Contributed by Ornithologist Laura Erickson

Includes:

• nest size, weight, materials
• nest site selection
• nest-building process
• roles of males and females
• unusual nesting behavior

Q. How big is a robin's nest?

A. A robin's nest is about 8-20 centimeters (3-8 inches) in diameter.

Q. How much does a robin's nest weigh?

A. About 200 grams (7 ounces).

Q. How long does it take to build a nest?

A. It usually takes 2-6 days for a robin to build a nest.

Q. What is the nest made of?

A. Mud, grass, and small twigs.

Q. How is the nest made?

A. A robin collects about 350 dried fibers of grass and small twigs that are about 6 inches long. After a soaking rain, the robin collects mud and travels to and from the nest several hundred times with beakfuls of mud. Next, the robin weaves the grasses together, cementing them to each other and to the supporting branch or windowsill. Finally, the robin lines the inside with the soft grasses and fibers to keep the eggs warm and protect them from sharp twigs or grasses.

Q. Who builds the nest, the male or the female?

A. Both the male and the female gather nest materials, but usually only the female does the building.

Q. What signs tell me that robins are building a nest?

A. Watch for the male or female flying with nest materials, or the female with mud on her breast.

Q. Where do robins build their nests?

A. The site should be protected from sun, wind and rain. It can be anywhere from ground to treetop in height; the site must be on something sturdy enough to anchor the nest securely in place. You don't want your nest to fall off! Your nest should also be very close to a good feeding spot so you can easily find worms while keeping an eye on it, and it shouldn't be too far from water. Choose a spot that is hard for predators to see.

Q. Why isn't my robin in her nest at night?

A. Remember that the nest is not a bed; it's an incubator and baby cradle, so the robin isn't supposed to be on the nest at night until she has a full clutch of eggs. Until then, she roosts on a branch.

Q. How long does a robin use the nest?

A. A robin uses a nest for about 5 weeks, from the time it is built until the young fledge.

Q. How many times does a robin build a nest in one breeding season?

A. Robins goes through the nest-building process each time they produce a new brood, so about two or three times a season. While robins might repair or build on top of a previous nest, most of them build a new nest for each "family" they raise. This is best for many reasons. A used nest is a mess, stretched out, and often home to mites, lice, flies and possibly poop.

Q. What can I do about a nest — with babies — that keeps falling out of the tree?

There has been a nest in our yard, and the babies and nest have been constantly falling out of the tree. Will the parents be able to find the babies or should we move the nest back where we found it?

A. Normally when there are tiny nestlings and a fallen nest, we try to get the nest back in place by putting it in something like a blueberry basket, and then placing that basket sturdily in the tree's branches. Robin nests tend to fall apart when they fall out of a tree, because the mud crumbles, and so the nest is difficult to replace. The "Wildlife Rehabilitation Information Directory" is a good website to check when you need assistance for birds in trouble: Unfortunately, sending an email to any website can't help in an immediate crisis.

Q. My robin built a nest and then disappeared before laying eggs. What happened?

A robin built her nest in our pear tree in the side yard and just finished it about two days ago, I have not seen her lately. Do they stay away while waiting to lay the eggs? I am hoping she has not been hurt or killed but I have not seen the male around lately either.

A. Here are some possibilities to explain why the robins have not come back to use the nest:

• Something dire happened to one or both robins: hit by a car, taken by a predator, etc.
• She laid an egg but then something came and got the egg, and she quit laying.
• She discovered a potential predator, such as a cat, jay, chipmunk, or snake, eyeing her nest and abandoned it because it wasn't a safe place to raise babies.
• She built her nest more quickly than expected (perhaps there was a a good supply of mud from a recent rain?) and she wasn't quite ready to start laying eggs.

I suggest that you give her just a few days to make sure it wasn't just an ovulation thing and she was indeed dallying until she was ready to start laying eggs. If she does not return after 2-4 days, go ahead and remove the nest. Any other robins that come will build their own nest.

Q. Are robins sometimes inept at nest-building?

I have a robin who started a nest in my front porch light. It appears there is some dirt or mud in the shade and the raffia-type grasses hanging loose and stingy, with no structure, all around the outside of the shade. During the day I'll see the robin sitting on top of it or flying back and forth from it, but the nesting materials aren't taking any shape. I'm wondering if the robin is actually considering the shade itself to be the nest, rather than building herself a normal nest, or if this is just a long process and the nest is still incomplete. She appears to be sitting on the light bulb when she's in the "nest." Is this normal behavior?

A. It takes two to six days for robins to build their nest. This robin sounds inexperienced. If this is not an appropriate place for her to nest, the more quickly she figures it out the better. Sometimes tenacity if important, but this bird is wasting time and energy. The male may be frustrated that she is unskilled, or he may be be inexperienced too. There are usually more males in an area than females to this should not be a female without a mate.

Q. Can I move and relocate a robin's nest?

We recently discovered that a robin built a nest in my daughter's swingset. My husband looked a couple days ago and there was one egg in the nest. He removed the slide and the steps so that children will stay away, but the problem is we are moving in three weeks and the swingset will have to be dismantled and moved with us. According to what I've learned by reading some of your information, the egg(s) will hatch by this time but it will still be too early for the baby birds to be out of the nest.

A. Unfortunately, no. If you move a robin's nest the parents will most likely abandon the nest, eggs, and young. Nest-site fidelity grows during the nesting season. The more time and energy the birds invest in the nest, the less likely they are to abandon it when disturbed. However, actually moving the nest is not merely a disturbance—it makes the entire nest environment different.

Do the birds know to abandon a nest that appears to have been discovered by a predator or do the birds think it's a completely different nest? As the mother builds, she is memorizing all the features around the nest. When those features are gone, she may simply not even recognize her nest anymore.I took care of four baby Blue Jay nestlings, well feathered, after their nest and its branches were knocked out of a tree in a storm. The people who found it all recovered the nest and put it in another near-by tree, but even with the babies calling, they simply didn't figure it out, and they'd invested a lot of time and energy into these babies already.

The birds' fidelity is to the whole nest setting. Interestingly, there is a documented case of a robin that raised babies on the structure of a crane that was operational during the time she built, incubated, and raised her babies in it. Another case of a robin that nested in a train car, and followed it when it moved from place to place. I can't find an instance of a robin staying with her nest when the nest was put on another structure.

So, I don't know what to tell you about moving your swingset. It would have been far better to take the nest apart as soon as you noticed her so she could simply build a new nest elsewhere and not lose well developed eggs or babies when the nest would be moved later, since they knew they would be moving. I's too late for that now, but I hope reading this may be helpful to others in the future.

This is still my best advice; Look for support of what scientists know about nest site fidelity, as well as how individual robins are smart enough to observe and learn—even to discover that nice people look out for ways to help robins:

Last summer a tree was chopped down across the street and a family of baby robins was left homeless. I took the nest and moved it across the street to my front porch and the daddy robin seemed to have no trouble finding his little ones. We got to watch three little fledglings grow up and had the honor of watching the last one fly away. I don't know if that is normal behavior but I wanted to let you know that it is possible.

I must be very lucky...I have moved several American Robin nests. I use to live in a home where my front porch was open and I had old plastic roll up blinds around the openings. As Spring started I left on a trip and when I returned the robins had a nest with eggs hatched on the end of the rolled up blind. This was on the West side so I needed the use of the blind. I moved the nest about 2 feet to the left of the blind and put it on the flat pipe of a metal down spout, plus I fastened it to the spout with duct tape! Not only did the robins stay and raise the babies, they came back 4 years in a row and did the exact same thing and each year I moved the nest and each year the robins never objected. The nests were completely protected under the porch roof on top of that down spout. I was so fortunate to move the nest successfully! This was in Cincinnati, Ohio in about the months, each year, of mid April to mid May each year.

Q. Is it common for a robin to build more than one nest at a time?

We have a pair of robins nesting under our deck on the support beam. We have been watching the female fly off to collect nesting material. She has built 2 nests within 5 feet of each other. At first, I thought she started one and abandoned it, but she actually worked on both and were almost finished in 2 days!

A. This is a question we hadn't been asked before, so we wrote to Len Eiserer, the author of The American Robin: A Backyard Institution. Len answered:

"Building multiple nests simultaneously happens every now and again with robins. One started 26 different nests on roof rafters of a garage under construction; another built 8 on successive steps of a fire escape. Support from underneath is the primary site selection factor for the female robin — it's more important than concealment. Because some human structures provide repetitive sites with strong support, the female can get seduced into building multiple nests.

"This is an example of 'supernormal stimuli' — artificial stimuli that are even more effective than those provided by Mother Nature (tree limbs). Animals have a hard time resisting supernormal stimuli. There are many examples. Your robin will probably settle on one site and just lay eggs in that nest, or else just incubate eggs in that nest after laying, say, one egg in one nest and two in the other. She won't lay two complete sets of eggs and try to incubate both of them at the same time."