Feathers wagging

The garden was resplendent, a vibrant palette of autumn colours. The oak tree was ablaze with reds, oranges and yellows. The leaves on the shrubs, bushes and trees varying from deep greens to bright reds. Many of the smaller trees had dropped their leaves, leaving twisted dark branches except for the silver birch whose striking white bark makes them stand out amongst all the greens and browns. Surrounding all this a carpet of deep green grass, scattered with brown crunchy leaves, and mirrored above by a bright blue sky.

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The garden at the ‘farm’

The birds were equally vibrant. The greens, yellows and black of siskin. The red, black and yellow of goldfinch. The black and orange of brambling. The blues and yellow of blue tit. The olive green and yellows of greenfinch.

It was a busy morning, not least due to the good number of birds, but also because we were taking extra data on the moult in blue tits as part of a BTO study. For each juvenile blue tit we recorded the number of old greater coverts, and the age of the alula, tertials and tail feathers, on both wings. The thinking is that post-juvenile moult (the moult that a young bird hatched this year undertakes after it leaves the nest) may play an important role in determining which birds survive the winter, where they go and whether they find a mate. Replacing feathers takes a lot of energy and takes time but there are big benefits not least in insulation and flight efficiency. The extent to which a young bird completes its post juvenile moult is thought to be a measure of the quality of a bird. The theory behind the study is that weaker birds that have not completed as much of the moult are less likely to survive the winter, so that the average number of replaced feathers will increase between the two sampling periods of November and February. Read more about the study in BTO magazine Life Cycle.

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Young blue tit showing old and new tertial feathers. 

But recording this extent of moult in young birds is however nothing new to us. At this site in Thetford Forest we have been recording detailed information on the extent of moult in finches for the last few years.

Bird of the Day did not however go to any of the finches or tits. It went to a bird with beautiful vibrant lemon yellow under its tail and on its rump, with pale yellow extending up the belly and onto its chin. Its wings were dark with a slate grey back and head. Its tail was long with brilliant white outer tail feathers and dark central ones. It was a grey wagtail. Its name suggests it should be dull and boring, it is anything but.

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Stunning grey wagtail

It is a bird we often see when walking along the river here, with its undulating flight and sharp, metallic call. They are always on the move, constantly in motion, continually wagging that long slender tail, bobbing up and down so strongly that the whole rear end of the bird rocks with it. Why? Well certainly there may be a benefit for catching food, with the long tail snapping up and down, and side to side helping to flush the mobile insects they tend to prey on. There may also be a social function. But considering that both male and female, juvenile and adult birds wag it is not necessarily that simple. Increasingly evidence indicates that tail-wagging is used to show a wagtail’s level of vigilance to potential predators.

While commonly seen along the flowing rivers and larger water bodies in Norfolk, it is a much more infrequent visitor to a relatively small, garden pond in the middle of Thetford Forest. Over the years one has occasionally visited this garden, especially during the autumn and winter months.

It is also a bird that up until this point I had not had the pleasure of seeing in the hand.

A first then for me and for the site, and definitely one to get tongues and feathers wagging!


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