Otmoor: 17th May

I made a brief visit to Otmoor this morning, with only enough time to scan Big Otmoor for waders. The overnight rain had continued and was torrential at times. I set up my ‘scope and scanned the rear pool of Big Otoor and immediately my viewfinder was full of waders. This is how it should be! 7 summer plumaged Dunlin were nice, but it was a glowing white Sanderling that stood out, complete with black legs and thick black bill. With 3 Sanderling at Rushey Common yesterday and 3 at Farmoor and 1 at Grimsbury Reservoir the day before, it looks as if small numbers are passing through the county at the moment, presumably grounded by the recent rain.  I also got a brief view of a Black-tailed Godwit (perhaps one of the three present on Monday?) before it disappeared behind one of the islands, never to be seen again. If a wader of that size can go missing, what else might there be at the back of Big Otmoor, between the islands?

I am never ceased to be amazed at the detail modern cameras can capture. Taking record shots of calidris waders at that distance in the rain is probably a form of photographic madness, but you can make out the Sanderling in with the Dunlin… if you squint just a little:

It would have been good to have had another hour or so this morning, although I was saturated after 45 minutes. It felt like there should be more good birds waiting to be found on the reserve.

Common Scoters in Oxfordshire

Common Scoter winter off the coast of Western Europe, from northern Norway to Western Sahara. Spring migration sees birds moving north into the Bay of Biscay and then east across the North and Baltic Seas before an overland route to their breeding grounds in northern Scandinavia and Russia.

A recently published web article by The Sound Approach records the nocturnal migration of Common Scoter over the Iberian Peninsula and also includes this map of the breeding range:

© The Sound Approach 2017

The Sound Approach team mapped hypothetical migration routes, plotted from nocturnal sound recordings, as green dotted lines on the map above. By joining up the green dotted lines that pass from Iberia to those that pass across the English Channel, to those that represent the Baltic flyway, one can plot a path that passes across south-east England and potentially, Oxfordshire. Although these green lines are hypothetical migration routes, they neatly explain the pattern of records of Common Scoter in Oxfordshire.

Common Scoter in Oxfordshire is considered to be an annual scarce passage migrant, see the table below. An analysis of records submitted between 2002 – 2012 show three peak periods of occurrence. The first is in spring, with frequent records in March and April, which coincides with birds moving from wintering areas towards their breeding grounds.

The second peak of Common Scoter records in Oxfordshire is in July. These mid-summer records are noteworthy, as the table reveals that one of the best months for recording Common Scoter in Oxfordshire is outside of the expected spring and autumn passage periods.

This spike of mid-summer records may be explained by the complex post-breeding behaviour of Common Scoter. After breeding Common Scoter move to favoured moult sites. In the UK large gatherings have been reported off the east coast of Scotland and in Carmarthan Bay.  The numbers involved are far greater than the small UK breeding population of under 200 pairs, so must involve birds from other breeding areas. In Europe, an extensive moult migration takes place, with large gatherings of moulting Common Scoter in the Baltic, the eastern North Sea and off western France (The Migration Atlas, BTO, p.689) . The number of records of Common Scoter in Oxfordshire in July could be explained by birds moving towards moult sites after breeding.

The main bulk of Oxfordshire Common Scoter records are from the autumn and early winter period of September to December. This coincides with the movement of birds from their moult sites to their wintering grounds. Studies of the British breeding populations show that birds disperse widely to a range of wintering sites. The Icelandic population is the same: birds from the same breeding areas spend their winters in different wintering areas over a large geographical range. As such, birds from a wide range of breeding areas will move south and west in autumn and some of these birds may be attracted to large water bodies within the county as staging posts on their migration. Virtually all records of Common Scoter come from Farmoor Reservoir, in the period 2002 – 2012 there was just one exception, a bird at LWV pit 60 on 18th September 2006. As summer approaches, so will post-breeding Common Scoters, heading to a reservoir near you.

An Alfrey, two Robeys and a Garganey

With only a short time free on Monday morning, I popped into Otmoor in the hope of seeing a few waders. The cold northerly winds may have been keeping some migrant birds back, but the windchill was surprising for May and made using gloves essential. With limited time, I restricted myself to scanning Big Otmoor. The only waders present were all distant on the pools at the far side of Big Otmoor: 2 Little Ringed Plover, 2 Dunlin plus the usual breeding Redshank and Lapwings.  Then two familiar figures appeared on the bridleway, Pete and Steve Roby, two thirds of Team Greylag, one of our competitors on The Big Day last Saturday. They were moving around to get better views of a drake Garganey, perched up in distant poolside vegetation. They relocated the bird, which was mostly asleep, but occasionally it raised its head to show off the boldest supercilium in the birding world. I took a few speculative records shots with my camera, though this bird was small even in a ‘scope:

Above, drake Garganey, Big Otmoor. Below, Cuckoo in the bridleway hedgerow:

It is always good to see the Robys. But the biggest surprise of the morning was a figure that appeared leaving Otmoor as I arrived. Someone I have never met before, but who was immediately recognisable: Peter Alfrey. Peter is best known for his sterling work at the Beddington farmlands in south London, where he is partly based and for putting the Azores on the map as one of the western Palearctics migration hotspots. His epic 2005 visit is part of birding folklore. I looked up and there was the distinctive figure of Peter Alfrey, walking towards me. “Mr Alfrey?!” I exclaimed. I explained that we had never met, introduced myself and we chatted birds. Peter is now partly based in Oxfordshire, so may be seen more frequently on Otmoor. Look out for a dashing figure with a long bird list. We discussed his morning and the general lack of waders that we had anticipated. Speculation then turned to a Red-rumped Swallow joining the gathering of hirundines over the reedbeds or the possibility of a Red-footed Falcon joining the Hobbys over Greenaways. I reminded Peter where we were: this is Oxfordshire. He may require a period of adaptation. Welcome to Oxfordshire Peter, I hope you can cope!