Construction work on a £90m shopping centre has been delayed by a rapidly increasing population of breeding newts.
The Monks Cross development in York was planned to open next Christmas but has been delayed until Easter in 2014, due to a "huge" rise in newts on the site.
The population of great crested newts has grown by more than 3,000 per cent, from nine to 300, in December.
They will have to be individually caught and re-homed in a nearby wetland habitat before building work can start, because newts are protected under Natural England guidelines.
Dr Mark Hampton, an ecologist, said the rise in numbers could be explained by the wettest summer on record in 2012 – leading to an "exceptionally successful" breeding season.
The shopping centre developers, Oakgate, said they were "disappointed" that work had been delayed.