For the first time this year, in order to give our migratory common terns some much needed empty nesting space, we launched a tern raft onto the tidal Oysterbeds lagoon. As noted in the mid-season blog, success in colonisation was rapid and great to see. With the season complete, I'm happy to report that although it's not been plain sailing, the rest of the season progressed very well and resulted in what may well be a breakthrough for the common terns breeding here. By mid September, 44 common terns had fledged directly from the raft and another 6 had fledged nearby (compared to just 5 fledglings from this site between 2014-2016).
Above: A common tern and it's chicks at home on the Oysterbeds Tern Raft (with a decoy common tern sat on the wall overlooking them).
Above: a chick gets ready for an incoming meal.
Hatching began in early June and despite often tough conditions, the raft colony remained amazingly dedicated throughout the summer and fledged two successive waves of chicks. The common tern breeding productivity on the raft was vastly higher than on the nearby shingle islets with the main differences being the density of Black-headed Gulls sharing the colony (only a handful on the raft, many hundreds on the islets) and the impact of tidal surges (lower nesting common terns on the islets were washed out whilst the raft was unaffected). Although the Black-headed Gulls are an essential part of the harbour's breeding seabird population, with limited space and terns arriving back to nest later, there is an element of competition between them as well as opportunistic predation when in close proximity (for more detail on this, see the original blog on why we trialed a raft here).
Above: A comparison of the success of common terns nesting on the raft with those nesting amongst the main gull colony on the lagoon islets (note: the tern young which fledged from the shingle islet all did so after the gull colony had departed). Although productivity was higher on the raft for common terns, they still faced the same environmental issues which limited the success of all the nesting seabirds this year. There were many heavy deluges of rain, regular days of wind speeds topping 30-40mph and difficulty providing food for multiple periods of days, all of which led to fatalities amongst the chicks. At the close of season, at least 16 dead young were found on the raft with only two being more than a week old.
Nevertheless, after several years of near zero common tern fledglings at the Oysterbeds, this is a great step forward and offers a very practical way for us to provide common tern specific nesting space in the future despite the great demand for undisturbed nesting areas from all species present. We'll be working with this in mind to see what further habitat we can provide in spring 2018....
Until then, here's some of the highlights of the rafts breeding season:
Above: Fledgling number 1 takes to the air!
Above: A chick learns that eating sandeels takes a little skill.
Above: A more successful meal delivery...
Above: Chicks galore on the raft as the first wave starts to fledge (whilst the 2nd wave are being incubated).
Above: a tour of the activity on the raft in early July.
Above: All three chicks on the camera monitored nest exploring on a windy day.
Above: Mid August on the Tern raft as the final wave of chicks prepare to fledge.
Once again, I'd like to thank the Hampshire Ornithological Society and the EU Life program for funding the building of the raft and allowing us to successfully make it a reality. Also, I'd like to thank the staff & volunteers at the Hampshire and Isle of Wight Wildlife Trust, my colleagues over at RSPB Pagham Harbour and the Langstone Harbour Board Environment Officer for helping us put together and launch this floating island home! #OneTeamForNature
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