Mistletoe Distribution in Britain
In Britain most mistletoe is found in the south and west midlands, with particularly good populations in Herefordshire, Worcestershire, Gloucestershire, Gwent and Somerset.
There is mistletoe elsewhere, particularly in the south, plus a few rare occurrences in north and east England, Wales, Scotland and Ireland.
But it is only regionally abundant in that core area of the south-west midlands. Many assume this to be somehow linked to apple orchards (apple is a favourite mistletoe host, and orchards a favourite habitat). This assumption is almost certainly incorrect – there are many apple orchard areas elsewhere in Britain that don’t have mistletoe, and studies across Europe link mistletoe distribution to particular climate preferences, which do seem to match the main distribution in Britain.
You can see some clear climatic preferences, particularly altitude, in the detailed enlargement on the right. The line of the Cotswold escarpment forms the main eastern edge to the mistletoe area, whilst on the western side the valleys of the Rivers Wye and Usk can be traced as lines of mistletoe records, taking mistletoe towards the Welsh uplands.
The northern boundary of the area is formed by the Clee Hills (north-west) and the Birmingham plateau (north-east). The central empty area is the upland area of the Forest of Dean – good proof that mistletoe, despite loving trees, isn’t fond of woodland.
The 1970s and 1990s Mistletoe Surveys
Much of what we know about mistletoe distribution comes from survey work co-coordinated by the Botanical Society of the British Isles (BSBI) in the 1970s and a follow-up project, jointly run by BSBI and Plantlife in the 1990s. Data from both periods are shown in the small maps on the left.
The 1990s survey aimed to assess whether the decline in traditional apple orchards was affecting mistletoe too – was mistletoe declining? Results were mixed - orchard loss is affecting mistletoe abundance, but distribution patterns remain the same as before. Indeed the new data suggested more mistletoe in the east and south-east, though that might reflect better recording effort more than real change. (For more information on mistletoe rarity v mistletoe abundance see the Is Mistletoe Rare? page)
Change may be happening though – new evidence from the 2000s suggest something is different:
Is the distribution pattern changing?
In the last 10-15 years there have been several reports suggesting that mistletoe is spreading faster than it used to in Britain. This is particularly noticeable in eastern areas, where established mistletoe populations, whilst often long-established, have previously seemed slow to spread as they are outside their climatic comfort zone.
Something is changing though – as many of those previously static mistletoe colonies are shifting. It could be subtle hints of climate change – computer modelling does suggest that mistletoe will head east with climate change. Or it could be something else.
One possibility is better spread of the seeds by Blackcaps, a bird species that is particularly efficient at spreading mistletoe. British Blackcaps migrate for the winter so they do not, usually, affect mistletoe here. But in recent decades continental Blackcaps have started overwintering in Britain, with many thousands now spending their winters here. Perhaps mistletoe is spreading more because of their activity.