Grackles, in particular, will remove the "poo sack" from the nest and prefer to deposit it on a rock or right at the edge of your pond. They do this to minimize ground predators finding the nest. You have some choices. a.) ignore it all and hope that it will stop once the babies have left the nest; b.) find the nest and destroy it; c.) hang pie tins and reflective "things" around to discourage the birds from coming in or even use owl or hawk decoys. As mentioned above, ducks and geese will essentially destroy a pond in short order. But sufficient trips from nesting grackles won't help it much either!! Also, if you have a bird feeder and feed the birds all year round or even up through the time when they establish their nests you can minimize this next year by stop feeding the birds for the months of April and May (usually the time when they set up their nests). Hope this helps. Been there, done that. ---David P.S. And then there's that old nursery rhyme: ...24 blackbirds baked in a pie...!!! :-)) Just don't tell the guests what they're eating!

Carolina Wrens are not destructive like House Wrens. CAWR are cheerful and welcome guests at my home any time! CAWR will nest in many odd places; a nestbox or shelf, a flowerpot, a fallen tree stump, an old boot, a clay pot, a bush, a motorcycle helmet, a hole in a stone wall or mudbank, nooks & crannies, mailboxes, an old hat, a coat pocket, ... surely I've missed a few? Our local garden center had a decorative nestbox on a shelf over the cash register. A pair of Carolina Wrens popped in and out as needed to feed their young surprising many customers, including me! BlueBars Here is a link that might be useful: http://www.sialis.org/nestscarolinawren.htm

"Nearly decapitated" sounds like House Sparrow. No,Native Sparrows will not kill your Blues The best option for keeping Bluebirds safe in a box,Is to mount the box on a slick metal pole with a predator baffle,aleast 10-15 feet from any fence, tree,etc.A Sparrow Spooker can eliminate House Sparrow attacks on a active Bluebird nest.See the link below,learn how to make and when to install a Sparrow Spooker.They can and will save your Blues life. Matt Here is a link that might be useful: SPARROW SPOOKER

It is defiantly not a starling. I have two different ideas of what kind of bird it is. 1- it could be a baby cuckoo bird (úÃÂúÃÂÃÂúð) who got to big to fit trough the hole. On the other hand if the hole is to small for fledgling, it should also be to small for a female cuckoo bird to drop an egg in there. 2 - by the looks of it's head,it could be some kind of swift (ÃÂÃÂÃÂøö). I don't think a starling would raise/feed a swift, it's probably just roosting there. I would open the birdhouse anyway to see if the bird is OK and can fly out.