Over wintering Yellow-Browed Warbler, Frampton on Severn, January 2025 One of the avian phenomena that perplexes me most is the yearly UK autumn arrival of significant numbers of Siberian Phylloscopus warblers. Every year I travel to see Yellow-Browed Warblers that are overwintering in the UK and wonder what on earth they are doing here. This is a really perplexing one as these delightful little leaf warblers breed in the eastern palearctic and migrate to tropical and south-east Asia for the winter. So overwintering birds in the UK have flown some 5,000 km in the wrong direction in perhaps the largest UK example of reverse migration. One intriguing possibility is that mother nature is using reverse migration to establish independent breeding colonies hence mitigating the risk of the species being wiped out by some environmental catastrophe in their home breeding range. I’ve ponder this perplexing question many tim...