Following good years for nesting Common Terns at East India Dock Basin in 2014 and 2015, no terns nested there this year. Terns appeared as usual this spring, and were active around the rafts throughout May, with pairs seen mating. At least one bird appearing to be on a nest in late May and early June, but it is not clear whether eggs were laid. If they were, the nest had failed by mid-June, and no further nesting attempts were made. The reasons for this are not clear. It could be that low water levels at critical times, when terns were seeking nest sites, deterred them from using the rafts, which are sometimes stranded on the silt after prolonged periods without a sufficiently high tide to bring water into the basin. Bad weather may also be a factor – it’s been a cool, damp summer with occasional torrential rain, which is not good weather for breeding terns. There is rather more vegetation growing on the rafts than in previous years, which might be a deterrent for terns, which like to nest on clean shingle. A bigger deterrent might have been the pair of Coots, which nested on the terns’ preferred raft just before the terns arrived, and have produced at least one brood of young. Coots often feed on other birds’ eggs, so terns may not have wanted to nest so close to potential predators.
Nor is it clear where the terns which usually nest on East India Dock Basin might have gone. New rafts were placed in Millwall Inner Dock and Blackwall Basin this spring, raising optimism that terns would return to these former nesting sites. Two pairs of terns appeared to be nesting on the Blackwall Basin raft in June, but there was no sign of any terns in early July, so, if eggs were laid, the nests failed. As far as we are aware, no nesting attempt was made on the Millwall Dock rafts, nor on the raft on Shadwell Basin, where terns have nested in some recent years.
Nor is it clear where the terns which usually nest on East India Dock Basin might have gone. It certainly wasn’t elsewhere in Tower Hamlets. New rafts were placed in Millwall Inner Dock and Blackwall Basin this spring, raising optimism that terns would return to these former nesting sites. Two pairs of terns appeared to be nesting on the Blackwall Basin raft in June, but there was no sign of any terns in early July, so, if eggs were laid, the nests failed. As far as we are aware, no nesting attempt was made on the Millwall Dock rafts, nor on the raft on Shadwell Basin, where terns have nested in some recent years.
Across the river at Greenwich Ecology Park, birdwatchers report nesting tern numbers slightly lower than usual, so “our” birds haven’t gone there either. Plenty of chicks hatched there, but very few fledged due to predation by gulls. Interestingly, this has never been a serious problem at East India Dock Basin in the past, as the terns generally seem capable of driving gulls away.
Whatever the reasons, it appears no Common Tern chicks hatched, let alone fledged, in Tower Hamlets this year. Let’s hope that this is a one-off, and that this charismatic species, a priority in the Local Biodiversity Action Plan, returns to form in 2017.
