Tuesday, 11 December 2012

Pied Wagtails...The Invisible Roost

Recently I found myself reacquainted, by fortune alone, with a more subtle but equally engaging annual wildlife spectacle. It had been raining for the past three and a half hours, the wind lashed and swirled its decent, robbing of warmth and chilling like ice under the cover of this cold December night. I had just been to a Bristol Natural History Society talk with guest speaker Oliver Smart, a wildlife photographer, where he talked about his visits to Alaska, Shetland and Finland illustrated with excellent images and interesting insights. Stepping off the bus and began walking through central Bristol. I passed shoppers pressed by the rain to quicken their pace, head down, busy with their own purpose of pursuit. And as I closed in toward the handful of London plane trees on the centre which are passed daily by 100's of feet I became acutely aware of two trees, I stopped on the spot and stared amazed into the branches and the deep impenetrable black of night that lay beyond.

Pied wagtails hung as if in suspended animation, the two trees sharing an estimated number of 130, if not more, individuals. I tried counting them in clusters of 10's but the density like a shoal of fish, made accurate counting difficult. The street light above the tree where the majority were illuminated with gave a softness to the white of their feathers with row upon row of long white under tail feathers extending below them. As I watched one or two would switch elegance and join the smaller group in the a joining tree in little bounding flights over the short gap, and the heads of passers by, that bridged the two trees. I felt the rain against my face still gazing up whilst around me I could have been one of the few smiling in the rain. People passed by me and benith the tree, unaware, unconcerned. Street lights and the traffic caught the rain in the beams of light and the wind still made its presence felt, although a little more sheltered than whilst I was waiting for the bus. It struck me how vulnerable they appeared. Usually the purpose of these roosts among other things is to provide shelter and warmth but this tree was not obviously so. Its branches resembled nothing more than sparse sticks offering little protection to escape the weather. Notably I have also read how roosts take advantage of the warmth produced by fairy lights each night. A number of trees near the centre have Christmas lights yet these pied wagtails paid them no attention and seemed in no rush to leave their chosen roost. It was dark by 4:30 that evening and it was now 10:30 so they appeared perfectly settled. During my time in Cumbria I discovered a regular roost near Penrith town centre last winter. I visited it again a couple of weeks ago and believe it may have moved however small groups were still observed moving through within the vicinity. I mention this as during last winter the tree they were using was lit with lights and sheltered on all sides by buildings. Among the humdrum of people and traffic, the lights, the general commotion, I left them and continued home.

My second visit came two days later. This time I hoped to watch their nightly ritual from dusk as they gather and roost as well as take some photographs. I arrived fairly early. A chill was setting in as the area became increasingly thrown into shadow by tall buildings that blocked the suns red bathe of light. The shadows creped along, scaling the buildings upward inch by inch, minute by minute, as if gradually submerging the area under a rising tide, the waves of shadows lapping at light. I watched the gulls circling and diving in between the two layers, rising and falling, their white feathers soaring into the fiery warmth of the last of the suns red rays, plummeting back to a land locked earth of shadow before reclaiming the sun once more. I was hoping for a raptor, the pigeons were flocking with their usual nightly acrobatics, no such luck however.
It started off with one. A classic little dot of a wagtail crossed the blue high above, punctuated occasionally by the chink of a flight call audible above the traffic. As I waited every now and then another would cross the heavens from the buildings to my right, over the pedestrian area, and disappear over the buildings to my left. It grew to a handful every so often with groups now appearing. And the more that disappeared away over the buildings the more I doubted that they may have moved. The surrounding light had now ebbed away. The vibrancy remained, washing the sky in an intensely soft peach watercolour. And as each bird came and went like the one before it my mind eventually got the better of me and I decided I would check the nearest location in the direction they were travelling  I did a loop of the second area with not so much as a chirp, it didn't feel right so I went back to the original plan.
Back where I'd first found them and eventually after another 10 minutes or so I re-found them. They gathered on the rooftops and assembled, still distant, as large clusters. Large groups took to the air in fluttering flight and, for what are small birds, took up a surprising proportion of the sky. They never bunched close as starlings would instead preferring more space, my observations would suggest. The whole thing is rather quiet and unobtrusive to witness. The groups flew around a little over the roost site and the Christmas shoppers, flying in a sweeping curve. Half a dozen or so birds committed themselves and flew in at first. The roost gradually gathered strength with a steady pour of birds quite literally bouncing in one after the other. It was not so much like someone pulling a giant plug as with starlings but a steady broken drip. I must admit by this point my concentration on unfolding events had been distracted setting up my camera as with a faint dusk trickling into darkness I felt I should try to capture something while I still can.

Its funny how people don't necessarily tend to notice things unless it flies in their face or bites them on the arse. Little things like a jay flying overhead, easy to miss I suppose, or say...well over 100 birds sitting in a tree. For the most part they are ignored or go unnoticed however, people are interested. When a tall guy turns up with tripod and camera to photograph a tree in the middle of Bristol people are inquisitive. (Incidently, I must mention that the tall guy did look rather conspicuous with a wacking great white lens.) People first ask what are they? The second question is pretty much always, what are they doing here? I was also asked once if there was anything people could do to help them? I caught mumbles on the periphery of my hearing of some questioning why anyone should want to photograph some birds in a tree, I find it ironic as to who is more mistaken. In truth all the questions are valid, the birds are taken out of context when viewed in an urban environment and most people I've talked to say the same. It's not the 'expected' place assumed by the vast majority.

I've recently been reading Mark Cocker's book Crow Country where he explores the magic behind the life of rooks and roosting as a particular fascination. Its made me think more about the act of roosting in all species and the mechanisms which they operate. Theories of warmth and predation protection all have a place but there is a series of deeper layers that constitute a complex web of interactions that govern roosting he suggests. The first time I saw the wagtail roost in town I noticed each bird was spaced out and visually look at intervals, they looked like the illustrations of atoms in the school science books. Why for instance would they not choose to roost closer together? Along with other ideas its fascinating that behind the simplicity greater things are at work.

The third visit to the roost recently as a result of me being late at the gates to photograph waxwings, finding the flock had stripped the last of the trees and moved on, had me waiting for a bus and not far from the centre so I went to observe them again rather than photograph. This time I noticed certain birds moving away from the obvious roost. After investigating the vicinity once the birds became settled I confirmed my hunch after finding another roost among an ivy clad tree. With no street light directly illuminating them and nestled among the ivy they kept a very low profile. I ask myself if most don't notice the obvious ones then how many have unlocked the secret roost? I rather like the secret roost.

So, I guess I'll leave you to find a pied wagtail roost. Winter is a great time for many roosts.