Sometimes there are interesting things on one’s doorstep.
I was taking a stroll to the postbox the other day when a flock of c25 Pied Wagtails flew over calling. It was nearly dusk and so I assumed that they were heading off to roost somewhere. I spent some time in the autumn searching unsuccessfully for gatherings of Pied Wagtails in Northampton and I have seen some decent roosts in the past, and I’d like to see them again.
So, I watched another half a dozen Pied Wags head in the same direction, thought about what possible roost sites there were, and jumped in the car. Five minutes later I was checking out the BP garage and McDonalds on the edge of town. They looked like likely places, and there is a small water-cleansing reedbed next to them which could be a wagtail roost too. But there was nothing.
Nearby there was the football ground with its large parking area – nothing there either.
So then I crossed over the road into the industrial estate of Warth Park and drove around. It was much bigger in there than I had realised. To cut a long story short I found the Pied Wagtails on top of the DPD warehouse building and its neighbour the Muller/Wiseman Dairy warehouse. There were scores of wagtails on each roof but also about 200 on the road between them that goes into the Muller/Wiseman dairies site.
Altogether I think, it’s a bit of a guess really, that there are over 500 Pied Wagtails using this roost each night. There may be as many as 1000. They sit and wait on the warehouse roofs and fly down into the bushes or onto the road. I noticed that when they are on the road they are very evenly spaced out – much more so than a random distribution – and that they are almost all facing in the same direction. A few scurry about a bit but mostly they just sit there.
If a lorry comes into the site, or if a car or van with its headlights on goes round the roundabout lighting up their road, then the wagtails are off into the air for a while, but they return very soon, evenly spaced, lined up, almost motionless.
And bit by bit, the roost fills up and the birds leave the roofs and the road and sit in the branches of the trees and bushes.
We don’t really understand what communal roosting is all about. In most cases the birds don’t snuggle up together so its function in saving heat loss is perhaps small. It’s difficult to believe that there aren’t plenty of potentially sheltered roost sites as good as this one – but then, I’m not a Pied Wagtail. But they must get something out of it because some of them must have some quite a long way.
I did, last week, see a Pied Wagtail in my road, but that is quite unusual. They aren’t very thick on the ground at my local patch of Stanwick Lakes (which is less than a mile from the roost). At Stanwick in January and February I see Pied Wagtails on around two thirds of occasions (I know that thanks to recording my species lists in Birdtrack), but rarely more than a single bird or a couple of them.
Let’s just imagine, and this is just for fun, that there is one Pied Wagtail every square kilometre in east Northants in mid-winter. What do you think – too high or too low? If there are 500 Pied Wags at the roost (and I think that is a lower estimate rather than a high one) then that is 500 square kilometres. Using πr², that means the Pied Wags are coming from a distance of about 13km (roughly 7 miles) in all directions to this roost. Does that sound likely? Not sure.
I doubt whether there were 500 Pied Wagtails roosting here when it was an arable field and before it was an industrial estate but I really don’t know.
Plenty of food for thought but the lasting memory is that Pied Wagtails are really cute birds – elegant, chic, cultured – Audrey Hepburns among birds. And these are practically on my doorstep.
Fascinating how what we think is a good habitat is so at odds from how wildlife exploits something like an industrial park. If you carry on down A45 to Whitworth Bros at Victoria Mills there is wet wood land and lakes on one side of the A45 and reasonably mature woods on the other side. We deliver quite a bit of wheat into the mill and I always see Woodcock using the sodium lights at the mill to flight back from the lakes. Quite odd sight in such a strange environment.
Hi Mark, Broadholme sewage works near Ditchford is an attraction for the local Pied Wagtails, there can be as many as 500 there during the day although I don’t know where they go to roost. There are also quite high numbers on Raunds sewage works, perhaps 50 or so along with a handful of Grey Wagtails.
I only see them in Tesco or Waitrose car parks in Salisbury. Only one at a time. Maybe it’s the same one. There are two magpie nests outside Waitrose. There is quite a camaraderie between the old geezers left outside with the dogs.
Very interesting, I work for a rival national delivery network (the one formerly owned by us all) in a similar grey warehouse with trees (some sort of maple) around it and we also have a large roost of pied wagtails behaving in exactly the same way. I’m leading on a biodiversity project so any tips for encouraging them to stay/nest would be appreciated
Tim B – doesn’t sound like ideal nesting habitat but I could be wrong. Insects are what they need.
I’d concentrate on giving them a safe, undisturbed, winter roost. That will be what they need for more than half the year.
http://www.bikerman.co.uk/images/audio/science/SelfishGene/files/basic-html/page139.html
Prof V. C. Wynne-Edwards would have said this roosting behaviour was a form of epideictic display — a population regulatory mechanism. But his theory was rebutted back in the 1950/60’s by David Lack and co.
The above link seems to provide some hope for its revival.
In the meantime let’s stick with the Love-Fun-Hepburn hypothesis.
I was at the Westfield shopping centre in Stratford (London) a couple of days ago. Never again perhaps, but it was around dusk and there were many Pied Wagtails about. At the time what struck me was that it’s a slightly indoors/outdoors environment and despite that they like supermarket car-parks I was surprised that they seemed happy there to be nearly ‘indoors’. But now I wonder whether they may roost very locally to where I saw them.
I find motorway service stations seem to be rather attractive to roosting pied wagtails.
On a sadder note I visited a factory in Yorkshire several years ago and found that the operators of the site had unwittingly created a lethal Pied Wagtail trap. They had a gantry for accessing the top of tanker lorries for unloading purposes and the work platform was surrounded by a simple shelter; in order to stop pigeons roosting in it they had erected netting around it but when I climbed up I found about thirty dead Pied Wagtails trapped inside. They did remove the netting at my request and the problem has been resolved but too late for the sad little carcasses I found that day.
Jonathan – Telford Services- is that M54?? M50?? is a good place for flocks of Pied wags. As is every racecourse at the time of the last race of the day.
Well climbed anyway. It pays to trespass.
Was going to mention a flock of 30 at the Billing Mill pub carpark, some old lady chucks seed down for the Geese etc which draws them in. But I’m actually not surprised by the location of your flock, industrial units/estates seem to be a magnet for them. Swan Valley/Pineham industrial estate is quite good near Sainsbury distribution centre.
Personally the roofs I believe have multi-functions. Often the roofs are metal so warm up quickly and most warehouses are twenty four hour operations so you have additional heat soak during the night. Most of the roofs are corrugated in style so you get more benefits of a water source and a food source the moss on some roofs is impressive.
‘The Audrey Hepburn of birds.’ – like that.
Interesting for me that is Mark. Sorry to dampen your love in with Muller and Wagtails ….. I worked at the Muller manufacturing plant in Market Drayton Shropshire for 12 years from 1993 to 2005. In c.2000 the roost Pied Wags on the roof of the main production building reached 1000 birds minimum, maybe a lot more. As it was a food manufacturing plant they tried to discourage them, netting off the areas they like to perch, however this was not so successful. The upshot was the birds were all killed. I think this was done with gas. Quality Dept and Senior management tried to keep this fact from everyone else, especially me but not all the birds died the night they did the deed. Next morning there were a lot of sick birds around the plant. The roost never reestablished itself.
The farmer we bought our place from used to call them ‘dish washers’; I’m not sure if that’s a common name for them.
Looking at your web site Dave you must have some photos of this massacre. If not why not? Where are all the ‘whistle blowers’ when you need them! Trump wasn’t around then!
A lovely article but I was disappointed to read that your first option for searching for them was to jump in a car. I use a bike to explore my urban environs, especially if the searching is too far to walk. I often find things between the start and finish that I would have missed if I drove, but there all the other things that car journeys add to our towns that I would rather not contribute to.
Adrian – it was on my way to somewhere else that I had to reach by car.
On way back from Birdfair 3ish years ago, several hundred in tree adjacent to door of one of M5 southbound service stations- lots of lovely warm air!