In a strictly limited, first in best-dressed outing, ten select COGites met at Aranda at 7:30pm on a somewhat balmy, windy Saturday for an evening’s owling with well-known Canberra owl expert Jerry Olsen and his colleague Sue Trost. Not really knowing what to expect given the weather conditions, we were pleasantly surprised with both the fairly benign conditions at the foot of Black Mountain, and the fabulous array of Southern Boobooks Ninox novaeseelandiae that Jerry and Sue showed us.
Within their study area, comprising the Black Mountain Nature Reserve / Aranda Bushland, Jerry and Sue have identified six Southern Boobook territories, and over a period of more than 10 years have come to know these extremely territorial owls and their habits intimately. Each territory is approx. 1 sq. km, with boundaries clearly defined by agonistic interactions between adult males in adjoining territories, where the protagonists take up defensive positions for vociferous, and sometimes physical, onslaughts. Males maintain their territories year-round, whilst females have separate, distinct territories, only returning to the male’s territory to commence breeding. Nesting hollows can be reused, or several may be used within a territory over successive years, but can be subject to competition from Sulphur-crested Cockatoos and Brush-tailed Possums.
In our search for roosting boobooks preparing for their night-time activities, we visited the territories of “White”, “Orange” and “V5” (identified by the colour bands of the breeding males, with the latter apparently named after a large sign painted on a tree), all within easy walking distance for us, aided by the propensity of the boobook families within each to cluster on the boundaries. Here adults can alternatively engage in foraging activities to feed the juveniles, and giving their neighbours a good verbal going over.
Southern Boobook (Ninox novaeseelandiae) “White” Juveniles.
Photo courtesy David Cook
Boobook diet varies from insects, such as cicadas and centipedes, mostly taken on warm nights, to birds, such as Eastern Rosellas, Yellow-faced Honeyeaters and pardalotes. Jerry informed us that insect prey is often taken on the wing and caught using the feet, making boobooks the only owl species in the world known to utilise this method. Whilst nesting and roosting occurs predominantly within woodlands, boobooks appear to prefer more open areas to forage, and are often found within school grounds.
After a short walk, we located the “White” male with two 10-week old juveniles in the top of a smallish eucalypt. Apparently the female hasn’t been seen for about 2 weeks, and Jerry thinks she may either be dead or has moved back to her winter territory early. We then found the female and 2 juveniles belonging to Orange, however, this male too has disappeared and is more than likely dead. Adding to the mix, a “floater” (a male without a territory or mate) has turned up in Orange’s territory, apparently with the intent of taking over from Orange, but appears to be reluctant to go near the female because of her aggression. Jerry and Sue have colour-banded this bird (now known as “Lime”) and attached a radio harness so that they can keep tabs on him.
Southern Boobook (Ninox novaeseelandiae) “Lime” Floater.
Photo courtesy Jerry Olsen
We then located the family of 5 in “V5”. These three youngsters are about 11 weeks old, and each showed characteristic circular head movements not displayed by adults, making them easy to identify when in silhouette. In total we saw 11 boobooks (4 adults and 7 juveniles), and all birds, with the exception of the adult “V5” female, which flew away to a nearby tree, tolerated our intrusion upon their territories. As darkness took over, we returned to “White” where we witnessed the male hunting and feeding insects to his 2 offspring, which made cricket-like chirring begging noises, before heading off across Caswell Drive into Aranda, causing a moment’s concern to Jerry as one youngster narrowly avoided becoming another statistic on our nation’s roads.
We ended a fantastic evening there, and greatly appreciated Jerry and Sue sharing their world with us.
David Cook