Wednesday 15th November – A Little Report

A “Little Report” because there is not much to report from today. The reserve was busy with a large group visiting from Christchurch U3A, but the bird news was fairly unremarkable.

Opening Tern hide I heard the or at least a water pipit calling, but could not see it. The lake had the now usual gathering of pochard. My count of 96 yesterday was by some margin the largest I have seen for a good while, there was a time when they were common at the lakes, with flocks into several hundred. Over the last few years pochard numbers have declined, not just here but right across Europe. Over the last 25 years there has been a 67% decline in wintering pochard in the UK. There are many possible reasons for this. They particularly like eating stoneworts, aquatic plants that grow well in oligotrophic (low nutrient) lakes, newly flooded gravel pits usually have very few nutrients and so are very good for them. However over time lakes acquire nutrients form many sources becoming less suitable for stoneworts and pochard. This is probably one of the main reasons for the decline at Blashford.

It might be expected that gravel pits in lowland England would gain nutrients, weed will grow and die, birds will import droppings and fish will mobilise sediments as well as adding their own contribution. In addition the rain is known to be contaminated with nitrogen which it picks up from the atmosphere, where we have added additional nitrous oxide to that naturally present. Recent reports by researchers at the British Geological Survey have highlighted that nitrogen fertilizers have leached their way down into the groundwater and will be coming out for decades to come.  These sources of nutrients do not include straight forward pollution by industry, sewerage etc. The increase in nutrients is impacting both natural and man-made waters and means that we are faced with a future where most lakes, at least in lowlands will be eutrophic, that is nutrient rich. Ultimately such lakes are likely to be dominated by algae, with little higher plant growth upon which most of our wildfowl depend.

Unfortunately for the pochard it seems that it is not just increasingly unsuitable waters that are against them. It has long been known that wintering flocks in the UK hold more drakes than ducks. Last winter wildfowl counters across Europe were asked to provide the sex ratio of the flocks they counted. This showed that across the whole of Europe the proportion of drakes in flocks had risen from 61% in 1989-90 season to 70% in 2016. The proportion of drakes being higher in northern Europe with more female wintering in southern Europe. It might be expected that females would suffer higher mortality at nesting as they nest on the ground where they are vulnerable to predators. However this is probably not the only reason fro the discrepancy. By wintering in southern Europe where hunting is more popular they are probably more often shot, but worse still they are especially vulnerable to ingesting shot and are more likely to do so in areas where there is more shooting. The paper outlining this research will be available soon at http://www.wwt.org.uk/conservation/saving-wetlands-and-wildlife/publications/wildfowl/ .

Anyway back to the day’s news, at the Woodland hide brambling was again seen and overhead a few redpoll could be heard in the siskin flock, things are looking good for large finch flocks later on. Towards dusk heading out to lock up I heard a firecrest again near the car park and this time also saw it, my first one seen this winter at Blashford, although  one was reported the other day from the main car park. On Ivy Lake Walter the great white egret was again at his roost in the dead alder with 150 or so cormorant also roosting in the trees around the lake.

I did have one non-bird sighting of interest, a common darter dragonfly still on the wing, my first for ten days or so, each year I hope to beat my latest dragonfly date of 19th November, which I have managed three times, I don’t think this is going to be the year though, with so few still flying.