Q.
What is the range of the American robin?
A.
The American robin is found over most of North America.
Q. What is the robin's habitat?
A. Robins
can be found in a wide range of habitats. You can find them in marshes,
fields, forest borders, orchards, hedges, cut-over woods, gardens, urban,
suburban, rural yards, and parks.
Q. What do robins eat?
A. Robins eat large quantities of worms and other invertebrates, berries
and fruits.
Q. What
is the robin's role in the ecosystem?
A. Robins are omnivores. They serve as predators mostly of insects and worms,
but also of small snakes and other small reptiles and amphibians. They
are also fruit and berry eaters. Sometimes they eat a berry in one place,
and then fly away. When they poop, their droppings often contain the seeds
of these berries, so the robins can "plant" them in new places.Robins
are in turn eaten by foxes, bobcats, hawks, shrikes, and owls, and crows
and blue jays often take their eggs and babies. These are all natural
predators. House cats, which are not natural predators because they are
fed by humans and maintained at an artificially high population, kill
exceptionally large numbers of robins because cats mostly stalk creatures
where robins do their feeding on the ground.
Q.
What are a robin's enemies?
A. Some of
the natural predators named above are enemies of the robin, though some
are also the robin's natural friends. Jays and crows eat baby robins during
the nesting season, but when they aren't stalking a robin nest, they are
very helpful to robins by alerting them of even greater dangers, and sometimes
chasing away hawks and owls. Robins may also consider mockingbirds, waxwings,
and other birds that compete for fruit to be enemies—they often chase
these birds away. Humans who leave cats outdoors and/or use lawn pesticides
are probably a robin's greatest enemies, endangering both the robins and,
especially, their newly-fledged babies.
Q.
What happens to robins when worms are in scarce supply?
A. Robins can easily switch from eating a lot of worms to taking almost entirely
fruits, so when the ground starts getting cold in fall, robins change
their diet. During droughts and other periods when worms are temporarily
hard to find, robins can eat fruit. If pesticides kill most of the worms
in an area, robins may stop nesting in that area.
Q. How do earthworms migrate?
A. In areas where the ground freezes, one sign of spring is the appearance
of the first earthworms of the season. This is called a "vertical migration."
Earthworms, in the fall, migrate deeper into the earth, below the frostline.
Sometimes they ball up to reduce moisture loss--as many as a hundred worms
being bunched together--and thus spend the winter in inactivity. When
spring comes and frost leaves the soil, the earthworms become migrants
again, tunneling upward. They appear at the surface, leaving the first
castings of the new seasons, as soon as the average temperatures of the
ground reaches about 36 degrees.
Q.
Where do robins spend the winter?
A. Some robins
retreat all the way to southern Texas and Florida, but others winter as
far north as they can find berries. So robins have an enormous winter
range
Q. What is the American robin's population status?
A. The
American robin is recorded in every state of the United States and every province
of Canada on Breeding
Bird Surveys. The total population is stable or increasing in most
places on a large scale, but in some urban locations where cats and pesticides
are common, robins appear to be declining locally.
Q. How can there be more robins today than when the colonists
first came to America?
A. When the
colonists first arrived, just about all of eastern America was heavily
forested, and there were few trees at all in the prairie. Colonists cleared
the forests, making it easier for robins to hunt on open ground, and also
introduced more species of earthworms from Europe. In the prairie, they
planted trees which robins use for nesting.
Q. How do humans affect robin migration?
A. When
humans used the insecticide called DDT in the U.S., many robins died during
spring migration as their bodies metabolized large amounts of body fat
at once--DDT from the worms robins ate all winter was stored in their
fatty tissues and all released into their bloodstream at once. This was
a harmful effect, and now that DDT is banned in the US, is no longer a
problem for our robins. Humans also have very positive effects on migration
by planting the trees that provide food and shelter for migrants.
Q.
How can we help robins?
A. Keep cats indoors, set out nest
platforms for robins, stop using insecticides in lawn sprays and only
spot spray weed killers rather than spraying the entire lawn. Plant the kinds of berry trees and bushes that provide abundant food for
robins and the kinds of trees and shrubs that provide good cover for
nesting. Set out bird baths and set out robin
feeders.
Q.
How can we make a robin feeder?
A. Robins
never visit bird feeders for seed, because they just don't eat seeds.
But some robins do learn to visit feeders to take berries, chopped up
apples, and mealworms. You can also offer mealworms in
plastic dishes or acrylic window feeders.
Q. What are the biggest dangers robins face?
A. Most robins die from cats, hawks, and other predators. They also perish from accidents such as flying into windows, getting hit by moving cars, being electrocuted, getting infectious diseases, and being poisoned. Chemical insecticides can be very harmful to robins. If you use lawn sprays, be sure that they don't have insecticides as well as weed-killing herbicides and fertilizers.
Q.
What are the biggest dangers facing robins?
A. Dangers
facing robins include (from most dangerous to least):
- Cats,
which are mainly ground hunters and kill many adult robins and even
more fledgling robins every year.
- Pesticides, especially insecticides, sprayed on lawns. The chemicals used in the
US and Canada break down into non-toxic molecules far faster than DDT
did, but most are still highly toxic to robins for the time that they
work on insects. Adult robins hopping on a freshly-sprayed lawn get
their tummy feathers coated, and then if they incubate their eggs or
babies, the toxins can be taken in, especially through nestling skin,
to kill the babies. Pesticides also hurt populations of earthworms,
which can make robins decline in areas where many people spray their
lawns.
- Crows
and jays, which eat robin babies. This is a significant problem
where these species are kept at artificially high numbers in cities,
but otherwise is offset by the help crows and jays give robins in warning
about other dangers.
- Hawks,
shrikes, and owls, which kill and eat robins. These natural predators'
numbers drop as their food supply dwindles, so they are far less common
than robins, and except in rare local situations simply don't affect
robin numbers any more than robins affect earthworm numbers!
- Snakes,
which eat robin eggs in the areas where tree-climbing snakes live. These
are uncommon natural predators, and don't hurt robin populations.
- Communications
towers kill a few migrating robins each year, but far fewer robins
than neotropical migrants such as warblers, orioles, and other thrushes. Other
accidents: bonking into windows, car strikes, and electrocution.
- Thorns,
which sometimes get stuck on robin feathers. One bird bander once caught
a robin with a large thorn stuck in its throat.
Q. What are good trees we can plant that provide food
for robins?
A. Choose species native to North America. Some summer berry
trees include:
- Serviceberry
- Red mulberry
- Wild plum
- Pin cherry
- Chokecherry
- Blackberry
- Raspberry
- Thimbleberry
- Elderberry
- Grape
Fall berries
include:
- Dogwood
- Silverberry
- Winterberry
- Apple
- Mountain
ash
Winter berries
include:
- Bittersweet
- Hackberry
- Hawthorn
- Red cedar
- Crabapple
- Highbush
cranberry
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