I occasionally mention some of the other birding blogs I follow. I should probably list those blogs because they usually contain something interesting. One I read on a weekly basis is A DC Birding Blog. Every week it pulls together articles and other blogs that are bird/nature related in a group titled “Loose Feathers”.
I was reading the articles from the Friday, February 12 post, and came across a coincidence. And like any good TV detective knows there isn’t such a thing as a coincidence. Two of the articles mentioned the same thing, something I don’t think I had previously grasped.
Two of the articles mention 2 totally unrelated species living to 65 years old – Laysan Albatross and African Gray Parrot. And the Laysan Albatross is still having chicks at 65!
And this is something I really didn’t know. And since I don’t believe in coincidences something must have been telling me to dig into this deeper.
First, I don’t think I really know how old birds live, especially our local birds. I have read if gulls can make it past the first, second, or third winter then they live longer. But I’m not sure how long they live. And I seem to know Red-tailed Hawks can live up to 30 years in the wild. And small songbirds, especially warblers, don’t live but a few years. But this is all kind of hazy knowledge.
I want to know more. And I don’t want to know the longest, I want the average. So I searched the internet.
I didn’t find a definitive answer but it appears that the first year for all species is about the same – BAD. It’s the going forward after the first year that makes the difference. And as always correct me if I’m drawing wrong conclusions.
From what I can tell the odds of birds living one year after fledgling from the nest is only around 50% (or less). From there the size of the bird takes over. If you are a small passerine your odds are around only 50-60% making it to the next and any subsequent years. If you are a large bird like an albatross your odds are about 95% you are going to make it each subsequent year. And hawks and gulls are somewhere in between.
And here is my rough interpretation of the data:
If we start with 100 birds that fledged the nest, only 50 (50%) will be alive the next summer.
That means only 60% of the 50 small birds will live to the next year – 50 x 60% = 30. But 90% of the larger birds or 45.
The third year 30 X 60% = 18 small birds. But 45 x 90% = 40 large birds.
Fourth year 18 x 60% = 11 small. But 40 x 90% = 36 large birds.
Fifth year 11 x 60% = 6. And that is about it for the small birds. But the large birds keep going with 32 still alive after 5 years. And on for another 5 years.
Hopefully you get the gist of what I was trying to show. At best a small bird has only a 1 in 10 chance living to year 5 and a larger bird has a much better 1 in 3 chance. If you want to get a better understanding read this paper, which shows the details of a study of Eurasian Blackbirds in England.
So the average life of a small passerine is under 2 years old. Studies show that the European Robin average age is 1.2 years. Here is a quote from that study that sums it up:
“So, the answer to our question is that most adult small birds in temperate regions such as ours live for between 1¼ and 1½ years, but that only about 10-20% of young reach adulthood. Big birds, seabirds and tropical birds can live much longer. But some individuals of any species can live as much as ten times as long as the average. But just like humans a few can live much longer.”
Reasons for living longer: size – top of the food chain, less predators, less involvement with man, large birds can avoid cats, skyscrapers, etc.
I really didn’t get an exact answer but I now know most birds don’t live very long, except the occasional albatross or parrot.