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Wing length difference in male and female blackbirds? (1 Viewer)

devilbirder

Well-known member
I was doing some maths homework when I came across a question asking about median inter quartile ranges and stuff of wing length of male and female Blackbirds turdus merula. From the chart males generally have longer wings. I'm just wondering if this is true and they got the info from the BTO or something or it is just made up, as I can't see why males would need longer wings than females, its not like they're migrating further or something.
Any comments?
 
Not very scientific but I can tell you that the wings are different from male to female, about 10 years ago I found a freshly killed pair by the side of the road and took them home to draw, the wings were definitely different length/shape. I'm sure someone will have actual measurements to hand.
 
The wings of many birds are bigger in one sex (usually the male). In some birds where the sexes look the same, it can be used to sex them very reliably.

The reason is simple - the males are bigger! Why? They're in a different genetic competition than the females, so have different pressures acting upon them that give advantages to bigger birds, such as defending territories form competitors. Females do less defending than males, so they don't have the pressure to be bigger. There are lots of other possible reasons too.
 
Hi David

You're very right that male wing lengths are longer than female ones in Blackbirds, and this is the same in many (most) species. This comes about as a result of sexual selection, where the bigger a mle the better able he is to provide for a female (whether that be defending a territory or finding food). For birds of prey, the opposite is true, with males being smaller than females, but in these cases a smaller male will be more agile and so 'fitter'.

Anyway, have a look at the attached graphic which shows a summary of Blackbird wing lengths by month for Gibraltar Point Bird Observatory in Lincolnshire. So in all months males are longer winged, but note wing lengths are different over the year. Scandinavian birds are larger than ours, so an influx of these birds in the autumn will push up the average wing length. So much so that winter females can have the same wing length as summer males. Interesting!

Mark Grantham
BTO Ringing Scheme
Gibraltar Point Bird Observatory
 

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