11 May 16

Priorslee Lake
Location

Gary Crowder: 18:40
To add to the tern extravaganza today there was a Little Tern too this evening but departed at c18:40 (saw it just before it left but not found by me)

John Isherwood: 15:30
3 Black Tern
7 Common Tern
1 Common Sandpiper

John Isherwood: 11:50
3 Black Tern
12 Common Tern

John Isherwood: 9:00am
3 Black Tern
7 Common Tern
1 Common Sandpiper

Ed Wilson: 7:15 - 11:20

Sunrise: 05:19 BST

13°C > 15°C Low cloud and light rain; heavier rain 07:50 – 08:30 after which cloud lifted somewhat and rain became more intermittent. Moderate NNE wind fell away. Moderate visibility, sometimes poor

(74th visit of the year)

Today was one of those magical days when all the trudging around seeing very little is suddenly all worthwhile.

When I arrived at the W-end lake-side at 07:20 it had just started to rain slightly and the lake was host to >70 hirundines among which at the far E-end were several terns – a Black Tern and 5 Common Terns. I set off towards the dam to try and get some record photos: by the time I got there the Common Terns had left. I then spent some 20 minutes in poor light and increasing rain trying to photograph the Black Tern

Eventually I was forced to take to the shelter in the SW part of the lake and while the rain sluiced down I watched a procession of hirundines pass by – keeping track of >150 birds was impossible but I got the impression many birds were simply passing through.

After the rain eased I noted that there were now 3 Black Terns and with much brighter conditions I set off having dried the camera. While shooting far too many pictures another 8 Common-type Terns arrived and joined the melee, with a lone Black-headed Gull for a short while. Preliminary examination of the pictures suggests that 3 or 4 may have been Arctic Terns and the rest Common Terns: I still find separation of Common and Arctic Terns rather hard and the photos were taken in poor light. After a brief ‘panic’ when a police car sounding its siren went by the birds returned but then stayed only a few more minutes.

At the same time what had been a jumble of hirundines rather sorted itself in to several single-species groups and apart from half-dozen Barn Swallow, perhaps birds from the village, they all left high W

The next excitement was a tight group of >50 Swifts screaming overhead and moving N

The Black Terns then rested on the buoys and as I moved to get closer I noted that another(?) Common Tern had arrived. Eventually there were six more, all Common Terns. After some ten minutes they also left leaving just the Black Terns.

During this time two different groups of Tufted Ducks came in.

All this made my usual counting rather disjointed and during the wetter parts many birds were disinclined to sing

This is by far the highest number of terns I have ever recorded at the lake and I can think of no other occasion when more than one species has been simultaneously present

Other notes
- no Mallard ducklings seen
- again three of the Reed Warblers were singing some distance from any reeds

Counts of birds flying over the lake (in addition to those on / around lake)
- 2 Feral Pigeons
- 11 Jackdaws
- 5 Rooks
- 12 Starlings

Hirundine etc. approximate maxima
- >60 Common Swift
- >35 Sand Martin
- >50 Barn Swallows
- >40 House Martins

Warblers seen / heard around the lake: numbers in brackets are singing birds
- 1 (1) Cetti’s Warbler
- 6 (5) Chiffchaffs
- 10 (6) Blackcaps
- 1 (1) Garden Warbler
- 1 (1) Common Whitethroat
- 4 (4) Reed Warblers again

The counts from the lake area
- 2 Mute Swans
- 7 (6♂) Mallard
- 8 (7♂) Tufted Ducks
- 2 Little Grebes heard
- 5 Great Crested Grebes
- 6 Moorhens
- ? Coots
- 6 Common Sandpipers
- 3+ Black Terns
- c.15 Common Terns
- 3 or 4 Arctic Terns

A rare sight indeed: here are 8 terns together at the lake: 2 Black Terns on the left and a mixture of Common and Arctic Terns on the right. At this range and angle I do not feel I can reliably separate those.

Another unusual sighting: a Black Tern passes three terns sat on the water. Terns are almost never seen doing this, preferring to perch on buoys and any floating debris.

Terns can look very different depending upon the angle of the light and whether we are looking at the upper or lower surface. This applies especially to Black Terns. This underneath shot shows just why they are called Black Terns.

The upper side makes the bird look grey with only the head being black.

another under- and ...

Upper- side view of a different bird.

Two Black Terns dispute who is going to occupy this buoy.

This is a Common Tern. Here we see the black-tipped orange bill and the ‘wedge’ of dark in the outer primaries.

upper- and ....

under- sides of Common Tern.

This Common Tern about to grab a morsel with everything spread. This makes the ‘dark wedge’ on the upper wing hard to discern.

Another underside shot showing the diffuse trailing edge mark. Note also the dark outer tail feather. This feature is shared with Arctic Tern but is rarely visible on flying birds.

Not a great shot but included to show how the angle of light can alter perception: just a Common Tern (we can see the outer wing ‘wedge’); but here looking very ‘dusky’.

This, at least, is an Arctic Tern. The most telling point here is the blood-red bill lacking any dark tip. The upper-wing trailing edge has some dark marks but not the ‘wedge’ shown by Common Terns. However this feature is very dependent on the angle and strength of the light.

Here are two Arctic Terns. One oft-quoted feature is the shorter head and the longer, more elongated look of this species when compared with Common Tern, but these are rather subjective features and depends on how the birds are flying. The average longer tail streamers of Arctic is shown here.

A Common Tern passes in front of a Black Tern. On the Common Tern note the orange tone to the bill and the rather diffuse trailing edge to the outer underwing.

Here are two Black Terns with an Arctic Tern passing by

(Ed Wilson)

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 The Flash
Location

John Isherwood: 15:00
No sign of any terns

Ed Wilson: 11:15 - 11:30

(45th visit of the year)

After the extended stay at the lake it was a quick canter along the E side of The Flash en route to catch the bus home. I presume many of the Mallard were unseen, asleep on, what was to me, the back of the island. The aim was really to see whether any terns were here to add to the site list: there weren't

Notes
- the immature Cormorant back in its usual position
- a Garden Warbler was singing at the top end – new for me here this year

Birds noted flying over
None

Hirundines etc. seen here today
- 4 Swifts
- 2 Barn Swallows
- 4 House Martins

Warblers seen / heard around the water: numbers in brackets are singing birds
- 2 (1) Chiffchaffs
- 1 (1) Willow Warbler again
- 1 (1) Blackcap again
- 1 (1) Garden Warbler

The counts from the water
- 2 Mute Swans
- 19 Canada Geese
- 1 all white feral-goose
- 3 (3♂) Mallard
- 4 (2♂)Tufted Ducks
- 1 Cormorant
- 1 Great Crested Grebe
- 10 Coots

(Ed Wilson)

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Trench Pool: 14:30

No sign of any terns

(John Isherwood)

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On this day in ...........
2015
Priorslee Lake
Today's Sightings Here

2014
Local Area
Today's Sightings Here

2012
Priorslee Lake
Common Scoter
(Andy Latham)

2006
Priorslee Lake
2 Ruddy Ducks
(Ed Wilson)