Escaping birds [SEC=UNCLASSIFIED]

["Whitworth, Benjamin - BRS" <>]

There are some useful references below.

Of course I completely disagree with their findings, they over-estimate the success rate, mainly due I think, to the fact that it is the proportion of ‘recorded’ escapees’. The number reported escaped would be incredibly low. From an informal survey I did many years ago at my finch club I estimated it would be about 0.01-.05% survival. In my experience survival time out of the aviary were usually about 20 seconds before currawongs would come in and kill them. But if something dramatic happened like an aviary being broken into/ blowing over, usually out of ~30 birds you would have 1-5 birds surviving outside the aviary for up to 1 week. Finches survival would be different to parrots or poultry, though.

The escape rate: I used to breed 100- 120 birds a year, plus kept ~120 breeders, and probably had on average 10 escape per year. Finches are fast so that would be high escape. There would be ‘official’ escape rates available through ACT gov due to records. But only about 10% of birds require record keeping by number (ie most are budgies, canaries, zebra finches).

That is an incredible escape rate for the owls, I would say surely they were being free flown due to falconry.

Long, J. L., Introduced Birds of the World. Reed, Sydney, 1981.

Bomford, M 2010 Risk assessment models for establishment of exotic vertebrates in Australia and New Zealand

http://www.feral.org.au/wp-content/uploads/2010/03/Risk_Assess_Models_2008_FINAL.pdf

 

Bomford, M. (2003). Risk Assessment for the Import and Keeping of Exotic Vertebrates in Australia. Bureau of Rural Sciences, Canberra.

(currently offline)

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From: martin butterfield [
Sent: Tuesday, 31 August 2010 12:41 PM
To: Philip Veerman
Cc: COG List
Subject: Re: [canberrabirds] Escaping birds

Thanks for those comments Philip.

Here is a link http://www.rspb.org.uk/ourwork/policy/species/nonnative/eagleowls.asp
to the article from which I extracted material in my last message.  The
only suggestion I can find as to why people might keep eagle owls is in the
reference to falconry (although when - in my youth in the UK - I hung out with
falconers I never head of anyone having an Eagle Owl).  I agree that there
is a leap from the number of certificates to the inference that there are a
large number of birds in captivity.

WRT to the last bit what I was hoping
for was someone who is connected with the captive bird situation in Canberra (or
indeed elsewhere in Australia)  to say something like "Our members, who
have got n birds of species A, have reported z escapes per
year.".    This would be to be a useful topic for research by
someone concerned about the impact of feral birds.

Martin

On Sat, Aug 28, 2010 at 6:31 PM, Philip Veerman <> wrote:

Martin,

 

That is curious. I wonder why would anyone want to keep an Eagle Owl. I wonder if they would cost more to feed than a dog. Most likely they would be fed on rats. I agree those figures sound like a high escape rate. Or are people not wanting them any more and releasing them, and calling that an escape. I don't follow the logic about counting certificates if a bird is sold enabling a suggesting that the number kept in captivity is likely to be considerably higher than this. Surely one bird could be sold many times. They can live a long time. I can imagine people would get bored with keeping one.

 

About your last bit, it is difficult to describe, as we know so little about how long individual escaped birds survive. Beyond that, as you know, the GBS Report comments on this issue for Canberra, as our GBS is a probably unique position to contain relevant (even if patchy) data. I don't know of any study that offers anything more than the GBS Report does (as minimal as that was), otherwise I would have cited it in the references................

 

Philip

 

-----Original Message-----
From: martin butterfield [
Sent: Saturday, 28 August 2010 1:57 PM
To: COG List
Subject: [canberrabirds] Escaping birds

As a result of reading about an Eagle Owl (in the UK) atacking a Hen Harrier I checked out the RSPB site to find about Eagle Owls, which I thought got no closer to the UK than the Alps.  It seems there are quite a few in the UK derived from escapees.  I thought it might be of interest to reproduce the words of the RSPB about this situation.

"The eagle owl has been known in captivity in this country since at least the 17th century and many were brought from India during the 19th century. Eagle owls are very commonly kept in captivity - often by people who are not falconers. There is no formal requirement to register these birds, but a certificate is required if a captive bird is sold. In the 10 years to 2007, 3,370 such certificates were issued. The number of eagle owls kept in captivity is likely to be considerably higher than this.

"Of the 440 captive eagle owls registered with the Independent Bird Register between 1994 and 2007, 123 (28%) were reported to have escaped. Of these, 73 were reported as not having been recovered. This equates to 9-10 escapees per annum, of which 5-6 were not recovered. If the same escape rate is applied to a conservative estimate of the British captive population over the same 13-year period, around 65 birds could be expected to escape each year."

This seemed an astonishing number of escapes.  I wonder if anyone has done any studies of the escape rate of Australian captive birds?

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