Migration….

By Tony

As a young birder, I was always fascinated by the subject of bird migration. I can remember being bewildered at the time, with the journeys undertaken by our summer & winter visitors. Birds such as the Swallow, Cuckoo, Fieldfare, Redwing and the vast array of warblers, all visitors to our shores but then how did this all happen and how did the birds take on this incredible feat? I soon began to figure things out, yet too this day, I still find it amazing how a fledged Swallow can find its way to South Africa simply on instinct and with no previous experience of the journey it is about to undertake. Or a Barred Warbler, straying off course and ending up on our shores when it should be in a completely different place altogether.

Migration Parallels – Examples

Barred Warbler – Sylvia nisoria – Unst, Shetland. A typical autumn “Drift” migrant

Prior to my interests in Moths and Butterflies, I was somewhat unaware that these insects also migrate and it wasn’t until I began to visit the Isles of Scilly, that I became aware of this phenomenon. For example, seeing my first Clouded Yellow and Monarch butterflies on UK soil certainly proved the point.

Clouded Yellow – Colias crocea – A migrant watched arriving in-off the sea on the island of Tresco, Isles of Scilly. Note how tattered the wings have become. This can often be a typical feature on a butterfly that has travelled a long distance.

Monarch - Danaus plexippus - One, if not the most famous migratory butterfly. The nearest colonies to the UK are on Madeira, Canary Islands and the Azores. The Monarchs that find their way to our shores are highly likely to have originated from these colonies, rather than having undertaken a trans-atlantic crossing. However it is a nice thought to think that one or two may have made the atlantic journey. Nevertheless an incredible achievement and a fantastic sight to see one of these beautiful butterflies in Britain.

Painted Lady – Vanessa cardui – A common migrant butterfly that visits the UK annually and sometimes, in large numbers. This was the case in 2009, when thousands streamed across the country, a sight that I was fortunate to witness and one that I will never forget.

The Migration MEGA Parallel

When moth trapping in the UK, especially at so called “Migration Hot Spots”, in particular the South Coast, Cornwall and the Isles of Scilly, the ”parallel” upon opening the Moth Trap, is to quickly be able to spot an interesting  looking moth amongst the sometimes large numbers of common moth species.

A similar parallel can apply in birding. For example, when scanning through large numbers of gulls, ducks or waders, one is continuously looking out for something that is different. During times of peak migration, we are always hopeful to discover a “Good Bird” and keeping fingers crossed to be the one to find the MEGA.

Here are some examples of MEGA migrant moths, that found their way into my moth trap during several years trapping on St.Agnes, Isles of Scilly. The thrill is exactly the same as the discovery of a rare bird – an adrenalin rush followed by several expletives!!

Crimson Speckled – Utethesia pulchells – Who says moths are little brown jobs? I would defy anyone to keep quiet upon finding one of these beauties in the trap. A Mediterranean species.

Antigastra catalaunalis – A rare pyralid micro moth from the tropics.

Palpita vitrealis – This moth is often a good indicator species of high migrant moth activity. A scarce migrant from Southern Europe.

Hymenia recurvalis – A rare migrant from the tropics.

Finally to conclude this feature – Here is a future possibility for discovery - Not YET recorded in Britain, so one to look out for. This butterfly is a long distance colonist, a recent colonist on Madeira and highly migratory. So it could arrive in Britain. Most probably somewhere along the south coast. Anything is possible –

Let’s hope it does one day soon!!

Lang’s Short-tailed Blue - Leptotes pirithous – Madeira August 2012.