Pied Wagtails

[Kelvin]

I've noticed that for the last few years, starting around now and continuing until the spring, pied wagtails fly in from seemingly miles around to roost in their hundreds in the trees right in the city centre. Has anyone else noticed this and does anybody have an explanation for this behaviour.

[Cetti]

Birds come together in flocks for a whole variety of reasons, but the main ones are: FOOD. Flocks gather to exploit a plentiful food source giving them a better chance of locating scarce food. SAFETY. There is safety in numbers, especially if there is a predator about. WARMTH. Especially during cold winter nights, small birds like Wrens or Pied Wagtails will huddle together in a communal roost to keep warm. Without this, any individual would stand a far lower chance of surviving the night. Apologies for the capitals but that's how it appeared in "Birding with Bill Oddie".

[Kelvin]

Thanks Cetti for that (& for quoting references - very professional) but my point was - Why they migrate nightly from rural areas to roost in the middle of town.I've heard of up to 50 wrens gathering in a nest box to get through a cold winters night but these wagtails just roost in the trees, without huddling for warmth & there are hundreds.

[Cetti]

Yes, I totally understand your point, Kelvin - where's Bill when you need him!!! I think it's purely to do with safety and survival. Out in the countryside they would be far more vulnerable to the cold and attack from Mink, Raptors etc. so therefore the middle of a city or any urban area would seem like a 'safe house'. There's also the problem of fitting in nest boxes or roosting pouches for Pied Wagtails, whereas Wrens being tiny and compact can squash up together the poor old Pieds are a bit handicapped with their long tails so trees are a safe alternative. Do hope this makes sense Kelvin!

[parkhead]

According to that nick guy on bbc the town centre at night is upto 1 degree warmer than the suberbs ( I think it is because of the heat given out by all the lights ) so most birds go there if they can.