Little Bittern (16th June 2012).

A few days previously a Little Bittern had been discovered skulking in the reeds and other vegetation along the edge of the River Colne near Stockers Lake/Bury Lake (in south-west Hertfordshire, and just off the M25). There had been no sign for a couple of days, but considering how secretive this species can be at times it was not especially surprising when it was found again this morning.

Dave and I travelled the short distance round the M25 to have a look, and it wasn't long before we were watching the first Little Bittern that either of us had seen in the UK - they aren't particularly rare as a vagrant, but neither of us had previously tried for any other individuals.

This one was a female (although it had previously been reported as a first year male).

It was completely unfazed by the 50 or so birdwatchers who were lined up on the river bank, and was happily stalking about in the reeds on the other side of the river, and repeatedly pulling small fish out of the water. The only thing that seemed to disturb it was when other birds, such as a Moorhen, actually entered the reeds close to where it was.

 Skulking at the edge of the reeds.

 It did come right out eventually though!

An idea of the size of the Little Bittern can be got from this (rather poor) photo

- they really are 'little'!

There was quite a lot of other wildlife to be seen in the area where the Little Bittern was present, including a Hobby which passed overhead, and variety of dragonflies and damselflies. Some of the odonata (dragons & damsels) were also noticed by the Little Bittern, which plucked a couple of damselflies from the reeds while we watched, and also 'lunged', unsucessfully, at a Hairy Dragonfly which passed close over its head. Surprisingly there didn't appear to be any Banded Demoiselles on what looked like a suitable river, but Azure Damselflies, Blue-tailed Damselflies, and Large Red Damselflies were seen.

Other birds that were in the area included singing Garden Warblers, a family of Blackcaps, and Common Terns - with some of the latter perching on tree branches over-hanging the gravel pits.

Identification feature: “willow-wrens” (Chiffchaff, Willow Warbler, and Wood Warbler).

 Many bird species can be difficult to identify, particularly when you are new to birdwatching, but there are some that tend to be more problematic than others, and two widespread and relatively common UK species, which can take birdwatchers time to get to grips with, are Chiffchaff and Willow Warbler.

At one time Chiffchaff and Willow Warbler were typically treated as just one species, along with the larger and brighter Wood Warbler. It is Gilbert White, an 18th century naturalist, who spent his life in Selbourne, Hampshire, who is generally credited with being the first to show that there was more than one different species. 

In a letter to Thomas Pennant, dated August 17th 1768, he writes:
“I have now, past dispute, made out three distinct species of the willow-wrens (motacillae trochili) which constantly and invariably use distinct notes” *
Later in the letter he goes on to describe the song and plumage of the most distinct of the three, the “largest willow-wren” (Wood Warbler), in some detail. Little mention is made of the differences between the “smallest willow-wren” (Chiffchaff), and the “middle willow-wren” (Willow warbler) in this letter, except the slight difference in size, and the fact that the smallest willow-wren had dark legs, in contrast to the other two species’ pale legs. 

(*From “A Natural History of Selbourne”, a published collection of Gilbert Whites letters to other naturalists of his time.)

The difference in song remains the easiest way to separate Chiffchaff and Willow Warbler in particular – but birds aren’t always singing when you see them!

Thankfully, there have been nearly 250 years of observations since Gilbert Whites time, and other identification features have been worked out!
'Hovering' over the photos with your mouse should reveal annotations pointing to the relevant identification features in each case.
With thanks given to Stuart Fisher for giving permission for the use of his recordings on xeno-canto.org (click on the triangular 'play button' to listen to each recording).

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Wood Warbler (Phylloscopus sibilatrix).

When seen well this is a distinctive species, with a very different appearance and structure from Chiffchaff and Willow Warbler, they are also slightly larger, although this isn’t always apparent in the field. Although they are less likely to be confused that Chiffchaff and Willow Warbler, for completeness it is worth mention this species first.

The least widespread of the three “willow-wrens”, Wood Warblers no longer breed in most areas in south-east and central England. In the UK it now has a distinctly western distribution bias, and typically favours mature woodland when breeding (although migrants can sometimes be found elsewhere).

Wood Warblers reach the UK in mid-late April each spring, and have left by mid September, with the species wintering south of the Sahara in a band across central Africa.

The main identification features are as follows: 

•  Long wings and short tail, giving a different shape to Chiffchaff and Willow Warbler. 
• The wing feathers have broad greenish edges. 
• Upperparts tend to have more of a green tone that those of Chiffchaffs and most Willow Warblers. 
• Broad yellow supercilium, cheeks, and throat which contrast with the white breast and belly. Beware of some Chiffchaffs and Willow Warblers which can have brightly coloured throats. 
• Legs tend to be pinkish, but can be browner.

Wood Warblers typical song is a trill that can be likened to a spinning coin coming to rest on a hard surface (as in the above recording). They can also be heard giving a loud, clear “Chee- chee- chee- chee”.

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Chiffchaff and Willow Warbler are far more similar to each other in appearance, and to make matters worse most of the useful features can vary between individuals! 

Both are small, slim, green-brown warblers, with yellowish or off white underparts. For identification in the field, the best feature to look for is the primary projection – the length of the exposed primary feathers visible on the folded wing, as compared to the length of the exposed tertial feathers. It is the length of the exposed part of the primaries that is important, not how long the wings look (although a longer primary projection can give the impression of longer wings). 

Song is also diagnostic when heard, and with experience calls can also be differentiated. Other features can be used as a guide, but are not diagnostic.

Willow Warbler (Phylloscopus trochilus).

Widespread and common throughout the UK, perhaps with a tendency to be more numerous towards the north. Open scrub, heathland, and similar habitats, with scattered taller trees tends to be the favoured, although they can also be found breeding in hedgerows and woodland edge habitats. 

The first migrant Willow Warblers arrive in the south in late March, with a more widespread arrival from early to mid April. Most have left for the southern half of Africa before the end of September, although a few may be seen in October. 

Adult Willow Warbler.

1st winter Willow Warbler.

The typical appearance is of a greenish or brownish, warbler with clean, largely whitish underparts. The yellow on the underparts is usually restricted to the head and upper breast, but can be especially prominent in juveniles and 1st winters, in which the entire underparts can be a uniform, and sometimes quite bright, yellow colour. 

Whenever possible it is useful to assess the 'primary projection' on individuals that aren't heard, the other features listed can also be useful but will not be seen on all individuals. 

• Primary projection of 75-100% of the length of the exposed tertials. 
• Usually a strong face pattern, with a long supercilium, and strong dark eyestripe. 
• Cheeks tend to be flecked with yellow, which makes them look pale centered. 
• A pale eye-ring is present but rarely stands out against the pale centred cheeks. 
• Underparts usually look ‘clean’ without the indistinct brown wash, or patches at the side of the breast that is often seen on Chiffchaffs. 
• Legs are typically a pale brown or flesh colour – they can be dark in a small percentage of individuals though, and even if they are not dark lighting can make them appear darker than they are.
• Pale areas on the lower mandible are often more extensive, and more sharply defined than on Chiffchaffs.

Typical cascading Willow Warbler song (left-hand recording), and a more 'hesitant' variant.

Typical calls are a clear “Ho-eet”, with the two notes usually obviously differentiated.

A few greyer/whiter individuals from the populations that breed in Scandinavia (Phylloscopus trochilus acredula) may be seen on passage.

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Chiffchaff (Phylloscopus collybita). 

A Common and widespread breeding species throughout the southern parts of the UK, becoming more local in northern parts of Scotland, which favours open areas with some mature trees, such as woodland edges. 

Since the 1950s and 60s, Chiffchaffs have become increasingly more numerous during the winter, predominantly in southern counties, but with a few wintering as far north as parts of Scotland. It seems that many, but perhaps not all, of the wintering birds originate from different populations from the breeding birds, which arrive in mid March after spending the winter in Iberia or northern parts of Africa, and head south-west again in the autumn. At least a percentage of those that are here during the winter tend to show characteristics of northern and eastern subspecies – though because individuals of all subspecies can be so variable it is often difficult to assign them to a specific subspecies in the field with any certainty. 

Chiffchaffs often have a tendency to look ‘duller’, and ‘dingier’ than most Willow Warblers, with ‘dirtier’ looking underparts - although they can be as bright as the brightest Willow Warblers. They also have a tendency to continually flick their tail downwards while moving around (Willow Warblers may also do this but it tends to be less persistent). 

• Primary projection of no more than 50-60% of the exposed tertial length. 
• The supercilium can be distinct, but it is often weak behind the eye, and there is usually no obvious dark line through the eye. 
• The cheeks tend to be plain and dark centred. 
• A pale eye-ring is present, and the lower half has a tendency to stand out strongly against the usually dark cheeks. 
• There are often indistinct dark markings on the breast sides, and sometimes a brown wash forming an indistinct dark band across the breast or on the flanks. 
• Legs are typically dark brown or black, but can be, or appear, pale in some individuals, especially those seen in bright sunlight.
• The bill tends to be dark, but may have pale areas on the lower mandible, which are often relatively diffuse, without sharp demarcation.

The song of the races that breed in the UK (Phylloscopus collybita collybita), and much of Scandinavia (P. c. abietinus), is one of the easiest to identify because Chiffchaffs are one of the bird species that sing their name – though sometimes even they seem to get a little confused! ('normal' song, and a variant version are linked above).

The calls are similar to those of Willow Warbler, but tend to be a more slurred, “weet” without the ‘dysyllabic’ sound of Willow Warbler, and with an upward inflection at the end. Calls can be heard in the first of the two song recordings (above), but two different versions of calls are also given (the "sweoo" type of calls heard in the right-hand recording seem to mainly be heard during the autumn).

Other subspecies of Chiffchaff are regularly seen in the UK, and these are briefly covered below: 

Scandinavian Chiffchaff (Phylloscopus collybita abietinus). 

Regular as a passage migrant and winter visitor to the UK, mainly between September and April, but not always separable from the P. c. collybita subspecies that breeds in the British Isles. 

• Typically greyer, or more olive toned, above and whiter below than most British birds, with very limited yellow on the underparts and in the supercilium. 
• Usually a more distinct supercilium, which extends further beyond the eye. 
• Often a faint greenish wash on the upperparts, and often greenish edges to the flight feathers. 
• On average tend to have a marginally longer primary projection than P. c. collybita. 

Song and calls are similar to those of P. c. collybita. 

Siberian Chiffchaff (Phylloscopus collybita tristis). 

A rare late autumn visitor from the east with some individuals staying for the winter. Occasional spring records may involve birds that have wintered elsewhere in Britain or western Europe. 

• Grey-brown and buff toned. Typically without any trace of yellow anywhere except at the bend of the wing, or any greenish tones, except at most on the rump and uppertail coverts, and the edges of the flight feathers. 
• Bare parts (bill and legs) are usually black. 
• Often a narrow pale wing bar on the greater coverts. 

It can be difficult to conclusively identify tristis without reference to the song or calls, which are both distinctive: 

The song of P. c. tristis is a jumble of notes very different from the ‘normal’ Chiffchaffs that we see in the UK and with a quality that is superficially reminiscent of Willow Warbler. Song typical of tristis can be heard in the first part of the above recording, which then switches to typical collybita/abietinus song. 

Calls are a higher pitched “eeep” than those of other subspecies, lacking the upward inflection at the end.

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So what are these three then? (hover over the image with your mouse pointer to reveal the answers, and the features that help with the identifications).

Macabre East End Entertainment (9th June 2012).

A brief visit to Three Mills Green a stones throw from the Olympic Park in East London turned up not only a few good birds but also showed me some surprising behaviour!

Just up from the Mill, on a low tide, I was watching a Grey Heron happily feeding when a flash of blue caught my eye as a Kingfisher shot through and landed briefly on the vegetation covering the river wall. It didn't stay for long before heading back along the river out of view. A Grey Wagtail was also feeding happily on the foreshore and Sand Martins were using the holes in the walls as convenient nest holes.

Nearby, a pair of Lesser Black-backed Gulls were feeding on the fairly fresh remains of one of the local Feral Pigeons. They sucessfully saw off a couple of Herring Gulls that were trying to get in on the act, but lost out to a Great Black-backed Gull. What happend next was something that I personally had not seen before - from under the mill an adult Mute Swan appeared, it headed straight for the gulls which were by now mid river with their booty, saw off the gulls and then proceeded to tuck in to the pigeon pulling off pieces of meat loosened by the gulls which it then went on to eat. As I said, a Mute Swan eating carrion is something that I had not seen previously but this one certainly seemed like it has done it before!

A slightly dirty Lesser Black-backed Gull waiting for its turn to feed. 

One of the Herring Gulls that showed an interest. 

Great Black-backed Gull with the remains. 

Mute Swan after taking the remains off the gulls.

(Although it can't be seen, the swan has the pigeon just below the water)

Although Mute Swans typically feed on plant material, they can be oppotunistic feeders and will take other food if it is available. Recorded food mentioned in Birds of the Western Palearctic (which is still the 'standard text' for birds in Europe, north Africa, and the Middle East) include fish and raw meat.

Night-time songsters (25th - 26th May 2012).

We have all been involved with the BTO National Nightingale survey, and the early hours found all three of us in the River Lee Country Park to see how many were singing in what is, without doubt, by far the best local area for the species (Mike’s tetrads - but we all thought a night time visit would be interesting).

Nightingales were already singing when we arrived on site shortly before midnight, and during the next couple of hours we heard at least 8 different individuals although a couple of others that had been heard on preliminary day-time surveys remained silent, assuming they hadn’t moved on.

A number of other bird species were also singing, including Cetti’s, Sedge, and Reed Warblers, as well as a Robin, and a calling Tawny Owl and quite a few other species were heard calling at various points (most notable perhaps was the level of noise from the nesting Grey Herons and Cormorants). Unsurprisingly few birds were actually seen although a few waterbirds were visible on the gravel pits.

We had a bat detector with us, which enabled us to pick up the echo-location calls of Common and Soprano Pipistrelles, Noctule Bats, and a single Daubenton’s Bat. Some of these were also seen hawking insects overhead, as well as Red Fox, Reeve’s Muntjacs and quite a few Rabbits.

So not a typical time for a visit to the country park - but interesting none the less!

Stumped by a duck! (25th May 2012).

On what was a nice sunny day, I spent the afternoon at two of the sites at the northern end of the Lee Valley Regional park - the RSPB reserve at Rye Meads, and the Herts & Middlesex Wildlife Trust Reserve at Amwell Quarry.

I had made the decision to concentrate on invertebrates, and had only taken a macro lens with me, rather than my usual photographic kit which includes a 500mm telephoto lens, so naturally when I made what was intended to be a brief visit to the first hide at Rye Meads, I found something I really needed a telephoto lens for!

 

In front of the hide (but still fairly distant) was the hybrid duck that had been reported occasionally during the previous winter, and which had recently returned to the reserve following a period of absence. The above photos are heavily cropped, but still show the duck very well. It is always very difficult to be certain about the parentage of suspected hybrids, and this one had me stumped when I first saw photos of it (though this was the first time i had actually seen it 'in the flesh'). Crosses between quite a few duck species can produce the yellow facial patches which give a resemblance to Baikal Teal, but in this case the consensus is that one of the parents is a Baikal Teal - it is thought to be a Baikal Teal x Chestnut Teal cross, which would mean that it definitely has captive origins. Never-the-less, a very interesting bird, and certainly something that you don't see everyday.

More usual duck species were also present, including the Shoveler, Gadwall, and Tufted Ducks which can be seen with the hybrid in this shot:

It was good to see several school groups being shown around the reserve, and making use of the pond dipping areas, even if their use of the bird hides did cause some slight disturbance to other visitors on the reserve. I helped to point out a few of the birds that were present in one of the hides, which I thought might show that I didn't mind the 'intrusion', but was still given an apology by the teacher/helper with the group for "having my day disturbed" when they left (there was no need - the more children are involved with wildlife, the more likely they are to want to protect it in the future!).

Most of the birds present on the reserve today were the sort of thing that can be found in any similar habitat in the area, but Pochards, Common Terns, Great-crested Grebes, and Cormorants were more than enough to keep the school groups happy - especially when they could identify them themselves using the pictures they had been given.

A Male Pochard that came close to one of the hides.

Birds that the school groups probably overlooked included Reed & Sedge Warblers, Chiffchaff, and Hobby.

I didn't manage to find much use for my macro lens on this reserve, although there were quite a few damselflies visible around the pond dipping pools, and a Hairy Dragonfly was hawking along one of the paths, but this thistle looked like it would be a good picture:

I didn't go as far as the Kingfisher Hide (where the first Kingfisher had apparently fledged) - no need to tempt fate, there was sure to be a Kingfisher motionless on the nearest perch if I visited without a telephoto lens!

Slightly futher north, at Amwell Quarry Nature Reserve, damselflies were very easy to find, and this time I was able to get close enough for some photos.

Blue-tailed Damselflies, Common Blue Damselflies, and Azure Damselflies were the most numerous, with many maturing individuals found along the fence line and in vegetation a short distance from water.

Female Blue-tailed Damselfly

Immature male Common Blue Damselfly

Mature male Azure Damselfly

A fair few Large Red Damselflies were also to be found, mainly mature males holding territories at the waters edge, and there were a few Red-eyed Damselflies on water lily leaves in one of the pits. At least two Hairy Dragonflies were also around.

Male Large Red Damselfly

Common Buzzard, Little Egret, Hobby, and a pair of Oystercatchers with three part grown young were the highlights among the birds present, and other wildlife included a Red-headed Cardinal Beetle.

An evening with Owls (24th May 2012).

A short trip out in the evening with Roy produced very good views of a hunting Hobby, as well as both Barn Owl and Tawny Owl near Waltham Abbey.

The Hobby came very low over our heads, and it looked as if the Barn Owl was going to do the same but it seemed to notice us standing quietly at the last minute and veered off and away.

Another London rarity! (19th May 2012).

Dave and I started the morning at the Chingford reservoirs, where we carry out a monthly count of the waterbirds present as part of the Wetland Bird Survey (WeBS), which helps to assess national populations of wetland species.

It was a glorious sunny day – but this is the type of weather conditions that aren’t likely to bring the more interesting species that we might hope for to the reservoir. The good weather meant that visibility was good, and the water was calm and flat, but poorer conditions, including rain, are more likely to make passage birds like Black Terns and Little Gulls drop in as they pass over at this time of year.

We weren’t at all surprised to find that bird-wise the reservoirs were very quite. With most wintering birds having left, and few passage species present, we found that the count didn’t take too long at all. Neither reservoir has any islands, and both are concrete rimmed with bare, sheep grazed banks, so they aren’t attractive to most breeding species. A few pairs of Canada Geese do breed each year though, and a pair of Shelduck were present on the King George V Reservoir, with a new brood of 14 ducklings. Also of interest were a couple of pairs of Linnets on nearby rough ground, a few passage Common Sandpipers, Common Blue Damselflies and some flowers that had escaped being eaten by the sheep.

During the morning we had received news of a Bonaparte’s Gull, the North American counterpart of the Black-headed Gull, which had been found on the River Thames not too far away (the second record in the London Area, with the only previous one in 1983).

It proved elusive during the middle part of the day, after having been seen at Crossness and Barking Bay in the early and mid morning,  but with three other observers we found it again in Barking Bay as the tide ebbed late in the afternoon.

It was a 1^st summer individual, although it had yet to start showing any sign of a dark hood. In size and appearance it was something like a cross between a Black-headed Gull and a Little Gull, superficially more like a Black-headed Gull, but with a black bill, pink legs, an indistinct grey wash on the nape, and a different pattern on the wings – most noticeably the pale underside to the primaries. It’s behaviour and flight action was more reminiscent of Little Gull, which meant that it could be fairly easy to pick out from the Black-headed Gulls at times – not always though!

The above, rather poor 'phone-scoped' photo (taken through a telescope with my mobile phone) does show the Bonapartes Gull, rather than the more numerous Black-headed Gull (honest!). Better photos were taken by other observers, closer to the bird when it had been seen in the morning, and over the following days. Remarkably a second Bonaparte’s Gull later joined it!

Exotic Melodies! (16th May 2012).

News of the discovery of a Melodious Warbler singing in back gardens not far from the River Lee in Leyton was quickly passed on to local birdwatchers, and I was able to spend a little over an hour and a half watching this exotic visitor, usually found only on the continent, late in the afternoon.

While I was present it returned several times to a Holly tree, and other trees/bushes close to the road, and was also heard singing from bushes further from the road. It was quite a bright individual with pale yellow underparts, and the typical shape and largish size that is associated with most Hippolais warblers. The separation from the similar Icterine Warbler can sometimes be tricky, but in this case the song made it relatively straight forward – and, although elusive at times, the bird showed well enough for the short primary projection to be seen clearly on a number of occasions.

Although I saw the bird extremely well, and it was well within range of my camera, on this occasion I managed to miss the best opportunity for a photo and was not able to spend time waiting for another chance.

As a result the best shot that I managed is completely unidentifiable- but I'll post it anyway! (Better photos taken by other people here).

This is a Melodious Warbler - but you'll have to take my word for it (sometimes you miss the shot!).

A short visit to a site on the edge of Epping Forest later in the evening to see if any Grasshopper Warblers were in, failed to find "Groppers", but hopefully there will be some at the site this summer. At least some of the other warblers weren't camera shy as the Melodious was when I tried for photos of that!

A Common Whitethroat wasn't keen on posing for the camera, but I managed a couple of shots, and a Willow Warbler (bottom photo) was happy to show himself off - you can tell it's a Willow Warbler because it's in a Willow!:

In search of Nightingales (14th May 2012).

Following a period of generally poor weather I finally managed to have a proper look round a tetrad (2 km x 2 km square) that I had been allocated for the BTO Nightingale survey. I had previously made brief visits to parts of the tetrad, and hadn’t found any sign of Nightingales.

The tetrad included Galleyhill Wood, just to the east of the River Lee Country Park, as well as nearby farmland areas with a few scattered copses, and it was a very pleasant area for an early morning walk, although very wet and muddy under foot due to the recent rain. Unfortunately I was not able to find any sign of the presence of Nightingales anywhere in the tetrad, and I was not especially surprised about this because the habitat wasn't really ideal.

 

Above: Cattle at Holyfield Hall Farm viewpoint, with part of the River Lee Country Park in the background. Red-legged Partridges, Pheasants, and Yellowhammers were on the farmland between here and Galleyhill Wood, including some very smart looking ‘melanistic’ type male Pheasants with glossy purple-black plumage.

In the woodland their were Nuthatches, Coal Tits, Sparrowhawks, and various warblers, and at one point I had four different male Cuckoos calling nearby, as well as a 'bubbling' female. The calls from the female Cuckoo attracted two of the males who flew directly towards the sound.

Various common mammal species were seen early in the morning, including a small herd of Fallow Deer that did their best to hide in a thicket as I approached them along the public bridleway, and Reeve’s Muntjac, Red Fox, Rabbits, and Grey Squirrels were also seen.

Greater Stitchwort (above) was one of the more obvious flowering plants along the edges of the bridleways and footpaths, with the relatively small white flowers quite detailed when viewed closely. There were also quite a few other flowers to be found, as well as a variety of invertebrates that were feeding on these or present on nearby plants, some of which I was able to photograph with the only camera I had with me today – the one on my mobile phone.

Hoverfly - probably Syrphus ribesii.

One of the more numerous insects that I didn’t manage to photograph were the longhorn moths with antennae about three times the length of their body and iridescent wings. These were of a species known by the scientific name of Adelea reaumurella, and given various English names including Green Longhorn Moth and Fairy Longhorn Moth. Quite a few of these were around hawthorns and other trees/bushes, hovering above them in small groups or perching on leaves in the sun.

After I had finished surveying the tetrad I paid a visit to the nearby River Lee Country Park where I did manage to find some Nightingales in the usual areas. There were also a few Hobbies hawking some of the emerging insects, which no doubt included the damselflies that were now beginning to appear. Various damselfly species were easily found in vegetation near, or at the edges of  the various ponds, rivers, and gravel pits, but almost all were not fully mature.

Male (top) and female Banded Demoiselles, a species which can be numerous
along some of the rivers and streams in the Lee Valley.

An Angle Shades moth, found in sparse vegetation at the edge of one of the ponds.