Tuesday, 31 July 2018

Visitors

A flock of Curlew Sandpipers with a Dunlin (David Lindo)

Stealthily under cover of darkness they move. And finding them in the first light of day helps me break the stasis of summer.  The season seems sluggish by the end of July. The afternoon spike of heat pushes all life to siesta. All appears still, even the sky is empty. The nights are relatively silent, compared to the amphibian and strident mole cricket choruses of late winter and spring, a gentle soporific hum of crickets broken only by the monotonous poot of Scops Owls. And yet across the skies at night, birds are moving.

Remarkably, shorebirds that were in the Siberian arctic perhaps just a couple of weeks ago are opting to cross the interior of the Iberian peninsular, rather than follow coastlines down to their African destinations. We came across yesterday a group of 13 Curlew Sandpipers,  all still showing their russet summer dress. They were feeding alongside some Little Stints and Dunlin. All were adults that had already finished nesting, or had failed to do so successfully, and were pausing en route to their wintering grounds. Just twelve weeks ago I was watching three Curlew Sandpipers feeding on a pool beside the rice fields in the centre of Extremadura, also along with Dunlin and Little Stint, taking a short break in their journey northwards. Now it was happening all over again, the birds now heading south. The modern landscape of the wet rice fields and their associated reservoirs have provided a significant resource for these waders. Have the numbers of shorebirds crossing Spain in the full blast of summer increased since their discovery of these feeding places, or did their ancestors simply make use of the existing water's edges, crowding along river banks and river islands?

Migration is happening year round in Extremadura. There is not a single month when birds are not on the move. The return passage of high-latitude waders starts in June with the arrival of Green Sandpipers fresh from boreal forests and marshes.  In July, the departure of White Storks and Black Kites is already underway. These latter two species will be migrating during the day, but waders and many of the smaller birds like warblers will be flying at night. Some of this migration across Iberia is quite astonishing. There is evidence that marine ducks like Common Scoter wintering in the Atlantic off the North African coast could be making nocturnal non-stop flights across the peninsular, reaching the Bay of Biscay the following day (see the post by Magnus Robb in May 2017 in soundapproach.co.uk). Unlike the waders seeking stopover sites for feeding, some of these migrants would only be detected if they had been forced to abort their flight at some point during the night. This might account for the my discovery a few years ago of a Common Scoter at the Sierra Brava reservoir in early summer.  Unless as Magnus describes, one is tuned-in to their flight calls. On one night in early May I heard a flock of Ringed Plovers flying high over our house.

A group of juvenile Audouin's Gulls in the mist (Martin Kelsey)

Another phenomenon is now being recognised as regular in the depths of summer in Extremadura. This is the appearance of juvenile Audouin's Gulls on reservoirs in our region. This is a coastal species of the western Mediterranean. After the breeding season there appears to be a dispersal of juvenile birds with several records, mainly in July, every year in Extremadura. I first witnessed this movement in 2015 when I found one and then subsequently a second bird at my local patch at Alcollarín Reservoir. This year, there had been a couple of reports of birds in southern Extremadura and my birding mate, David Lindo, found three at a site near Mérida. At my first opportunity to go, I went down to Alcollarín. It was dawn and despite the sky being clear at home, I arrived at the reservoir to find thick fog. I made my habitual stop to start the scan the water, but visibility was extremely poor. As I was wondering what to do, I caught sight of four juvenile gulls disppearing into the mist. All I could see of them was their rather long-winged and elegant shape, overall dark plumage and a distinctive white "V" on the base of the tail. I was almost certain that they were indeed Audouin's Gulls but frustratingly they seemed to have gone. I spent the next hour checking places along the bank where gulls often rest, but every stop drew a blank. I had just five minutes left before having to head back home, so I returned towards the place where I had started. On my way there, out on the water, I could see a group of dark gulls swimming. There were 13 of them. Despite the mist which gradually started to close in, I managed prolonged enough views of them to confirm my original  suspicion.  When one flapped its wing to show the diagnostic white panel in the centre of the underwing, therewas no doubt at all. At that moment a Black Kite flew low over them and they all took off. Gracefully the flock of Audouin's Gulls circled around in front of me before veering off towards the centre of the water body, disappearing again in the fog.

Juvenile Audouin's Gulls in flight (Martin Kelsey)

The following morning I was back, this time under perfect conditions. I spent two hours counting duck and grebes (including an amazing 570 Little Grebe), but of the Audouin's Gulls there was not a sign. I could only wonder where that enigmatic and evocative group of 13 had gone to.

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World of Animals, Inc said...

Incredible wildlife photography, it is amazing that you were able to capture these moments in time. Thanks for the share, hope you had a fantastic weekend. Keep up the posts.


World of Animals