Aythya Puzzle

TUESDAY 18 AUGUST

Another warm day, with SSW winds and predominantly clear blue skies. Passerine passage picked up a little today but most intriguing was an Aythya hybrid.

MARSWORTH RESERVOIR, TRING

Arriving at Marsworth mid-morning, the first bird I set eyes on was a reddish-brown diving duck with a striking pearly coloured eye. It was roosting with a small group of Aythyas, including 3 Pochards and 3 Tufted Ducks. There was little difference in size, and significantly it had the peaked rear crown, the almost black mantle and back and gleaming white undertail coverts. In many ways it resembled a drake Ferruginous Duck and on closer inspection, the black on the bill was restricted to the nail, which is rare in hybrids; they generally have black extending right back along the bill flange. It also had paler ferruginous brown on the flanks and sides and the whiter patch on the belly. It was a totally baffling bird but 1) the presence of some blackish feathering in the breast, 2) its apparent larger size comparable to Pochards and Tufted Ducks and 3) the lack of a contrastingly pure white upper wingbar, led me to consider that it was a hybrid rather than a drake Ferruginous Duck in full eclipse. Furthermore, there was some brown staining in the white undertail-coverts. I contacted DB, SR and MCo, the latter two observers arriving within ten minutes. Some record shots were obtained.

The bird continued to show very well, occasionally retreating to the reeds in typical Ferruginous Duck fashion before re-emerging and was still present when we all departed late morning.

It was another momentous day for the local grebe population - the two nesting pairs of Great Crested Grebe now harbouring two stripy young apiece - that makes FIVE young in total now.

There was also a single juvenile Little Grebe on Marsworth, a single adult Mute Swan, the escaped female Red-crested Pochard, 4 Gadwalls and a surprising sight of 3 Jays.

STARTOP'S END RESERVOIR

Mike Wallen had covered the early shift and made some good 'finds'. An eclipse-plumaged NORTHERN PINTAIL was the first of the autumn and was showing well feeding just off the mud bank in the shallows, whilst the two adult WHOOPER SWANS were present for their third day and washing and preening on the mud. These are the pair which bred unsuccessfully at Dunstable Sewage Farm for the second year running and are part of the non-naturalised population emanating from Wardown Park, Luton (in Bedfordshire).

A total of 26 Mute Swans was also counted, 2 Shoveler, the female Tufted Duck with her four young and 27 House Martins.

WILSTONE RESERVOIR
(midday; with Mike Collard)

Great Crested Grebes (23)
Little Grebe (the two juveniles still present)
LITTLE EGRETS (4 roosting together in the Willow)
Mute Swans (34)
Common Teal (22)
Northern Shoveler (32)
Lapwing (407)
COMMON SANDPIPER (1)
COMMON GREENSHANKS (2 juveniles remaining)
Common Tern (17)
LITTLE OWL (2 in tree by car park)

IVINGHOE BEACON

No shortage of people, eating ice creams, walking dogs, flying kites, flying aeroplanes, sunbathing, making love, smacking crying children, but a distinct lack of migrants. In over an hour of searching, my only rewards were two juvenile NORTHERN WHEATEARS - both commuting between the slope SE of the Beacon and the fenceposts to the east of the sheep pens. Steve had seen an additional bird to these that Mike and I recorded.

DOWN FARM, ALDBURY (SP 958 145)

I was delighted to find a large flock of post-breeding buntings feeding in the freshly cut stubble just left of the access road to Down Farm, consisting of 16 CORN BUNTINGS and 7 YELLOWHAMMERS. The birds were commuting between the field and the roadside hedgerow and included 7 juvenile Corn Buntings. There were also two migrant COMMON WHITETHROATS in the hedgerow.

MISWELL FARM, TRING (SP 913 120)

I retraced the steps taken by Roy Hargreaves each and every morning of the year and boy, am I impressed with that guy's stamina and that of his ageing dog. I did it just once and after the 125 minutes it took, I was absolutely knackered. No wonder he visits just once a day !

Anyway, the real reason for this craziness was to twitch the reservoir's first WHINCHAT of the autumn (and year if my memory serves me right). Roy had found this bird early morning and as I scanned the fence posts immediately west of the farm at 1400 hours, I quickly relocated the bird. It was favouring four posts at SP 910 120, at the far side of the first field NW of the farm, opposite where the motor homes and caravans are parked, and was a fresh juvenile. It was fairly settled, and on meeting local birder Nick Goss on my return at 1530, I was able to quickly relocate it and show him it.

This same area provided firm evidence of Linnet breeding - a pair feeding a single youngster in the hedgerow, whilst 63 BARN SWALLOWS were in noisy flight above Miswell Farm.

Walking down towards the Wendover Arm, a COMMON WHITETHROAT was recorded, along with several Common Chiffchaffs, whilst the fields being harvested yielded 105+ Jackdaws and at least 43 Rooks.

A male YELLOWHAMMER was in stubble adjacent to Rushy Meadow, whilst the fields west of the reservoir held 2 Common Chiffchaffs, 2 Common Kestrels and a family group of BULLFINCHES. At least 1 SPOTTED FLYCATCHER was still present in the field behind the hide.