Autumn migration hits its peak - for some species

The peak period for autumn migration, as measured by large movements of a particular species at a bird observatory, or migration watchpoint, is often thought to run from mid September to mid October. However, for some species the peak has already passed, the last of the satellite tagged BTO Cuckoos left the UK on 26 July.  For others, it is right now, as is the case for Whinchat, and it will be a few weeks away until Meadow Pipits peak. So there is plenty to look forward to.

Meadow Pipit by www.grayimages.co.uk

Of course, migration is influenced by the vagaries of the weather and birds can either be held up, or leave early, depending on the conditions.  BirdTrack is a good indicator as to what is happening as the autumn unfolds. The BirdTrack reporting rate for Whinchat illustrates this perfectly, and shows that unless things change Whinchat migration is bang on cue.

Whinchat reporting rate graph.

So, how might the weather influence migration this weekend?

Met Office pressure map - www.metoffice.gov.uk - 0100 Saturday 7 Sept

Low pressure is centred over the UK from Friday afternoon into Saturday morning and as a consequence of this the weather is going to be unsettled for most of us. On the face of it it doesn’t look like there will be much movement from the east, however, depending on the timing of rain on the west coast of Norway, migrants here might be tempted to leave and be drifted across the North Sea in a short window of easterly airflow. So with poor weather on the east coast, particularly from Shetland down to Yorkshire, we might see a fall of migrants that should include Whinchats, and possibly a few Red-backed Shrikes. And, who knows? Maybe something altogether more exciting, I’m hoping for a Norfolk Pallas’s Grasshopper Warbler  but will be just as happy with a small fall of Spotted Flycatchers.

Saturday morning looks best for the east coast, whilst on Sunday, interest could turn to the west and perhaps an early North American land bird.