Odd observations

Subject: Odd observations
From: David McDonald <>
Date: Fri, 26 Jul 1996 22:31:39 -0700
Hi all

I sent these three notes to the editor of our local birding journal, Canberra 
Notes, the other day.  Maybe he will think they are worth publishing, maybe 
Anyway, I thought that Birding-Ausers may find them of interest and have 
answers to the 
questions I pose.  I really loved the currawong/possum interaction!


1.    Early Nest-building Activity in a White-browed Scrubwren

On 23 July 1996 in the Rainforest Gully at the Australian National Botanic 
Canberra, I observed a White-browed Scrubwren Sericornis frontalis engaging in 
nest-building activity.  Over a period of about ten minutes I saw it fly four 
time to a 
clump of vegetation.  On each occasion it was carrying a large quantity of 
material in its bill.  It disappeared inside the vegetation, only to reappear 
later without the plant material.  It was a typical nesting site for this 

In the Canberra region the White-browed Scrubwren normally breeds in Spring.  
(1984, p. 274) states that the breeding season in the Southern Highlands 
extends from 
September to January (although it is earlier at the coast where the climate is 
 The Australian Capital Territory bird atlas (Taylor & COG 1992, p. 133) 
reports records 
of nest building in the ACT from late August to late October.  So far as I am 
aware, the 
1996 winter in Canberra is not unusually mild so it is unclear why this bird 
nest-building so early.  

Frith, H. (ed.) 1984, Birds in the Australian High Country, Rev. edn, Angus & 

Taylor, M. & Canberra Ornithologists Group 1992, Birds of the Australian 
Territory:  An Atlas, COG & National Capital Planning Authority, Canberra.  

2.    A Pied Currawong Harassing a Ring-tailed Possum

The Pied Currawong Strepera graculina has a well-earned reputation for 
harassing other 
birds, often for no apparent reason.  They are also known to harass domestic 
On 25 July 1996, at approximately 1230 hours, at the Australian National 
Gardens, Canberra, I observed a Pied Currawong doing somthing similar to a 
Possum Pseudocheirus peregrinus.  

My attention was drawn to the Pied Currawong as it was vigorously tearing 
leaves and 
twigs from a thick clump of rainforest-type vegetation growing on a horizontal 
branch of 
a tree overhanging (and part of) the Rainforest Gully at the Gardens.  Not only 
was it 
tearing off the plant material and dropping it, the bird also repeatedly jabbed 
its bill 
into the foliage.  After observing this behaviour for a few minutes through 10 
binoculars, I noticed a movement in the foliage some 20 to 40 centimetres 
below the Currawong.  It was a Ring-tailed Possum, apparently curled up in its 
nesting place.  The Currawong continued jabbing at the possum and tearing away 
vegetation above it.  After some ten more minutes of this, the possum uncurled 
in a 
sudden movement, jerking its upperbody towards the Currawong, which suddenly 
flight, presumably startled by the rapid movement of the possum.  The possum 
resumed its former position deep in the foliage.

Why was the Pied Currawong behaving this way towards the Ring-tailed Possum?  
currawongs are carnivorous but a healthy (if sleepy!) possum could not possibly 
be a 
prey item. It is unlikely that teritoriality would come in here, as the two 
species have 
totally different needs for food and territory. Perhaps the possum or the nest 
smelt, to 
the currawong, like carrion?  Or perhaps it is simply yet another example of 
inclination of Pied Currawings to harass other species of birds and animals, 
even when 
no survival advantage seems to be associated with such harassment?  

3.    Red-rumped Parrots Benefiting from Sulphur-crested Cockatoos? Feeding

Twice in early July 1996 I observed flocks of Red-rumped Parrots Psephotus 
feeding on the ground under Pin Oaks Quercus palustris in Kennedy Street, 
Australian Capital Territory.  While their usual foods are the seeds of grass 
herbaceous plants, along with green plant material (Frith 1984, p. 175), I was 
interested to investigate what they were eating at that location as they were 
feeding on 
all kinds of surfaces including hard bare soil, lawn and bitumen footpaths.  On 
observation it became apparent that they were feeding on the fruit of the Pin 
Oaks.  But 
how can a small, grass seed-eating  parrot possibly eat the very hard, 10mm 

For some days prior to this observation, large flocks of Sulphur-crested 
Cacatua galerita had been feeding on the Pin Oaks.  They had no trouble 
removing the 
acorns from their stalks, cracking them open and extracting the seeds.  
Apparently, in 
the process a substantial quantity of seed had fallen to the ground where it 
available to be eaten by the Red-rumped Parrots.  The seed was already removed 
from the 
acorn and so was readily accessible to the parrots, as accessible as grass seed 
similarly sized.  

Here is an example of one species benefiting from the behaviour of another, 
without any 
competition for resources being involved.  

Frith, H. (ed.) 1984, Birds in the Australian High Country, Rev. edn, Angus & 

David McDonald          Voice:       +61-6-231 8904 (home)
PO Box 1355             Voice:       +61-6-260 9231 (work)
WODEN  ACT  2606        Facsimile:   +61-6-260 9201 (work)
AUSTRALIA               E-mail:       (home)
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  "Things are more like they used to be than they were before"

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