Could be mixed flocks of species and age groups they are joining, we don't have the data on this yet currently to do more than guess though. Sorry for the long response, I love talking gulls 👀 🕊️4//

I can't say as to the mechanism of what causing these individuals to move further, they do receive quite a lot of post fledging care, but this does vary quite a bit it seems. My thoughts are that they seem likely to be following LBBG migrating through as the timing does seem to fit. 3/

These have been both wild and rehab juveniles reported from colour ring sightings. One of these juvs was also a GPS tagged individual from my studies! I'm hoping to publish about my study of juv HG movement and dispersal in Cornwall asap. 🙂 2/

Oo thanks for the tag Liam 🙂 And fantastic movement record for Irish HG!! As you both have rightly said we have ideas but we still don't know much about juv gull movements. We have had a few HG from Cornwall turn up in N Spain and 1 to N Portugal. 1/