Preston Docks Common Tern Colony

I had my lunch at the Preston Dock common tern colony today, my first visit of the year. The chicks are quite large now and many can fly, so the colony was very busy and noisy. Adults returning with fish to feed the chicks were usually harassed by other adults who presumably were intent on stealing the fish, and in the confusion a few occasionally landed on the wall next to me, some as close as 1m away.

I watched as a juvenile took to the air, perhaps for the first time, and tottered it's way over the colony and across the water, almost like a human toddler taking its first uncertain steps, and just like with humans, one of the chicks nervous parents followed it around and guided it back to it's nest box. Really nice to watch.

Most of the adults returned with sand eels, but sand eels are sea fish which means that the adults must be travelling at least 10 miles down river to the sea in order to catch the fish, and then return another 10 miles back.

Most adult common terns at Preston Dock seemed to be returning to the colony with sand eels, but one returned with what looked like a goldfish! Perhaps the adult was tired of a 20 mile round trip for another sand eel and took the fast food option from somebodys pond!

Life on a canal

This afternoon I spent a couple of hours along the tow path of the Leeds - Liverpool canal at Pennington Flash, between the footbridge near Ramdales (Common Lane) and the footbridge near the Atherliegh Way (Pilling Street). I was hoping to have a further look at the red-eyed damselflies I found there a couple of weeks ago, plus anything else I might find.

There were still plenty of red-eyed damselflies on the wing, where two weeks ago I counted 72 on this stretch of canal. On that occasion I walked along both banks, but today I only had time to visit the less productive south bank, but I still managed to count 25 individuals, including at least 5 pairs in tandem, so overall numbers were probably pretty similar.

I managed to photograph a few in tandem, or guarded oviposition. There's nothing romantic about dragonfly or damselfly courtship, the males just grab the females and cling on. After mating the males of some species including red-eyed damselfly grab the female by the neck and guard them from other males. This is because the eggs are not fertilised until they are laid, therefore it's possible that another male could grab the female and mate before the eggs are laid thereby usurping the original male. This means that any pair in tandem is constantly harassed by single males who are trying to dislodge the original male. Even males of other species will show aggression towards pairs.

Common blue harassing a pair of red-eyed damselflies.

The pair even fly in tandem.

The female egg laying.

I'm sure that some females must drown during egg laying, this one was forced under water by the male for at least a minute!

I also managed to photograph a couple of other species of damselfly in tandem today, namely common blue and Azure.

Azure damselflies.

Common blue damselflies. The male at the back is up to no good.

 
Common blue damselfly. Notice what looks like a water vaneer moth Acentria ephemerella just below the damselfly. I didn't notice this in the field.

I was made up to spot this beauty hunting on the lily pads! This is Pirata piraticus or Pirate Wolf Spider. It hunts by holding its front legs on the surface of the water and sensing any movement from an unfortunate insect, which it then sprints across the water to claim, causing barely a ripple on the surface.

Touching the water but you'd barely know it! There's hardly a crease in the surface!

I've seen tufted ducks with chicks on the canal in previous years, and I still don't know where they nest. Nowhere obvious that's for sure.

Apart from the two species of water lily on the canal (fringed and yellow), there is also arrowhead Sagittaria sagittifolia, which is part of the water-plantain family.

White-winged black tern, Rother Valley CP

Despite the poor weather today, we had some nice views of a smart looking adult summer plumage white-winged black tern at Rother Vallley Country Park in South Yorkshire. Then we moved to Old Moor RSPB where we saw a great bittern, but unfotunately not the little bittern.

The white-winged black tern was my 8th in the UK, and interestingly the first four were all juveniles but the last four were all adults. Obviously the juveniles were all different birds, but it makes me wonder if any of the adults might relate to the same individual, returning over the past few years.

Year: 238 (White-winged black tern). This day last year: 235, this day 2014:  265

It was dreadfully dull and wet day so I was pleased to get any kind of photo of the tern. A really smart bird though.

We found these sawfly larvae on alder today at Old Moor. Probably Croesus septentrionalis.

Great burnet Sanguisorba officinalis.

Bats in a haunted house

Last night I was out until the early hours surveying bats. It was an emergence survey at a deserted and crumbling old mansion house which is allegedly haunted. Most of our time was spent outside the house identifying and counting bats as they emerged, but we also went into the house before and after the survey to look for roosting bats or bats flying around inside the house. It was a really spooky experience, especially down in the cellar where there was water dripping and toads and frogs hopping around.

We didn't find any roosts but we did see bats flying around inside, and their presence was betrayed further by bat droppings and numerous wings of various lepidoptera all over the house. This was particularly interesting to me because most of the wings were of butterflies, especially small tortoiseshell and peacock. I would say that these accounted for around 90% of all of the wings we saw. There were a few moth wings, mainly large yellow underwing, but also dark arches.

Small tortoiseshell wings.

The dominance of butterfly wings and the fact that they are inside the building may seem surprising, but actually they give a clue to the identification of the bats in the house. Bats are well known to use echo location to catch flying prey, but some species, especially brown long-eared "glean" prey from the foliage of trees. This is a technique of hovering around leaves and picking off insects, which means that day flying insects such as butterflies are as vulnerable, perhaps even more so, than nocturnal insects such as moths. Finally the bats then often carry their prey to a night time roost  which can be a cave or tree, or in this case an old building, where they remove the wings and eat the more edible parts, leaving the wings scattered all over the floor below.

Black Guillemots, Holyhead Old Harbour

On Saturday during a visit to Anglesey, we stopped off at Holyhead Old Harbour and saw a few black guillemots on the sea. One bird flew right into the harbour mouth and appeared to disappear into the wall, presumably into a nest hole. We noticed that there were a few nest boxes high up on the wall, but couldn't be sure if the bird had flown into one of them or had flown into a "natural" hole in the wall. Today I was back on Anglesey and working quite close to Holyhead, so with work completed I decided to have my lunch at the Old Harbour and spend a bit of time watching the black guillemots.

The first thing I noticed was how much higher the tide was today. On Saturday the nest boxes had seemed ridiculously high above the water, but now they seemed perilously close to being submerged. There were a couple of black guillemots sitting on the water in the harbour and a couple of others out at sea. After a while one of the birds on the sea flew into the harbour with a fish and landed close to another bird which was swimming around under a nest box. After about 5 minutes the bird with the fish flew up to the wall, ignoring the nest box and straight into a hole. A few seconds later it flew out and landed on the water just in front of me and started to dive again. Eventually it came up with a fish which it kept dipping in the water whilst at the same time flapping its wings very fast and splashing in the water. At first I thought it migh be cleaning the fish, but why would a fish need cleaning and why was it flapping its wings so fast? Perhaps it was some kind of pair bonding with the second bird which was still swimimg nearby. After a few minutes it flew back to the nest hole where it presumably fed the fish to a chick before sitting at the entrance of the hole for several minutes.

During these observations I became aware of another bird which also kept flying into the harbour with a fish, but this bird disappeared right down to the bottom end and I couldn't be sure where it was going, but it was always in the same direction. Based on these observations I would say that there are two pairs nesting within the harbour itself, and a third pair just outside because I could see a bird in the distance keep returning to the same spot with fish.

As far as I'm aware, Anglesey is the only place in Wales where black guillemots breed.

I like photographing black guillemots in harbours, because the background always adds a bit of interest to the photo even when the bird itself is far too distant to be a good photo as in this instance.

Cemlyn Bay tern colony

Plenty of activity at the Cemlyn Bay tern colony today, with 2500 pairs of Sandwich terns, 60 pairs of Arctic terns and 60 pairs of common terns. Lots of fledglings around today as well, and as such the adults were constantly flying back and forth bringing back sand eels for their chicks. We started the day at South Stack where apart from the usuals there was an impressive passage of Manx shearwaters. Then we called in briefly at Holyhead Old Harbour where we saw at least five black guillemots including a bird which flew into the harbour and disappeared into a hole in the wall, presumably bringing food back for chicks.

Sandwich tern.

Arctic terns.