Trees for bees

Well, not just for bees, for wildlife generally.

But bees in particular ;)

I’m a beekeeper and I’m keen to keep bees on Ardnamurchan. This isn’t the place to describe the pleasure I get from keeping bees - though here are some clues:

A garden without beehives feels empty to me and it’s something I intend to fix soon.

Honey bees and bumble bees

Honey bees (Apis mellifera) are the only species of bee managed in Europe for honey production. The clue is in the name; in Greek, Apis means bee and mellifera means honey-bearing. They are small, not particularly hairy and they live as a large colony - a superorganism - containing a single queen, up to 50,000 workers (all half-sisters and daughters of the queen) and a couple of thousand drones (males).

Honey bees overwinter as a colony, using large amounts of stores (honey and pollen) to keep the bees alive through the coldest months of the year, until the days lengthen and the queen starts laying eggs again.

In contrast, bumble bees are (often) large and very hairy, they form small colonies containing perhaps 200 workers. The queen hibernates alone overwinter and starts a fresh colony the following spring.

Ardnamurchan is awash with bumble bees of several different species. I’ll post something more about them when I finally get around to identifying them all ¹.

In contrast, where I live there are no honey bees at all 😞 .

Throughout 2019 I searched for honey bees. There are lots of wildflowers and heather for forage but no honey bees. The willow trees - more about these in a minute - up the hill are thick with bees on a good day. In late April, on a calm day, you can hear the bees working the willow from 25 metres away … but none of them were honey bees.

Where have all the honey bees gone?

There are honey bees on Ardnamurchan. I know of a few other beekeepers on the peninsula. None are particularly close to me - either via the B8007 or as the bee flies.

Honey bees forage up to three miles from the hive. So this suggests that there are no hives within range. But what about wild (or feral) honey bees? These live in hollow trees or cavities in a wall.

This is where the story gets a bit more complicated and I have to make a distinction between Ardnamurchan and ‘just about everywhere else’.

The vast majority of honey bees colonies in the UK (and globally) are infested with an ectoparasitic mite called Varroa. The mite feeds on developing honey bee brood and, while doing so, transfers a smorgasbord of unpleasant viruses that - quickly or slowly - kill the bee.

Beekeepers use a variety of control measures to reduce mite levels and so avoid losing colonies. If done conscientiously Varroa control is extremely effective.

In the UK the average annual colony losses are 25-30%, largely because of the ravages of the Varroa mite and the viruses it transmits ².

In the absence of Varroa control the colony will die within a maximum of two to three years. Many colonies die within just one season, often when overwintering due to the mite reducing the longevity of worker bees.

Which brings me back to wild or feral colonies. Before the mite was introduced to the UK (in 1992) wild colonies were commonplace. Now they are exceedingly rare; studies show they have high pathogen levels and probably only live for a year or two.

So does that explain why there are no honey bees in my part of Ardnamurchan?

Probably not … parts of Ardnamurchan, and other regions on the far North-West coast of Scotland, are still free of Varroa.

As a beekeeper this is an exciting prospect and something to be very carefully protected ³.

So where are the honey bees?

Climate

Although honey bees are distributed globally, northern Scotland is at the far north and west of their native range.

It’s likely that the climate is borderline for the long-term survival of wild or feral honey bee colonies.

Rain (of which we have more than sufficient) reduces the time colonies are able to forage for nectar and pollen. Damp, cool conditions are tolerated well by bumble bees (this is one of the reasons they are both large and hairy) but can leave honey bee colonies low on stores and close to starvation.

Beekeepers can compensate for this. Hives can be supplemented with nectar or pollen, particularly very early in the season when natural forage is limiting and the weather is poor. This enables the colony to build up sufficiently to be self-sustaining through the remainder of the season.

This isn’t a luxury that wild or feral colonies have. If they starve to death there are too few other colonies on the peninsula to re-populate the environment ⁴.

Natural supplements

Although bees might be able to fly three miles when foraging, they’d prefer to fly 30 metres and would use up a lot less energy doing so ⁵. It therefore makes sense to try and enhance the pollen and nectar sources in the immediate vicinity.

Most importantly, sources available early in the season are likely to provide the greatest benefit.

Many of the best early season pollen and nectar sources are trees, not flowers.

Therefore, before I get bees I’m busy planting trees.

Willow and hazel are both excellent sources of early season pollen. Willow also produces reasonable amounts of nectar. The plan is to plant significant amounts of both.

Both hazel and willow have additional advantages. They are native trees and are a focus for lots of wildlife other than honey bees.

Hazel provides almost year-round interest. Pollen-bearing catkins are produced in February to April, followed by the fresh green leaves which remain on the trees late into autumn.

Willow grows well in damp areas. We have some very damp areas which are of little use for much else. Willow is rich in salicylic acid which can make the leaves unpalatable to insects and browsing animals. Anything that is unattractive to deer has to have a better chance of surviving as there are far too many of them in the area ⁶.

It is important to try and provide overlapping sources of early season pollen and nectar, rather than just lots of a single type with short availability.

I will therefore be planting quite a bit of alder which, like willow, is good in damp ground and provides pollen. In addition there will be native fruit trees - hawthorn, blackthorn and cherry - all of which are great for wildlife and provide flowering interest and nectar early in the year.

Making space

I’ve been clearing the triffid-like rhododendron from large areas of the site over the last year. This has been backbreaking work, but I’m starting to make progress … and have generated at least a full years’ supply of firewood.

Rhododendron creates such oppressive ground cover that there were almost no native trees or plants left in the cleared ground. However, within the year, a few things are starting to sprout. I’ve scattered some native wild flower seeds in the hope that they will get established before the land is invaded with bracken or reinvaded by rhododendron.

There’s still (lots) more to do, but for the first time I have some space to plant trees.

Native transplants and willow cuttings

Most trees will be planted over the winter(s) as bare-rooted ‘whips’. These establish quickly and are relatively inexpensive. However, they are only available when trees are dormant and they can be lifted from the seedbed.

I’ve previously discussed the fate of the majority of self-seeded native trees. They germinate, grow a few inches or a couple of feet … and are then browsed to the ground by deer.

I’ve therefore spent the year ‘rescuing’ self-seeded trees from the area - mainly hazel, rowan and oak - and moving them to parts of the plot I’d prefer them to grow, protected by a tree guard ⁷ where appropriate.

I’ve also taken willow cuttings from some local trees up on the hill. Willow are dioecious - with separate male and female catkins on different trees - and there are (conveniently) one of each adjacent emerging from a sea of rhododendron within a short walk.

If you cut foot long willow twigs somewhere between a pencil and a forefinger thick they readily produce roots if left standing in water.

I took cuttings in mid-April and they were ready to plant by mid-June or early-July. Within 4-6 weeks there was new leafy growth and by the end of the growing season some had put on 12-18" of growth.

Others, less well protected, had been eaten by the deer 😞 .

I’ve been reading the excellent Handbook of Scotland’s Trees by Reforesting Scotland which has a chapter on how to avoid the attention of deer. One suggestion is to plant huge 3 m willow ‘cuttings’ i.e. entire branches, so that the growing tips are out of reach of the deer. I’ll be giving this a try in 2020.

In the meantime the first ~100 bareroot ‘whips’ have arrived and are heeled into pots waiting to be be planted. This is planned for Christmas and the New Year, each being supplemented with a sprinkling of mycorrhizal fungi and organic blood, fish and bone to help it get started.

With a bit of patience and some tender loving care they should develop well over the next few years, providing pollen and nectar for the bees, and generally improving the habitat for other wildlife.

Happy Christmas and New Year