Falling temperatures (reaching -4C) have resulted in the whoosh netting coming to a grinding halt - partly because the whoosh nets won’t fire in such conditions but also due to the fact that Bank Island has completely frozen and is now duck free!!
The duck trap at North Duffield Carrs Top Pond has however been producing the goods, the resident Mute Swans are keeping the water around the trap ice free as they pick up any surplus grain. Combined with a few odds and sods picked up elsewhere, at total of 52 new ducks have been ringed during the first five days of February, bring the years running total to 208. Teal are still making up the bulk of the catch, numbers ringed in 2012 have reached 116, whilst as usual in February, Shelduck are starting to feature with 8 caught and colour-ringed so far in the last few days. 45 were present around the traps this morning (5th) so hopefully we’ll get a few more in the coming days.
It’s not just the numbers that are important - it is clear that the hard weather and freezing conditions are already having an effect on the birds. Over the last 8 days the average weight of Teal has fallen by about 30 grams (8-10% of total body weight) - probably due to both difficulty in accessing food and also in maintaining body temperature, so useful data too. It highlights the value of conservation measures such as voluntary restraint periods and why addressing access and disturbance issues are important, especially during cold weather.
There was also an interesting re-trap at North Duffield Carrs this week - a female Wigeon originally caught as a breeding female there in July 2010. The breeding population of British Wigeon is relatively small and very few are caught and ringed so we don’t know much about them and their movements. A significant proportion of those UK breeding birds that are ringed are probably done in the Lower Derwent Valley NNR but that only numbers c30 out of the 1950 Wigeon ringed in the valley. This is the first one we’ve re-trapped and it is interesting that it has chosen to winter on site as well.
Finally, whilst it might be hard on the birds, the weather is also impacting on us, the ringers. There’s been a fair amount of cold hands and feet during the week, but lots of ice breaking that’s had to be done in order to get to the traps. Tough these volunteers!!
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