One Swallow doesn't make a Century

We've ringed a Chiffchaff at the nursery, and in so doing we have equalled our annual best score.
David, the owner, has been burning the midnight oil over the winter planting wildlife habitat and maybe his efforts are paying off. We currently have 3 Chiffchaffs singing, and 4 Blackcaps (1 of these will also equal our site annual ringing total). In the meantime, all is not well with our Oldham Dippers, where a few birds have lost full clutches of 5 where all chicks have died within about 3 or 4 days of hatching; the adults are not returning to the nests with beaks full of food. Is this due to the unusually cold winter? Not all nests are failures and yesterday, which coincided with our first aphid hatch of the year, we ringed three decent broods of 5,5,4, well developed youngsters near Whaley Bridge in Derbyshire. Back at the nursery David has been watering his water plants to the apparent advantage of the Swallows. Up to twenty have been circling the nursery, a sight not seen for over ten years, they have been removing mud from the plant pots, and this has led them to realise that the pump house is a desirable nesting site; we are all delerious about this and David and Jake are fighting for the priviledge of ringing the first brood,