8th April 2015

On Monday, plant and butterfly expert Mike Poulton carried out the first of his 2015 butterfly transects on the Rowley Hills, on the lookout for butterflies, birds, plants and other spring interest. Here is his report from the transect.

It’s Easter week and spring has finally arrived here on the Rowley Hills. The sun was shining brightly as I strolled across Portway Hill Nature Reserve on my first Butterfly Transect walk of 2015.

The main aims of a butterfly transect is to count numbers of each species of butterfly seen on a weekly basis at a given site throughout a full butterfly recording season from April to September inclusive. The chosen transect or route remains constant from year to year and is divided up into a maximum of 15 sections. A count of the butterflies seen in each section is carried out each week and the results entered onto a recording sheet. These records are then submitted to Butterfly Conservation’s ‘Butterfly Monitoring Scheme’. By keeping weekly records comparisons with previous years can be made showing which species are prospering and those that are doing badly. Comparisons can also be made of the dates when different butterflies first appear. For example, here on the Rowley Hills, in an average year the first Marbled Whites can be expected around the middle of June, reaching a peak during the first 10 days of July and then slowly tailing off through the second half of July with just an odd individual or two persisting into the first few days of August. A cold spring could delay this emergence by as much as two weeks. A warm spring will advance the first sighting by several days.

Cherry Plum (Prunus cerasifera) (image ©Mike Poulton)

There was a great deal of bird activity on the hillside; Magpies, Robins, Blackbirds, Carrion Crows and House Sparrows I see regularly, and today I also noted Chaffinches and caught a fleeting glimpse of a Lesser Whitethroat, or was it a Whitethroat? Unfortunately the encounter was somewhat brief as it flew off in pursuit of one of two Long-tailed Tits that departed from the same Hawthorn bush. I also heard and then had a good sighting of a Chiffchaff calling from the top of one of the Cherry Plums that grow here. This shrub is very obvious on the hillside now with its leafless twigs smothered in 5-petalled, white flowers that open just before the leaves unfurl. Further into the site I spotted two Foxes blissfully unaware of my presence sleeping side by side in the warm sunshine half way down a secluded steep bank.

Peacock butterfly (Inachis io) (image ©Mike Poulton)

Small Tortoiseshell butterfly (Aglais urticae) (image ©Mike Poulton)

There was a great deal of butterfly activity from Peacocks and Small Tortoiseshells. These two showy butterflies have only just emerged from hibernation having overwintered in sheds, garages and old buildings. The male Peacocks were having aerial tussles with each other, darting off in an instant at the sight of a passing female of the species. The eggs of both are deposited on newly emerging stinging nettle leaves with a preference shown for plants growing in sunny places. The resulting caterpillars build a communal web in young leaves near the top of the plants and remain quite conspicuous, feeding both by day and night. Feeding continues until around mid-summer when the caterpillars pupate to produce the next generation of butterflies that will be seen on the hillside later in the summer.

Apart from Cherry Plum and the golden bloom of Gorse which covers the bank near the Wildlife Trust land, there are very few plants in flower on the hillside so far this year. I saw the occasional Pussy Willow, Colt’s-foot, Dandelion and Lesser Celandine in flower but the main display of flowers is still more than a month away.

Mike Poulton