More on the Great Northern Diver at Farmoor 23rd December 2020

Since the 3rd of November Farmoor Reservoir has played host to a juvenile Great Northern Diver. It settled down to almost exclusively feed off the eastern bank of Farmoor Two, the larger basin, and appeared quite content. Unfortunately, exactly a week later, a careless fisherman managed to sink a hook into its wing and the diver, calling in distress, had to be reeled in and disentangled from the hook. It was immediately released back onto the reservoir, physically unscathed and remarkably it elected to remain in the same area for the following four weeks.

Around the 9th December the diver was seen off the eastern bank with what appeared to be fishing line entangled around and hanging from its bill and it was feared the worst had happened, although to my mind the offending article appeared to be a little too thick to be fishing line. Whatever it was, it remained hanging from the diver's lower mandible and examination of photos showed that it was wrapped tightly round the base of the lower mandible but did not seem to inconvenience the diver as its behaviour and feeding carried on as normal with no visible deterioration in its well being over the ensuing days.   

Fishing line and birds do not mix and Farmoor is no exception, with the large number of fishermen coming to fish the waters creating an obvious threat to the birdlife on the reservoir and in this last month alone at the reservoir I have seen a Mute Swan with line entangled in its bill and a Coot seriously injured with line wrapped around its leg, cutting off the blood supply to its foot. Special containers have been placed by Thames Water around the perimeters of both the reservoir basins, where discarded line can be securely deposited and the majority of fishermen do make an effort to not leave line lying around but regrettably a minority are less conscientious.

On 11th December the diver was found to have moved to the more distant and altogether quieter, less disturbed southwest corner of Farmoor Two and has remained there ever since.

After the diver had moved to the southwest corner it would come much closer to the bank than it had ever done when off the eastern bank, possibly due to the reduced disturbance and this allowed me to better examine the thin strands hanging from its bill. Again I was struck on how it looked slightly too thick to be fishing line. Could it be wire from a trace used by pike fishermen, a simple piece of string or was it just weed after all? It was impossible to tell.

Day after day the same thin strands hung from the diver's bill but on one sunny and still late morning,  sitting in the company of the feeding diver, I noticed that whenever the diver surfaced it was bringing up varying amounts of thin strands of weed that hung from its bill and which it freed by violently shaking its head from side to side, but always the same thin piece of suspected line remained hanging from its bill. Could there be both weed and fishing line involved?

I carried on watching the diver and finally it surfaced with no visible strands of anything hanging from its bill. The persistent strand  that had hung from its bill for days was no longer there! It must have been weed or far less likely may have been fishing line that finally became dislodged from the diver's bill by becoming entangled with some of the strands of weed the diver brought to the surface on a subsequent dive and discarded.

The Great Northern Diver finally free of any artificial attachments!

Last Sunday walking around the reservoir with Dave and Amanda we noted the diver surfacing and re- confirmed it was still free of anything hanging from its bill and today I went to have another look at the diver and it was still free of anything hanging from its bill. I watched as it dived and surfaced and noticed that it regularly brought up strands of weed in which a small fish was trapped. The diver would extract the fish from the strands and swallow it. This was probably what happened all those weeks ago when a strand of weed became trapped around its bill.

So it is with relief all round that I can report the diver seems happy and safe in its quiet corner of the reservoir. I do hope its stay is prolonged and, you never know, it may remain until the Spring which is a pleasant prospect to look forward to.

With the current lockdown coming into force on Boxing Day it should be much quieter than normal on the reservoir over Christmas and New Year which can only be beneficial as far as the diver is concerned.

Postscript

The diver was last seen on the 23rd of December.