The possible interaction between increasing overwintering Blackcaps and increasing spread of mistletoe In the UK is fascinating – and I’ve mentioned it in this blog several times.
The basic story is that Blackcaps, Sylvia atricapilla, have started overwintering in Britain in increasing numbers since the late 1980s, a few dozen at first but now 1000s. And during the same time period mistletoe distribution seems to have subtly changed. Basically there’s more and faster spread of mistletoe in eastern parts of the UK than there used to be.
This change in mistletoe might be due to climate change – studies suggest mistletoe will move east with predicted climate change. Or it might be due to those blackcaps – one of the few birds that likes mistletoe berries – spreading berries more efficiently. They tend to ‘plant’ every seed by wiping it off their beaks on to a branch, whereas thrushes – our only other regular mistletoe eater, consume the berries whole and excrete the seeds, with most missing a branch.
I thought this story was relatively well-known by now, and have referred to it this season in articles for the RHS and the Society of Biology.
So I was surprised today to find Monty Don, in the Daily Mail today, claiming that he has the answers to mistletoe distribution. According to him;
- it occurs in its core area (the SW midlands/welsh border) because that’s where blackcaps migrate to – which is utter nonsense, not least because it’s been in this core area for hundreds of years and our overwintering blackcaps have only been here a few decades at most. And they overwinter across much of Britain, not just in the SW midlands.
- the blackcaps all come from Siberia – which they don’t – they come from Germany and adjoining areas and are a well-studied sub-race for which there are several recent scientific papers
- they excrete the seed – er, no they don’t Monty. Mistle Thrushes excrete the seed. Blackcaps wipe the beak. How can you get that wrong?
Monty says he knows all this as the result of a new study – I wish I knew what ‘new study’ – as his critical facts are completely untrue. The impact of Blackcaps will be that mistletoe core area is blurred and widened – they don’t/won’t define it, they potentially ruin it. He couldn’t have got it more wrong. But the references to blackcaps and mistletoe and new studies do imply he’s heard something – perhaps a chinese-whisper version of the real story and just extrapolated it randomly? He should have access to the account in RHS’s The Garden, perhaps he should read it.
Mr Don has written some nonsense about mistletoe before – but this article headed ‘Monty knows the answers’ really is an insult to the Mail’s readership. He gets paid for this? The Mail should be asking for their money back.
PS and don’t get me started on his weird statement about doubts whether seeds can survive birds’ digestive systems – how do you think seeds from berries are distributed in general Monty? That’s what berries are FOR – to be eaten by grazing birds and animals who then excrete the definitely-still-live seeds elsewhere. That’s the whole basis of why plants have berries…. Sigh…