Phil Tizzard raised the question of ageing Northern Wheatears in the UK in autumn. This is far from easy in the field, particularly with females. I’ve always thought that adult (winter)males exhibited a plainer, darker wing with less obvious feather fringing than juvenile/first-winter males, which is why I would have been inclined to have aged the Stanford individual as a juvenile/first-winter had I seen it in the field. It appears, however, that this is far from clear cut. According to Svensson (Identification Guide to European Passerines), the only infallible criterion for ageing these birds is the colour of the inside of the upper mandible, which is yellow in juveniles/first-winters as opposed to grey-black in adults. This means that attempting to age autumn Northern Wheatears in the field could be very tricky! The Stanford individual had a yellow inside upper mandible and so could be aged confidently as a first-winter (or, if you like, ‘older juvenile’). Here is another photo of it with its wings closed. Note how the upperparts appear greyer here than in the image in the previous post.
I like a challenge so I will be paying a lot closer attention to autumn Northern Wheatears in future … Thanks to Phil for bringing this up and to John Cranfield for helpful comments.
At the moment Stanford Reservoir is looking good. Very good. I spent this morning there with the Stanford Ringing Group, during which time 104 birds were trapped – although 28 of these were local retraps. As well as local breeders, many of those caught were autumn migrants with Blackcaps and Common Whitethroats predominating, although there were reasonable numbers of Willow Warblers, a few Chiffchaffs and a couple of Lesser Whitethroats and Reed Warblers. From next week just about all of the warblers trapped will be migrants. Two Treecreepers provided a great opportunity for close, in-hand scrutiny of their intricate plumage detail, which also enabled them to be confidently aged. The best bird trapped, however, was a Northern Wheatear, which is only the second ever to be ringed at Stanford (the other was on 5th September 1982) and, as
such, caused a not undue amount of excitement among the members of the SRG! This individual was a juvenile and the black lesser and median coverts – along with some grey just visibly appearing on the scapulars – sex this as a male. It’s worth mentioning that the SRG will, for a small donation, organise ‘demo days’ in order to raise funds now that their previous funding has recently been withdrawn. By the way, rings now cost 20p each and the group is responsible for its own finances. With mist-nets costing in the region of £100 each ringing is not an inexpensive activity!
The water level at the reservoir itself is very low, almost resembling a small estuary, and the habitat there is proving a massive draw for waders. Among today’s haul were Knot, Spotted Redshank – initially found by Mark Piper – 7 Greenshanks, 11 Ringed Plovers, 2 Dunlin, Black-tailed Godwit and, together with Dave Warner, I counted a total of 18 Ruff – a tremendous figure for Northamptonshire in recent years.
My thanks to SRG’s John Cranfield, Mike Townsend, Adam Homer, Ed Tyler and Debbie for their jovial and instructive company this morning.
Autumn waders start to appear at local reservoirs and gravel pits from July, although some (e.g. Green Sandpiper, Common Sandpiper) are as early as mid-June. These are returning adults but from about mid-August the first juveniles start to appear. Here are a couple of waders which were at Hollowell Reservoir this evening. Dunlin and Ringed Plover are common enough but how hard do we look at them? These two individuals are clearly
juveniles. The Dunlin has many fresh, broad, pale fringes to the upper parts – including a white mantle ‘V’ – and coverts but already there are two plain grey scapulars, with a dark shaft streak, of first winter plumage clearly visible. The Ringed Plover, as well as having a partly broken brown breast band, also has neat pale fringes to the mantle and coverts and I’m guessing it’s a nominate hiaticula race as it’s fairly pale, the supercilium behind the eye is quite broad and the bill appears quite thick, even though it’s collected a lot of mud. Other waders at Hollowell this evening were five move Ringed Plovers, three Green Sandpipers, two Common Sandpipers and four Greenshank. The water level continues to drop and it’s looking good for autumn …
Found late yesterday at Pitsford Reservoir and, despite its best attempts to outwit and elude this morning’s would-be observers (including me!), this fine summer-plumaged Black-necked Grebe finally gave itself up to those who entered Maytrees Hide and found it hugging the shoreline behind the reeds, where it remained invisible to birders looking from the perimeter path.
Only a few Black-necks are found in the County annually and many of these are juveniles in early-mid autumn plus the odd one or two in winter. Summer-plumaged individuals are rarely encountered so this one provided a real treat to those who were fortunate to see it this afternoon.