Thrushes like Redwing and Fieldfare migrate across to the UK from Scandinavia in Autumn, often by the tens of thousand. I’ve written about this before.
However, they tend to fly at night, and at such a height that you don’t see them till they land. But that doesn’t mean you can’t spot your first winter thrushes. You just need to use another of your senses.
Redwings make a high, thin ‘tseep’ call in flight. Stand outside on a night, or very early on a morning, and you can hear them overhead.
If you want to hear what they sound like, there’s a great archive of sounds at Xeno Canto
I heard my first this morning, having kept an ear out for the past week or so. It’s a good one to log if you are keeping phenological records for your local patch. You can also then help the BTO out by recording your spots: http://www.bto.org/volunteer-surveys/winter-thrushes
Phenology is the study of plants and animals that follow seasonal cycles. Tracking this information over a long period of one time can tell us a lot about how life responds to changing climate.
I’d recommend everybody keeps a record of the first time they encounter certain species each year, such as snowdrops, bumblebees, swallows, and of course, winter thrushes.