Friends of Priorslee Lake Wildlife Site: 6 Sep 22

Priorslee Lake and The Flash

14.0°C > 16.0°C: Broken cloud to start; low cloud and mist rolled in with some very light drizzle; began to lift and clear after 09:30. Light SSE breeze. Good visibility except during drizzle when moderate.

Sunrise: 06:28 BST

* = a photo from today

Priorslee Lake: 05:15 – 09:20

(189th visit of the year)

Bird notes:
- The Coots had decamped to the middle of the North side where it was harder to get an accurate count.
- 'Best effort' on Great Crested Grebe numbers. There was certainly a pair without any juveniles but whether these were in addition to the previously noted six breeding pairs I am unsure. I could only find five sets of adults / juveniles. The light-level was not good and some of the juveniles are well-developed enough to be diving on their own.
- One or more Tawny Owls were calling in the Ricoh copse at 05:20.
- There seemed to be significantly fewer Magpies than usual. This is not a species that I systematically count other than occasional roost totals; or groups of post-breeding families so it can at best be an 'impression'.
- This Autumn has seen my highest passage totals of Barn Swallows for many years. One group today comprised 21 birds [while at an airfield near Basingstoke over the weekend I noted several hundred birds passing through]
- The House Martins seemed to be on the move too, though as they would likely have been heading SE when feeding (they usually feed in to the wind to minimise the closing speed with their insect prey) I cannot be certain.
- Chiffchaffs were also noted in different locations from usual and it seems they too were on the move.

Birds noted flying over here:
- 7 Canada Geese: outbound together
- 23 Racing Pigeons: two groups
- 1 Stock Dove
- 169 Wood Pigeons
- 1 Black-headed Gulls
- 18 Lesser Black-backed Gulls
- no Jackdaws
- 25 Rooks

Hirundines etc. noted:
- 32 Barn Swallows: three groups
- 31 House Martins: four groups

Warblers noted (no song recorded unless specifically noted):
- 1 Cetti's Warbler: song heard
- 9 Chiffchaffs: one in song
- 3 Blackcaps

Counts from the lake area:
- *2 + 4 (1 brood) Mute Swans
- *2 (0♂) Gadwall
- 10 (4♂) Mallard
- *2 (0♂) Tufted Ducks: departed
- 10 Moorhens
- 111 Coots
- *12 + 10 (5 broods) Great Crested Grebes: see notes
- *96 Black-headed Gulls: 81 of these were on the football field at 06:15
- *11 Lesser Black-backed Gulls
- 1 Grey Heron: arrived and departed

Noted on / around the street lamp poles pre-dawn

Another bumper haul of strange things

Moths:
- *1 Snout (Hypena proboscidalis)

and:
- *1 Pond Olive mayfly (Cloeon dipterum)
- 2 plumed midges
- *1 caddis fly
- *1 'bouncing' crane fly?
- 1 Garden Spider (Araneus diadematus)
- 1 Bridge Orb-web Spider (Larinioides sclopetarius)
- 1 Dicranopalpus ramosus/caudatus harvestman

Noted later

Even less than last Thursday

Bees, wasps etc.
- *Honey Bee (Apis mellifera)
- Common Wasp (Paravespula vulgaris)

Hoverflies:
- Chequered Hoverfly (Melanostoma scalare)

Other flies:
- *Grouse Wing caddis fly (Mystacides longicornis)

Beetles:
- *Alder Leaf Beetle (Agelastica alni)

Slugs etc.:
- *Black Slug (Arion ater agg.)

Mammals:
- Noctule-type bat sp.

Just a touch of colour before the mist and drizzle rolled in.

The Mute Swan family party, the cygnets now well-grown. I have seen them thrashing their wings so they no what to do. The flight-feathers need to grow more yet as do their wing muscles.

The extensive orange on the side of the bill identifies this as a duck Gadwall.

Well it was still about dawn. One of the two duck (or juvenile) Tufted Ducks just before they flew off.

These two (a pair?) of Great Crested Grebes seemed to have no juveniles.

This adult nearby did have juveniles. Here it is in threat pose to the others.

There are usually several empty buoys but that does not stop Black-headed Gulls from usurping others sitting peacefully. In humans this is called bullying. In nature it is called establishing the pecking order.

"I'll try this unoccupied buoy".

Here a Lesser Black-backed Gull usurps a Black-headed Gull...

...and does the same thing on a different buoy.

The same rather scruffy and moulting adult Lesser Black-backed Gull in flight. That is not a black feather in the left part of the tail but something in the water behind.

From below we see the wobbly trailing edge with its mixture of new, worn and regrowing feathers.

The immature Lesser Black-backed Gull formation team in flight. Having said that the inner primaries of the middle bird look rather pale and I would like to have had a picture of the upper wing to eliminate the possibility of it being a Yellow-legged Gull.

This moth was not in a good position for a clear photo. My first Snout (Hypena proboscidalis) here this year (I noted one in the Priorslee Avenue tunnel last week). Moth species #86 for me at the lake this year.

A Honey Bee (Apis mellifera) dives in to a Field Bindweed flower (Convolvulus arvensis) while, an unnoticed at the time, tiny spider scurries away.

The bee emerges with some pollen on its head and front legs.

And immediately dives in to a different flower.

It emerges covered in even more pollen. Strangely there is no pollen on the hind leg pollen basket.

What is most likely a Pond Olive mayfly (Cloeon dipterum).

A plan view shows the large eyes possessed by the male of the species, apparently to enable him to see females in their dancing swarms.

It is not obvious what this is....

..until a side view reveals it a dew-bespattered caddis fly.

Later I found this caddis fly I can identify. It was on the wall of the sailing club HQ. It is a Grouse Wing caddis fly (Mystacides longicornis). The long banded antennae identify it. A few individuals lack the otherwise diagnostic patterning on the wings.

This fly was 'bouncing up and down' on its long legs. There is a post on the internet that suggests female crane flies do this to release pheromones to attract a mate. Perhaps that it what it is - it was too 'bouncy' to get a clear photo even with camera flash.

Two Alder Leaf Beetles (Agelastica alni) tucking in, living up to their name.

They have already had a good feast here.

Despite its colour this seems to be a Black Slug (Arion ater agg.). There are, at least, four species in this complex, one of which has yet to be formerly described. They can only be specifically identified by dissecting the genitalia (that must be a challenge given they are hermaphrodites). DNA analysis does not always provide a definitive answer either. All the species may be black, grey, red, greenish....

A close-up of the breathing pore.

(Ed Wilson)

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The Flash: 09:25 – 10:15

(185th visit of the year)

Bird notes:
- All four cygnet were with two of the adults, though one seemed to be slightly behind the others. It looked perky enough.
- The drake Gadwall was with the Mallard again: perhaps that is why the two ducks seem to have decamped to the Balancing Lake.
- All four juvenile Great Crested Grebes were again with the only parent I could find.
- At least eight Cormorants: seven were on the island together; at least one was fishing in the water.
- Three Grey Herons again.
- One or more House Martins heard high overhead but not seen.

Birds noted flying over here:
- 1 Lesser Black-backed Gull
- 1 Sparrowhawk
- 8 Jackdaws: together

Warblers noted:
- 1 Chiffchaff
- 1 Blackcap

Noted on / around the water:
- *32 Canada Geese: 23 of these flew in
- 6 + 4 (1 brood) Mute Swans
- 1 (1♂) Gadwall
- *28 (18♂) Mallard
- 1 (1♂) all-white duck (Aylesbury Duck)
- 15 (?♂) Tufted Duck
- *11 Moorhens
- *37 Coots
- 1 + 4 (1 brood) Great Crested Grebes again
- 6 Black-headed Gulls: four first winters
- *8 Cormorants at least
- *3 Grey Herons again

Noted on / around the street lamp poles:
- *1 Elbow-stripe Grass-veneer moth (Agriphila geniculea)

Noted later:
- 1 Garden Spider (Arameus diadematus)

One of the arriving Canada Geese is almost inverted as it makes space to splash down. Note that its neck is twisted so that the head remains the right way up.

There was food in the offing...

..and this drake Mallard was going to get some.

Note that it is yet to complete its moult in to breeding plumage: the pale bill identifies it as a drake.

The head and bills of two drakes show how the progress of the moult can vary from bird to bird. An adult Moorhen gatecrashes the photo.

Rather sad. One of the fishermen had heard this Wood Pigeon squab drop out of its nest on to the ground beside him. Wood Pigeons are not known for their nest building skills: a few twigs to stop the eggs rolling away will do. This must happen a lot. There is no way I could help.

An unusual sight of a Coot – here a juvenile – on the grass alongside the water. Usually Coots stay in the water and it is Moorhens that venture on the grass.

Two of the eight Cormorants at rest. The one facing us is still an immature with some pale on the belly and a rather brown tone. The bird on the left looks set to pollute the water.