Sunday, 7 March 2010

and Today the First 'Proper' Twitch of the Year

Justify FullA photograph from yesterday of a (white-winged) Carrion Crow which has frequented my local area in the past couple of years. This is only an anomaly and not a true species.

The only word on the mind of the majority of Dorset 'birders', and many, many from further afield, over the past 24 hours has been Bufflehead, as a result of a most bizarre report received around noon yesterday. I was at the Portland Bird Observatory enjoying a coffee when the news of a 'probable' Bufflehead was received, from what I considered to be a most reliable source. Alan Barrett a long time birding mate was watching his local patch at West Bexington, a few miles from Weymouth, when he saw what he suspected to be an adult male Bufflehead. I know the feeling when you find a bird of this magnitude, and start thinking was it really that, have I got the identity right etc, etc. Unfortunately, no more was heard until dusk when it was re-located at Abbotsbury, a short distance to the east, and confirmed as such. A few locals were able to get there before darkness fell, but the main thrust was always going to be this morning when a further search would be made.

Please note, the following photographs do not relate to today's bird.

Adult male Bufflehead

Having chosen many years ago not to be a car owner, I would be reliant on others if the bird should be re-found this morning, but among an army of like minded friends there was no shortage of a volunteer. A little after 09-00, I was having yet another cup of coffee with Joy, my next door neighbour, when the news came through that it had been seen even further east on The Fleet near the tiny hamlet of Langton Herring. My informant, Paul Harris, was by chance close at hand and quickly popped round to pick me up, then came the decision of where to park. The unmade road leading to the bird is 'private' and the village small, so out of respect for the locals most parked at the top of the track leaving just a mile or so to walk. Even half way down the incline several people had already picked it up by telescope, associating with a small group of Red-breasted Merganser, so entered the log before closer views from the foreshore.

Bufflehead female left, male right.

What is a beautiful small sea Duck the Bufflehead Bucephala albeola originates, mainly, from the USA and Canada and is part of the Goldeneye group. It ranges from 32-40 cm long (12.5-16 inches) at between 270-550 g (.6-1.2 lbs), with the drake larger than the female, it rivals the Green-winged Teal (Anas crecca) as the smallest American duck. Adult males are striking black and white, with iridescent green and purple heads with a large white patch behind the eye. Females are grey-toned with a smaller white patch behind the eye and a light underside.

They are migratory and most of them winter in protected coastal waters, or open inland waters, on the east and west coasts of North America and the southern United States, and is an extremely rare vagrant to western Europe. Their breeding habitat is wooded lakes and ponds in Alaska and Canada, almost entirely included in the boreal forest or taiga habitat. They have evolved their small size in order to fit the nesting cavity of their 'metabiotic' host, a woodpecker, the Northern Flicker (Colaptes auratus). Due to their small size, they are highly active undertaking dives almost continuously to sustain their high metabolism. They do not tend to collect in large flocks; groups are usually limited to small numbers, where one duck will serve as a sentry, watching for predators, as the others in the group dive in search of food. They are amongst the last waterfowl to leave their breeding grounds and one of the world's most punctual migrants, arriving at their wintering areas within a narrow margin of time.

Monogamous, the females return to the same breeding site, year after year and nest in tree cavities, primarily aspens or poplars, using mostly old Flicker nests, close (usually <25 style="font-style: italic;">Sialia currucoides), Tree Swallow (Tachycineta bicolor), and European Starling (Sturnus vulgaris) There was one recorded instance of a female Barrow's Goldeneye killing a Bufflehead adult female and her brood, so smaller cavities are preferred because of less competition with these larger ducks. Females may be killed on the nest by mammals, such as weasels (Mustela spp.) or mink (Mustela vison), and by Goldeneye (Bucephala clangula) over nest competition.

Male Bufflehead in flight.

Average clutch size is 9 (range 6-11), and eggs average 50.5 by 36.3 mm. Incubation averages 30 days, and nest success is high (79 % in one study) compared to ground-nesting species like the Teal. A day after the last duckling hatches the brood leaps from the nest cavity. The young fledge at 50 - 55 days of age. Predators of adults include Peregrine Falcon (Falco peregrinus), Snowy Owl (Bubo scandiacus), Bald Eagle (Haliaeetus leucocephalus), Great Horned Owl (Bubo virginianus) and Cooper's Hawk (Accipiter cooperii).

These diving birds forage underwater, preferring water depths of 1.2-4.5 m (4 to 15 ft). In freshwater habitats they eat primarily insects, and in saltwater they feed predominantly on crustaceans and molluscs. Aquatic plants and fish eggs can often become locally important food items as well. It's name derives from the North American Buffalo who bulbous head is similar, especially when the drake puffs up its head feathers giving the impression of greater size.

This is not an addition to the Great Britain Life List for me as, along with many of my peers, saw the Colwick bird in Nottinghamshire in 1994. Since then I have been fortunate to encounter many during wanderings through the USA and Canada, especially during a long stay in 2008 when all of the photographs above were taken. Much of the information shown was taken from Wikipedia - with thanks.