Back at Cliffe with a possible Little Stint, thinking of Golden Plover

Made it to Cliffe about an hour before high tide, just in time to see many of the waders arrive off the Thames.

Great numbers of Avocet, Dunlin, Black-tailed Godwit, Redshank, Little Egret, Great Crested Grebe, Little Grebe, Black-headed Gull, Black-backed Gull, Herring Gull, Shoveller, Teal, Shelduck, Mallard, some Pintail.

One possible Little Stint actively feeding on the drier sand behind a large group of Dunlin.

Woodpigeon, Stock Dove, Woodpigeon, Robin, Blue Tit, Long-tailed Tit. Some warblers seen, possibly an autumn call of a Chiff-chaff.

It was very nice to see the Golden Plover on the edges of the pools. There were a number of the Grey Plover as well, looking tougher as they so often do, with their heavier bills. However the Golden Plover, Pluvialis apricaria, were my main interest today. These may be breeding in Northern Europe or Russia, but they could be from the uplands of the UK as well. The breeding in the UK might be regarded as somewhat on the edge of its range, and also slightly artificial as upland moorland is largely created by historic land management, but there has been quite a lot of research on the breeding ecology of these gorgeous birds. The UK population could be regarded as at the southern edges of its breeding range and particularly subject to potential warming and drying climate change, which could reduce food sources such as cranefly (Tipulid) larvae. In order to preserve this potentially threatened population, 9Pearce-Higgins, 2011) suggested thart efforts could be made to improve habitat, and thus breeding success, and reduce predation on the other hand.

One very interesting and unexpected feature - the males and females split incubation period in an interesting way: the males incubate during the day, while the females incubate at night.

The research has shown some rather odd features of this species' breeding ecology. When not incubating their eggs on moorland, the adults can often be found on neighbouring agricultural pasture fields rather than moorland, where they are likely to be feeding (perhaps) or resting for about half their time.  This is however less true for the males. The average distance moved to the fields was about 2.7 km in the Sunderland study, with females flying further than males. Individual flocks of birds tended to show fairly strong faithfulness to their individual favourite fields, both within a year, and from year to year. Relatively few of the available fields were used for feeding, with those used tending to be large, old, with some cover of rushes Juncus spp., and grazed by sheep. Leatherjackets were possibly the favoured prey.

Although field size did not seem to determine whether fields were occupied or not, field size was correlated with the numbers of birds in an occupied field. Having wet flushes did seem to increase the popularity of a field being chosen, as did the sward kept short by sheep. The nature of the boundary did not seem to have much of an effect, although this might have been expected to have affected ease of predation. The number of molehills, as a proxy for earthworm numbers, was a good indicator of field attractiveness, (according to Whittingham et al, 2000).

Once the eggs hatch, the behaviour of the adults changes, and then they spend much motre time foraging on moorland.

It was estimated that there were about 2,000 pairs breeding in Caithness, of which about half would have been nesting in the Special Protection Area (declared because of the importance of this area for the total breeding population. The fields used while incubating need to be managed appropriately: Management of areas of pasture to maintain their suitability for feeding golden plovers should, in general, avoid ‘improvement’ in the sense typified by agricultural intensification (Wilson et al., 2005). Specifically, the following practices should be avoided: Draining; Application of pesticides to control tipulid larvae (cranefly larvae = leatherjackets); Ploughing and re-seeding with single palatable grass species; Application of inorganic fertilisers; Removal of grazing; Conversion to silage or hay crop.

Based on the apparent preferences of golden plovers, the following characteristics of fields should be maintained: Field size (although enlargement through removal of fences between fields should not have an adverse effect); Poor drainage (as revealed by at least some coverage of Juncus rushes); Multi-species grass community; Grazing regime to maintain a short sward less than 5 cm

Tipulid larvae abundance is also enhanced by the presence of a taller sward during the adult tipulid emergence period ( July – September); this is thought to be because taller grass prevents airborne laying females being blown away by the wind and hence encourages them to lay their eggs in a small area around their emergence site (McCracken et al., 1995; Bignal et al., 1996). Thus a grazing regime whereby livestock is put on to fields in late winter (to create a short sward) but is removed shortly before the adult tipulid emergence period begins in July (to allow a taller sward to develop and retain laying female tipulids) should create favourable conditions for feeding golden plover. In this context, fields used as ‘lambing parks’, especially where ewes and lambs (or other livestock after lambing has finished) are held until mid-June before being hefted to other areas, are likely to be favoured by golden plovers, assuming other field characteristics are compatible.

Clearly these practices should be targeted at those fields already known to be used by plovers, although, as noted earlier, identification and maintenance of suitable ‘alternative’ fields nearby should also be desirable. The proportions of all fields which are used by golden plover are so small (about 3% overall) that it should be feasible to strike a balance between maintaining sufficient suitable fields whilst still being compatible with any intensification deemed as necessary by farmers, although in some holdings the proportion of ‘plover fields’ may be locally greater. Maintenance of fields which are potentially or known to be suitable for golden plover should also benefit several other wader species which appear to have similar preferences.

The chicks obviously feed closer to the nest, and appear in NorthEast England to like patches of mixed heather and grasses, as well as wet areas. Mixed grazing of appropriate intensity to create the vegetation mosaic, as well as stopping up drains to create the wet areas, might therefore be very helpful in aiding their feeding, possibly primarily in Tipulids (according to Whittingham et al, 2001). In Swedish Lapland the pattern differed somewhat according to (Machin et al, 2001), where the chicks fed largely on Coleoptera but also  first on Tipulids on more open areas, then switched (as these ran out (?)) to Bibionids in Willow Scrub a bit later, which might also have helped to protect them from predators.

A lightning look at Crystal Pool, Cliffe

A very brief look of a minute or two at Crystal Pool, as the rain clouds rolled towards us, revealed a Herring Gull on the old woodwork, and a male Mallard together with a male Pochard, the first one for me this winter! Fantastic!

As we reached the car after our brief outing, the heavens opened. Excellent timing!

Phyllonorycter species at Dene Park

Interesting to think about leafmines at this time of year.

I found some nice blotch mines on the upper surface of Hornbeam leaves at Dene Park this afternoon, which I thought must be mines of a Phyllonorycter species from their "general look". The most likely species should be Phyllonorycter esperella, (Goeze 1783), according to the pictures on the leafminer website. The species has an old synonym, Phyllonorycter quinnata, (Geoffrey, 1785).

Phyllonorycter esperella mines are generally found first in June, then again in September-October, specifically on Hornbeam, Carpinus betulus (L.). The young mines are roundish, on the upperside (generally unusual for a leaf-mine), usually centred over a side vein, silvery with brown speckles, and they then expand to be larger ovals, often substantially contracting the leaf beneath them as they do so. All these characters seem to fit very well the mines that I found today!

The adults emerge, like many other Phyllonorycters, first in May and then again in August as a second brood.

I don't think it could be Phyllonorycter tenerella, as although this species is found on Hornbeam, it is described as being on the underside of the leaf, from the midrib to the edge of the leaf, and quite narrow, generally between only two veins.
http://calderdalemoths.blogspot.co.uk/2008/09/phyllonorycter-tenerella-challange.html

Equally it is very unlikely (but not absolutely impossible) that it should be Phyllonorycter ulmifoliella, which normally feeds on the underside of Birch leaves. There is however one recorded instance of this species feeding on the upperside of Hornbeam leaves, noted in the Entomologists Record of early 2013 following the emergence of an adult from a mine collected in the autumn of 201.?

I also do not think it will be Phyllonorycter messaniella, as that is generally found on Oak, Beech or Sweet Chestnut,  and less commonly on Hornbeam. On Beech and Hornbeam this species is found on the lower surface between two adjacent veins, with a sharp fold, so again this does not really fit the majority of mines found. However there was one mine, clearly different, and I thought it was most likely to be this! It started well out from the midrib, and finished well before the leaf margin, and fitted the pictures really quite well.

Black tern at Cliffe again, even better views.

A good day, although a little bit wetter.

About 1,000 Avocets, 300 Redshank, 150 Black-tailed Godwits, 80 Lapwings, 70 Great Crested Grebes, 80 Little Grebes, 1 Pochard, 1 Tufted Duck, 12 Wigeon, 4 Shoveller, 40 Teal, 15 Mallard, 4 Cormorant, 3 Grey Heron, 1 Greenshank, 10 Greater Black-backed Gulls, 10 Herring Gulls, 40 Black-headed Gulls, 30 Dunlin.

It was lovely to see the Wigeon arriving, circling and whistling, and then settling.

And 1 Black Tern, flying well, steadily and buoyantly in the still conditions and regularly swooping down to the water surface and just the beak touching (in an on-line swoop straight ahead), possibly to drink??

Still plenty of Bumblebees and Dragonflies and a warm day!

Black tern at Cliffe

A much nicer afternoon than morning, so after getting a whole load of College admin done before lunch I headed off to Cliffe pools with Monty. On the Radar viewpoint there were about 200 Black-tailed Godwits, 12 Little Egrets, 20 Redshanks, 3 Greenshanks (including the one-legged bird), 20 Great Crested Grebes, 15 Little Grebes, and some Black-headed Gulls. Across on the Ski Pool there were about 70 Shelduck, 49 Avocets and some Greater Black-backed and Herring Gulls amongst the Black-headed Gulls.

And then I saw a Black Tern over the back of the Ski Pool, noting the quite even grey of the uppersides, the grey breast smudge more visible in flight, the white forehead and black cap, and the slightly forked tail. I was also struck by the generally easy and steady flight, not making a lot of ground speed, quite bouncy and occasionally twisting and swooping down to close to the water surface and then back up again. I now think that it would have been taking insects from above the water surface, although at the time I thought that it was searching for fish and failing! This all ties in with its reported diet, mainly insects but also with small fish and amphibians on the breeding grounds and a mix of insects and fish on migration and on the wintering grounds.

After a while I trailed up towards the flamingo pool lookout, and saw the Black Tern again (unlikely I think to be a second bird), and this time it also settled on a distant rock at the near end of the Flamingo Pool.

On Flamingo there might have been another 30 Coots, 40 Great Crested Grebes and 30 Little Grebes. I also got a fleeting glimpse of an odd duck that might have been a Wigeon in eclipse.

A birder coming back from the Thames told me that there had been another half dozen black terns going West up the Thames. This seems to be a fairly typical movement for this species - I wonder where they are all heading for? Birds regularly migrate Westwards from Europe into England in the autumn (but are less regularly seen on the return trip). Presumably they then head South down the coast of Europe and perhaps the Atlantic coast of Africa to their wintering quarters along the Western African seaboard, centred in the Gulf of Guinea. Juveniles may often accompany them, but may not make the return journey for 2 or 3 years.

The Black Tern, Chlidonias nigra, is spread across the Paleartic, with the nominate subspecies nigra breeding in Eurasia and wintering in Africa, while the subspecies surinamensis breeds in North America. They tend to be fairly gregarious and can commonly be found in groups of 2 - 20 on the breeding grounds or on migration. However they can also be found in much larger aggregations of up to thousands in certain migration points, or in Africa. Some birds may move South down the Nile and Rift valleys, perhaps wintering around the Sudan.

Spring migration of adults begins in late March, mainly via the West African coast. On reaching Spain many birds may move along a Mediterranean route while others follow the Atlantic coast, of which some may be seen in Britain. The "Sudanese" winterers come back up the Nile, and may join the main stream of migration as some of them on the Mediterranean route move Eastwards along the Northern coast of Africa before moving across to Eurasia.

The breeding grounds seem to be under some threat due to habitat loss, but the species is not declining fast enough to be considered threatened (by extinction). Interesting that the species can be declining and generally disappearing from specific areas, but not thought to be under threat! The birds arrive in a group at the possible breeding area, and explore it, finally settling to jointly build the nest - a pad of vegetation on the marsh or water or a scrape on the drier ground - and laying only about 3 days later. There are some great behaviours described in BWP, and overall it is a fascinating bird.

Courtship is primarily monogamous, at least for the current season. Courtship is both aerial and ground-based. There is generally only one clutch, of 2 - 4 eggs which take about 21 - 22 days to hatch. The young are precocial and nidifugous. They are fed by both parents (up to 80 times a day), and also brooded for the first week or so, staying in the nest itself for only 2-3 days, then wandering further as they explore the area around the nest site, and then heading off into the surrounding vegetation.  They start to fledge after about 19 days and are capable of independent feeding and then flight from about 25 days old.