Pigeon with bird flu ?

New to the group so apologies if this is in the wrong area !

we have a lot of pigeons in our garden and over the past few days we’ve noticed one of them acting strange on the bird bath.

it takes a drink then stands very upright, almost toppling over backwards, it looks like it coughing or having trouble swallowing?

is this normal?

not noticed it before, any advise ?

it moves around, flies in and out the garden ok