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BIRD COLUMN FOR NOVEMBER 14,
2004
By Benjamin P.
Burtt TOPIC: THE
CHANGE IN THE ATTITUDE OF CROWS TOWARDS HUMAN BEINGS Many more crows
are being seen in cities and near our homes than in the past. They roost in cities where they never
roosted before. They visit our yards and even our feeders. Are there just
more crows or has something else made them more tolerant of human beings? INTRODUCTION This column is
divided into two sections Section 1 contains a copy of the column as it
appeared in the Post Standard in Syracuse on the above date. Section 2
contains additional information for the reader who is interested in learning
more about the change in habits of
crows. SECTION
1: THIS IS A COPY OF THE COLUMN THAT
APPEARED IN THE POST STANDARD ON NOVEMBER 14, 2004 Mr. Burtt: These
days I have crows in my back yard under my feeder. Years ago I only saw them in the distance at a road kill. Are
they less wary now? K.M., Nedrow, NY. Dear K.M.: Indeed
they are more tolerant of humans today. Several things have happened. There are more
crows in the State. Some of them live and nest in urban areas where they
never lived before. They have always
gathered to roost together in a patch of woods on winter nights. However, the
big change is that many of these roosts are now in towns. There was a huge roost a few miles south
of Auburn in 1911 and it was still there in the 1930s. Now the crows roost in
the center of town. What are the
reasons for these changes? Why are crows living closer to humans? I consulted
Dr. Kevin McGowan at the Cornell Laboratory of Ornithology. He has been
studying the behavior of crows for years. Here are some
suggestions. Crows were scarce in New York before the forests were cleared
for farms. After land was cleared and crops planted, more food became
available and there were small wood lots where nests could be placed. Crows thrived, but
were considered pests. There was no law against shooting them and were they
were killed at every opportunity. They began to keep away from people and
their population grew and reached a peak around 1938. After that, the numbers
decreased as agriculture declined. At that time, crows
did not visit feeders, did not nest in towns or roost there in winter. Starting in 1972,
hunting crows was restricted to only 124 days per year. In the years
following 1972, the feeder survey shows an increase in the percentage of
people who had crows around their homes. This suggests that crows were losing
some of their fear of humans. There are some roosts in towns
these days. Roosting in towns has advantages for crows. Discharging firearms
in cities became illegal in the 1950s so they avoided the shooting by
sleeping in town. It is also warmer in town. Their most feared predator, the
great horned owl, is seldom there. The town is well lit so an owl that
wanders in will be more easily seen.
CAPTION: Crows are not as afraid of humans
as they once were. This crow in the town of Dryden finds easy pickings on
trash day! ( Courtesy of Kevin and Jay McGowan) SECTION 2. More
About Crows .( Much of the following is adapted
from writings of Dr. Kevin McGowan mentioned above). The
material in Section 1 that was published in the newspaper serves as an
introduction to my answer to the question, why do we see more crows near our
homes nowadays? Seeing
more crows near our homes is true whether we live in the country or in a
city. Two things come to mind, it could be because there are just more crows
in our state, or perhaps crows have changed their habits and are more willing
to live near people. Actually, I believe the latter is the major reason. Some 40
years ago, if we lived in a city, we never saw a crow. Even if we lived in a
small town the same thing was true.
You had to drive to the country to see crows. Crows did not come to feeders or feed
under them as they do now. When they roosted in huge flocks during winter
nights, such roosts were far from buildings or barns or towns. Crows just kept away from people. Their
fondness for corn early on earned them the title of pest in the eyes of the early farmers. This
gave rise to the shooting in the 1800s and early 1900s. Crows are
attracted to corn when the plants are just a couple inches high. They go down
a row tearing out the little plants as they go. Presumably it is the soft and
nutritious seed and perhaps the tender plant that attracts them. Later when
the plants are tall and the first ears of corn develop and are soft and
tender, the crows return again. This time they attack the rows at the edge of
the field or along a roadway that goes through the field. They do not wander into the center of a
field where they are unable to watch for danger. Crows were
a serious threat to corn and other crops. Scarecrows were put out and many
crows were shot. The crows became wary of humans. Crows have the same habits
today and are still a serious threat to corn. Population has grown. How has
the crow population changed in New York State? Breeding Bird Surveys have
been conducted since 1966 and these give a rough approximation of the change
in the population of crows. The breeding population now is about 1.7 times
the population in 1966. Where are the crows being seen?
When we
examine the Feeder Survey, we find that the percent of people who report
crows has gone up from about 30% to 80%.
Remember, on a survey, observers list the species that are either at
their feeder or can be seen out the window or from a point near the house. Birds on hikes nearby are not to be
tallied. So the survey results are actually for birds seen near houses!
The graph shows the percent of
feeder survey reports that list crows seen near homes in and around Syracuse
in Central New York over the past 32 years. The observations were made by readers of my newspaper column in the Post
Standard. Note that the first large
increase came after 1977. This
suggests that crows were responding to the decreased hunting pressure. It took about six years before we began to
see a significant increase in the number of crows around our homes. Crows are
more abundant on farms too and a real problem for those who grow corn. Joe Mueller has had a farm on Seneca
Turnpike in Jamesville for years. He
sees more crows now and says that crows
are more of a threat today than they were 10 years ago. Frank
Mueller, Joe’s father, worked that same farm and often said, “we always have
to use extra seed. Only about a third is harvested. About one-third doesn’t
grow and the remaining third is eaten by wildlife .” After
1990, the percent of the reports listing crows has remained constant at about
85%. So it appears to me that the decrease in the amount of shooting is quite
likely the reason crows are not as wary as they once were and it probably is
the reason that the population has gone up too. The Family Life of Crows
Dr.
McGowan studies crows by attaching numbered leg bands and wing tags to the
nestling crows so he can track them (at least until the wing tags fall off,
which they do). The wing tags have a color and a large printed number and
letter which makes it possible to identify the bird at a distance. After the
tag hs dropped off, the aluminum leg band and its number identify a bird if
it dies and the carcass is found. Crows mate
for life. Offspring from several
earlier generations remain with the
original parents to form a family group for several years. Several of
these adult crows help with the nest building and incubation. They feed the
nestlings and they bring food to the parent on the nest. These
helpers also spend some time chasing away predators such as horned owls and
red-tailed hawks. Since there normally are huge losses of eggs and nestlings
for most birds, these extra helpers
for crow families probably have helped the survival of the crow and have
accounted for the increase in numbers in spite of the shooting. Each breeding pair of crows has an established home
territory where they build nests and raise their young. In towns, territories
are about 10 acres, but rural territories are much larger. Crows hold their
territories year-round. Non-breeding
crows may leave the family territory for a while in the winter, but many
return to their parents in the spring. Young crows don't leave to breed for two
or more years, so family groups on the home territory can grow large. One
crow family in Ithaca has up to 15 members. And it's not unusual to have
three or more adults attending a single nest. Crows in
cities do eat a lot of earthworms. One year there was a very dry winter and
spring in Ithaca and the crow nestlings that season were quite underweight.
The dry earth meant fewer worms and smaller crows. . For most
birds there normally are huge losses of eggs and nestlings during the
breeding season when only two parents are available. With the crows extended
family, there is extra help from grown offspring of earlier nestings. This
probably contributes to their success in raising so many offspring. So crows are adapting to city life and
living around our homes They are interesting and successful birds, try to
enjoy them! To read
still more about crows, visit Dr. McGowan’s web site at http://birds.cornell.edu/crows/ If
clicking on this does not work, you can copy and paste it into the address
bar of your browser or just type it there. |
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