Re: YRT Behaviour

To: Robert Davis <>
Subject: Re: YRT Behaviour
From: Stephen Ambrose <>
Date: Sun, 29 Jun 1997 15:59:34 +1100
Hi Rob,

Your observation of the Yellow-rumped Thornbill was quite interesting, and I 
would like 
to offer a possible physiological explanation.

YRTs are usually found in small flocks, but you only refer to a single bird. 
Does this 
mean that it was indeed alone? If so, it may have been an unwell or injured 

>From 1987-89, while I was working at the Australian National University, I 
>studied the 
energetics of Brown and Striated Thornbills in  the Brindabella Range of the 
ACT. In 
particular, I was very interested to see if I could induce torpor in these 
species at 
low temperatures. I know some subscribers to Birding-Aus visited my study site 
and saw 
this work in progress.

Although I and my research team were not successful in inducing torpor, we were 
able to 
depress their metabolic rates considerably at low ambient temperatures, as well 
having lowered cloacal temperatures. Some birds were quite listless and had 
balancing on branches when they were released immediately after being in a 
chamber at low temperatures. The feathers were also fluffed up in these 
making the birds look like a round ball of feathers (did your YRT look like 
this?). So 
their behaviour was very much as you described. These birds recovered after a 
minutes, once they had warmed up, and flew away if we picked them up and placed 
them in 
the sun to warm them up. Sometimes, we put a thornbill into a calico bag before 
it was 
released, which I placed under my jumper for a few minutes to allow my body 
heat to warm 
it up.

I know that WA does not get as cold as the ACT in winter (I have lived in both 
but anything the size of a thornbill will find WA winter temperatures cold, and 
need to be feeding continually throughout the day to fuel a high body 
Perhaps your YRT was not able to find enough food and so had a depressed 
metabolic rate 
(as we found in the ACT thornbills) and became hypothermic which, in turn, 
affected its 

Just a thought ... Shane may have other suggestions from a veterinary 



Dr Stephen Ambrose
Research and Conservation Manager.

Birds Australia (Royal Australasian Ornithologists Union).
Australian Bird Research Centre,
415 Riversdale Road,
Hawthorn East,
VIC   3123.

Tel:    (03) 9882 2622.
Fax:    (03) 9882 2677.
Email:  S.Ambrose <>  (at work)
          (at home)

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the birding-aus mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU