Sunday, March 8, 2009

Song Thrush Turdus philomelus

I am an amateur naturalist trying to discover something about everything alive in my garden.

Photo 1 shows a photo of what is, I think, my favourite garden bird, the Song Thrush (Turdus philomelus), snapped on a snowy day in February.

In case you're wondering about the piece of wood lined with seeds in the foreground incidentally, I can tell you it is the latest in the small arsenal of apparatus I'm acquiring to catalogue my garden's natural history. Ladies and gentlemen I present to you...(drum roll)...The Walloon IR-Beam-Breaker!

Photo 2 explains: Having often been frustrated at seeing a bird on my lawn that I've been too slow or too far away to photograph well, and having a modicum of electronics knowledge, I've recently cobbled together a system for automatically capturing photos. With the cable in photo 2 plugged into my camera, anything crossing the line between the two margarine tubs interrupts an invisible, (harmless) infrared beam and sets off the camera's shutter. Though its rightful place might be my dedicated robin posting, you can see a robin in photo 3 kindly demonstrating the correct technique.

Anyway, back to the star of today's posting. What I've leaned about the Song Thrush (Turdus philomelus), has mostly come from the pages of Eric Simms British Thrushes (New Naturalist Series).

Thrushes are a large, globally distributed genus that includes the blackbird, the American Robin and the Ring Ouzel (an occasional visitor to the UK and perhaps the bird I'd most like to see incidentally).

Song Thrushes average about 32cm long and 74gm. The feathers on their back are a warm brown and they have a creamy-white, speckled breast. (The superficially similar Mistle Thrush (Turdus viscivorus) is about 4cm longer and has a whiter breast). Song Thrushes have a characteristic direct flight, easier seen than described (Mr Simms quotes speeds of around 48kph).

Song Thrushes breed from early March through to July and moult in July. UK birds typically do not migrate any great distance, though birds that do, do so around October.

Song Thrushes have a lovely piping voice (you can hear a clip on the RSPB site). Their repertoire can include imitations of other birds and supposedly even car alarms and the trilling of mobile phones. Singing peaks around April/May, when birds are most active in breeding and defending territories. One physiological trigger for singing is temperature: Mr Simms describes his own careful observations on how singing in his garden thrushes correlated with ambient temperature and also mentions that some researchers have induced premature singing in thrushes in winter by artificially raising the temperature.

In a study of territorial behaviour in Oxford, male/female pairs of Song Thrushes were observed to hold territories of around 150feet square during the breeding season. During winter, most territories were held by solitary males, though occasionally one would be held by a solitary females. (No doubt there's enough ecological complexity underlying this behaviour to motivate a whole PhD's-worth of research, if indeed such a study hasn't already been done).

It's not uncommon on a country walk here in the UK (does this happen elsewhere?) to hear the 'tap tap' of a Song Thrush engaged in the business of removing the shell of a snail by smashing it against a rock ('a thrush's anvil'). You can find some video footage on the RSPB site. Interestingly, Mr Simms says that snails tend to be a last resort food for Thrushes - their preference being worms, insects and berries (including those of Holly, Ivy, Yew, Honeysuckle and Hawthorn). Something I had not hitherto known was that Song Thrushes will forage on shorelines where they've been recorded feeding on periwinkles, dogwhelks and sandhoppers.

I'll close with a personal comment: For me much of the fascination and enjoyment of natural history comes from trying to acquire a smattering of 'scientific' understanding about my garden's life. At the same time of course, like everyone, I have an emotional response to the things I see. Actually however, in the case of garden birds, although I find them wonderfully formed and love to hear their singing, I personally don't find them 'cute' or 'charming' in the way I think some people do. I've heard the idea that birds evolved from dinosaurs ("dinosaurs that grew feathers"). The scientific truth of this is hotly disputed and I don't know enough of the debate to knowledgeably comment, but watching blackbirds scurrying around on my lawn, for me there is more than a passing resemblance to a hunting pack of miniature Velociraptors! No one's said it better than English poet Ted Hughes in his poem Thrushes

Terrifying are the attent sleek thrushes on the lawn,
More coiled steel than living - a poised
Dark deadly eye, those delicate legs
Triggered to stirrings beyond sense - with a start, a bounce,
a stab
Overtake the instant and drag out some writhing thing.
No indolent procrastinations and no yawning states,
No sighs or head-scratchings. Nothing but bounce and stab
And a ravening second.


thebfg said...

My wife and I have a song thrush nesting in the fork of a tree in full view of our lounge window. The behaviour of the female is very puzzling to us. she leaves the nest for long periods of time, before returning. te male seems to take no part in the process.
If eggs have been laid, surely they will get cold, when they are not tended for an extended period of time.

what is going on??

ny reply would be very much appreciated.

Anonymous said...

The female will not sit on the eggs until a full clutch is laid. It does not matter if they get cold before the 'germination' process has started. i.e. Only once the female has started to sit and the clutch is warmed can she leave the nest for short periods only so that they do not, thereafter, get cold. Until then, it doesn't matter.
This contrasts with, for example, some birds (particularly birds of prey) that start to sit before a whole clutch is laid. In those cases the eggs hatch over a period of days and the younger (and usually weaker) nestlings die when food is short as they cannot compete with their older siblings for food.

Anonymous said...

Dear Mr. Walloon, I've come across your very interesting blog doing research for my novel, set in Oxfordshire. Will I be correct if my protagonist opens a window in Chipping Norton and hears a song thrush? I do wish to be accurate with the details!
Sincere regards,
M K Graff