One year during the spring nesting season, I noticed a sparrow making soft alarm calls and following a squirrel around the forest.
Of course, I became instantly fascinated as to why this was happening, and it got me wondering whether squirrels ever steal and eat bird eggs.
As it turns out, squirrels do eat bird eggs when they have the opportunity. If a squirrel locates an active nest, they will climb up and steal eggs while the parent birds are away.
This predatory behavior often comes as a surprise because most people think squirrels are vegetarians.
However squirrels are not actually vegetarians! Squirrels are omnivores and eat everything from plants & insects to bird eggs & sometimes even meat.
So I did a quick check to see just how common egg stealing is amongst squirrels and found that pretty much every type of squirrel can at times be observed hunting bird eggs including:
- Grey Squirrels
- Red Squirrels
- Flying Squirrels
- Douglas Squirrels
- Ground Squirrels (various)
- Chipmunks (various)
Each of these different squirrels will all occasionally eat bird eggs when the opportunity is present.
So let’s take a closer look at what’s happening with this surprising and misunderstood area of squirrel behavior.
Why Do Squirrels Eat Bird Eggs?
Squirrels eat bird eggs because they are opportunistic foragers. This means a big part of their survival strategy comes down to maximizing every possible opportunity for acquiring food, including stealing eggs.
Opportunistic feeding is an extremely common trait amongst omnivores like squirrels, simply because it gives them the greatest flexibility to supplement their diet with whatever food is easy to get.
There are many different benefits squirrels could be getting from having eggs in their diet. Some of the most likely reasons include:
- Pregnant females & mothers with newborns might have extra dietary needs that make them seek out a more nutrient dense source of protein.
- Certain food sources might be lacking in locally rare minerals like nitrogen, phosphorus or calcium, which bird eggs can help to supplement.
- Seasonal lacks in their usual food availability could increase squirrel motivation to take advantage of an abundant egg supply.
- Certain habitats might simply make it easier for squirrels to locate nests.
While there’s still a lot to learn here, it’s pretty safe to say this all goes back to the often forgotten fact that squirrels are opportunistic rodents, very similar in biology to rats.
One of the reasons why rodents are such a common problem on farms with chickens & other egg-laying birds is because rats love to steal eggs.
Incidentally just like rats, squirrels will also climb into chicken coops to steal eggs as shown in the following video:
Is It Possible That Squirrels Just LOVE To Steal?
Another interesting thing to note about why squirrels steal eggs comes down to the fact that stealing is almost like a daily part of life for many squirrels.
There was a funny study published in 2005 in the journal of mammalogy measuring how much food squirrels were stealing from other squirrels.
It was shown that even after storing up enough food to survive the whole winter, some squirrels still went out and stole as much as 100% of their cones from other squirrels!
They found that squirrels stole on average 25% of all the cones they ate from other squirrels. That’s a whole lot of stealing!
Squirrels As Predators: Do Squirrels Eat Baby Birds Or Just Eggs?
Even beyond bird eggs, squirrels will sometimes steal nestlings after the eggs have hatched. During the nestling stage, baby birds are essentially helpless while their parents are away finding food, which gives squirrels the perfect opportunity.
It all just goes to show that squirrels aren’t the peaceful vegetarians many people make them out to be.
In fact, the following video provides a vivid demonstration of just how brutal squirrels can be when they find an active nest.
(Fair warning: if you’re squeamish about seeing baby animals being hunted, feel free to skip this one. It is however, a very informative example)
Notice at the 4 minute mark when the chipmunk goes in to attack the birds, as the nestlings scream for help, you can hear the robin nearby giving a very soft alarm call.
It’s amazing to me this response isn’t more intense like it normally would be for active nest robbers.
Nest robbers typically cause some of the loudest and most intense alarm responses from birds, which suggests that while squirrels obviously do pillage nests, it’s probably not as common as the more traditional egg stealers like crows & ravens.
Over the years there’s been a lot of research documenting squirrels as predators.
If you really want to nerd out on the predatory habits of squirrels, there’s an article in the great basin naturalist called squirrels as predators, which provides an in-depth overview of squirrel predatory behaviors in academic research.
Which Birds Are Most At Risk From Squirrels?
In general, young birds are always going to be the most at risk from squirrels. This especially includes birds while they’re still in the egg or nestling phase.
It’s also been observed that birds may be at increased risk of predation from squirrels if they have any of the following characteristics:
- Birds who nest above the ground in open forest habitats with minimal shrubby cover.
- Birds who nest in the forks of trees, especially up in the canopy (which might make their nests easier for squirrels to find).
- Birds who nest in locations with higher population densities of squirrels.
- Birds who nest in locations with less alternative food sources for squirrels.
- Birds who nest in locations with a higher population density of songbirds.
- Birds who nest in locations with less food abundance for songbirds (which means they will have less time & energy for nest defence).
These observations come from a fascinating study on grey squirrels back in 2003 which sought to help predict the most vulnerable bird species based on their nesting habitats.
It’s been observed that nest predation by squirrels doesn’t affect all songbirds equally.
It would seem that some songbirds only experience minimal risk, while other species like the canopy dwelling Chaffinch and Hawfinch mentioned in the above article experience significant risk from squirrels.
How Do Birds Protect Themselves From Squirrel Predators?
Birds will always take appropriate steps to protect themselves from danger. This includes everything from taking evasive actions (keeping their distance), to scolding & mobbing nearby predators with loud alarm calls.
Birds are highly intelligent when it comes to avoiding danger, and we can actually learn a lot about the danger itself by studying how birds react in different situations.
An important concept is to realize that birds will only take as much action as they believe necessary to mitigate the risk.
Stated another way: birds won’t take high risk action for a low risk predator.
This means in the case of nest robbing squirrels, birds will tell us exactly how significant they perceive this threat to be by their behavior & body language.
This study is also called bird language because it reveals how birds send messages that communicate the locations of potentially dangerous animals in the landscape.
Big alarm response = big perceived danger.
Small alarm response = low perceived danger.
So if you remember back to my opening story about the sparrow alarming at the squirrel… We can observe that the sparrow alarming at the squirrel was barely even noticeable.
In fact, I wasn’t even sure at first that it was an alarm until I was able to see the sparrow’s body language and how closely it was following the squirrel around the forest.
This is a major contrast to most alarms directed at nest robbers, which can be among the loudest and most intense of all bird alarm calls in the forest.
Can Squirrels Kill Adult Birds?
As we’ve already seen, squirrels can easily kill baby birds in their nestling phase. However it’s important to note that in the vast majority of cases, adult birds will not need to worry about predation from squirrels.
While under the right circumstances, a squirrel would likely be capable of killing an adult bird, it’s just not something that happens very often.
It would simply take far too much energy for squirrels to be hunting adult birds on a regular basis.
Adult birds are extremely well equipped to escape and protect themselves from squirrel attacks, so hunting would likely only be successful during unique opportunities, like when a bird is already injured.
An easy way to confirm this is by observation of how squirrels and birds normally interact.
Truly dangerous predators develop a reputation amongst songbirds, which results in specific patterns of alarm calling & evasion whenever that predator is in the area.
Now I’ve spent a lot of time observing squirrels at bird feeders, and for the most part they share the space pretty well, just like this peaceful little fox sparrow with a red squirrel I caught on video recently.
It’s a very common sight for squirrels to be feeding on sunflower seeds and just a few feet away, the birds are sharing that same space.
Remember, birds are pretty darn smart, so they just wouldn’t be comfortable doing this if there was any significant risk from the squirrel.
As always, one thing I always love about nature is we can learn so much just by observing. So what are you waiting for? Let’s get outside and watch some squirrels!