A tale of birds, sticky berries and a new experience in our garden…
Mistle Thrushes, named after their fondness for mistletoe berries, are the main 'vector' of mistletoe in the UK. They are one of the few birds that recognise the white berries as edible, and put up with their stickiness. But they are inefficient, gorging on the berries, swallowing them whole and excreting the undigested seeds, still in a sticky slime, at random. If the thrush turd [did you know the latin name for a thrush is turdus?] lands on a tree branch any seeds lucky enough to stick may germinate – but most hang below in a slimy string and are doomed to failure.
Blackcaps, another mistletoe specialist, are more efficient, as they wipe each seed direct from their beak – but they only overwinter in quantity in continental Europe – where, unsurprisingly, they are considered the main mistletoe vector.
Now in recent years we've had a growing overwintering population of blackcaps in the UK, especially around here, in the Severn Vale, where mistletoe is happily plentiful. So there are some interesting possibilities here – of more efficient mistletoe seed distribution/planting. No-one can say what this might mean for the amount and distribution of mistletoe.
But exactly how efficient are they? Well, we've just found out, by piling up cut mistletoe on our garden picnic table (where else?) to see if we can tempt our lone local overwintering blackcap to partake. He's played hard to get until the last few days, preferring the apples on the bird table, and shooing all the other birds away (impressive considering his small size) but yesterday he started on the mistletoe… and is doing so well I'm beginning to worry for all our trees and shrubs, as he's wiping those seeds off everywhere.
And how efficient is he? Well, have a look at the pics below – all are absolutely genuine blackcap mistletoe seed plantings, and I'm stunned at how good he is. No shrub is immune – the close-ups are on false acacia (a good host) and the wider shot showing 4 seeds (2 in focus on the near branch and 2 just out of focus behind) are on buddleia (not a good host).
If he carries on like this we may have to ration the supplies – the picnic table is covered in mistletoe at present, so there's a lot more to plant yet! But perhaps it's better to have a blackcap feeding on mistletoe there than the alternative – a few weeks back a sparrowhawk used the same table to sit on whilst calmly dismembering a goldfinch (well it is designed for picnics…)