Thursday, 19 April 2018

Tracking the rare

Common Tern - a scarce species in Extremadura (Martin Kelsey)

Birding is thriving in Extremadura. This is driven partially by the numbers of people visiting through "turismo ornítologico" - the rather formal-sounding Spanish description for people coming to Extremadura for birding holidays  - but mainly by the growth of birding amongst those who live here, especially young people. There is an email forum with several hundred participants. All this translates to a huge increase in the number of person hours that are being spent in the field, both in terms of participating in survey work and censuses (such as the annual Common Crane census), engagement with eBird (now holding over 13,000 submitted checklists) or simply birding.

Couple this with digital photography, better optics and access to first class information, the quality of the observations and increasing skills of the observers, are, I am sure, also improving. And through this, so more and more scarce or rare species are being reported.

A group of us felt that it was time that Extremadura followed the example of some other regions of Spain and established a local Rarities Committee, to work with the local recorders as well as the national body, to ajudicate on records submitted. Thus would be established an independent and objective verification of sightings of unusual birds. This would ensure that the key information concerning records would be standardised and stored,along the decision from the ajudicators. Records of birds that are considered as national rarities would still require acceptance from the national rarities committee, but perhaps what is most interesting would be the monitoring through the local committee of the changes through time of the status of scarce species in Extremadura.

The first report is now available and you can see it through this link. It has been achieved through some quite considerable hard work, aiming to review not just records from the last couple of years, but following up records dating back almost twenty years. There is still a backlog of old records to be reviewed and incorporated, and I urge anyone with records of any of the species listed by the Committee to submit them (which can be easily done on-line). Over time the annual report will be more and more focused on the most recent.

The number of records received of certain species  such as Audouin's Gull, Mediterranean Gull and Ring Ouzel are such that they can no longer be considered as rarities in Extremadura. The latter is clearly a regular passage migrant, with stopovers especially in Badajoz province, with small numbers probably overwintering there regularly. With the advent of eBird recording, the ongoing situation of these species can be monitored.
Cream-coloured Courser May 2017 (Carlos González Villalba)
Some species in the report are particularly intriguing. Last year, Cream-coloured Coursers were recorded from three different locations in Extremadura during May. Two of these locations involved pairs of the species. Last year also saw breeding of the species in mainland Spain, for only the third time. Did the species breed in Extremadura as well last year? No one knows. Are we seeing the start of the spread of this North African species into the Iberian Peninsula?

The acronym for the Extremadura Rarities Committee is CREX (Comité de Rarezas de Extremadura). which is also the genus of Corncrake. The report includes records of this species too. The evidence from injured or dead birds found suggests that Corncrakes (whose Spanish name means the Quail's guide) pass through Extremadura at the same time and in the same habitats as migrating Quail....but a healthy, live Corncrake has never been seen by a birder here. Now there is a challenge!

The next report will be published sometime in the first quarter of 2019...and without spoiling the ending, I can tell you that there will be some more fascinating discoveries. Take a look at the website for updates of unusual birds being reported in Extremadura - and if you find something yourself, do send in the record!




Sunday, 8 April 2018

The reassurance of spring

Bee-eater (John Hawkins)

Conclusions of recent research on wildlife populations across Europe make for seriously depressing reading, especially for those of us with memories of what things were. Even in Extremadura, where the populations of larks and Corn Buntings appear still robust, my own notebooks carry testimony of the collapse of species such as Little Bustard and Montagu's Harrier. Rachel Carson's arresting image "Silent Spring" has been retrieved by journalists. And so I face this spring with anxiety, foreboding.

The rains only started at the end of February and to date we have already received  since then 86% of last year's entire total of rainfall total recorded in the immediate vicinity of our home. Whilst the landscape now looks luxuriously green, it was striking how the wetter and colder weather delayed flowering of many early species this year and how few butterflies were on the wing in the first half of spring. The result has been bittersweet: water resources have recovered, the middle spring plant growth looks set to be magnificent, but early breeding birds, especially raptors, have taken a big hit. Nest failure among the Griffon Vultures has been massive.

Barbary Nut Iris (Martin Kelsey)

And yet for most of the migrant birds, the phenology of spring unfolds predictably. As I write I can hear a Nightingale singing in the garden. It arrived yesterday, pretty much on cue. This first week of April has seen the flood of Bee-eaters, creating a buzz of excitement in text messages and social media as, with extraordinary synchrony, people hear their heralding calls and catch glimpses of their bounding flight across the region and beyond. Notwithstanding our anxieties, the resilient return of migrant birds generates a sense of reassurance and relief. Whilst there are survivors, there is hope.

Black-eared Wheatear (Martin Kelsey)

I stood at one of my favourite places on the plains, jagged dog's teeth of rock erupting from the thin soil, which now has a green mantle becoming increasingly polka-dotted by colour, A newly arrived Black-eared Wheatear perched on one of these rocks, its quiet song interrupted only with periodic drops to the ground to snatch and pound a caterpillar. Its buff-sandy body spoke of deserts. Just a couple of metres away, a Northern Wheatear en route between the Sahel and the mountains of Central Europe had also paused. Looking in the other direction, I could see a male Little Bustard jerking its head backwards as it give its courtship call, while a small party of Great Bustard crossed the same field of view. Above them, a Roller sat on a wire and unseen Bee-eaters prrrted overhead. A pair of Stone Curlew stood hunched and morose, ignoring the zigzagging chases of rival Calandra Larks. All of this happening at the same time, in the same place, unscripted juztapositions. This too created a heady combination of emotions in me, as the observer: a sense of sheer good fortune, touched by the vitality of spring but underlaid with poignancy and nostalgia.


Wednesday, 14 March 2018

Recovery

Black Vulture drying its plumage (Martin Kelsey)

It has been an extraordinary transformation. Just over two weeks ago the horrendous drought broke and we have barely had a day since when it has not rained. Indeed, in this month alone (and we are only half way through it) we have received over 65% of the rain that fell in the whole of last year. Rivers that had ceased flowing last spring have come back to life, with water thundering down their watercourses.
Almonte River in November 2017 (Martin Kelsey)
Almonte River in March 2018 (Martin Kelsey)


Pools have appeared on the plains and following rain, whole slopes glisten with the run-off, tracing the routes taken by livestock. Land that had been grey and weather-beaten, bereft of hardly any growth apart from resilient sand crocuses, are once again green and spangled by daisies, marigolds and crucifers. Grim visages have been shed and even the most dour of those who live from the land exalt the promise of a spectacular spring.

Rain-filled pool on the plains of Extremadura (Martin Kelsey)

During this period, the rain has been accompanied by Atlantic winds, sweeping across the meseta of south-western Spain. Banks of heavy clouds unroll above us, dramatic and daunting. Birding is challenging in such windswept and wet conditions, but during lulls the birds respond. Respites offer opportunities for feeding, song and mating, or simply drying their plumage, giving those of us who have braved the conditions the reward of witnessing these peaks of activity. Two days ago, during a brief moment of calmer weather beside the Alcollarín Reservoir, a Common Cuckoo called from the oak dehesa, a newly arrived Woodchat Shrike sat on a clump of brambles and an Iberian Chiffchaff sang its hesitant, jumpy song, culminating in joyful "sweeet" notes. It interspersed its song with anxious foraging, hovering and flitting through the foliage, sometimes sharing the same small tree with its Common Chiffchaff cousin.

Alcollarín was the site on 6th March where I stood watching the hordes of Barn Swallows fluttering hard low over the water against the head wind and noticed an interesting-looking gull swimming, making short flights and returning to the water again. It was a first-winter Kittiwake, the first I had ever seen in Extremadura and far from its usual winter habitat: the high seas. I had heard that the storms had brought Kittiwakes into inshore waters in southern Spain and I confess that when I set out that morning, I half-wondered whether something like a Kittiwake might have been blown-in to my local reservoir, but there had been no records of any inland.
First-winter Kittiwake at Alcollarín (Martin Kelsey)

Two days later, standing on the massive dam  of the Sierra Brava reservoir, buffeted by the wind, with the mass of choppy water in front of me, it felt just like being on a sea-front. And as we stood, gliding past on stiff wings, we saw another Kittiwake, this time an adult. The Alcollarín youngster has not been relocated, but the adult at Sierra Brava was still present at least until yesterday, entertaining birders with its zooming flypasts at the dam, as if it was homing into a coastal cliff. These two birds remain the only ones reported from the interior of Spain, yet it is inconceivable that there are not others at reservoirs elsewhere.

Adult Kittiwake Sierra Brava Reservoir (Thomas Reickmann)

Thursday, 22 February 2018

Circles

Vortex behaviour by Shoveler (Martin Kelsey)

With an unaided eye, they appear like dense, floating mats. There are four of them visible on this small water body, along with a selection of busy evenly-scattered ducks: up-ending Mallards, pootling Shovelers, diving Pochards and Teal nibbling at the water's edge. But there is something about the motion of these mats that intrigue: they are alive. With binoculars the species responsible is instantly recognisable. With brilliant white bows, toffee-brown flanks and bottle-green heads, the drakes are Shovelers, and they seem to outnumber the females. And I become spellbound at what they are up to. 

These boldy patterned concentrations of Shoveler are circular in form and are spinning anti-clockwise. These duck mats vary in size, but the one I am watching has over 40 birds. Shoveler swim in to join the cluster, becoming tightly embedded into its form. Almost all of the birds have their bills, or even whole heads, submerged, whilst those in the middle are upending. It is almost as if the sheer pressure towards the centre forces those positioned there to be pushed vertically, so tight is the concentration of bodies. The mass continually circles in the same direction, a metaorganism, a vortex.

This pack of spinning Shoveler is creating a swirl of currents under the water, enough indeed to stir up the sediment on the bottom of the pool, bringing it up in a spiralling column to within the reach of the feeding duck. There their spatulate bills, edged with filtration combs, are ideally formed to collect the range of tiny food items they seek: seeds, insects, crustaceans. Biologists have described this as "Collective Vortex Behaviour", indeed there is even a paper about it in The Quarterly Review of Biology, published in 2016 by Johann Delcourt et al. They describe a model of how these spinning arrays of Shoveler form. Shovelers when feeding alone usually move either by simply ploughing forward in a straight line, or going round in little circles. This circular motion is an attempt to stir up sediment. If another joins it they circle close together in the same direction in order to avoid colliding with one another. Then there may be one or two more joining them. The result is a vortex which becomes so effective that it brings to the surface more food than they can eat. This then becomes an attraction for other Shoveler nearby and very quickly the group becomes much bigger.

I watch a place where three vortices were quite close to each other, and there is a steady movement between them of individual birds moving from the periphery of one to the other: sneaky opportunists perhaps.

I have watched this pool over several winters, but never before have I seen so many Shoveler on it and never so many showing this spinning behaviour. But the difference this year is that the water level has reduced hugely because of the severe drought. Perhaps this year the water is shallow enough across the whole pool for the vortex to work effectively, whereas in previous years the Shoveler seemed to spend most of their time snoozing on the surface: dormant and gently rocked by the ripples.
Spiralling Common Cranes (Martin Kelsey)

Above me, as I watch the vortices, birds are spiralling. A multitude of Common Cranes on northward migation rising on a thermal. This is a wholly disorganised circle, noisy and atomised. It rises anti-clockwise too but takes no clear form - each individual bird using the rising air to gain height. At its climax it undergoes an amazing transformation. Somehow they organise themselves into a strewn-out skein and proceed on their north-east trajectory. Having used thermal forces for ascent, they are now pulled by gravity, aided by the slipstream from the shape of the skein. There is beauty as they move, wings held in a glide with the occasional sine wave of gentle flaps. The sky is braided by this long string of birds. 

Braids of Common Cranes (Martin Kelsey)



Wednesday, 31 January 2018

Tented colonies

The homes of the Winter Webworm Ocnogyna beatica (Martin Kelsey)

I am standing beside pasture in late winter, facing the low sun, and watching the light refracting from silvery patches that freckle the field. They glow like medallions on the green baize of the meadow. I approach one and bend down to take a closer look. The structure is a canopy, closely woven, holding tiny globules of dew which collectively provide the silver sheen on the web. But I am more curious of its inhabitants, for below this tent squirm several hundred tiny caterpillars. They are the Winter Webworm, the larva of a tiger moth Ocnogyna beatica, a species of the western Mediterranean basin.

The Winter Webworm Ocnogyna beatica colony (Martin Kelsey)

Hatching in the middle of winter, they spend the first few weeks of their lives in these tented colonies. Their diet is catholic, consuming the winter greens of fresh foliage of clovers, mallows, vetches and mustards, and probably pretty much anything else growing around them. It strikes me that these veiled tents under which they are domiciled not only protect them from hoar frosts, but must also act like cloches for the food plants around the larvae. In a dry winter like this one, dew formation is a crucial source of moisture and perhaps the structures that the caterpillars have made create a favourable micro climate for the plants they feed on.

Winter Webworm larva on a sand crocus in early March (Martin Kelsey)

Once they are two or three centimetres long, come late February, the caterpillers evacuate their tents and roam widely. In places they become super-abundant, masses crossing tracks and roads, all heading in one direction, synchronised around a mysterious cue. By late spring they enter their pupa stage, a chrysalis that lies deep in the ground (10 to 20 centimetres) far from the severe dessicating drought of summer. This is the longest stage of  their annual cycle.

With the autumnal rains the adults emerge, the male with attractive variegated black and white wings and the wingless female, looking like a miniscule yak - plump with shaggy auburn hair. She will lay clusters of eggs and her progeny just three months further on will dapple the pastures with their minature greenhouses.

Sunday, 21 January 2018

Returning north

Migrating Greylag Geese at dawn on 20th January (Martin Kelsey)

I have seen a couple of Barn Swallows already this month, and they are most likely to be early returning migrants rather than overwintering birds, but it is still mid-January and, as the proverb says one (or even two) swallows do not make a summer. However, one clue that happened yesterday as I was hanging out the washing was an incontrovertible signal that the wheels of seasonal change are starting to roll - and it summoned a tinge of sadness within me.

The sun had yet to break the horizon of the hills to our east, but the House Sparrows were stirring with their chirruping waking conversations. Above this sound came another. It too was conversational but more strident and urgent. It was the honking of geese. Then from the south, and crossing my field of vision, was the skein. This was no short-distance foraging foray. These birds were flying high and with a purpose. They were returning north, Sightings of geese over our garden are exclusively birds on migration: in October and November heading south and then late January and February heading north. There are wintering populations just 25 km away as the goose flies, but nowhere closer to home are there any favoured feeding areas.

These geese were Greylags. This is a species which arouses little interest for visiting birders from Britain, for whom this species is associated with large,boisterous feral flocks. But these Greylags are truly wild birds, starting a journey back to their breeding grounds in Scandinavia. For me, our wintering Greylag Geese provoke a sense of wonder and respect, as do the Cranes, in their highly visual and audible migration. When I see them like this, I can only marvel at the drive, part innate and part learnt, that triggers the timing and direction of their journey.

In the centre of Extremadura, the Greylags feed mainly on rice stubble fields, alongside the cranes. But they select just a few particular zones, perhaps because there they are close to water bodies where they will roost. One of my favourite winter pastimes is spending the last hour of daylight at a spot where I can look across one of these sites. The low sun behind me provides wonderful viewing conditions across an expanse of rice stubble. Marsh and Hen Harriers will be out, causing flurries of Spanish Sparrows and Corn Buntings to erupt from amongst the dead stems. Common Cranes in family groups daintly pick at the debris on the ground. But it is the geese I focus on, aware that with each minute that passes, I have less and less day light to work with. It is about patience, lots of it. I am searching the flock for any unusual geese that may have migrated south along with the Greylags. As anyone who has watched feeding geese will know, most of the flock will have their heads down feeding, others will be asleep, leaving just a few with their heads held high in vigilence.  The problem is that when searching for unusual species, it is the bill, head and neck that carry the easiest to spot differences. In the tall rice stubble, the situation is even more complicated. Sometimes just the top of the back of a goose will be visible, and sometimes it will disappear completely as it moves into a runnel. And as good as my vantage point is, some of the flock will simply be too far away to see well.
Wintering Greylag Geese in rice stubble (Martin Kelsey)

On almost every visit, therefore, I content myself in knowing that  I have at least tried and that, despite the frustrations, it was a truly wonderful way to spend a late winter's afternoon. Twice though this winter, the effort did pay off. Once with finding two White-fronted Geese and then a month later, discovering a much rarer Pink-footed Goose in the same place.
White-fronted Goose (closest bird) with Greylag Geese in rice stubble (Martin Kelsey)

Seeing the migrating geese yesterday, prompted me to return to this viewpoint in the afternoon. I had passed by there just two days earlier and several hundred geese were present, but I could not pause for long there because  I was busy counting cranes, and besides the light was too bright to scan the geese carefully. Back there yesterday, the message conveyed by the migrating geese was all too clearly confirmed. Just three Greylag Geese remained. And so my afternoon goose watching season had ended for another year. 

Sunday, 31 December 2017

A landscape for raptors

December's leaden skies (Martin Kelsey)
I relish the sight of troubled skies, heavy smudged charcoal, brush strokes of cinder-grey. And never more so than above the open steppes of Extremadura, bearing subtle tones of emergent green now. Westerly winds roll the banks of cloud, which fracture to allow angled beams of light to illuminate a distant dehesa, like a moving searchlight. The combination of open terrain and a vast sky creates a multi-dimensional space fully exploited by one group of birds in particular, the raptors. The Extremaduran plains are bird of prey habitat par excellence

In the first hour of daylight on a winter's morning there is movement. Multitudes of small birds are woven across the pasture. Jerky Meadow Pipits are walking, a fluster of Skylark settles, small parties of Corn Buntings tic-tic in urgent flight above us. There are White Wagtails and Lapwings on the ground. Two Thekla Larks shuffle beside a lichen-dressed piece of ancient slate. An Iberian Grey Shrike faces us on the fence, using its long-tail as a balance, with an accompanying Stonechat perched attentively just a few metres away from it. A roving, rasping party of Calandra Larks surge across the field. We bird by simply standing still and watching.

Suddenly, I hear a different sound, a high-pitched warning call and instinctively, like all the birds around me, I look up. Against the grey sky I see first of all a fluttering speck, a tiny Meadow Pipit. From the right another shape pitches in, compact and menacing. The Merlin skims across the pipit and swerves upward in an arc, then swooping downward, missing its target again. In barely a second, it has launched vertically to attempt another strike, its tail and wings spread as it brakes in pursuit of the prey. The pipit escapes. Then, as the Merlin, having overtaken the pipit, banks to plunge, another Merlin with arrow-like direct flight, enter the scene. It too swivels into attack. The Meadow Pipit disappears behind the skyline, both Merlins now following it. But the performance has not ended. One of the Merlins rises above the horizon and then dives down below it. In a perfection of timing, the second does the same, followed again by the first. It is as if they were trampoling, rising and falling, one after the other. How can the pipit possibly escape? But evidently it does because one Merlin flies off, in low direct flight, followed by the other, both looking empty-handed. 

In a nearby river valley, we watch an Otter moving upstream. It is the first time the river has flowed since the spring, so entrenched has been the drought. The heavy cloud does not bode well for sightings of large birds of prey, but perhaps because of the wind, there are Griffon Vultures gliding slowly above. Below them, a dark, longer-tailed bird rises, its wings in a shallow V and bearing a buoyant tilt. The Golden Eagle quickly gains height, pauses, closes it wings and in sheer exuberance, dives earthbound, until opening its wings again and allowing its own momentum to push it skywards once more. Again it dives down and rises, its skydance mirroring the trampoling Merlin.

The road follows the route of a Cañada Real, an ancient drovers' trail - a strip of uncultivated common land, 75 metres wide. The vegetation here is tall and withered, with scattered Retama bushes. Ahead of us, in low sweeping flight is a male Hen Harrier, a young bird, judging from the brownish tone in the middle of its back, but with gull-grey upperwings, black tips, and white underwing, neatly bordered by black on the trailing edge. We stop to watch it as it carefully quarters the verges. Its long glides are broken by a banking motion, as it stops and backtracks, prompted by a potential prey, before continuing in forward motion. It reminds me of an absent-minded pedestrian, stopping mid-stride, turning around abruptly, before changing his mind and resuming his walk.

A larger bird of prey appears to our left, caramel-coloured with dark flight feathers, fringed with white and white also on the rump. It flaps heavily before gliding, the ground falling away below it, its wings rigid and flat. It is a young Spanish Imperial Eagle. As it disappears from view, another identically marked bird approaches us from the left, taking a few flaps before it too drifts away. I feel feebly terrestrial, contemplating the space that this bird explores. We then notice another observer. Standing on a small dog's teeth of protuding rock, and resplendent with white epaulets, thick cream head with its neat black mask, is an adult Spanish Imperial. Despite its acute vision, our presence unremains unacknowledged.  I like to think that we are perhaps insignificant to it as it surveys this terrain, a landscape fit for eagles. As maybe was the cow, sitting nearby, which like us, also watched the eagle. All on a winter's day.

Spanish Imperial Eagle watched by a cow (Martin Kelsey)