The nice and the nasty

Tuesday, 29 June

Spending time watching a sea bird colony gives me the chance to see some fascinating and incredible behaviour. I have mentioned before the predation of tern chicks by Mediterranean Gulls and, right at the end of a long and hot weekend at Hayling Oysterbeds, I witnessed yet another predation event. The same returning adult male Med Gull took under ten minutes of patrolling over the islands in the lagoon on Sunday evening to nab a small Common Tern chick. The deadly act all happened, as usual, in the blink of an eye, and for the most part went undetected by the other birds. Even the terns themselves seemed mostly oblivious to the overhead menace, excepting one of two which drove the gull away from their own young. Perhaps these are the wise ones. But most are not.

The Med Gull, with its beak full of stolen booty, landed quite close to me at the northeast end of the ‘northwest embankment’ near to the main weir. It was here that I was able to make a few short digiscoped video recordings. These show how the gull mashes and squishes the corpse into a package more suitable for swallowing by bashing it against the rocks. It attempts several times to swallow it whole, and will eventually succeed, but on this occasion I was unable to record it as it was chased off by a Black-headed Gull. Still, the poor dead chick was already halfway swallowed…

Sadly, this gull has almost certainly been responsible for more deaths of tern chicks than I have witnessed. Last Friday I watched it patrolling over the islands for a long time before I took a break from the lagoon area. On returning I found it sat on the water with a rather large (tern chick-sized) lump in its throat! Most of the tern chicks are now too large for Med Gulls to predate, but there are several new broods of small chicks, just the ‘right’ size for predatory Med Gulls, appearing on South Island. Hopefully this Med Gull will go away before it has more impact on the breeding productivity of the terns this summer.

Prior to the above incident I had been taking pictures of the Common Terns in flight, and managed a couple of pleasing shots (bear in mind these are heavily cropped images):

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There seemed to be lots of fish in the lagoon (or perhaps they were just more visible, coming to the edge and the surface in the hot weather) and one particular Common Tern was taking advantage of it. Many times it came back to the same spot in the lagoon, hovered, plunge-dived, emerged with a small silvery fish, and flew straight back to feed its hungry chick on South Island. Most of the terns fish elsewhere in the harbours. Some obviously go as far as the south end of Chichester Harbour or the sea off Hayling Bay and return overland across Hayling Island to the breeding colony at the Oysterbeds, a round trip of perhaps five or six miles. Prey species appears very variable. And it’s not just fish either. Shore crabs are currently being bought in by many of the adults, the young not having quite the trouble in swallowing them as they were a week or so ago. What look like tiny shrimps are also being bought back to feed the young. If there’s anyone (perhaps a student) out there particularly interested in marine biology then there is opportunity for lots of observation-based field work here, as I reckon that most of the items being bought in by the terns could be identified to near-species (or species) level with the aid of a telescope.

Good weather is helping the birds

Tuesday, 22 June

It’s not really too surprising that the fine weather this summer is currently helping the sea birds to do well at the Oysterbeds. Since my last update yet more Common Tern young have hatched and, just in the last couple of days or so, several new incoming pairs have set up territory and have begun nesting. These are perhaps likely to be pairs that have failed on there first breeding attempt on the main Langstone Harbour islands. In fact, I strongly suspect that, as well as the attraction of the new shingle on South Island this year, the increase in the numbers of breeding Common Terns at the Oysterbeds this summer is also been a function of their higher breeding success here. Although second attempts are often not as successful as first attempts some have gone on to raise young on the reserve late in the season here during recent years. My guess is that ALL of the successful breeders quickly return in the next spring to the site they were last successful on, which helps to attract in all the others (at the Oysterbeds this has all been helped by the improved habitat, of course!). Like Little Terns, the provision of viable breeding sites for Common Terns is now important in Langstone Harbour, bearing in mind that the harbour, including the Oysterbeds, support over 1% of the UK breeding population of this species.

OK, so you’re bored with the stats.... Moving on swiftly, some of the tern chicks are now a fortnight old. During next week some will be taking their virgin flights. In the meantime they are jostling for position on the islands. South Island is positively bristling with hungry chicks! Inevitably there are a few squabbles and fracases, mostly minor but sometimes more violent. Most days I spend at least some time watching the terns closely and have witnessed quite a few attacks on chicks from adults. Most of them appear to involve neighbouring adults and chicks, the latter getting too close and wandering into a neighbours territory. But it does seem that a few Common Terns are much more prone to unprovoked attacks on chicks, and I have seen adults attacking small home-alone chicks still at the nest site while the parents are away. It’s not always entirely clear if these more aggressive attacks are made by adults with their own chicks or not.

Those who have visited the reserve recently (wot, you mean you haven’t visited yet?!) will have seen the strange wooden structures on the South Island. As noted in the previous post they are “chick shelters” and specially placed! I have been really pleased to see that many of the chicks are using them for a variety of reasons. Mostly they use them for shade during the heat of the day, or as a wind break. Others are using them as a hiding place from unwanted attention from neighbouring adults. A slightly comical video clip can be seen below...



Predation of chicks from incoming aerial predators is a real risk but so far it has been largely absent. I have chosen my words carefully, as this evening two tern chicks were taken in quick succession by a hungry adult male Mediterranean Gull. Maybe he is the same bird which predated chicks for a couple of weeks last summer. After his chick feast he flew to South Binness Island in the main Langstone Harbour where some 400 pairs of Mediterranean Gulls are nesting. The tern chicks need to grow up fast! Earlier this month I had seen a Mediterranean Gull take eggs from the colony, on each occasion apparently stray eggs from the bare shingle (of which there are a scattering, if you look really closely through a telescope). On Saturday I watched an visiting adult Lesser Black-backed Gull take two Black-headed Gull chicks from the colony.

The young Black-headed Gulls have grown fast, and the first one has already fledged. The following images show how developed some of the larger fledglings are (click on each one to enlarge them). The one in the first image is looking out over the lagoon waters just prior to taking its first fluttery flight on Sunday.



Many more young will have fledged by this time next week. But, as there are still a few birds still on eggs, and a few very small chicks, the fledging season will be protracted. Already more and more broods are moving away from the lagoon islands and ending up around the edge of the lagoon or in the sheltered bay just to the south.

For a complete picture story of the progress of the various species on the Oysterbeds this summer please visit Peter Drury's excellent photo gallery.

Just a little bit of bad news for the Oystercatchers. One of the three pairs nesting on the North Island has failed within 48 hours of successfully hatching one chick. Exact cause unknown, but a similar thing happened to this pair last year. There are two pairs still on eggs. The pair on South Island still have their one youngster, which has already got into the high tide roosting habit of its parents (rather than trying to snuggle under the wings or body of mum!).

A tern for the better

Tuesday, 15 June 2010

Sorry, I couldn't resist the media-like headline! But it does sum it up quite well. The weekend was a success for the birds at the Oysterbeds. More of the clutches of Common Tern eggs hatched and, up until late yesterday evening, all of the adults that had hatched young still had some or all of their family. There are plenty of broods of two and three young. In fact, Sunday gave me an opportunity to count pretty much all of the young chicks as the adults kept coming and going to feed them. The final tallies were: 80 pairs nesting; 46 pairs with young; at least 104 young including 16 broods of three. It was too windy yesterday to establish comparative numbers after another 24 hours but at least three more clutches had hatched.

From a predators viewpoint all these chicks are potential food packages. In effect, the islands in the lagoon are currently a natural fast-food restaurant ready to be turned into a take away by any hungry predator! One worrying aspect of the weather at the moment is the wind strength. This makes finding food for the terns more difficult, and both adults will more often leave the chicks 'home alone' to find food for them, this exposing them to increased chances of avian predation (in this case, gulls). Once again, as one day last week, I noticed that in the moderate breeze of yesterday more of the food items being bought back to the colony and fed to the chicks were tiny flat fish rather than slender (and easier-to-swallow) silvery fish.

I have provided some artificial shelters for the chicks. These are just simple constructions of wood that were placed close to individual nests. Already by Sunday several of these shelters (there are nine in all) were being used by tern chicks. I watched one chick disappear into the darkness of one (an upturned V-shaped shelter with a peak of about 20 centimeters) only to scamper out, like a starving clockwork Gremlin, when it saw that its siblings were being fed by dad!

Mediterranean Gulls continue to provide a threat to the chicks, and yesterday evening I witnessed, for a third time recently, an adult patrol the colony and leave with a stray gull egg. It could easily have been a tern chick. They need to grow fast to reduce their risk of predation from Med Gulls.

The Oystercatchers on South Island lost one of their chicks last Thursday night/Friday morning. I'm not sure why, but a proportion of wader chicks do seem to die in their third day of life. This may be because they never learn to feed properly and, once their post-hatching energy resources are used up, they perish. The remaining chick seems to be doing well. Oystercatchers are very good attentive parents and bring in fresh food for their young. This is unusual for a species of wader. Most wader chicks learn to feed for themselves within hours of hatching. Oystercatchers learn very slowly, and are fed right up until and often after fledging by both parents, predominantly the male to begin with. As well as feeding on worms, they feed on crustaceans and shellfish such as crabs, cockles and clams. The skills needed to crack the shell of a cockle and prize the contents out are learned. I have seen juveniles, fledged in August, still begging for food from their parents in October. Worms form the staple diet of these younger, inexperienced birds.

Common Terns face wet and windy 24 hours

Thursday, 10 June

It was a damp afternoon at the Oysterbeds today, and with an increasing northeasterly wind and the forecast of a period of heavy rain through the first few hours of daylight tomorrow morning things do not look quite so rosy for the Common Terns. There are now at least 24 broods of small chicks on the islands in the lagoon and the first signs of stress were appearing. The showery rain wasn't too much of a problem, as there were gaps in the wetness and the chicks are still all small enough to be brooded successfully by the females (i.e. they fit underneath them!). However, it was likely the wind strength was becoming troublesome, as a high proportion of the prey being bought in by the adult terns for the chicks were very small flat fish. Not TOO much of a problem, but it became obvious that some of the chicks weren't able to swallow them, and there weren't too many alternatives being bought in. Yesterday there were plenty of tiny silvery fish being bought back for the chicks which were ideal.

Mike, our evening volunteer, later reported to me that he had seen a tern chick predated by a opportunist visiting Herring Gull which snatched it from a pair of squabbling Black-headed Gulls after they had plucked it from South Island and dropped it into the lagoon waters. Okay, one down, quite a few to go.

Here's a couple of short video clips of the terns that I have taken during the last two days. They show the same pair of terns from two different angles with their three young:

Oystercatcher family relations

Wednesday, 09 June

I have delayed some of the next few snippets of information from Hayling Oysterbeds until this evening… simply because I wanted to present the full story. It concerns an Oystercatcher chick being accepted and brooded by a Black-headed Gull and the (presumed) subsequent shift back to its real parents. Let me explain.

There has been a pair of Oystercatchers on a nest scrape with two eggs right in the middle of the mixed Common Tern and Black-headed Gull colony on South Island for the last four weeks. The eggs were, by my reckoning, due to hatch on Monday. So, with expectation, I set myself up to watch on that day. I duly found a very small Oystercatcher chick but watched as it staggered around in front of a Black-headed Gull nest before venturing onto the nest and, eventually, under the sitting female gull! This is over 1 metre from the Oystercatcher, which was still sitting tightly on her nest scrape seemingly oblivious to what was going on next door, so to speak. What amazed me was that there was no adverse reaction by the gull, it behaved exactly as it would have done if the chick was her own, brooding it at the nest. A while later I saw that the chick had ventured out again and was lying near a neighbouring gull nest where it was quickly attacked. It made its way back to the first nest and, this time, managed to be welcomed by not only the sitting female but also the attendant male who had recently flown in.

On Tuesday evening it was obvious that the Oystercatcher had at least one hatched chick underneath her (rather than eggs) and the aforementioned pair of gulls were sitting on just eggs at their nest. There were no other signs to indicate what had gone on during my absence, but I was confident that the Oystercatchers would lead their chick, or hopefully chicks, away from the nest scrape during the following morning…

Cue this afternoon after ‘the following morning’ had gone, and it was no surprise to turn up on site and find the pair of Oystercatchers had indeed moved their chicks away from the nest scrape and down to the water’s edge. Yes, I just wrote ‘chicks’. There are two. One for each egg! So, by cunning powers of deduction I can say with reasonable accuracy that the Oystercatchers hatched each egg on consecutive days (it’s not uncommon for Oystercatchers to hatch their clutch over more than 24 hours) and that the first chick that hatched was taken under the wing (literally!) by a neighbouring, or should that be neighbourly, Black-headed Gull. I have noticed before that Oystercatchers aren’t too good at incubating and brooding at the same time, often leaving the first chicks that have hatched on one side of the nest scrape while incubation of the other eggs continues for up to a day or so. I once saw a female Oystercatcher determined to keep incubating her eggs long after the first chick had hatched which resulted in the chick dying because the adults, not even the male, recognised that they already had a chick to feed. So, in this recent case of Oystercatcher hatching, the gulls have done the Oystercatchers a favour.

Both Oystercatcher chicks are being brooded by the female and fed by the male this evening. I just hope that the oldest chick doesn’t think that all gulls are friendly as sadly they are often not. I have seen, on more than one occasion, Oystercatcher chicks being killed by gulls. But you probably didn’t want to know that!

For the sceptics out there I took several video clips of the gull brooding the Oystercatcher chick, two of which can be seen below. The quality isn’t great due to distance and haze but they do provide a record of what went on:





[Of course, it could just be that the gulls were incubating an Oystercatcher egg amongst their own, but unless their eggs hatch soon I think that’s unlikely as Oystercatcher and Black-headed Gulls share approximately the same incubation period]

Common Terns now with chicks at the Oysterbeds

Tuesday 08 June

Another update from Hayling Oysterbeds! Common Terns have now started hatching their eggs, the first yesterday morning, and this evening there are at least five pairs with young. Being so small they are easily brooded by their parents (usually the female) and not easy to detect unless you watch them for long periods or chance upon a chick actually poking their heads out from underneath the adult. They do sit differently as well, with wings slightly looser to the body and tail held more horizontally. Lots of squirming about by the adult is also a good indication, although sometimes they are quite fidgety while incubating eggs. Two of the pairs I saw with young this evening are between markers A and B so should provide good views from the seawall path for those with binoculars and exceptional views for those using a telescope. There are now a total of 78 nesting pairs on the lagoon islands. The increase in numbers since last week is perhaps likely to be a result of second nesting attempts by those which had early failures through tidal flooding out on the main harbour islands (some nested too low on the shingle beaches). Will we get to 80 pairs I wonder? That’s about 50% or so of the current total Langstone Harbour breeding population.

Yesterday I witnessed a Mediterranean Gull take a misplaced egg from the South Island and then eat it nearby (there was a fully-formed chick inside...nice!). I actually thought it had taken the first tern chick as that’s where the egg was picked up from but it hadn’t (although I would say that I can’t actually say whether the egg was a tern or gull egg – I think the latter but who knows - apart from their slightly smaller size and different shape the eggs of common terns are often very similar in appearance to gull eggs). A pair of adults was patrolling/quartering over the colony later. That’s not good news for the terns as last year such activity heralded the start of a period of chick predation by one individual Mediterranean Gull.

The pair of Little Terns nesting on the new shingle island at the north end of the reserve recently failed but may hopefully try again. Certainly they are still in the area. Another bird is regularly coming to fish in the western corner of the lagoon. It's a distinctive individual as it has a displaced secondary feather in its left wing and provides some awesome views if you watch from near the low wooden rails at the end of the seawall path. I think it must be a bird nesting on the main harbour islands as yesterday it left the lagoon, with caught fish, in that direction at least twice. At other times it was just fishing for itself.

Summer 2010 - a fresh start to blogging!

Tuesday 01 June

It’s been a long time since I updated this blog and I have now decided to use it to waffle on about the wildlife, again mostly birds, at West Hayling Local Nature Reserve (aka Hayling Oysterbeds) where I am currently working as the Seasonal Warden. There might also be updates from Farlington Marshes and other sites around Langstone Harbour….

The Oysterbeds had a bit of a make over in April when the Wildlife Trust, working closely with Havant Borough Council and the RSPB, and with some money ‘left over’ from the Environment Agency-funded RSPB Langstone Harbour Little Tern project, made some habitat improvements. Work has taken place in two areas. At the oysterbeds lagoon we have recharged (augmented) with shingle and topped with ballast approximately 50% of the length of the southern island, while at the same time re-profiling the sides. At the northern end of the reserve we have made a completely new area of bare shingle habitat, using the same materials used at the lagoon, on the highest ‘finger island’ there.

OK, you’re now getting bored and want some news about wildlife. Here goes…

The late May bank holiday provided me with an opportunity for a thorough look around and a fair bit of bird watching on the reserve. As typically this time produces a late spring peak in the number of concurrent first nesting attempts by the ground nesting species this worked quite well for me in getting my notes up to date. Currently, we have 461 pairs of nesting Black-headed Gulls, a total arrived at by a one-off nest count undertaken by myself in fine weather on 24 May. On this day the first major hatching of eggs was taking place after the first had hatched the previous day, with a total of 35 broods (or partially hatched clutches) noted. Subsequently many more clutches have hatched and the islands are bristling with small gull chicks and attendant adults. The total of 461 compares with 450 nests counted on 21 May last year.


On bank holiday Monday I confirmed the presence of 65 pairs of Common Terns on nests, with at least four other pairs displaying and nest scraping. I am plotting all the locations of all nesting attempts by the Common Terns, helped partly by the placement of lettered posts along the length of both islands. The majority of them are on the new shingle recharge area on South Island (between markers A and E), with some up to posts F, and a further three on the south-western slope of North Island between markers N and O. There have also recently been interest by up to two pairs on the northwest embankment to the lagoon, c.10 metres northeast of the ‘south’ fence line, but they haven’t yet settled. The first eggs are due to hatch on South Island on about 07 June but the majority of the clutches were not laid until just after the last of the frosty nights in the third week of May. So, hopefully, it will become busy with tern chicks during the middle two weeks of the month.

Little Terns have again chosen not to nest on the lagoon islands. However, one pair has found the new shingle area at the north end of the reserve, joining the seven decoys which I expertly (some may say deceptively!) placed in a ‘colony’ towards the furthest end of the island. The real McCoy (not the decoys…sorry I couldn’t resist) is slightly closer to the landward path on the Oysterbeds (i.e. in front of the decoys) and can easily be found by looking from the big bramble bush next to the pile of large ‘reject’ stones. However expert or not I was in the placement of the decoys (which were provided by Chris Cockburn – thank you Chris) it has worked and one pair of Little Terns is a 100% increase on last year. They are just about to enter their third week of incubation. They typically take 21-22 days at the Oysterbeds to hatch. The stones under the decoys may take a bit longer….

Oystercatchers are having a bumpy ride again this year. Three pairs are nesting on the lagoon islands, one on the south and two on the north. The one on South Island, between markers C and D, is a relay after a previous nesting attempt failed on account of Black-headed Gulls taking over the nest scrape! As I carried out the gull nest count last week I confirmed that these gulls are still incubating Oystercatcher eggs!! Who knows what happens when (if) the eggs hatch. One of the two pairs on North Island has now failed twice, the first attempt was hijacked by gulls (who may well still be sitting on Oystercatcher eggs as well) and the second was washed away by high tides last week. The other pair on North Island is on a nest at marker Q, easily seen from the eastern path around the lagoon, and is (I think) a first attempt. The pairs at C/D and Q are due to hatch on about the 07 June and 18 June assuming a full incubation period of 27 days for each. Nine other pairs are scattered about the reserve, including several on the northwest embankment. Two of the pairs on the outer embankments at the north end of the reserve are currently on nests, but they take their chances with fisherman out there! The species can be extraordinarily uncanny in their choice of nest site however, and several years ago a pair nested and successfully raised one young to fledging on the shingle spit just south of the lagoon. It can be done but only without human disturbance.

Single pairs of Ringed Plovers have settled on both the northwest embankment of the lagoon (currently sitting on a nest, although difficult to see even through a telescope) and on the northern embankments/islands. The latter pair had previously tried to nest on the new shingle area but failed (nest robbed of eggs) but I think are trying again. At least one new male has been present this weekend but is constantly being chased around by the resident bird.

The spring migration of waders though the reserve has been very slow this last few weeks and I only really have tales of one evening this month which was worth the trouble of looking for migrants: on 26 May a nice mixed flock of 16 Ringed Plovers, 10 Sanderlings and four Dunlins were along the shoreline just south of the lagoon, and a late Greenshank was along one of the outer embankments. One or two Whimbrels, Grey Plovers and Turnstones continue to be seen throughout.