On the Move



Last Saturday I spotted my first butterfly of the year, an unmistakable pale green Brimstone, on a scrubby roadside verge in Purfleet, Essex. After several cold months of interminable grey skies this momentary encounter was a reason to smile. Along with the clues adorning trees, shrubs and flowerbeds, it was a welcome reminder that, although it might not have hit its dizzying heights yet, spring is here.

Dog's Mercury (Mercurialis perennis) -

a shade-tolerant woodland plant that flowers early,

before leaves appear on trees and light reaching the woodland floor decreases

Alien-like Goat Willow (Salix caprea) catkins

For us birdwatchers, Spring means the hours of sitting in freezing hides with sodden jeans and only a lukewarm flask of ribena for comfort can be forgotten about (until the summer at least!) And those tormented dreams of missed Waxwing twitches can perhaps finally be laid to rest with the promise of the riches to come. We can again look forward to hearing our green spaces come alive with birdsong. We can also look forward to one of nature’s myriad wonders – spring migration.

Each spring thousands of migrating birds arrive in the UK. The majority of these will be returning from their wintering grounds in equatorial Africa and will have crossed the Saharan desert, the Mediterranean Sea and the mountains of southern Europe prior to alighting in our gardens, parks, woods and fields. Given the distance and the dangers en route (hunting, exhaustion, unpredictable weather events) it’s a miraculous concept but one that clearly works for many birds. So why undertake such an epic journey?



The simple answer is that these birds are seeking food and suitable breeding sites and for many, the British Isles are a perfect destination. The nature of our seasons means that although it may be cold and dark for several months, when the situation improves in spring, the natural world responds with a burst of life and conditions that are hard to ignore. Vegetation blooms and invertebrate numbers rise, providing an endless food supply for birds. This abundance is complemented by the increase in daylight hours we experience.

So what species should you be looking out for in March and April?

This interesting table from the BTO shows the average arrival dates of 24 spring migrants from four bird observatories around the UK. If you’re a city dweller like me, the first migrants you are likely to encounter will be small passerines from the warbler (Sylviidae) family. Chiffchaffs are generally among the first to arrive, followed by Blackcaps and Willow Warblers (it can be tricky however to determine whether or not the bird is a new arrival since both Chiffchaffs and Blackcaps are now known to winter in the UK!)But regardless of their origin these understated birds are worth keeping an eye, and ear out for, since you are most likely to hear their sweet, flutey songs emanating from parks, deciduous woodlands and scrub before you actually see the bird itself.

Chiffchaff (Phylloscopus collybita) photo from RSPB Images - listen out for its repetitive 'chip-chap chip-chap' song

The general consensus so far (and by that I mean a brief consultation with Birder Dave and a look at the Portland Bird Observatory website) is that spring migration is off to slow start this year. But that just means it can only get better.

Have you spotted a migrant on your patch? Or heard an unusual birdsong in your garden? I’d love to hear about it.