I have just received the original ringing details of the Danish-ringed Nightjar that I controlled in North Wales. It was ringed as a juvenile on 21st August 2021 at Glæde, Thisted, Viborg, Denmark.
Given the age at ringing and the date of ringing there is still some uncertainty about the provenance of this individual. In many species of bird juveniles often make exploratory movements away from their natal area before heading south on migration. This bird could have been a bird reared in Denmark that has subsequently nested in Wales or perhaps more likely it could also have been a British-bred bird that dispersed north (or even got blown north whilst on migration) before correcting itself and heading south to its winter quarters.
Normally we would be left not knowing which scenario was correct but in this instance we may have an ace in the hole that could give us more clarity. Over that past few seasons, as assistance to George Day (a PhD student at York University working on European Nightjar breeding systems) I have DNA sampled a large proportion of the birds breeding and reared on the wind farm monitoring site at Clocaenog. I also managed to collect a shed feather from the Danish-ringed bird. It may therefore be possible to compare the DNA profiles and see how likely it is that the bird was from the local Welsh population or whether it was sufficiently different to imply a more distant origin.