Age!!

[Steve]

Taking the theme from another thread, Does anybody know the average life expectency of your average Garden Bird ie Robin? I have had the same Cock Blackbird in my Garden for Three years.

[burhinus]

Hi Steve

As a fairly high % of birds of the year do not even make Christmas this brings the average down quite a bit. BWP has quite a lot of figures on ages of species of bird. Small jobs usually do have a shorter lifespan than larger ones, though of the smaller ones I seem to remember from my ringing days that Reed Warblers are quite an exception. According to BWP the oldest ringed Blackbird was 20 years!!

burhinus

[flabbyguy36]

People tend to think they see the same robin every year, but as burhinus suggests, most dont make winter.

[Blaumeise]

From Sibley's Guide to Bird Life and Behavior:

Thurshes:
Adult annual survival 30-75%. Among oldest on record: 20 years, 3 months (Eurasian Blackbird); 13 years, 11 months (American Robin).

The stats are of course primarily for American birds, but I'd imagine they are similar for European birds (esp. since one of his examples is a Eurasian Blackbird). So it's not entirely impossible that you are indeed seeing the same individual three years in a row.

[Jos Stratford]

Taking the theme from another thread, Does anybody know the average life expectency of your average Garden Bird ie Robin? I have had the same Cock Blackbird in my Garden for Three years.

The average is pitifully low, the majority don't make it through the first months of their first year, but should they get lucky and avoid the cats, sausage-fingered ringers, hawks and cars, the odds get somewhat better. I'd say a reasonable lifespan for a Robin-sized bird is about three to four years, but some become right little veterans. As well as the Blackbird example given above, I had one (ringed) Coal Tit return to winter in my garden til he was the ripe old age of at least seven ...not bad given the number of days down to minus 30 he had to endure!

[joannec]

The average is pitifully low, the majority don't make it through the first months of their first year, but should they get lucky and avoid the cats, sausage-fingered ringers, hawks and cars, the odds get somewhat better. I'd say a reasonable lifespan for a Robin-sized bird is about three to four years, but some become right little veterans. As well as the Blackbird example given above, I had one (ringed) Coal Tit return to winter in my garden til he was the ripe old age of at least seven ...not bad given the number of days down to minus 30 he had to endure!


Jos is right, the average for most small birds is very low. Blackbirds can live up to 5 years. Interestingly, swifts, which aren't very big, average about 10 but some have lived 20 years, I think I have read. Raptors (and I know you didn't ask about them) are another story with many species living 20-25 years; some, osprey, for example, up to 30.


Joanne

[Ausable Bird Observatory]

sausage-fingered ringers,

Unneccesary.

My fingers are more like Twiglets.

Peter

[Jos Stratford]

Unneccesary.

My fingers are more like Twiglets.

Peter

And twiglet-ringed fingers ;)

PS I'm a ringer

[KnockerNorton]

If you think that a pair of blackbirds will raise around 10 young a year from 2 successful broods, then that makes 12 blackbirds by the end of the summer. In order for the population to remain the same, 10 of those 12 will have to die before next year, so the overall average is very low. Several months at best for a juvenile.

Mortality for juvenile blue tits is about 70-80% in their first year, while mortality for adults is about 50%. So if they get through the first winter and manage to get established in a territory in the spring (which is critical to their survival), their odds improve a lot. I'd scale down Jos' figure and say that your average robin-sized bird (having survived the first witner) could expect to make 2-3 years of age. But 4-6 year old garden birds are not uncommon. A few can live much much longer, as ringing has shown, and get well past 10 or even 15. A tit population I keep an eye on has 50 adults and 120 young each year. But that's EVERY year, so 120 die to take it back to 50 birds each spring. Most of those are juveniles, and the adult population is made up of mainly of 1-3 year olds, with a fair few 4 year olds, a few aged 5, and tailing off to one or two getting to 7 or 8. One or two birds were adults when first ringed, and lived for over 5 years more, so could have been over 10 when they died.

[Mark Grantham]

For most common British species, average first-year and adult survival rates can be found on BirdFacts:
www.bto.org/birdfacts

Thanks to the sausage-fingered amongst us ;) some longevity records for British birds can be found here:
http://www.bto.org/ringing/ringinfo/longevity.htm

for European birds here:
http://www.euring.org/data_and_codes/longevity.htm

and to keep everyone happy, for American birds here:
http://www.pwrc.usgs.gov/bbl/homepage/longvlst.htm

Mark Grantham
BTO Ringing Scheme