yesterday feathers from what seemed to be a robin were found on top of the castle house and on the ground.  This morning two small dry, owl down feathers were found. the Martin's have been much less active these last two mornings.  It has and is still cool rainy and overcast which also causes reduced activity as well as egg laying is in progress which I think lessens activity.  

   How much is the owls presence affecting the colony?  Is it attacking or just using the site to hunt and eat.   

I will be keeping a close eye on the activity and records.