Strange Flutter

On the rare occasions over the past couple of weeks that I’ve been out into the garden – we’ve had pretty relentless cold winds and rain – I haven’t seen a huge amount of nest site activity. I suspect they’re either sitting on their nests keeping eggs warm, or the chicks have fledged and the families moved on.

There is one site though, where there have been plenty of comings and goings: the Long Tailed Tits’ nest in the brambles. And it’s a slightly weird kind of activity that I’ve not seen before.

Both parents seem to be visiting the nest regularly with beaks full of mushed up insect life – they clearly have a hungry brood – but they don’t go straight into the nest. They usually land nearby and then fly a few feet into the air above, and do a sort of fluttering hover for a few seconds, before dropping down into the tangle of brambles and the nest below. But they don’t always go down into the nest first time. Sometimes they land on the brambles and fly up and do the hover-flutter thing again, occasionally several times before finally dropping down to the nest.

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It’s a strange and delicate display, almost a dance. And it’s conspicuous too. I’ve been wondering what the purpose of it is.

Pretty much all the other species of birds do everything they can not to be noticed entering their nest, or otherwise do it very quickly. Which is understandable with all the potential nest raiders around.

But not the Long Tailed Tit.

If they wanted to alert a partner of their arrival, a partner perhaps sitting on the chicks to keep them warm in cold weather, why not just make a gentle tweet, or call out in some way like other species do, while staying safely hidden and not giving away the location of the nest to any watching eyes. 

I can understand why they would need to enter the nest from above: The Long Tailed Tit nest has a roof to it, and the entrance is on the side near the top, so from above would be the easiest way to access it in a bramble thicket with sharp, potentially wing-shredding thorns on every side. And I can also understand why they might want to alert their partner to get out of the nest to allow easy access for feeding the chicks. But why be so conspicuous?

I wondered whether fluttering above the nest was some kind of evolutionary trade off: the security of a thorny bramble protection weighed against a necessarily conspicuous entering-the-nest-from-above behaviour. Maybe. But it seems odd that no other birds seem to do it.

Apparently Long Tailed Tits have a nesting success rate of less than twenty per cent and I’m tempted to think their conspicuous behaviour may be part of the reason. But then again their population is currently stable or increasing so they must doing something right.

And then I saw two of them fluttering above the nest at the same time. What was that about? If both the long tailed tits were off the nest either one could have entered straight away. Why still hover?

A little while later, I noticed three Long Tailed Tits together, foraging in the large willow tree near by, and it occurred to me that the third adult might be a related bird perhaps from a failed nest that was there to help the original couple (Long Tailed tits are apparently well known for this behaviour). So maybe there were now three Long Tailed Tits – or more – raising the brood. After the very blowy, potentially nest-wrecking weather we’ve had lately (gusting to 45 mph today and all tomorrow), a few casualties would have been inevitable. So perhaps when there are two birds hovering over the nest at the same time, they’re waiting for a third to make way.

Thinking about it some more, I can’t remember ever seeing magpies or Jays trying to get at a nest in a bramble thicket, so maybe the Long Tailed Tits’ behaviour isn’t that reckless. Even if they know where the nest is, the corvids may not want to risk damage on the thorns trying to get at it. I’ve seen sparrow hawks going after birds from blue tits to pigeons, but their prey is usually taken when perched on a branch or in mid air by the pursuing raptor. I’m wondering if, when Long Tailed Tits are hovering up and down they would be difficult, unpredictable targets. And I suppose if a Sparrow Hawk mistimed its strike, it could easily end up tangled in the thorns, which would be a bit off-putting as well.

Whatever, their hovering dance behaviour seems to work, though a Whitethroat who was watching from another bramble patch near by looked sceptical.

I first noticed him about a week ago. He seems to keep his head down most of the time. I haven’t seen a female yet, but I have noticed him returning now and again to another bramble patch not far away, so he may be another bramble-patch-nester. Or it may just be coincidence. We’ll have a better chance of knowing when the chicks – if he has any – start demanding food. It’ll be interesting to see, if he does have chicks, what the Whitethroats’ nest-approaching behaviour is. I can’t see it being as much of a delicate dance as the Long Tailed Tits.