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| Starlings Galore |
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Jean Lawman witnesses the spectacular twilight display of the Starlings at Marazion Marsh... We were a small group waiting on the bridge. In a willow, standing alone in the reed-bed, another waited, though for different reasons. Ours was the visual thrill - the spectacle of avian aerobatics, the immense energy and beauty of the display. The hawk was there for a simpler reason, an easy meal - survival.  A starling in the snow (picture by Pete Cross) It wasn’t the perfect evening I’d anticipated and indeed experienced in the past - the still, chilled evening with the water quiescent and reflective in the bay, pink-tinged in a winter sunset. Instead, there was a bitter wind to numb the cheeks and a line of billowing clouds on the western horizon. They were an impressive, almost threatening, purple-indigo, but they were thinly outlined in gold. The clouds and the ominous roar of breaking surf over the traffic noise hinted at a wild night to come. The sky above our upturned faces was clear - translucent blue with an unlikely lemon wash - a brilliant backdrop for the dark, swirling mass of birds we were hoping to see. We scanned the horizons, looking east then west then north, and seeing nothing, glanced down again at the shining surface of the pool where even in this late hour Little Grebes slipped quietly below the surface, and a diving Cormorant left skeins of silver ripples. Then we were alerted to a flock of Curlew flying over, by their melancholy, liquid cries; they were heading southwest, either to roost or to feed. Their activity, like many wading birds, is often more tuned to tidal rhythm than to daylight. They were most likely heading across the bay to St. Clements Island, that little spread of rocks off Mousehole where I had counted over a hundred flying in and settling to roost before dusk on the previous day. I tried to imagine them standing out there among the Christmas lights. At last, a small, dark ball came spinning in from the west; the vanguard had arrived. About thirty Starlings sped overhead, gyrated upwards then traced a neat spiralling curve down over the reed-bed, to be joined, or rather to coalesce with another group before heading skywards again. One second they were black silhouettes above, next they were pale brown as they skimmed over the reeds. Some eyes followed one flock eagerly; others searched around for more. We wanted more – bigger flocks, more fantastic manoeuvres, scaling up as time went on, and they came. The show got better and better, but what seemed like hours was actually minutes. A contingent of about five hundred swept in from the west, and then another came, and another. They arrived from behind us too, from the east, rushing low over the stone bridge to join the swelling ranks. There were thousands soon and we were sure there would be no more but then thousands more would arrive. With loud swishing sounds, impossible numbers of them they filled the sky, wheeling, twisting, spiralling, rising and falling, perfectly co-ordinated, behaving in fact like a single organism. As flocks spread they sometimes tapered and left tails, or they bunched as another group sifted in. One thought of comets and swirling smoke. We wanted to know how many there actually were, but how to count them? How can anyone count them? The usual way of counting a flock of birds is count to ten, draw an imaginary ring round them, then count rings of ten until you reach a hundred, then count rings of a hundred and so on, but not with these surely; the speed they travelled, the wayward flight and constant new arrivals made it impossible. It’s best not to worry about numbers and just enjoy them. Some began falling like spilt grain onto the reed-bed, darkening the tawny tips before they slipped down further to find their space. More and more birds followed, literally falling out of the sky; eventually, the reeds turned black. As soon as the first birds were down, intense chattering began, becoming louder and louder as numbers grew. Starling language is an incredibly diverse mix of airy whistles, wheezes, metallic chinks, bone-cracking clicks and much more. It sounds excitable, urgent and must be very important social discourse. It was then, as we tried to focus our binoculars on the ever-darkening reeds, that we became aware once more of the Sparrowhawk. It was gliding leisurely over the reeds, just above the topmost birds, causing much agitation. Groups of birds rose above the reeds and dropped down again a short distance away. It was getting dark and it was hard to see what was going on, but there was no impression of serious hunting or of a bird being caught. The hawk may have already singled out a bird that was alone and vulnerable while we were distracted by the flight of the masses, or perhaps it would strike yet under cover of darkness. It was difficult to see more. The starlings had settled; the silhouettes of the Little Grebes could still be seen on the pool and the Cormorant had gone. The cloud was thickening and advancing. It was time to head for home. As I drove back, I thought about the starlings in the reed-bed; were they clustered tightly together for warmth, in tiers above one another, or were they well spaced out? Were they clinging to reeds or hugging the ground? However they had arranged themselves, most were probably safe, except for those on the extreme outer limit of the roost. What could threaten them? Sparrowhawk, Mink, Otter, Rat, Weasel, Stoat. No, you wouldn’t want to be a Starling on the edge. The advantages of forming such large roosting flocks evidently outweigh the disadvantages otherwise they wouldn’t do it. It is not for play or for entertaining humans. It is a highly organized affair, like a military occupation, involving the formation and joining up of numerous pre-roosting flocks from all over the surrounding countryside, prior to their arrival at the reed-bed. Clearly large flocks of birds attract predators, keen to cash in on an easy meal, like the Sparrowhawk, and sometimes a Peregrine. A bird roosting on its own is 100% vulnerable, but the risk of being caught goes down with each additional individual, 2 – 50%, 4 – 25% and so on, meaning there is safety in numbers – as long as you keep up with the rest. The slightest inability to manoeuvre in synchrony with the rest means that a bird may be singled out for chase by the hawk. It would be dangerous for the predator to penetrate the flock, as in the confusion it could injure itself: better to stay on the edge, to antagonize the birds, and then to attack the one that makes a mistake. Watching a predator in action is spectacular, and arouses excitement among the onlookers. In the Starling world, the young, especially females, get a bad deal as far as their position in the roost is concerned, for the best places in the centre are occupied by older, experienced birds, males dominating over females, hence all the shuffling about after the birds have gone down, and research has shown that they do not huddle together for warmth; possibly because there is less risk of diseases spreading through the flock. If they are at risk on the edge, why do the juveniles join the roost, especially as it may involve flying from distances of up to 50km away? Researchers believe they have an explanation: the roost is said to act as an information centre where the birds learn about the whereabouts of good feeding sites in the surrounding countryside. For young and inexperienced birds this can be an important survival issue, outweighing the disadvantages they face at the roost itself. In the early hours of the morning, starlings leave the roost, not all at once, but in groups with intervals of about 3 minutes between departures. By first observing, and then joining, or following plump, well-nourished individuals to their feeding grounds, inexperienced birds will benefit, as the alternative would be their own random and usually less effective foraging. The well-ordered manner of leaving the roost was discovered accidentally by people working with radar screens, who became mystified by the appearance of a concentric rings that moved outwards in all directions from one point and then slowly disappeared. It happened at the same time every morning. They called them ‘angels’. These ‘angels’ were later discovered to be starlings leaving their roost, and demonstrated the distinct pattern of departure. First there is a rise in the volume of chattering until it reaches a crescendo, followed by sudden silence as some birds make short flights over the roost. These birds then leave. This sequence is repeated several times before the final group of birds take to the air and head off to feed. The importance of spacing, and flying in perfect synchrony, twisting and turning at precisely the right moment, is associated with keeping safe within the flock, and its importance cannot be over-emphasized. How they manage to do it is a constant source of wonder to us. Our Red Arrow teams are brilliant but there aren’t hundreds of thousands of them in the air at the same time, are there, thank goodness! In a large flock of small birds, such as these starlings, it appears that there is no leader to initiate each manoeuvre, but each bird follows every slight adjustment of angle or direction in their part of the flock: this can be instigated by a bird joining it. The birds immediately adjacent to the change respond relatively quickly, but as the alteration spreads, the other birds in the flock are able to anticipate the move more rapidly as it happens, and adjust more quickly, hence the speed of the operation. This is the theory, and perhaps it can be detected in slow motion filming. The roost at Marazion, has been used regularly for a number of years, and may be traditional. It has been estimated recently by photography as consisting of somewhere between 100,000 and 200,000 birds. Ornithologists say that the Starling population in Britain is declining, although when you see this annual spectacle it seems impossible. They have declined though, by 66% since the mid 1970’s, and are now on the Red List of highly threatened species. Problems appear to be chemicals, the lack of permanent pasture, and a dearth of nest sites. The fact is that most of these Starlings are not British birds, let alone Cornish, and they disappear by the end of February. Ringing has shown that they are visitors from Europe – Holland, Germany, Poland etc and possibly from Scandinavia. British Starlings don’t migrate, and certainly winters in Cornwall are usually mild with ample food. Not everyone likes the starlings; we marvel at this twilight display, but the roost does cause problems. Accumulated droppings mean that high levels of phosphate end up in the water and may or may not get flushed out in to the bay, and physical damage to the reeds themselves results in less vigorous re-growth in the spring. So there is a cost, but this is no reason why it should detract from our enjoyment and wonder at this simply amazing event happening throughout the winter here in Cornwall. You cannot help but be enthralled by it. | |