And other than the ‘stressful migration’ theory, the other speculation that I’ve heard relates to the variable climatic conditions experienced by Australian
birds.
I have no references, but it goes along the lines that climate is so erratic or unpredictable from year to year, e.g. droughts etc, that birds in Australia
tend to have different breeding and life strategies than birds in the northern hemisphere with more predictable climatic conditions. Birds there have large clutches and timing of breeding tends to be very tightly tied to the season/time of year. In Australia
birds tend to have smaller clutches and tend to be more opportunistic in when they breed. This is linked to a survival strategy where it is better for an individual bird to survive for many years and weather (sorry – bad pun) the bad conditions and live to
breed again, rather than put all their effort into a few shorter but more prolific breeding efforts.
Something like that, anyway. I’m sure someone can come up with a better explanation and references.
Harvey
From: Paul Mahoney [
Sent: Wednesday, 23 January 2013 3:00 PM
To: ;
Subject: RE: [canberrabirds] Longevity of Australian passerines
A selection of longevity records from the banding scheme's database for some of the local small passerines:
Grey Fantail 9 years, 8 months
Eastern Yellow Robin 14 years, 7 months
Striated Thornbill 23 years, 6 months
Brown Thornbill 17 years, 7 months
White-browed Scrubwren 17 years, 7 months
Superb Fairy-wren 10 years, 5 months
Spotted Pardalote 4 years
Striated Pardalote 6 years
Silvereye 18 years, 7 months
Eastern Spinebill 15 years, 5 months
Red-browed Finch 23 years, 5 months
Paul
Date: Wed, 23 Jan 2013 14:42:54 +1100
From:
To:
Subject: Longevity of Australian passerines
Further to Erika Roper's link to Scientific American re Citizen Science, I followed a few links, and came across this story "The Oldest Northern Shrike in North America."
http://ebird.org/content/wi/news/the-oldest-northern-shrike-in-north-america
What immediately attracted my attention was the age "record": "at least 8.5 years old and the oldest Northern Shrike ever known in North America."
What - 8.5 years is a "record"?
This confirms something I vividly remember my father, Steve Wilson talking about with his American friend and colleague, Don Lamm - namely that the small Australian passerines such as Brown Thornbills and White-browed Scrubwrens easily outlive the "normal lifespans"
of many Northern Hemisphere birds.
I hope that Banders such as Mark Clayton or Anthony Overs, or other COG members such as Philip Veerman, who keep up with the Literature, might be able to provide more details on longevity of small Australian passerines. But from memory, many of the birds we
banded at New Chums Road, exceeded 12 years, and no doubt there are other heroic examples which have gone closer to 18 years. We all know stories of captive Cockatoos living 60 years or more - but they might not be representative of wild birds (and they are
not Passerines).
I recall the theory for this was along the lines that our small birds did not have to undertake stressful migrations (either across to Mexico, or across the Mediterranean - to Africa, in the case of European migratory species). Whereas a "Scrubbie" once it
survived its first year, and established a territory, more or less knew all about the threats which would face it for the rest of its life, except for catastrophic events such as severe bushfires which might totally destroy its habitat.
As Dad used express it, once and "Old Scrubbie" woke up every morning, it knew how and where to find its Breakfast. That's more or less all it needed to know.
Anyway, I found the article interesting - hope others do too.
Denis Wilson
"The Nature of Robertson"
www.peonyden.blogspot.com.au
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