The first migrants arrive

The first of our summer visitors have arrived and over the coming weeks their numbers will increase as others join them for the northern summer and the bounty of invertebrate food that it provides. Over the last few days there have been reports of Swallows, Wheatears and, more widely, Chiffchaffs from across the county.

The predictable and annual journeys made by many of our breeding bird species have always fascinated me, as they have done many generations of naturalists before me. Now, with an extensive literature published on the subject of migration and new technologies available to us with which to track the movements of birds, we have a great (though not complete) understanding of how and why they undertake such incredible journeys. For some species it is easy to see the driving forces behind migration – a summer bounty of invertebrates for insectivorous birds that are then forced south as the bounty vanishes with the approach of winter. But what about those birds that eat seeds? Why do some of them (for example the Turtle Dove) migrate when close relatives remain in one place (either here in Europe or elsewhere, in Africa)? Perhaps this is part of the attraction; that we don’t have all of the answers, that there is more to learn.

The arrival of the first migrants brings with it a need to recall temporarily forgotten songs and calls, all-important if I am to identify the newly arrived songsters. Some are easy and never truly lost, perhaps helped by the onomatopoeic nature of their names. Foremost amongst these is the Chiffchaff, a small ‘leaf warbler’ which is one of the first migrants to reach us each spring and whose ‘chiff-chaff’ song can be heard in woodland and well-wooded farmland. Many of the first Chiffchaffs to arrive appear to be associated with damper habitats, perhaps because this is where the first of the season’s insects are to be found. Later into the month and there will be a half a dozen or so singing Chiffchaffs in the birch scrub that dominates some of the more open areas of plantation woodland through which I walk each morning, but right now I am still waiting for my first.

The Chiffchaff is one of three related species (it is joined by Willow Warbler and Wood Warbler) that show certain similarities in appearance but which have very different songs. While the two smaller species (Chiffchaff and Willow Warbler) may be encountered pretty much anywhere within the county, the later arriving Wood Warbler is a rare visitor, its distribution now largely restricted to the oak woods of western Britain. The Wood Warbler’s song is a spring highlight for me but then so is my first Chiffchaff.