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"?
So I put together the following notes, and sent them off to the Canberra Ornithologists Group Chatline.
"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 Bird Banders such as Mark Clayton or Anthony Overs, or other COG members, 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."
I have included a link to a report of one of the Bird Banding trips to West Wyalong I have made with Mark Clayton. That report and the photos will give you a better idea of what Banding is all about, And how small these long-lived birds are.
|Eastern Yellow Robin|
A bird commonly banded by my father
at New Chums Road,
high in the Brindabella Ranges, ACT.
This one was at Charcoal Tank, West Wyalong, NSW
"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.
Shortly after I sent that note out, I got this reply:
"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
That confirmed my vague memory - and added a few years to known lifespans of small Australian birds.
John Rawsthorne then added this interesting "take" on the problem.
- Very interesting comment. Certainly I’ve pondered this long survivorship of Australian birds before, and this applies as much in the tropical north as it does in temperate Aust. Perhaps the best example that surprised me was from the Iron Range Cape York expeditions, where the 2008 banding trip turned up (I think) five birds which were banded on the first major expedition in 1990! These were little shrike-thrushes, white-faced robins and yellow-spotted Honeyeaters, from memory. All sedentary birds. It seems that if these birds are able to survive the first year or so and then claim a territory, then they just keep ticking on. The flipside of this situation, though, is that recruitment (ie addition of birds to the breeding population) must be quite low – I don’t know whether this is due to low breeding output, or subsequent high mortality of younger naïve birds.
- Another observation I would add is that at the banding sites at Weddins and Charcoal Tank the number of old re-traps now is very low and there are very many young birds now being trapped (which indicates some form of recovery after the long drought). Nonetheless there have been some very old birds in their late teens recorded at these sites.
Anthony Overs, another Bander, then added:
- Thanks Denis, and thanks Paul for the summary from the banding scheme database.
- Overseas visitors are often astounded by the fact that our birds are so long lived. Many years ago, during some banding work at Barren Grounds, I had immense pleasure in showing a recaptured Brown Thornbill to some foreign visitors; the bird was 15 years old, it weighed seven grams and had been retrapped a dozen times in the same spot, right by the warden's residence. In the same day I retrapped a 12 year old "scrubbie" and two 10 year old Eastern Spinebills. From memory (which is fading...) the birds were all adults when banded, so those ages are a minimum!! That Brown Thornbill could have been ten years old when it was initially banded. Known age birds such as juveniles and immatures are so important in banding studies as it gives you a baseline or starting point. As an example, that's how Bill Lane worked out that male Satin Bowerbirds got their black plumage in their sixth and seventh years, by banding juveniles and recapturing them repeatedly.