EricB

BWAx1.jpg (76.33 KB)

10/02/2011 18:14

BWax2.jpg (69.13 KB)

10/02/2011 18:14

Here are a couple of pics from Northumberland , from around Christmas.This is the nominate race 'garrulus'.  Males are said to have a broader yellow terminal tail band and a better defined throat patch.Adults have white 'hooks' to the tips of the primaries , which the juveniles lack - I think this holds true for the 'centralasiae' subspecies,which means this is a  first winter. Shame about the tail,but look on the bright side,at least it managed to escape from its bars.  
The waxy appendages on the secondaries remain of mysterious  functional significance -like me; I Hope it finds its way home!

eric

[ Last edited by RUWright at 11/02/2011 01:40 ]

EricB

The waxy appendages on the secondaries are not closely related to age or sex.I have seen some literature that suggests that adult males are more likely to have more waxy appendages(>8) than females and young females are likely to gain them earlier than young males.Some have postulated that older birds have more appendages and perhaps are recognised as better mates (like male swallows with deeper tail forks) but the evidence is pretty limited and clearly hampered by the difficulty in ageing and sexing birds in the field.The reason for their presence has been debated since the time of Wilson and Bonoparte!The flock photographed in Northumberland had about 50 birds; my recollection of things was that asymmetry of the appendages was not unusual.
eric

[ Last edited by RUWright at 10/02/2011 18:12 ]