Ruler of The River
In the uplands rivers of the UK, there is a small, shy, charismatic creature that rules our waterways with a subtle determination and spectacular efficiency. Camouflaging himself amongst the river bank debris, he goes unnoticed by many who pass him. Occasionally, we catch a glimpse, a flash of brown and white, a tuneful song, as he flies stealthily over the water surface.
The white-throated dipper. A plump, little passerine, unique to his order Passeriformes, as the only aquatic member. Due to his flashy bobbing and quirky dipping (he’d have moves on the dance floor) behaviour, which he displays whilst he perches on rocks and vegetation on the side of the river, the dipper is aptly named. As a highly territorial species, each dipper pair usually commands around 500m-2km of a river stretch, viciously fighting off any trespassers. In addition, the white-throated dipper is an important little bird to us humans, because we consider him a vital bioindicator species. But this aquatic master is a sensitive and slightly picky little bird, as only the cleanest upland waterways will satisfy him. This is largely due to the presence of his invertebrate prey, who dwell on the river bed and are only present in those waterways that do not experience high levels of pollution.
In the summer of this year, I decide to get to know this charming bird a little better, choosing to study his feeding behaviour for my postgraduate dissertation. His importance as an indicator to the health of our environment was my main basis for this decision and I wanted to know the particular requirements that this bird demands. Or at least get an idea. Armed with my dad’s astronomy binoculars (yes, they were very heavy), some recording sheets, an invertebrate net, a stop watch and some buckets, I traipsed down to the beautiful upland river, near my parents house, in Northumberland. I already knew there were several dipper pairs present, having walked many stretches of the river and getting an idea of their territory boundaries. I had seen some spectacular fights between neighbouring pairs, and often the dippers were good enough to sit on rocks at the very boundary of their territory, keeping a close watch on their neighbours.
So, all I had to do at the beginning of each day, was find them. All? Easier said. Occasionally, I was lucky enough to settle myself in the undergrowth (I looked very odd to walkers), arrange my equipment and look up and there one of my dippers would be. Other times? Not so lucky. I waited and waited and waited, is that rain I feel? After an hour or so on one day, one of my dippers arrived, plonking himself on a rock, ready for a dive. He had been there less than a minute, when a large springer spaniel called Furgal (my own springer spaniels father) came crashing out of the woodland, into the river and chased my dipper away. Furgal was happy. Me? Not so much. A sigh, a soppy lick from a wet dog and I settled back down again, resigned to my fate of forever waiting. Maybe they would find me one day and make a film about me and my determined effort to observe these birds. Though I doubted it, it would have been a huge flop at the box office, but I can dream!
But then, after all hope felt lost and what seemed like the passing of a few geological periods, my dipper would appear. Occasionally, if he was near enough so that I didn’t need my binoculars, he would glance over at me, staring and surveying me, as I froze. He probably knew I was there, staring at me and saying:
‘Look. If I splash about a bit, will you go away?’
My answer in this imaginary conversation? Yes. Yes, I will.
But if I was reading this, I realise there would be a couple of questions I would be asking. First, what exactly was I looking for? And secondly, why in the world did I have a net with me? Well, reading the literature, information on their exact feeding behaviour seemed either a little vague or contradictory. Now, we know they feed in fast flowing riffles and occasionally deeper pools and this seemed to be the general consensus. And as I wanted to focus on the dipper, I decided to see if I could find out what he preferred, pools or riffles? Also, if there were a particular feeding behaviour he displayed more frequently, out of walking and pecking (in very shallow water), swimming, or diving. And the net? No, I wasn’t attempting to catch our little bird. That would have resulted in my dipper flying off, unfazed, whilst I ended up face down in the water. No. In fact, I had to do some invertebrate sampling to try and see if I could correlate a particular food source to a particular behaviour or area (pool or riffle).
In total, I observed 10 dipper pairs (time was limited), and as it was summer, juveniles were still present in their parents territories, but I did not include them. Not because I didn’t value them of course, but because their foraging behaviour would not yet have developed to the extent of their parents. Now, I won’t bore you (if I’m not already, sorry) with any more details, or go into my exact methods and statistical analysis (which was a delight), but I did manage to get some interesting results. Across all habitats, I identified over 4000 invertebrates. Through the method of kick sampling, invertebrates were collected into nets and emptied into buckets of water to be identified. When this was finished, I would place them back into the river areas I collected them from. Now, if I’m honest this was a bit long and laborious and if I said I enjoyed it, I might be lying. But it was necessary and all in the name of science (well, I tried anyway).
So, what was the outcome? Well, to my surprise and in contrast to some of what I had read, my dippers actually spent more time at pool areas, diving and swimming. They also spent time pecking and swimming at riffles of course, but this seemed a less popular choice. Again, I won’t go into the details of everything, but it seemed there was one clear reason for this. Fish. More often that not, dippers were diving into deep pools and re-emerging with fish. Fish provide large meals and good energy sources, whilst at riffles, they were generally catching smaller invertebrates such as mayflies and stoneflies.
But who cares? So what if they are catching fish and spending their spare time hanging out at pools? And who say’s what I found was right? Well, good point and I’m not suggesting that what I found is the final, full stop, no need for anymore thank you very much, definitive research. But, none the less, it was interesting (to me and my supervisor at least). In addition, as a bioindicator species, if they are absent from a watercourse, we know that the water quality is probably poor and lacking in prey species. But if we want to attract this species, it can’t hurt to know exactly what they like in a habitat. If they do in fact spend a lot of time at pool areas, and these are lacking in certain stretches of a river, this may explain why the species is absent, or why there are very few dipper pairs. The more information we have, the more chance we have of better understanding a species that is very important to our riverine environments.
Go on, see if you can find a dipper near you. You might have a bit of a wait, but they’re fabulous to watch and really are a charming species.
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