Friday 19 February 2016

Slavonian Grebe at Dungeness

Wandered down to Dungeness in the late afternoon, largely to have an afternoon away from the house.

At the Visitors' Centre the kind volunteer lady let me in without my membership card, on my word alone. What very nice people in the RSPB.

I went to have a brief look at the feeders, but there were only some very tidy Great Tits there, no Tree Sparrows that I could see! I then went over to Dennis' hide where there were plenty of Tufted Duck and Pochard in front of the hide, with some Coot, Shoveller and one Great Crested Grebe as well. There were Great Black-backed and Herring Gulls off to the right. At the back in the distance and to the left was the Slavonian Grebe, nice and tidy!

I could see the white breast and cheek, with the red eye very obvious when struck by the light. It was similar to a Little Grebe, but with a tidy shape, with the rear less fluffed up, a slightly greyish lower side, and a very clear demarcation between the black of the cap and the white of the cheek. The head shape was relatively flat, with the beak reasonably level, so not quite as would be expected from a Black-necked Grebe, which has a "peaked cap" above the eye.

Importantly I couldn't see any brown on the bird, so rather unlike most views of the Little Grebe in winter, and thus the monochrome colouring suggesting Slavonian, Black-necked or Red-necked Grebe. The features I didn't really see were the narrowness of the rear neck-stripe as seen from the rear, and the patterning of the smudging on the neck.

At one point all the duck just underneath the hide windows took off as one, and then a lady in the hide pointed out the female-type Marsh Harrier on the other side of Burrowes Pit, which steadily flew left to the right over the far shore.

The grebe swam about quite actively, then had a dive, starting with a very small jump (Helm has it as "tends to spring forward with a quick dapper action", and when I left it was "asleep", resting its head and beak on its back, in amongst a small raft of Tufted Duck.  A lovely bird, even in its somewhat monochrome winter plumage!

I went over to the ARC pits, but saw little more apart from more Coots and Gulls, although as I was leaving I thought I saw a Raven fly over the track.

The winter plumage description states that the cap is glossy black while the back of the neck is really actually a dark grey, as opposed to black, and it may be broken up with pale feathers. The cheek,sides of nape, foreneck and breast obviously white. Flanks a mottled dusky colour, and the back should be a matt black.

The habitat is said to be a bit more northerly than other species, properly holearctic boreal in fact. Generally prefers eutrophic well vegetated waters, but can be found on quite oligotrophic "naked" waters in Iceland for example. Can be at higher altitude than the other species, but rarely higher than 300 m. Prefers depths of water generally 2.5 m or less, with submerged vegetation. If nesting on very small ponds, may fly to feed on larger water bodies. It flies quite readily. Tolerates quite close human presence. It first bred in Scotland in 1908 and has increased slowly since then. The Scottish Lochs are generally occupied from March to September, failed breeders leaving first.

Overwinters either inshore on the coast or sometimes large lowland lakes. The (large-billed form) Scottish birds probably winter in the North Sea or the Atlantic Coast of Ireland. The birds in the Southeast appear to be the (small-billed form) birds from Northern Europe eastwards from Sweden across northern Russia.

Food chiefly arthropods (such as insects and larvae) and small fish, occasionally crustacea, mollusca, annelids and plant material, obtained mainly by diving with the average dive lasting about 30 seconds, depending on density of prey. Feathers generally also eaten. Can also feed on surface. Feeds mainly by daylight, usually solitary.  

Monogamous pair-bond for the season, generally initiated on migration or in winter quarters, so most paired on arrival. Various posture displays and dances. Nest well hidden, spread out as breeding pairs are quite territorial. Often floating but anchored to the substrate. Usually one pair per small pool, or per bay of a large lake. Both parents incubate, eggs covered with down if sitting parent disturbed. Hatching asynchronous, egg-shell removed. Usually one brood, occasionally two. Young carried on back of parents after second day. Fledging period 55 - 60 days. Young become independent at 45 days or less. After departure of the parents, the siblings and perhaps other young may form small groups. Outside the season generally found as singles, or pairs or small groups on the wintering grounds. Age of maturity probably two.

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