Early siskins

Whilst taking a relaxing break from gardening this afternoon, dozing in the pleasant warmth of a real May day I was kept from nodding off by a very melodious Whitethroat in the shrubbery. Then much to my surprise a family party of five young Siskins descended on the Nyjer feeder. Is this early? BTO Species facts page does not have any information on the time of laying the first clutch. Any one know?