December

Mistle thrush

Mistle thrushIf there is a mild spell in December and you happen to out and about, keep an ear cocked for the powerful song of the mistle thrush (Turdus viscivorus). He can be heard almost anywhere, including parks within our largest cities. Wherever you come across him, he will almost certainly be perched on the highest branch of some tall tree, shouting out his song of rich, fluted, short phrases, each one a little different from the previous one. (To the birders amongst you – I often think that there are chunks of song included that are very similar to that of the golden oriole.)

His song can carry for a very long way on the wind, although sometimes he appears to suddenly turn the volume down, fooling you that he is much further away than he actually is. He also has the habit of singing very loudly at the height of a powerful gale, earning him the popular country name of the ‘storm cock’.

The obvious bird that you might get the mistle thrush muddled up with is its close cousin, the song thrush. However, the mistle thrush is altogether a more powerful, larger-looking bird, with a plump breast covered in brown spots, which go all the way down the front of the bird to its flanks. The song thrush, on the other hand, is quite a slim-looking bird whose spots turn to streaks as they descend down the front of the bird.

In flight, the mistle thrush appears to have relatively long wings, and its tail shows a whitish edge as it flies, holding its wings tightly shut against its body for a couple of seconds, in between a number of wing beats, so creating a very undulating flight.

It is a bird that has a wonderfully loud rattling alarm call, not unlike an old-fashioned football rattle. Any gamekeeper worth his or her salt will immediately know that an unwelcome predator is in the vicinity, as mistle thrushes don’t use their alarm calls without good reason, unlike blackbirds!

Indeed, should this be heard from February onwards when nesting starts, woe betide any predator that comes too close to the nest site, as they will receive the full ferocity of the angry mistle thrush pair. They appear to be completely fearless in defence of their nest, attacking and actually hitting crows, magpies and even foxes.

My parents once had a pair of nesting mistle thrush in a conifer tree in their garden, which was also a favourite tree for their Labrador to sit under. During the nesting season, the poor dog had to choose somewhere else to relax, as the pair of irate birds would attack him relentlessly, until he reluctantly moved, tail between his legs, to another more restful place.

During the first part of winter, quite often a mistle thrush will take over a berry-laden shrub or crab apple tree filled with fruit, and fiercely set about all other intruders who might want to share in the larder. This is known as resource guarding and ensures that the bird has a constant food source through the winter. Research has shown that these birds may well nest a little earlier and have a slightly larger clutch size than birds who do not adopt this protective behaviour, but instead travel around looking for food.

Although the mistle thrush is found across the whole of the UK, it is normally thinly spread across the countryside, with nesting sites well apart from each other. However, in many places across Europe, they will often come together to nest, forming loose breeding colonies.

Also, all British birds seem to sing from a perch high up on a tree, whereas, quite often on the continent, mistle thrush males will put on a singing display flight, something I have never seen here. Why there should be these differences, nobody seems quite sure!

Around 1800, the mistle thrush was only found in the southern parts of the UK, but then in a period of just 50 years, they suddenly spread to the rest of the UK, which they still inhabit to this day. Again, why this happened, nobody seem quite certain!

Finally, why is the mistle thrush so called? Well, back in 1661, when the first attempt to come up with a comprehensive list of all British birds was made, this bird was then known as the mistletoe thrush, because it has a particular liking for mistletoe berries. The scientific name Turdus viscivorus literally means ‘the thrush that devours mistletoe’!

It may well be that the mistletoe plant is relatively dependent on this bird to spread its sticky seed around, either by wiping the seed onto a new twig or by swallowing the berry and later pooing it out onto a branch. The very fact that the seed has travelled through the bird’s gut will help to vernalise the seed, making it more likely to germinate, once it has been deposited.

Should you have a little playful kiss under the mistletoe this Christmas, you might also need to raise a glass to the mistle thrush for helping to provide an ample supply of mistletoe, in order to keep this tradition going. If you are looking for an excuse for another drink, then a second toast could be proposed to the bird that can sing his beautiful fluty song throughout the festive season!

Peter Thompson
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Read more from Peter Thompson at his blog.

Photo credit: Alun Williams

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