Thursday, 4 July 2019

Flight paths at the riverside

Watching dragonflies with Mark (Martin Kelsey)
Late June and July are when things really take off. I am sitting on a water-worn rock in the shadow cast by a single-arch stone bridge. My body adjusts to its smooth contours and I relish its coolness and the shade: a respite from the heat surging from Spanish-blue sky. The ancient bridge, which is just wide enough to walk across, also carries a stone channel along which clear cold water races, on its way to irrigate vegetable gardens  on the other side of the deep valley. Water dribbles from the rim of the arch of the bridge, leaking from this channel, creating  a silvery cascade dripping down to the river below. Dodging this constant trickle, a pair of Red-rumped Swallows bring food every couple of minutes to young hidden in the bowel of their mud-built nest at the apex of the arch. The adults give their friendly budgerigar-like chortle. A pair of White-rumped Swifts zoom up the valley, somewhere they will be using an abandoned Red-rumped Swallow nest like this for themselves.

Today these are but delightful distractions, because I am becoming totally absorbed by action at the water's edge. From my perch I can see half a dozen species of Odonata, both dragonflies and damselflies. I leave the photography to my companion Mark. My defective camera has been a blessing, and I am granted the sheer freedom to put it aside and to observe. I am engrossed.

Around me is a community of these extrordinary insects, busily meeting the demands of their brief adult lives. What I start to see are differences, each species behaving in distinct ways. I can identify each species simply on what I am learning through these minutes of careful observation. Some of the species indeed bear common names based not on their appearance, but on their behaviour. Thus the chunky-bodied Splendid Cruiser sweeps past me on a circuit that takes it over the quiet water to my left and back again across the boulders and torrents to shady pools to my right. Almost the whole time it is on level flight, cruising as it were, and repeating this flight path every five minutes or so, only deviating from it when a chance encounter with a neighbouring Splended Cruiser sends them both skyward so fast that I can barely follow them.

Western Spectre (Martin Kelsey)

A Western Spectre, less showy and a bit smaller than the Cruisers, lurks close to the water, right next to the bank, pausing where vegetation hangs down, disappearing briefly from view as it explores the shade under the fronds. On the very same leaves hang Western Demoiselles, their pigmented wings in semaphore. Into view comes an Orange-spotted Emerald, hovering at the entrance of a small bay, stationary in mid-air before chasing off a much larger Splendid Cruiser or a Keeled Skimmer. It is feisty and pugnacious, keeping its patch clear of all intruders. This constant aerial motion contrasts with the behaviour of the pincertails which sit, abdomen raised with the heat, atop mid-current rounded stones, making just the briefest of sortees out across the water before returning.

Looking for Hooktails with Mark (Martin Kelsey)

The next day we are at a very different river, wide and slow-flowing with tangled vegetation spreading across the gravel banks mid-stream. Instead of a mountain stream, it is a languid, almost tropical river. Another community of Odonata is there to be enjoyed. Violet Dropwings perch on Typha stems, making forays and returning to their perches where they obelisk with the heat. Tiny White Featherlegs shift from hiding places in the vegetation as I struggle through it. They have a slow, gravity-defying bouncy flight, as if suspended by fine elastic.
White Featherleg (Martin Kelsey)


Across the water, another dragonfly darts at great speed, just above the water level. It crosses the width of the river in what seems like a fraction of a second, and then zooms back again towards me. As soon as its path leaves the water and crosses the gravel bank I lose sight of it, not knowing if it has landed or simply done a large loop, because soon it is back over the river. For minutes on end, this action is repeated but I remain frustrated at not being able to work out what it is doing. Mark and I carry on walking, putting up Little Ringed Plovers and finding a singing Western Olivaceous Warbler in the gallery woodland of willow shrubs.
Green Hooktail (Mark Ferris)

We return with renewed impetus to see this dragonfly. It rushes in from the water, but this time I am better positioned and spot where it has landed. I approach it carefully, immediately identifying it as a male Green Hooktail, a particularly striking species, bearing an almost prehistoric demeanour. Perched on a piece of dry vegetation, it watches me. Something drives it to be airbourne again and off it goes on his zigzag flight path across the water. But this time I am patient, I know this species too and anticipate its return to the same perch. I do not have to wait long for its re-appearance there. A reward for patience and for figuring it all out, understanding and intepreting these myiad of marvel.

Friday, 31 May 2019

Reaching for the sky

Gredos landscape (Martin Kelsey)

On the plains spring is over and the vegetation is blanched blond. Hay has been cut and gathered and harvest is underway. On more lightly grazed land, the dominant shrub is now in flower. A wispy grey-green untidy plant, commonly mistaken by visitors as tamarisk, it is in fact a type of broom called Retama sphaerocarpa. As I drove north from Cáceres, I entered a landscape turned lemon yellow by the sheer abundance of this species, growing on otherwise sparsely vegetated, thin-soiled badlands. It offers a final respite, along with the thistles, before summer closes in, for nectar-seeking insects.

But my journey was taking me further, rising a thousand metres more onto open country, the rounded granite mountain tops of the Gredos. Rising through the soft greens of the deciduous Pyrenean oaks, I arrived at a place where spring was just starting. Indeed, the white brooms so characteristic of the granite berrocal near Trujillo, which is in full bloom in March, were only just starting to flower at this height. Before me was an artist's palate of colour: whites, russets and purples, but predominantly the rich yellow of the mountain broom species Cytisus oromediterraneaus. Locally know as Piorno, it gave its name to the highest town in Extremadura: Piornal, which was founded in the middle of the 13th Century.
Ortolan Bunting (Martin Kelsey)

The birds too were exuding spring passion. Most characteristic of this terrain is the Ortolan Bunting, whose poignant song, carries in its tone and its simplicity an evocation of space and depth. Rufous-tailed Rock Thrush delivered a more embellished fluty song. As I stood, I could hear the song of no fewer than nine species of birds. As instruments in an orchestra, they melded into a exaltation of the mountain, but for many their performance became even more exuberant. Positioned at this mountain top, an interface of the earth and the heavens, birds launched themselves into the sky, parachuting down with tail and wings outspread. Rock Thrushes and Wheatears, Water Pipits, Whitethroats and Bluethroat all deployed the same technique, carrying their song to join the continuous offering of Skylarks, so high that they were hard to locate against the blue of the sky. Only the Ortolan stayed put, stoically atop a granite boulder, its haunting song filling the horizontal dimension, mingled with a tapestry of colour.

Sunday, 7 April 2019

Milestone for an icon

Peña Falcón in Monfragüe National Park (Martin Kelsey)

Erupting as a ribbon of parallel ridges across an ocean of dehesa, the hard quartzite strata stand as proud relics to the turbulance of the Variscan orogeny, the tectonic movements that formed the supercontinent Pangea. The results of this collision between the ancient masses of Euramerica and Gondwana can be found in the form of the Pyrenees, some of the Alps (including Mont Blanc) and here in Extremadura, the syncline that shapes the Monfragüe National Park. Standing amongst the visitors at the viewpoint in the southern entrance to the park, I look across onto the the massive Peña Falcón (the Falcon's Rock: which indeed does host a pair of Peregrines). The rock strata laid horizontally as sand on beaches and under the sea about 500 million years ago were metamorphosed into quartzites and slates, violently folded 200 millions years later and pushed vertically as waves across the Earth's crust.

"Think about geology to understand landscape" a geologist once told me. Below me the Tagus (Tajo) River flows from the right. There it had sought the route of least resistance, smoothing a valley through the softer and friable layers of slate until she hit the wall of quartzite. Gravity drew her direction of travel southward and it was at this point where through a long-gone fault or weakness in the rock, the water pushed through. Over millions of years of erosion, the gateway or Portilla, was formed, creating this iconic gorge.

Prehistoric rock art in Monfragüe (Martin Kelsey)

The overhangs and crevices in the quartzite offered refuges for the first human visitors to Monfragüe and thus started the agency of the human hand and mind in shaping this landscape. The rock paintings just below the castle in Monfragüe date back 11,000 years. The name Monfragüe itself is derived from the Roman "Monsfragorum" which means a rocky zone with abrupt relief, but also lush: describing perfectly the vast Mediterranean mixed forest which still covers the north-facing slope of the castle ridge. In medieval times a bridge was built crossing the Tagus, visible to this day when the water level is low enough, but travellers were at risk from attack by bandits hiding in the steep, wooded terrain. The rocky hillsides and impenetrable vegetation also provided cover for groups of maquis, guerrilla fighters who maintained resistence against the Franco regime for several years after the Civil War.

The Cardinal's Bridge, built in 1450 and today only visible when the water level is low enough (Martin Kelsey)

The dehesa wood pasture was developed across the vast latifundias, the estates bestowed by the monarchs after the Reconquest, and which still define much of the land tenure around Monfragüe. For centuries the landscape would have changed little. This was until the 1960s when a dramatic new chapter in Monfragüe's history opened. Dams were built across the great Tagus (one inside what is now the park) and another downstream at Alcántara. The result was to change forever the way in which the river passed through the gorge, replacing waterfalls and rocky torrents with the sluggish feel of a backwater. And then, at the end of the decade, work started to convert the hillsides of native Mediterranean woodland into vast and sterile eucalyptus and pine plantations for pulp and paper production.

It was at that time when perhaps Monfragüe's most significant visitor first set foot in the area. Jesús Garzón was studying Spanish Imperial Eagles and was staggered to experience a place where it was possible without leaving the road to obtain  unequalled views of timid species like Black Storks, five species of eagle and nesting vultures. These deep impressions are shared even today by the numerous visitors that gather at the viewpoints in the park. But he saw too  how this extraordinary place was being ripped apart by the conversion of land underway, and with much more under threat. He spearheaded a campaign in the early 1970s, involving conservationists, activists and, significantly, local schools to oppose the spread of eucalyptus. These were times of great change in Spain with the death of Franco and the transition to democracy. The campaign struggled against what was then government policy and the interests of big business. But the public voice triumphed - indeed Garzón says that "Monfragüe was saved by the local children".

Campaign material from 1973 to mobilise people to save Monfragüe (from the historic archives of Monfragüe National Park)

Exactly 40 years ago the objectives of the campaign were realized with the declaration of Monfragüe as a Natural Park and a change in government policy to prohibit the planting of eucalyptus in the Mediterranean region of the country. Over a decade ago, Monfragüe was further upgraded to a National Park, covering over 18,000 hectares, sitting in the middle of a Biosphere Reserve of over 110,000 hectares. This vast buffer zone is crucial for the integrity of the park, offering foraging ranges over dehesa farmland for the breeding birds of prey, most notably the world's highest density of Black Vultures, a species that has increased tenfold in Extremadura since Jesús Garzón's first fell in love with Monfragüe.

Saturday, 23 March 2019

Town park birding

Little Ringed Plover (Martin Kelsey)

There is nothing quite so dapper as the ringed plover Charadrius species in breeding dress. Neat and precise black bands crisply border the front half of the bird, contrasting with pure white underparts and, in a modest concession to their surroundings, smooth mud-brown upperparts. Their rotund bodies, rather short legs and simple short bill give them an appealing cuteness, strengthened further by their  typically tentative demeanour. They are hesitant birds, foraging by means of a few paces in one direction, a pause to peer and peck, followed by a few more steps in what seems to be a random trajectory. They seem both endearingly vulnerable and friendly at the same time.

In its full nuptual plumage, the Little Ringed Plover blasts its European congeners away with an almost alarmingly swollen ring of bare-skin around the eye. This ripe lemon yellow orbital adorns the dress uniform of the bird like parade-ground braid. Little Ringed Plovers are common breeding birds in Extremadura, found at the edge of water bodies, along rivers and even nesting along the farm tracks in the rice fields. It is an increasingly familar sight in winter too (see the Spanish blog by Javier Prieta).

I know of no better place to get better views of this little wader than the San Lazaro park at the edge of Trujillo. Here there is a body of water of about two hectares in area, with a perimeter path and footbridge going right across its centre. In places there are small gently sloping patches of bare ground on its shore, elsewhere reduced clumps of reed mace. At its far end there is a children's playground and bar. It is a favourite spot for dogwalkers, joggers, families and those simply out for a paseo. And for me, an ideal drop-in spot before heading to do some shopping nearby.

On my visit there yesterday, I counted four pairs of Little Ringed Plovers, each quietly keeping to favoured zones, where they trundled and paused, almost as if by clockwork. They were a total contrast to the chic dainty elegance of Black-winged Stilts (three pairs were present), with their absurdly long red legs, needle-like black bill, acting like pincers to lift prey from the water.

Black-winged Stilt (Martin Kelsey)

From the Typha a migrating Sedge Warbler had stopped off and was singing loudly, right beside the footbridge. The same patch of emergent vegetation is cover for wintering Chiffchaffs, that fly out in short hovering motion to feast on yuletide midges. Barn Swallows hawked the open water, where Coot, Moorhen, Little Grebe and Mallard all pootled around, and all nesting around the pool. Serins performed their buoyant songflights above me.

The San Lazaro park in Trujillo (Martin Kelsey)

From my vantage point, on the path beside the water, I  look up towards the centre of the town and to the Moorish fort crowning the heights of the granite foundation of Trujillo. A building a thousand years older than the concrete silo dominating the skyline to my left. But the latter too featured in my town park birding, a dozen Lesser Kestrels wheeled in the sapphire sky above it. Thanks to installation of nest boxes on its roof, this monolith  has become one of the most important single Lesser Kestrel colonies in the region.

Friday, 8 February 2019

Eagles in the Spanish savannas

Male Bonelli's Eagle (Martin Kelsey)

A western outreach of the Montes de Toledo, the Sierra de San Pedro is a chain of low-altitude mountains dividing the basins of the Tagus and Guadiana Rivers, and acting as a political boundary too, with Cáceres province to the north and Badajoz to the south. It extends for over 60 km, running east-west from the city of Cáceres to the Portuguese border. Part of the Sierra is a Special Protection Area for birds, covering over 115,000 hectares.  Despite its relatively low elevation, from our vantage point, and thanks to a morning of extraordinary clean winter light, we could look north across the plains of Brozas and see the arc of the Central System of mountains, with the snow-capped Serra da Estela in Portugal, spanning east to the Sierra de Gata and then the Sierra de Gredos, the granite wall marking the northern limits of Extremadura, views extending for perhaps 150 kilometres.

Sierra de San Pedro (Martin Kelsey)

Closer at hand, we could look down on broad, gentle valleys covered by dehesa woodland, where the cork oaks and holm oaks grow far enough apart for light to reach the ground and for grass to grow. A medieval wood pasture, managed as such still today. But our panoramic view evoked a more primeval response. Our host, Helios, described what we saw as "savanna" and this huge landscape of open woodland, ruptured by wild rocky ridges, bore an African feel. As if to reinforce this sensation, Helios told us that across this expanse there were numerous dolmens, megalithic tombs, remnants of a human presence over thousands of years. The dehesa landscape itself was shaped by people, much more recently than the cultures who built dolmens. But paradoxically within the undulating arenas surrounding us, save for occasional meagre collections of farm buildings, people were absent. Indeed, during our whole morning we saw just one other person.

People were far out-numbered by birds of prey. The Sierra de San Pedro has the largest population of Black Vultures in the world and Extremadura's largest Spanish Imperial Eagle population (about 25 pairs). We were visiting the area with Helios to get front-row seats for another eagle species, one that epitomises sheer power and mystique.

Bonelli's Eagles never give advance notice of their arrival. They hunt by subterfuge and ambush. They are not called in both German and Spanish "Goshawk Eagles" for nothing. They are birds of deep-wooded valleys, crowned by rocky outcrops. The topography of such landscapes is intrinsic to their hunting technique. Their craft is to hug the contour, rising only to make a final stoop on their prey, of which pigeons are a particular favourite. Claudia and I entered the hide and took a seat whilst Helios started hanging pieces of dead bait on exposed branches of cork oak in front of us. His very appearance seemed to be a cue for the eagle. Indeed as Helios was climbing a ladder to our left, the Bonelli's Eagle swung into view and briefly perched on a branch to our right, before taking off and disappearing behind the spur of the hill. Task completed, Helios departed to leave us to sit and wait.

I had forewarned Claudia that we may need to wait a couple of hours. A couple of minutes, more like! As soon as the stage was empty, the Bonelli's Eagle returned. It was the male and he stood for moment to check the scene before starting to feed. This was the start of an extraordinary session of four hours, during which the Bonelli's Eagles were present the entire time.
Male Bonelli's Eagle (Martin Kelsey)

About two-thirds of the way through, the male started to call quietly: a series of soft piping notes. He paused and looked earnestly across the domain of the valley in front of us and towards distant crags. He called again, this time fractionally louder. I looked in the same direction as his gaze and saw a movement. It was his mate approaching from the outcrops, over a kilometre away. Had she heard this barely audible call? She approached on a long glide, coming to settle beside him on the branch in front of us. He had left some food for her and as she fed, he shuffled along the branch to stand in the shade.

Pair of Bonelli's Eagle (Martin Kelsey)


Young female Bonelli's Eagle (Martin Kelsey)

She was a much younger bird. Whilst his trousers were white with blackish oak-leafed shaped centres to the loose soft feathers and his cheeks were white with fine greyish streaks, she had tawny-plumaged legs and her face bore a warm buff tan. We were close enough even to observe the difference of the colour of their eyes.

The creamy-coloured eye of the older bird (Martin Kelsey)

The older male with a rich butter-cream iris, with suffused grey radial marks, whilst the bigger female had a deeper orange-tawny iris, and it seemed to me, a sterner stronger brow. Those eyes had evolved a far greater acuity than my own.

As they departed, we watched as they crossed the valley, their shape just discernible against the stippled background of the crowns of the dehesa evergreen oaks and the grey eruptions of rock. Then, they disappeared, absorbed as it were by distance. And like wherever I have encountered this most alluring of eagles, this place became enchanted.


We visited the Bonelli's Eagle Hide set up by Photo Raptors in the Sierra de San Pedro. Photo Raptors can also offer hides for Spanish Imperial Eagle, vultures and passerines, as well as for Common Cranes in the winter.  


One of the hides for Bonelli's Eagle offered by Photo Raptors 

Thursday, 31 January 2019

Elegy for the Little Bustard

Little Bustards in winter (Martin Kelsey)

It was the second of March 2006 and the late afternoon light was just at the right angle to push through the ashen-grey stems of the dead thistles and reflect against the white feathers on their bellies. Their upperparts were a marginally sandier tone than the thistles that gave them cover, but the vermiculations of darker streaking on the feathers gave crypsis, blending their outline into the jarring, discontinuities of the withered spiky plants. Nevertheless, from where I stood, my back to the sun, I could scan across the slope where they stood. The flock was at rest, stationary, and I could count them one-by-one. There were 330 individuals all told (give or take a couple) and they were Little Bustards.

For a few winters after that, I could still come across sizeable flocks, but never much more than 150. But by the time I was helping with fieldwork in 2016 for the winter census of the species across the whole of Spain, the largest flock I found was 92 birds. Indeed at the national level there were only two flocks bigger than the group that I had counted ten years earlier (and only 14 flocks greater than 100 birds counted in the whole of the country!). This winter the biggest flock I have seen was 39 birds.

SEO/BirdLife has just published the results of the 2016 Little Bustard census. There are two populations of the species: an eastern one which extends through Central Asia to North-east China and which appears to be in good numbers, and the western one, in the Iberian Peninsula, France and Sardinia (with populations on mainland Italy and Morroco practically extinct). The western population is in very fast decline. In western France the species suffered an extraordinary drop of 94% of its population over the last two decades of the twentieth century, whilst the SEO/BirdLife census documents a fall in Spain of both the wintering population and the count of males in spring of 48% between 2005 and 2016. In Extremadura the decline is somewhat sharper, with a drop of 56% of males in spring and a decline of 33% in the winter population.

It is estimated that across Spain over the same period, 17% of suitable habitat was lost. But what is a telling indicator is the lower density of the birds compared with a decade earlier (1.13 males/square kilometre to 0.67). This is showing that, more important than habitat loss, is the reduction in the quality of the habitat. It is a creeping, insiduous threat, invisible, but happening under our very noses, under our watch. If I look at photos I have taken across the plains of Extrenadura over that period, it is hard to see any obvious  difference. But when I walk across the plains in late spring, every footstep I take tells the same story.

When I first visited Extremadura over 25 years ago, I wrote down in my notebook the number of Great Bustards I saw at each place I visited. To my subsequent regret, I did not count the Little Bustards: they were present everywhere I stopped. And on the ground, as I walked, there was an eruption of leaping grasshoppers. Even ten years ago, each step through the vegetation spoke of a vast biomass of invertebrates.  No more. Changes to the plains have not dramatically changed the landscape, but are breaking the trophic pyramid. Shifts towards more intensive grazing, less arable land - and those crops that are grown are now harvested earlier in the season, destined as they are for livestock feed.

As Nigel Collar in his prologue to the findings of the Little Bustard census says, there is the danger of shifting baselines. Twenty years ago people found winter flocks of a thousand Little Bustards, ten years ago we looked for flocks of a hundred, now I am relieved to come across two dozen. Is that now our norm?  Mark Cocker in his book Our Place speaks of environmental melancholia. It is a syndrome I recognise when I see these wonderful creatures hunched amongst the dead thistles on a winter's day, or springing with a shock of white in their whirring wings which sing their Spanish name "Sisón, sisón" as they take flight. I do not believe I shall ever see a flock of 330 Little Bustards again.

A flock of Little Bustard (Martin Kelsey)



Sunday, 30 December 2018

The evening of the day

A winter's evening at Arrocampo Reservoir (Martin Kelsey)

At a quarter to six the action starts, flagged by the arrival of a band of forty Cattle Egrets, pushed by a sense of purpose and giving their craggy calls as they pass. A guttural wrenching call incongrously emergences from the elegance of a Little Egret. Why is it that a family of birds so suave that demand for their nuptual plumes decimated their populations over a hundred years ago, are the authors of such coarse squawks? My musing is quickly overtaken by the next ribbon of dusk activity as I count over two hundred Jackdaws, lining-up and all facing the same direction along high-tension cables. These are suspended from pylons that cut a tangent along the eastern fringe of the Arrocampo Reservoir. Unlike other reservoirs, the water level of Arrocampo barely fluctuates during the year. It acts as the source of coolant water for the Almaráz nuclear power plant, the white domes of which I can see across to my left. The combination of shallow water, absence of changing levels, a fertile catchment and sightly warmer than average water temperature has resulted in a wide margin of emergent vegetation, dominated by reed mace. 

These Typha beds support a rich avifauna (as well as being superb for dragonflies). All of Europe's species of herons, egrets and bitterns have bred here and there are populations also of Purple Swamphen, warblers such as Savi's and Great Reed, and Penduline Tit. Crakes sneak through on passage. But in winter the Typha beds are where an extraordinary mixture of birds bed themselves down for the night. Before their descent, some of the birds are making pre-roost gatherings, such as the Jackdaws on the cables. As I watch them, a group of Lapwings cross my field of view, a staccato of black and white.  Also heading for roost, their choice venue will be a shallow pool nearby.

Pre-roost of Spotless Starlings (Martin Kelsey)
On two pylons hundreds of Spotless Starlings bead the cables and festoon the structures, waiting for the moment to make their descent to the roost. The sun is sinking, the western sky slowly blushes like a bed of embers, as the foreground becomes increasingly monochrome and detail fades. Sound become as important as sight. Reedbeds always host strange utterances from creatures hidden from view. There is a satisfied rounded squeal from a Water Rail. A Purple Swamphen gives an explosive trumpet blast. A Bluethroat tut-tuts. Movement continues as Great White Egrets arc inwards, swirling on stiff half-opened wings to descend into an area of vegetation just to my right. Packs of Jackdaws noisily "jakking" clear from the cables and twist into the same area of reeds. Cattle Egrets are streaming in as well. The combination of black and white: Jackdaws and egrets, seems perfectly matched and assorted, echoing strangely the image of the earlier flock of Lapwings.

Many species of birds roost communally, especially in the winter. The functions of coming together at night include the hypothesis of the information centre, where information may be transferred about the best foraging areas. If birds huddle together close enough this may help to reduce heat loss. Being together will also enhance viligence against predators and, in the event of an attack, increased likelihood for the predator to be confused and distracted by the multitude. As if to prove the point, there is a sudden frenzied eruption as the egrets and Jackdaws take off. A hunting Marsh Harrier in the twilight makes a couple of wavering banking manoeuvres in the midst of the commotion before straightening its trajectory and drifting off and away, doubtless to its own harrier communal roost.

As the cocktail of birds calm down and disappear once more in the vegetation, they start to produce a rather enchanting cacaphony of sound: growls from the egrets and the sharper calls from the corvids. Mixed together it takes on a gentle bubbling character, rather like a thick soup simmering. I imagine the gathering of now several hundred birds fidgeting as they settle down, a mysterious myriad of interactions between neighbours. 

As I leave, with the night closing in, another sound emerges. It is the gruff "waaaa" of Black-crowned Night Herons. A string of these chunky birds fly high across the marsh from right to left. Unlike all of the activity so far, they departing from their roost and heading off to forage. The changing of the guard perhaps, or the ebb and flow of the tide.