Although only a minor part of the work we do here on the Langstone and Chichester Harbour RSPB reserves, the provision of nesting rafts for common terns at West Hayling is one of my favourite seabird conservation projects. In a world where 70% of seabirds have been lost since just 1950 and widescale changes are urgently needed, it's a reminder that even small projects to provide nesting habitat can make a big impact on a local level.
As previously recorded on this blog, thanks to broader conservation work and the launch of a specially designed nesting raft, 2017 saw a transformation in the fortune of common terns breeding at the West Hayling Local Nature Reserve (and as a result, Langstone Harbour) after years of failure. Having set that precedent, we cautiously started 2018 with the hope that something even more important could be achieved, a second year of back to back success. It's now my pleasure to update you on the details of how this years breeding season not only repeated this success, but significantly surpassed it, seeing the highest number of common tern fledglings here for almost a decade!
Above: A great year for tern chicks but a busy one for their parents (click for full resolution).
As always, the seabird breeding season in Langstone Harbour began with Black-headed Gulls forming territories on the shingle and salt marsh islands early in the spring. After a near complete absence of gulls on the colony sites all winter, the noisy cacophony returned with the first sunny day in late February. The business of finding (or re-finding) a mate, building a seaweed lined nest on the shingle and setting up for the season ahead began in earnest and by the time our migratory common terns arrived back in the harbour in mid April, they were greeted with this familiar sight:
Above: The Black-headed Gull colony at West Hayling on April 19th, 2018
The gulls are a vital part of the breeding seabird assemblage here but are also locally dominant by their nature. In our semi artificial world, the amount of suitable shingle nesting area within the Solent is limited and as a result, the West Hayling Oysterbed site is premium real-estate for all shore nesting seabirds looking to raise a family. For common terns arriving in April, this means that the remaining nesting choice is to thinly spread themselves on the periphery of the gull colonies rather than form a denser colony where they can protect each other. This has not worked out well for them and chicks have usually been predated very quickly after hatching. The long term solution to this is the restoration of a larger network of shorebird nesting sites, allowing different species to colonise areas in sequence as they would do naturally. This is still some time away though and so a quicker solution was needed. It was after observing this that the raft project was initiated in 2017 (full details here) with the concept of providing new, desirable nesting habitat each year, exactly where they wanted it, at the time they needed it.
On the morning of April 26th, a motley crew of both RSPB and Hampshire and Isle of Wight Wildlife Trust staff and volunteers (as well as others) set to work placing the nesting raft back into the lagoon. With all the component parts bolted and tied together over the course of a few hours and then covered in a layer of suitable shingle, the raft was floated out to it's position near the lagoon islands. As per 2017, a number of hand made plaster common tern decoys were added to welcome in their flesh and blood colleagues. This year, occupation of the raft was near immediate with both Common Terns and Black-headed Gulls investigating within a few minutes.
Above: A pair of common terns courting by displaying with fish & scraping bowls into the shingle.
Above: The beginning of May on the tern raft with a host of common terns plus some black-headed gulls selecting breeding territories.
Colonisation of the raft took place rapidly and by the end of May it was jam packed with it's 20 square metres supporting 45 pairs of common terns as well as 12 pairs of black-headed gulls (meanwhile, at the same time, the nearby lagoon islands were supporting a further 25 pairs of common tern and 788 pairs of Black-headed Gull). Common terns make simple bowl shaped scrapes into the shingle and incubate their eggs directly on the ground for about 22 days. They usually decorate the "nests" with pieces of grass or small bits of seaweed and shell but from a distance, it appears they're simple sat down on the bare shingle.
Above: The nesting raft in late May, packed with nesting terns, black-headed gulls and draped with seaweed dropped whilst nest building.
The first common tern chicks started hatching en-masse during the first week of June and their parents then joined the host of other seabirds within the harbour busily provisioning their young with small fish. As common terns only take 22 to 28 days between hatching and taking flight for the first time (see full details from the BTO here), the chicks didn't stay small for long..
Above: Common Terns, Sandwich Terns, Black-headed Gulls and others feeding and collecting small fish within Langstone Harbour in early June.
Above: Common terns parents feeding an increasing army of small chicks.
Above: Common tern chicks in late June, getting bigger by the day.
Whilst the first wave of tern chicks were heading towards fledging age, a second wave of adults were beginning to nest on the raft and it was clear that demand for suitable nesting territory was still very high. With the help of some great RSPB volunteers, a second smaller raft was put together over the course of a day and launched in late June. This second raft was more experimental in nature and was made of a discarded pallet floated on hundreds of plastic bottles contained in metal gabion cages. Although we were slightly cautious at first, it proved to be amazingly hard-wearing. Once again, the new raft had common terns investigating territories immediately and within less than a week, a further 5 pairs of common tern and 1 pair of Black-headed Gull were incubating eggs on this tiny floating oasis.
Above: A packed little raft.
With the second wave of nesting now well under way, the first wave of chicks were fledging on the main raft. After making the first clumsy flight, most would beat a hasty retreat back to their shelter and take some time to summon up the courage to have another go. Some couldn't quite make it back onto the main part of the raft but a platform on the water's edge gave them an area to recuperate in whilst being fed and gradually improving their flying skills.
Above: The first fledgling common tern of the year recovers after getting mobbed by surprised terns and gulls.
Above: Later common tern fledglings taking it easy on a platform next to the raft whilst they preen.
In a total, 45 pairs of common terns nested on the raft during this first wave and raised 23 chicks to fledging, an impressive amount given regular raids by Mediterranean Gulls as well as opportunistic Black-headed Gulls nearby. Mediterranean Gulls have been seen predating tern chicks within Langstone Harbour for some years now and at the West Hayling LNR, can be watched patrolling above the colony before diving in to snatch small chicks (gull or tern). Such is nature, if a bit exotic. As in previous years, the 25 pairs of common terns on the lagoon islands in this first wave were unable to fledged a single chick, illustrating the benefit of the raft nesting site starkly.
Above: A common tern disappears down a successful Mediterranean Gulls neck (just the foot is visible).
The main gull colony began to disperse in July after a relatively successful season with 792 pairs of Black-headed Gulls having fledged 487 youngsters and by the middle of the month, it was mostly just common terns left. With the sudden lack of nearby threats, the second wave of common terns being raised around the lagoon (now composed of 25 pairs on the almost deserted lagoon islands, 16 pairs on the larger raft and 5 on the small one) were having a much easier time than their predecessors. To add to the bonus, sand smelt spawning within the lagoon gave a nearby food source for busy parents.
Above: Sand smelt basking in the shallows.
Once again, a host of small tern chicks hatched across the lagoon noisily demanding food. This time though, with the place to themselves, even the shingle islands did well and chicks waited at the waters edge as their parents flew in with meals. Along with terns, several pairs of Oystercatchers benefitit from the extra space, raising a number of chicks which they bought down to feed on the mud several times a day.
Above: A common tern chick in it's fast food delivery spot.
Above: An oystercatcher teaches it's young how to feed on the shore.
Rapidly growing chicks require plenty of food and sometimes this comes from a novel source. For several days during late July and August, flying ants erupted from the mounds spread over this side of Hayling Island and the gulls and terns were quick to take advantage of the new food source, catching them in the air in a frenzy of feeding. Though small, the ants were plentiful and terns were frantically bringing them back to chicks as fast as they could be caught and delivered.
Above: Gulls & terns "hawk" for flying ants.
Above: flying ants being delivered as fast as they can be caught.
Flying ants were a bonus food supply but nothing can replace the all day air-lift of fish that takes place in a tern colony from first light to late dusk. The terns here feed on a variety of fish and over the course of the season we've seen Sandeels, Herring, Sandsmelt, Gobies, and even some small Bass being delivered to hungry chicks. The harbour's small fish supply was mostly good this year and further showed the benefit of the increased marine protection and recovering seagrass meadows.
Above: Incoming. A small herring is delivered.
Beyond simple enjoyment and scientific interest, seabirds have earned my deep respect over the years I've spent working with them and the West Hayling colony this year was no exception. On many occasions over the summer they were faced with storm force winds, drought conditions and a litany of mortal threats, all of which they persevered through. Watching these world travelers battling through wind and waves, unfailingly bringing food to their young as a matter of life and death, you cannot help but be inspired by them.
Above: Battling the elements, the fish deliveries must continue no matter what the weather.
As August progressed, the second wave of common tern chicks began to take to the skies with short flapping flights in the warm summer air. Like every one of their ancestors back to the Jurassic must have been, each chick was both surprised by it's new found ability to swim in the liquid air whilst instinctively pushing to go higher and further.
Above: Learning to fly.
Counting the fledglings taking off one by one in the hot evenings of August, it was clear that the second wave had been very successful. In total, a further 47 (!) chicks fledged in the second wave, 19 from the large raft, 5 from the small raft and a much welcome 23 from the lagoon islands.
Along with their parents, the newly fledged terns formed roosts on the high tide shingle and rock areas whilst practicing their fishing and flying skills. Other terns passing through joined them in these nightly assemblies and there were often several hundred terns wheeling around the lagoon islands in the late evenings. Sights like these are a good omen for the coming season as it's likely that visiting birds are also assessing the sites value for future breeding attempts.
Above: Terns roosting on the chalk rocks of the lagoon wall.
Amazingly, this wasn't the conclusion. Whilst the second wave were fledging, an encore was beginning to take place with a final third wave of terns incubating clutches of eggs. Throughout mid to late August and into September, 10 more pairs of terns had a successful late season bonus fledging a further 9 young.
Above: Yet more chicks..
Above: Taking a bath after those first flights.
Finally, the last chick to fledge took to the air on September 11th, drawing to a close an epic 5 month long breeding season. All that remained was to head out into the world with its natural and unnatural perils and begin the long journey ahead to the wintering grounds in western Africa.
Above: No beer thanks, I've got a long journey ahead.
I'm pleased to report that a total of 79 common terns fledged throughout the lagoon this year, the highest number since 2010 and the 2nd highest number of fledglings at the West Hayling reserve ever (!). The final scores for the West Hayling LNR common tern colony in 2018 were as follows:
They're on the up. This is what a successful conservation intervention graph looks like! (click for full resolution).
Here in the depth of winter, it may feel far away but soon enough, spring will return and with it, a pulse of migratory terns moving up the Atlantic to find a home here on the coast of northern Europe.
We'll be waiting for them :)