The first predator I need to worry about is the English (or) otherwise known as the House Sparrow (HOSP).   Here is a drawing of the male and female HOSP.  They may look “cute”, but they are destructive and nasty birds.  They take away cavities from our protected native birds.    Source:  www.    Thanks to Bet for a terrific site for our bluebirds!

These need to passively or aggressively deterred from killing our bluebirds!

These non-native invaders need to passively or aggressively be deterred from killing our native bluebirds and other native cavity nesters! As much as I love all birds, this particular species bird is overpopulated and out of experiment gone terribly wrong. It's indeed unfortunate we bird lovers have to deal with this pest.

Here is a HOSP nest found in one of my boxes on March 9, 2009.  This is the first nest in all my boxes for the season.  Note the pieces of cloth used in this nest, picked off from a grave nearby in the cemetary where a craft decoration was placed.    Many times, HOSP use paper trash…really anything they can find to incorporate “stuff” into their nests.    They are aggressive killer birds that need to be controlled for the conservation of our native bluebirds and other cavity nesters.
This is a 5-day old HOSP nest.   Part of being a monitor is learning to know what kind of bird is occupying the bluebird boxes.  If it's a HOSP, this nest should be removed.

This is a 5-day old HOSP nest. Part of being a monitor is learning what kind of bird is occupying bluebird boxes. If it's a HOSP, this nest should be removed. It is not a protected bird since it isn't a native bird in the USA, so it is legal as a bluebird conservation monitor for me to do this. Then I need to do whatever I can to keep this happening again. It's a challenge to all bluebirders dealing with the House Sparrow. All other sparrow species in the USA are decent, gentle birds, such as the Chipping Sparrow, for example.

History of the House Sparrow can be found here on the Sialis bluebird site.  This is very educational reading!


  1. My 7yr old mating pair of bluebirds just rewarded are efforts with thier first time ever third clutch. Unfortunately right before fledging they were all murdered in house with a new nest built on top of their corpses.
    My devestation is not explicable.

    I now understand who the perpetrator is. My new mission is to destroy all hosps.


  2. my question has to do with fledglings. so far I have found 3 dead in the yard. first one was in the yard under a tree and with no apparent injury. yesterday, 6/17, a little guy showed up to my birdbath, a shallow pan, and was sitting on the edge like he was looking “Where’s the water?” so I went to check and refill it. he didn’t move. strange. but I added water and went back in. about 20 minutes later i caught a little movement and saw he had fallen over into to water. I dashed out only to find it dead. This morning we had a storm and when I was checking for damage I noticed another little dead body on the deck. yep, another bluebird. all of them had spotty chests and were not as blue as the adults. and as I said, none appeared to have been injured in any was by any other animal or bird. any thoughts? I’m so sad and worried. thanks.


    • There can be many reasons: Chemicals in the lawn such as RoundUp or pesticides in nearby gardens (chemicals on insects they get from the ground). If there are any roaming cats outside, they can cause small puncture wounds on a fledgling not seen with the naked eye. The saliva from a cat is toxic to birds which causes slow and painful deaths to birds.


  3. Today there’s been a fight over the box (nest). I know sparrows have been in the house. Is it too late to remove whatever they’ve brought in? Bluebird trying to block entrance but sparrows are five bombing the bluebird. Help please.


  4. Hi I had two bluebird eggs in box looked and the two eggs out of the nest broken on the ground could what can I do to protect the eggs in the future


    • Can you positively ID species that did the damage? It could be damage from a House Wren. I need more details to assist. I also need to know what the hanitat is. It could be a mammal predation. Feel free to email me directly at send pictures showing your full nestbox and how it is installed, please. I can better help troubleshoot.


    • Howard Robb again wrote this year I had 4 blue bird eggs in the box been watching and checking the box twice a week checked on Fri and when I checked to day eggs were gone I found one in the grass with a hole pecked in it now I have chickadees going in and out of the box I have all the PREDATOR guards so it has to be birds would the chickadees remove the eggs
      They had a nest in another box some ways away now they are at this box
      Thanks for your help


  5. I have a blue bird box at our family lake. Every year there a 2-3 nests but something either kills the babies or the parent. What do you think it is? I’ve just read that sparrows are problematic but they never nest in the box.
    I would love to hear your thoughts on this.


    • Hi, Teri. Well, that is why boxes have to be monitored at LEAST once a week. It would be difficult for me to help you troubleshoot what predators are getting to your nestbox. There are SO MANY. How is it installed? Do you have predator guards on it? Yes, only the non-native House Sparrow can kills bluebird adults and young inside nesting boxes, but I would need to know if you have positively ID’d House Sparrows at your location. YES— ALSO — House Sparrow not only use manmade bird housing, but they will dominate them and take over so that the native birds cannot use them. The other native sparrows do not using bird housing. Give me more info, Email me pictures of your box setup, etc., at


  6. I just came across your site while doing some info searches. I have a bluebird box. I saw birds going in/out, & wanted to check if nesting was going on. YES! They are small all blue eggs. From what I see, they are blue bird eggs. But I don’t see blue birds (Unless they are not blue) going in the box. I have only see Eastern Bluebirds once in 20+ years of living here. So 2 eggs. I ruled out they are house finch eggs, not speckled. How can I verify they are bluebirds, and how can I protect them. With eggs already there, I don’t want to scare away the parent(s) by doing anything to the box to help protect them. There are tons of other house sparrows, chickadees, wrens, etc all around here. (Central IN). I fear I will have to act fast though (if there is anything I can do at this point) to help save them, especially if they are EABL. Thanks.


    • Hi, Chris. Thanks for the inquiry! Yes, you have bluebirds nesting in your box. Congrats. If the egg clutch is completed, the female is now incubating and her mate is probably just hanging out waiting for the big hatch day, at which point he and his bluebird lady love are busy feeding the young from dawn to dusk averaging 5 x a day! He is probably also bringing his mate food while she sits on the clutch inside the box. Perhaps you just missed him going to the box to do this. You won’t get House Finches using the boxes, as they are not cavity-nesting birds. Be careful of the House Sparrows. Do not allow them to procreate in your box. They can nest anywhere, so don’t let them take away the box from the native birds who need to use the boxes. House Sparrows are not really a sparrow, and they are considered a non-native invasive species. They will cause harm to your bluebird eggs and young and even kill the incubating female inside the box. If you are doing any bird feeding, make sure no feeders are near your nestbox and do not feed any cracked corn, milo, and millet in your bird seed foods, as those attract House Sparrows. If you can Email me your nestbox setup, I can take a look at how you have it installed and protected. I am happy to make any recommendations to help your bluebirds raise their family safely (and families). Just send your photos to I will get back to you as soon as possible. I especially want to be sure you have it installed with predator guards. That is the best way you can help save them.


      • Hello again! I did sent an email to you..but wanted to update from that and when I sent this.
        I checked nest/eggs again today…4 eggs! And yes, that mom is there dive bombing me repeatedly. =) But I watched her and got a couple photos, although not very good, or close, but when blown up..I can clearly see it IS EABL!! I am soooo excited!!
        Can’t wait for your reply (via email).


    • Yes….I have info on my site about it. Look at the tab titled Two-Hole Mansion. The purpose is to give the bluebird or other native species such as the Tree Swallow an escape route out of the box during a HOSP attack inside the box, which happens often in standard size nesting boxes. This makes this Two-Hole Mansion box a “defensible” box, which means the native bird can get out in an attack and take the battle outside the nestbox and have a much better chance to defend it’s nest OUTSIDE THE NESTBOX as opposed to being killed by a House Sparrow inside the box. Of course, this is for the adult birds only, not young inside the box during an attack. You can read more about this box design on Linda Violett’s website. Look for the Virginia TEST 2010-2012. I am now starting my 7th year of success using this nestbox. I’ve added another one on my trail in HOSP locations where it’s not convenient to trap the HOSP because I can’t monitor the trapping.


  7. We had had good luck with our Bluebirds for the past 3 years until now~ this year something killed all but one of our babies~ thank goodness he escaped. Four days later they are rebuilding and I am so worried that whatever killed them will do so again. Is there anything we can do to keep this from happening?


    • Hi, Carolyn. I’m so sorry to hear you lost bluebird babies. For me to know more about the situation, can you explain in more detail of your nestbox setup (use of any predator guards and what they are), how is the nestbox installed and where, approximate age of the babies that were taken, any sign of scratch marks, such as from a raccoon claw, or any nesting material coming out of the entry hole, any sign of blood droplets? Did you look on the ground by the box for the babies? Did you find dead babies inside the nestbox, but one survived and fledged later? If you prefer, I can Email you privately on this. Let me know. If we discuss here, it will be educational for others to read on this site. I want to help you troubleshoot what happened, but I need more information. I hope to hear back from you.


Thanks for your comment. Since I review and approve all public comments before publishing, give me a few days to respond to your comments and inquiries. Thank you.

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