Unknown bird with unusual flight pattern

["Peter Ormay" <>]

Hello Paul,
I have seen Pied Ceurrawongs perform this type of flight when descending to 
a lower elevation i e an undulating flight where they open their wing partly 
(1/2 to 3/4, very rarely fully) to check their descent giving them a lift 
for a while then closing them tight to their side for a while allowing them 
to drop a bit then opening them partly again giving them another lift. I'm 
sure other species perform this type of flight sometimes. There must be a 
term for this type of flight.  I find the size of a bird difficult assess at 
a glance sometimes and it may have been a currawong that looked smaller than 
it should on another sp.
Cheers
Peter O