from the American Robin Expert
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Answers from the America Robin Expert
Special thanks to Laura Erickson, for providing her time and expertise in responding to your questions below.
From: Manassas, Virginia
Jennie Dean Elementary School
Q: Why did Nature give the robin a red breast? Maddy T.
A: Good question! And the answer is: Nobody knows! A lot of basic patterns of bird plumage are adaptive--sometimes for camouflage, sometimes for making bright displays that can be seen in the distance or to show that a particular bird is exceptionally fit, sometimes for other purposes. And it's adaptive for most species to stand out from other species, so they can be recognized by appropriate mates. The thrush family has a wide variation in plumage patterns. Robins can recognize one another easily by their red breast. But why not a green breast, or a purple one? Or why not a red back and black breast?
The second question is easy to answer--just about all birds have their darker colors on their back and their lighter colors beneath. That's because the underside of birds is in the shade of their own bodies. If it's lighter than the back, overall the bird is a little less conspicuous.
But why the red color? The colors of birds depend on the pigments their bodies can manufacture or get from food. Robins have an easy time making the red pigment, and their bodies simply can't make many other colors. In most of their range, American Robins are the only species with a grayish or blackish back and a red breast, and the color of the breast may be a big part of what helps them recognize adults of their species. Adult robins are territorial against other adult robins during spring and summer--it's interesting that most baby robins don't have a red breast. Maybe if they did, adults would fight with their fledglings instead of feeding them!
Robins living in the Pacific Northwest and in Newfoundland have the deepest, brightest colors. They live in areas with very high relative humidity. Robins living in Baja California have the dullest, palest plumage, which may help them blend in a little better in the dull, dry area where they live. Male robins are more brightly colored than females. And baby robins have dark speckles on their breast. But despite these variations, a robin's color pattern gives it a look that tells other robins, and us, that it's a robin.
From: Edinboro, Pennsylvania
Q: When American Robins walk along a lawn side by side in a zig-zag pattern, are they: 1) a breeding pair affirming a pair bond? 2) a courtship display? 3) two males in a kind of standoff? or 4) a breeding pair maximizing the area covered while foraging?
A: I have often seen a mated pair of robins feeding side by side in this pattern, especially early in courtship until the eggs hatch. This is probably not an active courting behavior, but allows the pair to cement their bonds in a comfortable way while getting worms. When you see this behavior, look carefully and you should be able to observe that one robin is a male and one is a female.
During fall and winter, I've occasionally seen groups of robins feeding close to one another. Sometimes two seem to be zig-zagging together, but that could be just coincidence.
Q: When two robins fly up together facing each other, as if to touch bellies, what are they doing? Copulating, courtship, or fighting?
A: Fighting. This is usually two males, or two females,
engaged in a territorial dispute.
From: Rolling Meadows, Illinois
Rolling Meadows High School
Q: I have read about non-native birds that have caused problems for the native birds. Are there any non native birds that have directly affected the robin?
A: Robins sometimes compete with European Starlings for food, but overall, non-native birds haven't had much effect on robins. Interestingly, robins have profited greatly from earthworms, many of which are not native species.
Q: Are robins more territorial than other birds? It seems that when other birds will fly away the robin is still up in its tree calling away.
A: A great many birds are just as territorial as robins. But different species of birds react to things in different ways. What makes other birds fly doesn't always interest or affect robins. Robins sing persistently in early morning, late afternoon-early evening, and on and off throughout the day. Their song is loud and very easy to hear, so we, like other robins, pay a lot more attention to it than we do to many other bird songs.
Q: Has the robin migration changed over the years at all?
A: Everything in nature changes! Robin migration has changed some as people plant more fruit trees and shrubs. And climate change is making the "early date" for spring robin arrivals get, on average, earlier in spring than it used to be in many northern places.
Q: Have humans had any effect on how long the robins will stay before migration?
A: Before migrating south, robins often gather in areas with abundant food. The kinds of plants humans grow affect robins because of this. The impulse to migrate is strong in most robins, so even while food is abundant the majority of robins in the north suddenly move on. But when a great amount of food remains, individual robins and groups of robins often remain.
Q: Has urbanization had an effect?
A: Urbanization has had good and bad effects on robins. People often plant fruit trees and berry bushes in their yards, and these help robins. Lawns often have worms, and these help robins. Windowsills and other nest sites on houses have some good protection from weather and predators, so these help robins.
But some people use lawn pesticides--especially insecticides--that hurt robins. Windows and car mirrors confuse robins, who sometimes start "shadowboxing"-fighting with their own reflection. House cats kill many baby robins, especially in the days after fledging.
Q: Do you think global warming might have an effect on this since robins seem to migrate with temperature?
A: Yes. Robins will probably appear in the far north earlier in spring, and their range will probably reach farther north. And their range may recede in the south-that is, they may stop breeding in areas that become too hot and dry for them.
From: Ithaca, New York
Cayuga Heights Elementary School
Q: How do robins know which way to migrate?
A: There is a powerful instinct that makes them grow very restless in spring and fall. And that instinct includes telling them which way to head. After wandering during winter--and individual robins can go to entirely different places from one winter to the next--robins often find their way to the exact backyard they nested in year after year. As daytime migrants, they may well find their way by using the angle of the sun to guide them. Some birds have tiny bits of magnetite in their brains that helps them know which way is north--I'm not sure if robins have been analyzed for this.
The trickiest migration to understand is fall migration. How does a baby robin that has never migrated before know which way to head? Again, more research is needed. But it's quite possible that part of their migration is learned, because young robins tend to join with adults in big migratory flocks. But as with many robin behaviors, it's probably a mixture of instinct and learning both.
Q: Which state has the most robins in it?
A: Hmmmm. That's a great question! The states and provinces bordering the Great Lakes, the mid-Atlantic coastline and the Pacific Northwest are richest in robins. But currently there is no source I could find that estimates how many robins live in each state or province to compare. You can see a map showing how abundant robins are in each state and province here:
A: The oldest known wild banded American Robin lived to be 13 years 11 months. But in captivity, some robins have lived to be over 20. Most robins die before they're one year old. One scientist found that the rate of survival between fledging from the nest and November 1 was only 25%. Fortunately, after robins have survived a year, their chances of living much longer increase.
Q: Do robins molt?
A: Yes they do. Robins start molting their flight feathers in mid-June, and have finished molting them by early September. They molt their body feathers from late July into October. One-by-one, each feather is pushed out by a new one, and most feathers last for a whole year. If a feather gets pulled out when the robin isn't molting, it replaces that feather fairly quickly.
From: Ithaca , New York
Cayuga Heights Elementary School
Q: In what part of the USA do robins spend the winter?
A: Individual robins can spend the winter just about anywhere in the USA or southern Canada. The largest numbers of them winter in the central and south eastern states, and up the Atlantic coast. You can see the map at right showing where Journey North participants reported robins wintering this year.
Q: How long can a robin fly before it needs to rest while migrating and where and how does it stop to rest?
A: At the beginning of spring migration, robins may average only 15-25 miles per day, while near the end of migration they may average 100! Some individual robins may go 200 miles in a single flight.
The farther a robin flies, the more tired it is and the longer the rest period it may take. Robins migrate in the daytime, and sometimes a flock will all come down to a stand of fruit trees or shrubs together. They may have seen the food from above, or may have heard other robins calling. They often come down to rest in muddy farm fields or at the shores of lakes and rivers--they can see the wet ground from the air, and may recognize that as a promising feeding spot. When they stop flying, sometimes they sit in a tree resting for a while, and sometimes feed first.
Q: Why do robins have different colors on their breast and what happens to the black dots as they get older?
A: The shades of red vary depending on whether the robin is a male or female, and depending on where on the continent they live during the breeding season. The color is deepest and brightest in birds who live in the areas with the moistest air.
The black dots on a baby robin's breast feathers stay on those feathers forever. But the robin grows new, rusty red feathers which push out the old ones. By October, young robins have lost just about all their spotted feathers.
How to Use FAQ's About Journey North Species
Since 1995, experts have contributed answers to students' questions about each Journey North species. These questions and answers are archived in our FAQ's (Frequently Asked Questions) section. You can use today's Answers from the Expert above, along with those from previous years, in the activities suggested in the lesson, "FAQ's About Journey North Species"