Friday, 14 May 2010

Signs of the times: Spring #15

More comparisons between the British countryside of today and that from 1959-1961 in the paintings of Charles Tunnicliffe in the Ladybird "What to look for..." series of books.

I found a strawberry blossom in a rock. I uprooted it rashly and felt as if I had been committing an outrage, so I planted it again.” Dorothy Wordsworth

(Copyright: Ladybird Books)
In Spring picture 16, we are back down in the woodland, but in the undergrowth this time. We see brambles, the long-petalled white flowers of the greater stitchwort and the small white flowers of the barren strawberry. Perched on a briar of bramble is a wren, a violet ground beetle has crawled out from under the barren strawberry, and what looks like a bumblebee is actually a cuckoo bee – read on to find out why they are bad news if you are a bumble bee (I’m sure you aren’t).

On the plant front, the New Atlas of the British and Irish Flora provides a comparison of the distribution of the three plant species in 1962 and 2002. The bramble (or blackberry, Latin name: Rubus fruticosus aggregate – the “aggregate” because it is a mixture of 320 microspecies!) has not changed its distribution since 1962. Brambles can form dense thorny thickets and are spread by seeds in bird or animal droppings, and by long stems that form roots where they touch the ground, allowing it to “leap-frog” and spread many metres by vegetative growth in a couple of seasons. Richard Mabey, in Flora Britannica, writes quite profoundly, about the blackberry fruit of the bramble: “Blackberrying is the one almost universal act of foraging to survive in our industrialised island and has a special role in the relationship between townspeople and the countryside. It is not just that blackberries are delicious, ubiquitous and unmistakable. Blackberrying, I suspect, carries with it a little of the urban dweller’s myth of country life: harvest, a sense of season and enough discomfort to quicken the senses.” But, again, I am looking unseasonably ahead to a wild harvest that is not due to appear for several months, on the other side of summer.

The New Atlas also indicates that, since 1962, neither the greater stitchwort (Stellaria holostea) nor the barren strawberry (Potentilla sterilis) have changed their distribution in Britain or Ireland. Richard Mabey describes greater stitchwort as a “familiar spring flower of hedge-banks and wood-rides, much loved for its modestly beautiful white flowers” and it is a truly lovely, delicate little plant. The barren strawberry isn’t really a strawberry but belongs, rather, to the same genus as the cinquefoils and the widespread yellow-flowered tormentil.

The wren (Latin name: Troglodytes troglodytes) is Britain’s second-smallest bird species, only marginally larger than the goldcrest. The Ladybird text describes the way the male wren will build several nests and then try to attract a female to each one to lay her eggs. I can sit in my garden in Spring and hear male wrens doing their rounds of their nests in our and neighbouring gardens, singing their remarkably loud and penetrating song at each nest, flitting from one to the next (you can hear various wren song recordings here). According to the British Trust for Ornithology, “the Wren's current UK population estimate is the highest for any species”- there were estimated to be 8,512,000 territories in Britain in 2000. The trend since the 1960s is very much upwards, although very cold winters tend to cause temporary drops in abundance (the following graph shows a smoothed trend which somewhat masks the annual drops from cold winters).

Fortunately for the wren, despite cold winter mortalities, it has a high breeding potential. Climate change may be having an effect on the length of its breeding season, as between 1968 and 2007, the average egg-laying date has moved six days earlier.

I can’t say (as I don't know) much about the violet ground beetle (Latin name: Carabus violaceus), other than that, as a carabid beetle, it is a member of a family of "long-legged, fast-running predators with powerful jaws” (from Michael Chinery’s “Collins Field Guide to the Insects of Britain of Northern Europe, 3rd Edition). It may be yet another friend of the gardener, as the larvae of large carabid beetles will actively hunt for and feed on slugs. I cannot source any evidence about trends in beetles like this one since 1959-1961.

The final feature to discuss here is the cuckoo-bee (from the genus Psithyrus) which is associated (in a parasitic way (with bumblebees. Chinery says that each species “sticks pretty well to one or two host species, which they tend to resemble quite closely". They are known as cuckoo-bees because they lay their eggs in bumblebee nests. Unable to kill or oust the tougher cuckoo-bee, the bumblebee workers soon tolerate the cuckoo-bee which then lays its eggs and these are then reared by the bumblebee workers. The cuckoo-bee will encourage this either by eating the bumblebee eggs as they are laid, or by killing the bumblebee queen. Again, I don’t have much information about the trends in cuckoo-bees over the past 50 years but their fate is likely to be linked to that of their bumblebee hosts. I'm sure I'll be writing about bumblebees again in this series!

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