Friday, 27 January 2017

Northward bound

Black-tailed Godwits on northward migration through Extremadura (Martin Kelsey)

It is late afternoon towards the end of January. We are driving slowly along a dirt track between small rice fields. In some there are still rows of stubble and family groups of Common Cranes are quietly feeding. A rank of Greylag Geese stick their heads up, periscope-like, as we pass, grey-brown with heavy triangular light orange bills. Most of the fields, however, have already been "mashed" over by tractor, as near as ploughing that you can get in this squelching mud. The result is an expanse of shallow water. Groups of Black-headed Gulls are settled on some of these pools, with their curiously angled necks poised forwards, matching harmoniously their uptilted wing-tips, giving them a dainty demeanour as they bob about, as if they were tip-toeing on the surface.  Many of the fields seem empty, with perhaps a single Green Sandpiper, which freezes as we approach, before erupting in a shock of black and white. However, the next field we come to has action.

Here a pack of over three hundred large waders are clustered. A profusion of dry Typha in the ditch beside us offers concealment and thus we can slowly approach. We watch the birds at close quarters, hidden from their view. A low afternoon winter sun makes the birds glow against the reflected soft blue sky on the water. There is a pleasing hum of activity from the flock. We listen to a gentle murmur of nasal contact calls, soft and reassuring. I smile. The birds have the appearance of having very recently arrived. They are keeping close together. Some are sleeping but most are either preening or busy feeding, their long bills submerged, deep into the ooze, so that the water reaches their faces.  They are Black-tailed Godwits pausing in Extremadura on their journey from West Africa to Holland.

Some are starting to show the russet-orange chests of breeding plumage, but most are still in winter dress. Extremadura is one of the most important late-winter stopover areas for this species as it crosses the Iberian Peninsula. Over recent decades the availability of feeding areas in Extremadura has increased with the development of rice production. The management of the land means that during the period of the peak spring passage (late January to early March) most of the fields are wet and muddy. Tens of thousands of godwits pass through. But their highly gregarious behaviour means that to find them requires considerable searching. The area which has the highest concentration is the the central area of the rice belt in Extremadura, close to the small town of Santa Amalia. There last February we stood and watched a flock of 4000 birds, rising and banking in unison as they moved from one feeding area to the next. The fields they choose to forage in seem to be carefully selected, to the exclusion of adjacent fields that appear to our eyes as identical. Yet there must be something that tells the godwits, from one year to the next, that certain plots have a higher yield than others.

Black-tailed Godwits at Santa Amalia February 2016 (Martin Kelsey)

As I watch the birds I see that at least four are bearing coloured plastic rings on their legs. Black-tailed Godwits are being studied extensively and many are ringed by researchers. The colour-combinations that are recorded will be sent in. I will eagerly await the information that comes back: insights into the individual life-histories of such engaging birds.

Two colour-ringed Black-tailed Godwits (Martin Kelsey)

1 comment:

karen izod said...

lovely to read this, and to see the transformation of the rice fields at this time of year.
Karen