The more I learn about migration the more unbelievable I find it. The number and variety of birds which travel vast distances to breed is staggering. From humming birds flying between Mexico and Alaska, to gulls which circulate between Newfoundland and Chile, returning via Africa.
Many garden birds take part in these epic voyages too. Cuckoos are probably the best known, but Swallows, Swifts and House Martins make much the same journey and are a lot smaller. All these species are now on their way back, many of them already in southern Europe, and are being tracked by the BTO, using a range of data loggers, to help understand better where they migrate to, and by which routes, and maybe learn why their numbers are in decline.
During these early months of the year, we see short-range migrants moving through our gardens. Birds such as Siskins, Chaffinches and Goldfinches are moving northeast towards their breeding grounds, having spent the winter in the south and west of the country.So far this year most of the numbers reported are lower than usual, suggesting that fewer birds came across the North Sea in the first place.
Blackbirds from Fennoscandia and northern Germany also spend their winters here and move back east in early spring. I’ve seen Redwing and Fieldfare in my garden recently, possibly forced away from their usual feeding locations by the snow, but also starting to make their way back north-eastwards to breed.
As you mayhave heard, The Yorkshire Arboretum stillhostsa flock of around a hundred Hawfinches, a very rare event. They will presumably be returning to their breeding grounds soon, though there is always the hope that a few may stay and breed.
Migration habits are changing everywhere. Climate change allows many species to overwinter closer to home, as exampled by German Blackcaps wintering in southwest England rather than around the Mediterranean. Ever more species are breeding in the UK as well as in continental Europe, witness the spread north of Little Egrets which are now to be seen regularly in Yorkshire.
At the other end of the journey, both climate change and population growth are affecting our migrants’ summer quarters. Increased populations need more food and fuel, so forests are rapidly being eroded and land use is changing, with farming becoming more widespread and intensive. All of which reducethe availability of food for wildlife.
Food is key to migration: birds consume a vast amount of energy flying long distances, often across hostile terrain such as the Sahara. To do this they must fatten up before their journey, and then refuel on the way. Climate change produces ever more extreme weather conditions, which often mean insufficient food is available to migrants at their point of origin and en-route. We know that this is one of the major causes of migrating Cuckoomortality through Spain, where droughts and wildfires have caused major problems recently.
On the brighter side though, now is the time to keep your eyes peeled. You never know what might choose your garden to rest and refuel in on its way back home! Particularly if we have some strong winds to blow them off-course.
If you find the lives of our garden birds interesting and would like to join in and count the feathered occupants of your garden, please contact me or visit the BTO Garden BirdWatch website(www.bto.org/gbw). If you know of an organisation not a million miles from York which would like a talk on garden birds call: Mike Gray 07596 366342 or gbwmike @gmail.com.