Robin with a head nod twitch

I can't say I have seen that before. Was there another Robin nearby? Maybe just above or below? It could have been territorial behaviour. It doesn't look like it was coughing up a pellet. That is typically a 'gulping' motion. Interesting little clip. Keep watching and let us know if you see any more interesting behaviour.

It does look an awful lot like that video. He came back later in the day and he was still doing the same thing. It is constant and all the time though.
If it is sneezing could it possibly be some kind of respiratory issue indicative of bird flu?

Hmm I don't know how big of a part the cold weather could play too...A blackbird I knew has, in the past, had a spell of repeated sneezing though he started in early March and thankfully 'recovered' (I used a wild bird supplement in his food as extra support). I think with the sneezing, the real concern would be if the robin was producing visible nasal discharge - hopefully he will be fine in the coming days. I've read that high pathogenicity strains of Avian flu rarely break out into wild populations of small songbirds but I'm no expert on that myself.

I have a house pigeon who sneezes on occasion. That is definitely not down to temperature. The Robin that I used to hand feed at my local railway station suffered from a clear mucus discharge a few years ago. There's probably a YouTube clip somewhere. It was like he was vomiting. He survived, but his singing was greatly affected by it. They didn't stop him from raising a brood the following year. He's still around. His rather flat song gives him away.

Interesting indeed how his song was affected. Is the flatness a subtle thing or more pronounced?

To me, it's pronounced but I was used to his song. He was unable to make the typical 'ditting' noise for several days. He can't hit some of the high notes.