I'm sorry for your mama and babies blues. What an awful find. I would think as soon as an egg is laid you should put up sparrow spookers on your BB and TRES boxes wether you see HOSP around or not. Better safe now than sorry later. I can not answer your questions about the wren guards since I have not had any problems with wrens myself (triple knocking on wood). I do not have any experience with them. I think a HOWR is way too small to attack an adult BB or TRES. I doubt that it was a EAPH either I've never heard of them displaying that kind of behavior. If there was so outwards signs of an attack. Such as blood or obvious pecked areas like what you'd find in a HOSP attack. It sounds more like pestisides.(sp) Of course thats just a thought on my part. I'm not an expert so hopefully someone with more knowledge with chime in soon. Again, I'm sorry for the loss of your mama BB and little babies.

Definitely HOSP. Until I monitored my boxes, I was clueless to the senseless behavior of these birds straight out of hell.
You may not see them or hear them but just wait until you get a box with TRES, blues or TUTI nestlings. By the time you see the HOSP, they have already "visited" the boxes and killed the nestlings and any adult nesting there.
You will have to trap and dispose of the HOSPS. Some folks think this is against nature but unless you actively and passionately wage war against these birds from hell, the bird songs you were used to hearing will become constant, irritating, monotonous chirping and you will continue to find dead nestlings in ALL (I mean ALL) of your nestboxes.

sialis.org is the site you need to visit. Know thy enemy and good luck taking "care" of these ratbirds.

Linda

Hi, i'm so sorry about your loss. It sounds to me like pesticides or something ingested by mother. This is truly awful because while you can make sure you don't use anything on your own yard you have no control over what your neighbors use. I doubt if it has anything to do with the nestbox itself. Very very sad.

Sorry Nina. That is so tragic and I know emotional. Are there peck marks on your adult and babies?

Since you saw no outwardly visible signs of attack, my vote is for pesticide/herbicide. The bright color of the babies tells me that they probably ingested insects that had come into contact with the poison--and mama, as well. Believe me, if your blue died as a result of a house sparrow attack, there would be no doubt. Hosps are not subtle--they destroy, obliterate, over-kill. House wrens cannot kill an adult bluebird--they are too small, though they can and do wreak havoc on eggs and young hatchlings.
I would say that poisoning is probably what happened and you might want to do some investigating in your neighborhood to see if anyone has been using chemicals.
So, so sorry for your loss.
Kathy

Nina, I also am thinking pesticide/herbicides. I'm just sick for you and your momma blue and her babies. :( Sometimes terrible things just happen that are out of your (our) control. You can control what they eat from your yard/property but you can't explain to them that they should not eat in areas that might have been treated with pesticides.

(((Hugs)))

The more I think about this, the madder it makes me. While some people use chemicals/pesticides/herbicides responsibly, many use them indiscriminately, without a care for what wildlife may be affected. I truly don't even like to walk down that aisle in the stores--the smells are so strong--it makes me wonder what damage is being done to us as well. I try very hard to use things that are "green" so-to-speak: diluted dish detergent, insecticidal soaps, tobacco "juice". Janie, you're absolutely right. I wish there were a way to let the birds no that our yards are safe 'chemical free' zones.
Poor mama and poor little babies.
Kathy

Thanks everyone --

I honestly never considered poison or pesticides as a possibility until you all suggested it, because I haven't ever used any on our property. In the past 7 years I've had a lot of BBs and TSs nest in my nest boxes without anything like this happening. I'll have to ask around and see what my neighbor, a farmer who raises hay and cattle, uses on his fields.

I am very annoyed with myself for not thinking to freeze the bodies of the mother BB and babies and trying to have them analyzed, although I am not sure if the state of CT has anyone who does that. I guess I was too upset to think like a forensic scientist!

Hopefully it won't happen again, but thanks, everyone, for your helpful suggestions and support!

Nina I'm very very sorry about this. It just makes me sick to ever lose any adult females. I have Phoebes nesting in my shed every year and hunting right along side my blues and they never ever even look at each other never mind have any kind of scuffle at all. I'd have to agree with folks here. In the future though I would never take a chance with a nest and not use a spooker. We never put them up until after the first egg is laid and then always take them back down after fledging. Although it can't protect against everything it is like a 24/7 babysitter for your blues. They have so many obstacles to over come and this we can control. Most of us here trap hosps and we all use spookers. Check out our favorite website for everything you'd ever need to know about bluebirds.
Again sorry for the loss
Cathy

Here is a link that might be useful: sialis

Nina, sorry for your loss. Most often it is nothing that we have done wrong, or something we have no control over. Even when wild birds choose to nest in a natural cavity or in the fork of a tree, they have many more losses than we see in our nestboxes. We just don't see them up close and personal. Hopefully the losses are few and far between.
When we lost a nestling in the last brood, it turned pure white. I've wondered if there was a way to know by color exactly what happened, although there is still little we can do. Sometimes, like human and other animal young, they might have a weak heart or some other malady. But when the whole brood and/or adults perishes (without obvious trauma), that seems like an environmental issue, such as cold, heat, or poisoning. The source of poison is not likely to be found or proved, and very difficult to prevent their use by other people. In this case, since the mother bird perished, the young were most likely doomed at that age, and in the nest under her, even the father could not feed them.
And sometimes, we will never know. Take a deep breath, and look forward to better days.
BlueBars

So sorry to hear about your Blues, Nina. How very sad. Like Bluebars said, you will probably never know what happened which is too bad. Sparrow spookers are a great invention. I have to tell you a story about one this year. I had it on a house that the Blues started laying eggs in. After the 4th egg was laid Daddy Blue disappeared. Momma during this time was so very skittish. One day was a pretty windy day and you could see she didn't like the noise the spooker was making when the mylar strips would hit each other. She kept going into the box but then right back out several times. I decided to see what she would do if I took the spooker off so I went down and took it off. Got back to the house and looked at the nestbox and there was a TRES looking in the box. That fast there was another bird at that nestbox, nothing ever bothered it once the spooker was on it but as soon as it was down, bam something was checking it out. Needless to say it went back up immediately. I didn't intend on leaving it down, just wanted to see if that was what was bothering momma so much. Thankfully on day 5 of Daddy's disappearance he returned and momma settled down.

Take Care

Donna

Enjoy the success (lots of it) and grow beyond the losses. BTW, I am totally paranoid about HOSPS, but pesticides are a real possibility, especially those in granular form (like home foundation treatments for ants).

What is a TRES and HOSP?

Catlady - Tres = Tree Swallows; HOSP = House sparrow; HOWR = House Wren; BOSS = Black oil sunflower seeds

Sorry to hear about your Blues. I'm very new at this and haven't has tragedy yet (KNOCK! KNOCK!) but I can imagine the devastation of losing an entire nest and not knowing why. Hang in there - we're all feeling sad with you.