Like Tony's nests, the regular House Martin pair under my front gable in Penrhyncoch has also failed this week. On Sunday and Monday the birds were making very frequent visits to the nest, leading me to assume the brood had hatched. By Tuesday evening almost all activity had stopped, although the adults were still roosting in the nest overnight. The nest itself was intact.
Then yesterday evening there were broken nest fragments on the windowsill under the nest. The entrance hole has been enlarged by something to three times its usual size. No sign of any broken eggshells or dead chicks. There a were a couple of Magpies loafing about on the roof tops earlier in the week so it's possible they could have been the culprits(?)
The adult Martins still came back to the nest at dusk last night and after a lot of flying about agitatedly, squeezed in to roost in the open nest cup.