Common Tern arrive back in the Lee Valley from Africa each summer to breed in colonies on the artificial rafts which mimic the shingle beaches and gravelly shores of their natural breeding habitat. The first raft in the Lee Valley was installed at RSPB Rye Meads in 1963 and since then have been installed in various locations including Seventy Acres Lake at Fishers Green, Walthamstow Reservoirs and Ponders End Lake.

In 2008 the first Black-headed Gull pair also nested on the raft at Rye Meads and since then their numbers have grown to a peak of 155 on Seventy Acres Lake in 2017. As the gulls arrive earlier than the terns, they tend to monopolise the space and research by the RSPB found that the gulls prefer to nest against a structure, for example against the edge of the rafts, and the terns prefer an open space such as the middle of the rafts, so the design of rafts has been adapted making them larger to accommodate both species.

Common Tern lay two to three eggs on the gravel which are incubated for up to three weeks before they hatch, and after 3-4 weeks they are fully fledged. The chicks at Fishers Green are carefully monitored and each year they are ringed by a licensed bird ringer, this involves putting a small metal ring on their leg each with a unique number. Which means if they're ever recaptured, recorded or recovered there's a fascinating insight into their movements.

The typical life expectancy for a Common Tern is approximately 12 years with breeding starting when they're three years old, however one chick ringed in Northumberland in 1963 was record in the field in Liverpool and incredible 33 years and six days later!