Tuesday, 5 September 2017

Horrid autumn- 5/9/17

HorridHill 6:15-8:15. Quiet again.
Point- Whitethroat one, Blackcap one, just one Yellow Wagtail over.

Left to Robins to provide stimulation. Numbers almost doubled. Not suspecting 'migration' as such, but could this be dispersal? Local youngsters, from the Country Park itself, being pushed out of their natal territories by their parents?

Most species will have a spread of dates for the completion of post-juvenile moult. Early nesters may be a bit leisurely about it, late broods will get a move on and perhaps complete a week or more quicker than first, second broods, but effectively they do not all change to looking like adults at the same time. Mums and dads will stop recognising their youngsters at various times through late summer. Many species will not complete and feel the need to undertake a migration straight away. Daylength in late summer is not yet short enough in some species to kickstart seasonal migration. Why locally bred Robins are likely to be resident/short-distance migrants. Adults prepare to hold ground for winter, youngsters go a little way looking for a place to call their own. Only if fail to hold somewhere down might they move come the 'autumn proper' and the arrival of continental birds.

Carry out Robin ringing on a large scale at one site, and you'll find new arrivals in early autumn tend not to go too far. October? Chance to get more of those overseas encounters. Plus a few more local movements; there will be plenty of displacement going on, and plucky Brits can and do lose ground to the incoming. So, statistically, not every apparent arrival on the coastline in October will have a continental accent. And around now, most apparent arrivals here on Horrid will, if not full Kentish accent have a twang of 'Estuary English' about them. So, all good stuff, but early days fer proper migrayshun 'ere 'ennit?

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