Eurasian Tree Sparrow Aggression Toward Bluebirds and Other Native Cavity Nesting Birds (USA)

Eurasian tree sparrows are another introduced bird species in North America. Because they are cavity nesters and look similar to house sparrows, bluebird, tree swallow, chickadee, purple martin, etc. landlords wonder sometimes if they post the same threat to native North American house sparrows as their cousin the House Sparrow does.
In this video, I talk about a recent attack that was caught on film of a eurasian tree sparrow attacking a female eastern bluebird in a nest box. This video does show a quick clip of the attack, however below in the resources section will be a link to the full attack. This was not the first incident of a Eurasian tree sparrow attacking a bluebird. A week or two before, one fatally attacked another female bluebird. This video also talks about Eurasian tree sparrows evicting chickadees and house wrens for nesting sites.
Because we don't have as much data on Eurasian tree sparrows as we do house sparrows, it's harder to gauge their aggression. However with these recent observed attacks compiled with years of other observations, they're starting to show up as more aggressive toward North American songbirds than we once realized. And even though they're smaller than a bluebird, they can still fatally harm them.
RESOURCES ---
1. Link to the full video of the Eurasian Tree sparrow attacking the bluebird (NOT FOR CHILDREN - GRAPHIC) • [WARNING- GRAPHIC] Eur...
2. Differentiating house sparrows from Eurasian Tree Sparrows: • Another Introduced Spa...
3. Article written up based on this observation: nesthollow.com...
4. Bluebird Coloring Book (Educational Coloring Book) - This is a pretty comprehensive guide to caring for bluebirds, but aside from just reading, you can color! I spent a year illustrating and writing this coloring book. On the right-hand of every page is a topical illustration, and on the left hand is information about that topic. Check it out on Amazon: amzn.to/3wlifZS

[@carlas123]

I am a few hours north of you. Since I watched this episode, I have been on the lookout for Eurasian tree sparrows and have not noticed any and don’t remember any coming up on Merlin. Thanks for a very informative video.

[@nesthollow5159]

Whew. That's good you don't have them so far. Maybe as years to come, keep a lookout I'm case they do start to expand.

[@kooale]

You do great work & many thanks for mentioning the MBTA. THANKS!

[@nesthollow5159]

That means a lot. Thank you very much.

[@dennisbuchmiller5164]

Here in the St. Louis area, Eurasian tree sparrows are a real problem for many reasons. We have a very difficult time keeping them away from bluebird houses and feeding stations. I hate them!

[@nesthollow5159]

Yea, they've really overwhelmed that area. The Missouri department of conservation does not protect them. They are also not federally protected. So if your city area has no ordinances against trapping, that is an option. Falconers can sometimes take live birds too. If you go that route, research safe trapping practices and identification. Managing them is really tough, especially since they can get into chickadee-sized nest box holes.

[@Javaman92]

And yes, thank you for getting this information out there. Now I know from your video that I probably don't have them here in upstate NY. At least not yet. But we all should know this information.

[@nesthollow5159]

Thank you. Probably for you, there would be so very few if any at all. But Ebird is a great resource to track them. It's interesting go see that they've expanded into some small pockets farther than most of us were aware.

[@Javaman92]

By any chance do you know if Merlin accurately identifies the Eurasian Tree Sparrow? I have 3 nesting boxes up now and so far I have not even seen a House Sparrow. Two of the houses have birds in them, a Tree Swallow and a House Wren. I just put the third box up yesterday. I'm hoping that neither the House Sparrow or this Eurasian Tree Sparrow are in my area.

[@nesthollow5159]

I just looked at my merlin history, and it seems to be able to differentiate. The Birdnet app also can. I do know it's not always perfect and will sometimes guess a house sparrow when really it's a Eurasian sparrow, but it does a good job overall. Over the years, I've gotten better about hearing the difference. The house sparrow has a surprisingly higher pitch compared to the Eurasian. But it's soo subtle.

[@UrLocalCockroach1]

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