Do Chickadees Invade Active Bluebird Nests and Harm Eggs?

Very rarely will chickadees invade active bluebird nests, peck the eggs and take the nest over. However, this extremely rare behavior has been reported by bluebirders. All cavity nesting birds can potentially behave like this, but there are ways to protect active nests.

Something very important to keep in mind is that while all cavity nesting birds can potentially do this, their natural behavior should not negatively influence our opinion about one species of native bird over another.

While house wrens are well-known for invading active nests and destroying eggs, chickadees don’t typically do this. But we have heard three reports within the birding community of observed nest box.

One really important observation we’ve noticed since we have been collecting feedback on this is that we have not observed instances of chickadees throwing out nestlings (something house wrens do). As of right now, observations have only occurred with eggs or inactive nests.

But we are still collecting information on this, so if you witness it yourself directly (or via camera) please complete our form so we can keep this information updated.

Important: It is critical you do not harm or demonize a native songbird. As backyard bird hosts, we are obligated to act as stewards over our native wildlife. We cannot and must not fault birds for acting on instincts and naturally competing with other birds. It’s also important to understand that as much as we love our bluebirds, they sometimes get aggressive toward other birds when competing and will sometimes evict other birds. It is hard for us to watch, but we must NOT hate the native songbirds we host.

An active nest is a nest with at least one egg, and is considered active until the nestlings fledge.

So what does this mean over all? Should we be concerned about chickadees the way some bluebirders are cautious with house wrens?

As of right now, with observations being so minimal, there is no need to worry if you have a chickadee in your yard. But there are some important things to consider and steps you can take to ensure peace between all native birds in your yard.

Report your observations to Nest Hollow

At the moment there are very limited reports of having chickadees invade active bluebird nests. Whether you have observed this with a bluebird nest, tree swallow nest or other cavity nesting bird, please share the details.

While this will only give us a small sample size, over time, we might be able to get a better sense of this and the factors that might lead to these events.

2024 Cases of Chickadees Entering Active Nest Boxes:

This section details cases from the current report form of chickadees that have entered an active bluebird box. Thank you to those who have submitted a report using the report form.

As of right now, there have been 3.5 reports (one invasion was not in an officially active box) via the website’s form, and about 3 from external sources.

Report Submitted 4/7/24

Here is the report sent in by Carolyn Hart:

I have a bluebird box and a bluebird pair had built a nest and I believe there was probably at least one egg in the nest because I found blue shells on the ground under the bluebird box. And now there is a chickadee nest with five eggs in this box. The chickadees built a nest on top of the bluebird nest. I always clean out the nests when the bluebirds were done with them so I know the nest was not a leftover from the previous season. I only have one bluebird box, and no other nest boxes. For the 6 years I’ve lived here, blue birds have always had at least two and sometimes three families in this bluebird box every year. This year with the chickadees is a first!

– Carolyn Hart

This picture shows a former bluebird nest now lined with fur, which is classic for a chickadee. And there are chickadee eggs inside. This image was submitted with permission from Carolyn.

Image| Five chickadee eggs in a former bluebird nest. The nest is now lined with fur and small wood peelings, which is a signature of a chickadee. Image generously contributed by Carolyn Hart.

Report Submitted 4/8/2024

Here is the report sent in by Mary Beth Nelsen:

We have four bluebird eggs in a nest box that has been used by bluebirds for several years. The pair have been in and out of the box since early Feb, and just got serious in the past couple of weeks. Nest was quickly finished, and eggs laid over past 4 days. Today I saw for the first time a chickadee enter the box. Tonight, the camera alerted me to the female bluebird, who entered the box and sat quite vigilantly for quite awhile. Have never seen either bluebird in the box at night before. I could hear noise outside. I went outside to check things out. She flew out. It’s been quiet since.

– Mary Beth Nelsen

The following images were submitted with permission by Mary Beth Nelsen. They show a chickadee about to enter a bluebird nest box that has a nest with four eggs.

Image generously contributed by Mary Beth Nelsen

Image generously contributed by Mary Beth Nelsen

Image| closeup of a bluebird nest with four eggs in the cup. Image generously contributed by Mary Beth Nelsen

Report Submitted 4/15/2024 via Email Contact Form

This report was not of an officially active bluebird nest. A nest becomes active when it has eggs or nestlings within. However, this case was of a chickadee entering a freshly made bluebird nest.

This observer reported that after the male bluebird checked out its nest, two chickadees entered the nest box and started removing material. The observer scared off the chickadees and intends to put up a second box to minimize competition between the species.

Report Submitted 4/28/2024

Here is an excerpt of the report:

At the back of this garden bed, facing the Cedars, we have a couple upright logs and bluebirds have built a nest in one of them. Earlier this week as I was sitting on a fallen tree close to this garden bed, I observed a Chickadee enter the Bluebird’s nest log. Very soon after the female & male Bluebird came over & the female was visibly upset. She was flapping furiously & making many sounds, as she hopped from perch to perch & onto the ground very close by. She would periodically land on the log and peer into the hole. The get upset again & jump from perch to perch (mostly
on T-posts adjacent to the log). This went on for at least 20 minutes w/ the Chickadee not coming out. I also noticed as the male Bluebird came over to the log a few times the female seemed to chase him away. This happened right before sunset ahead of a freeze warning (4/24/24) so I did not see the conclusion of the incident. I went back a couple days later to check & saw another bird quickly fly out of there- it was not a Chickadee but it moved too quickly for an ID.

Have multiple nest boxes in your yard

The first best way to protect active nests in your yard and keep the peace between all native birds is to ensure you have the resources they need. In this case, nest boxes are in high demand.

You can use bluebird nest boxes for chickadees. In fact, we recommend doing so for a number of reasons:

• They can be used later for other larger birds.
• They are good for winter roosts.
• They provide more room for smaller birds.
• Certain ones are big enough for nest box cameras and van ert traps.

Just make sure you have all of your nest boxes properly mounted on a pole with a good stovepipe baffle.

When it comes to spacing, we recommend having a minimum of 50 feet between a chickadee and bluebird nest box, or 30 feet at the very least (though you may need to move it if there is aggression or stress observed).

It also helps if you have a larger tree or something large in between the nest boxes that blocks the line of sight.

Don’t add chickadee hole reducers (1 – 1/8 inch) until you have confirmed a chickadee is interested in the nest box

When protecting chickadees, the standard advice is to get a 1 1/8 inch hole reducer to prevent chickadees from being evicted by other larger birds, especially house sparrows.

And though chickadees don’t usually mind the tighter hole, it might be a good idea to wait on the hole reducer until you have confirmation that a chickadee is interested in the box and is at least starting to add nesting material.

Some even advise training the chickadee up to a 1 – 1/8 inch hole reducer by beginning first with a 1-1/4 inch reducer. Once they’re used to that, they can graduate into the smaller hole guard.

The 1-1/4 inch hole reducer won’t exclude house sparrows. But if you haven’t had one immediately in your area, you might be safe to use it for a day while the chickadees get use to having a hole reducer in the first place.

We would also say that hole reducers are a must when housing chickadees. In the end, it gives you a lot of peace of mind and the chickadees a lot of peace of mind for them to nest safely.

Wren guards may also help prevent other birds from invading active nest boxes

Wren guards are little hoods that fit over a nest box and are added after the first egg is laid. They hide the visibility of the nest box entry hole and make it somewhat difficult for birds to enter the nest.

A pair of birds committed to the nest, will try harder to access the box and figure out a good fly-in routine for quick entry. But invading birds are more likely to give up the obstacle for an easier box.

Wren guards have become standard practice when house wrens enter backyards. They are a great way to discourage them from invading active nests. But we have found them useful in minimizing entry from other invading birds including cowbirds, and Eurasian tree sparrows.

With this in mind, if you have an active bluebird nest, whether or not you have house wrens in your area, it’s just a good idea to add a wren guard to the nest box as soon as you have your first egg.

You can make a wren guard out of cardboard with this instructive video.

Sparrow spookers aren’t a bad idea either

We tend to recommend combined discouragement tactics. So after you’ve added a wren guard, it’s not a bad idea to add a sparrow spooker to bolster protection from invading birds, whether it be a chickadee, house wren, house sparrow or something else.

There is no proof that this will deter chickadees from invading a nest, but it is a practice that can help overall.

You can buy a sparrow spooker here, or use this fairly simple video tutorial to make one.

One thing we want to mention about sparrow spookers is that it’s not recommended that you use this instead of a wren guard.

The wren guard should be your primary method of discouragement from native birds invading active nests. We only suggest adding the sparrow spooker alongside a wren guard to increase protection.

What to do if it’s too late – a chickadee pecked your bluebird eggs

If a chickadee has pecked your bluebird eggs and you have indeed confirmed this, it’s ok to be sad and heartbroken. It’s ok to be a little angry too. Your feelings about this situation are real, and it is one of the more difficult sides to landlording songbirds.

But do not take this anger or sadness out on the birds. They are acting on instinct and nature and are influenced by their own biochemistry. Take a breath, feel the pain, and remember your main objective is conservation.

Step 1:

After registering your feelings and cooling off, our advice is to watch the nest box. Do you notice a sprig of moss in there? If so, the chickadee has claimed it.

While this may seem counterintuitive after what has just happened, you must now protect the chickadees in that box.

Add a 1-1/8 inch hole reducer and let them have the box. Chickadees can be a lot pickier than bluebirds. And after this situation, your bluebirds might want to hunt for a new nest.

If chickadees haven’t added material to the nest over the course of a few days, wait and see if your bluebirds come back. Whether they will or will not really depends on the birds. Some bluebirders have experienced bluebirds trying to nest again after a wren invasion, while others have seen them move on. Which means that there is a real possibility your bluebirds may return to the nest after a chickadee invasion.

Step 2: In either case, what you know for sure is that you have bluebirds who want to nest, and you also have chickadees wanting to nest. This means it’s time to add another nest box.

Try to put the nest box about 50 feet or more apart (this is the pairing distance when talking about 2 different species).

If you don’t have the space, the least recommended amount of room is 30 feet. Or, try a front yard/backyard setup to where your own house blocks the view between the nest boxes.

If your chickadees claimed the former bluebird nest box, then adding a second box will give your bluebirds another option. And if your chickadees decided they didn’t like the bluebird house, well now it’s vacant for your blues to hopefully return to, and the chickadees now have a new option.

Step 3: Step three may need to take place in conjunction with step 2 or soon after. But it is to watch your nest boxes, and protect them once they’re claimed and eggs are laid.

For chickadees, that means adding that 1-1/8 inch hole reducer. And once eggs are laid, you can add a wren guard to the chickadee nest. Most chickadees are tolerant of wren guards, but we do have some advice about that in this article.

Once your bluebirds have claimed a box and started trying again, wait for that egg to be laid and then get a wren guard on and sparrow spooker up as well.

Step 4: Now it’s time to hope for the best. Remember, you can only do so much to protect the wildlife in your backyard. As long as you’re taking steps to protect native animals, it’s ok for nature to take it’s course (not ok when it comes to invasive birds).

Step 5: The next thing you can try to do is just make sure you have enough natural resources for the birds in your backyard.

If you have a mostly grass lawn, consider introducing some shrubs or starting a garden. This will increase the bug diversity.

This is only a hypothesis, but if birds sense there are more available resources, it might be that they could be potentially less competitive in their behavior.

You can offer food, but we don’t usually recommend feeding birds during nesting season except in extreme situations. This is because it invites other predators to your yard as well as tempts invasive species.

Instead, start focusing on ways to turn parts of your backyard into a natural buffet. Plants like coneflower and native thistle will feed finches and attract a lot of insects and larva that in turn feed your nesting birds.

At this point, you have done all you can do. And if heartbreak still comes, we want to encourage you to keep going. Keep trying, but never take your anger out on the birds. Try as hard as you can to remain calm cool any anger so that it doesn’t turn to hate.

I have another nest box with an active chickadee nest, and chickadees still invaded my active bluebird box

While house wrens are known for building several dummy nests and then only settling in one, this is not common for chickadees. Some research suggests that chickadees will abandon nesting sites before eggs are laid for another location, but it is rare for this to happen in an active nests with eggs or nestlings.

If you indeed have an active chickadee nest (eggs or nestlings) and a bluebird box was still invaded by chickadees, what might actually be happening is that there is another chickadee or pair of chickadees coming into the territory.

This may be more the case if you live in a region where you have both Carolina and black-capped chickadees. They are extremely hard to tell apart, and both have different territorial demands.

In this situation, you can play the add another nest box game, and that might be a good option. But something to keep in mind is the size of chickadee territories. We have a guide on chickadee nest box spacing that may help you decide what to do.

Our only other suggestion in a situation of another chickadee coming into your yard is to follow the listed steps, or sit back and just let nature do what nature will do.

It can be very frustrating. But remember, this is nature. We cannot control everything, nor should we in the end. Our goal is to be stewards over the backyard and make it as peaceful as we can, but accepting the fact that things will still go wrong from time to time.

Do not demonize chickadees for invading active bluebird houses.

It is very important, as we consider this rare behavior, to continue to maintain a true heart for bird conservation. And part of that means that we should not demonize or start hating certain native birds for acting on instinct.

Our objective is to protect them as much as possible, but we must understand also that birds are animals.

Likewise, as heartbreaking as it is when a house wren gets into a nest box and destroys bluebird or chickadee eggs, house wrens are native birds. We must try to appreciate this fact and move forward by employing other techniques to protect all of our native birds.

It is illegal and bad for local ecosystems to trap or harm chickadees

Chickadees are native birds federally protected by the Migratory Bird Treaty Act (MBTA). It is not only illegal to trap and harm them, it is disruptive to the natural order of your local ecosystem.

While trapping invasive birds is legal and does actually help the overall ecosystem, this is not the case when it comes to native birds.

Never tamper with an active chickadee nest. And do not try to discourage chickadees from nesting in your yard. They only have one set of babies (brood) per year. After their turn, a bluebird or tree swallow might take the nest box.

Key takeaways:

• This is a heartbreaking situation and your feelings of grief are valid.
• Remember what helping birds really means – it’s hard work and heart work.
• Protect chickadees, even when things have gone wrong.
• Do what you can to maintain peace, and then let nature take over.
• The invader might not be your resident chickadee – but you can still use the same protective tactics.
• Anger in the moment is ok, but never take it out on a bird. And never let it turn into hatred toward a bird species.
• Never harm a chickadee or chickadee nest.
• Try to remember reasons to appreciate chickadees.
• If this has happened to you, please report it.

Video Footage:

Chickadee in an active bluebird box

This video was generously contributed by Theresa of NC. It shows a chickadee in an active bluebird nest box pecking at the eggs. In an update from Theresa, the bluebirds managed to lay another set of eggs and have been watching the nest box more carefully.

Chickadee entering an active bluebird nest

This video was generously contributed by Joyce W. Foster of NC, and depicts a chickadee entering an active bluebird nest box with eggs that are due to hatch very soon. Fortunately, the male bluebird is around to defend the nest box.

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