Wildlife Gardening – Garden Varieties

N.B. If your new to David’s monthly column then please be sure to read the ‘setting-the-scene’ opening piece first.

Gardening for Wildlife

It’s always puzzling why we have certain wildlife in the garden and not other species. If you and I compared the birds that visit our bird tables they could well be different. This is all to do with – niche.

Niche is about the role, or profession, an organism has within its community of wildlife. If you have the niche to support that beastie it well be present, lack that niche and no way will you see it. The niche of a dormouse would be: a nut, berry and leaf-eater in a hazel coppice, or similar, environment. Ling: a producer (photosynthetic) on open acidic soils.

© Laurie Campbell. Cormorant and Shag, similar looking with common traits but enough differences that they can generally share areas successfully.

© Laurie Campbell. Cormorant and Shag, similar looking with common traits but enough differences that they can generally share areas successfully.

As a youth I was confused by the differences between cormorants and shags. They looked similar, were often seen together and appeared to eat similar food. Yet they were distinct species. How could they both feed and live together? Of course the answer was that they couldn’t. The cormorant nests on broad cliff edges on the seacoast and feeds off bottom-living marine creatures in shallow estuaries. The shag, while nesting on cliffs, can occupy shallower ledges and captures mainly fish in the upper layers of open water. Hence their niches are different and they can live in the same area. That is not to say that they never compete. There will be some ledges that suit both species, and some marine life that’s available to both, but there is sufficient non-overlapping for both to get by together. Should the shag population be eliminated, by some disease, one could bet that the cormorant numbers would increase, because all the overlapping resources would be theirs alone.

My own garden has a healthy population of (comparatively uncommon) marsh tits, but few (fairly common) goldfinches. Why?

My guess is that the healthy marsh tit population is because there is ancient woodland at the end of my garden with, importantly, a good number of shrubs. This tit appears to specialise in seeking food at or near ground level amongst shrubs. If you lack these aspects of its niche, marsh tits could well be missing from your bird table.

Goldfinches are small seed specialists. I see few because the woodland offers little of this food type; I have the wrong niche for them. But they are present, in low numbers, especially when the teasels are rich in their seed supply and briefly their niche is on offer.

The wildlife fits the environment, so if you’d care to diversify the species in your garden – fit in different niches. How? Add a pond, a few decaying logs or leave flower heads uncut over the winter. You know what to do!

If the niches of two organisms overlap there will be competition between them as they strive for the same resources. Generally great tits feed nearer the trunk of trees than do blue tits but, as with the shag and cormorant, there will be an overlap and some competition. In an extreme case of competition one species could die out completely.

© Laurie Campbell. Goldfinch are specialist small seed feeders making teasel one of their favourite foods.

© Laurie Campbell. Goldfinch are specialist small seed feeders making teasel one of their favourite foods.

The concept of niche and competition applies across the whole spectrum of organisms. In the lawn the flat daisy and plantain leaves try to creep over and cover the leaves of grasses, the taller grass attempts to grow above the daisies and shade them out – they compete. Who wins depends on the cutting regime of the lawn and the enthusiasm of the gardener.

Primroses grow in damp shady parts of my garden and cowslips in the more open and drier parts. The two plants almost never grow together because they have different niches.

Why not compare your tit populations with others then find out the differences between the garden environments that cause these differences?

What % are

Blue tits

Great tits

Coal tits

Marsh or willow tits

Crested tits

Bearded tits

Long-tailed tits?

In my case I estimate: Blue tits – 15%; Great tits – 40%; coal tits – 35%; Marsh tits – 10%. Long-tailed tits – absent this winter. Crested and bearded tits have never been spotted.

Environment: edge of deciduous forest, large grassy areas with trees and shrubs, some farmland. Few conifers, no wetland.

 

David is an ex-lecturer in Environmental / Biological Sciences.
He has written for most of the UK gardening magazines, including the RHS.
Forest Edge’s garden has been widely covered in magazines and has been featured in a BBC’s Gardeners’ World special.
He also maintains a blog at https://nwhwildlife.org/