

Our region is home to three species of masked owls: the barn owl which is also called the white owl, or sometimes the ghost owl; the masked owl; and the sooty owl which can be almost black. Sound is gathered in the disk, like in a satellite dish, and the owl’s ears underneath it are unusually large. Masked owls hunt in the pitch dark and can hear a mouse’s heartbeat from 500 metres.

An injured owl has two defences. First it’ll flip onto its back, facing the unlucky carer with its talons. Here’s where it is good to have two old towels in your car, says Troy, instead of the usual one for injured koalas. Throw the first towel over the talons and the owl will instinctively grip the towel. Drape the second towel over the owl, covering the face, and you can then pick it up without getting bitten. Put it in a cardboard box for transport to a caring situation.

Troy loves to get dead owls. He has a feather bank in his freezer. Using titanium shanks, and feathers saved from dead owls, he can repair a broken wing or tail well enough to last until the bird’s next moult.

The barking owl, the powerful owl and the boobook are our hawk owls, that use the early light of dusk and dawn to catch their prey by. There may be only eight breeding pairs of powerful owls remaining on the NSW north coast. Only the boobook isn’t a threatened species.

Monitoring programs may show only 30% of nest-boxes in use. Yet evidence around the boxes leads to the conclusion that up to 90% of nest-boxes may be being used through a year. Animals such as gliders may use up to nine dens per year as they move around their territory.

It’s all right and even a good idea to mount boxes one above the other. Possums will opportunistically take a lower box, leaving the higher one for owls and wood ducks, also a high nesting species. Owls may use a nest-hole for twelve weeks, but will come back to it yearly.

It takes a few years sometimes for a particular species to use a nest box. In the meantime others, possums, gliders, ducks and galahs have built up a good layer of duff. Many species import eucalyptus leaves as nesting material, thought to be disinfectant against bird parasites.

There are hundreds more things to learn. Hopefully while we are installing our nest-boxes, at present being made here and there, with the funds we are raising. $5145 with 3 days to go. Afterwards by monitoring, and enjoying the fledglings and possum young. Our fundraising page:

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