FREQUENTLY ASKED QUESTIONS ABOUT CROWS

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FREQUENTLY ASKED QUESTIONS ABOUT
CROWS


Note: Most of these answers pertain to the American Crow, Corvus
brachyrhynchos
. Much of the information here is from my own research on crows
in central New York; where I used other sources I have tried to reference the material. – Dr. Kevin J. McGowan, Cornell Lab of Ornithology.



This page is still very much under construction!


Last updated 9 November 2010




Return to the Crow Page.






Basic biology


Identification


Bad crow behavior


People and crows


Other things I haven’t answered completely yet

  • What do crows eat?
  • Why do crows gather in flocks during the day?
  • How smart are crows?
  • Are crows getting bigger?
  • Are crow populations increasing?
  • How can you tell a male crow from a female?
  • How many different calls do crows make?
  • Why do crows hate owls?
  • Do crows play?
  • Do crows make good pets?






Why do crows congregate
in large numbers to sleep?


One of the great animal phenomena of the world is the congregation
of large numbers of birds into a single group to sleep together. Such communal sleeping
groups are known as “roosts.” Many species roost in groups; such things as
crows, robins, starlings, blackbirds, swallows, and herons. Most do this only outside of
the breeding season. Some species, like starlings, also forage together in great numbers.
Others, such as herons, disperse out from these gathering areas to forage singly. For
crows, roosts are primarily a fall and winter thing. Numbers peak in winter and then
decrease near the beginning of the breeding season (usually in March). It appears that all
crows will join winter roosts, even territorial breeding crows. Most breeding crows sleep
on their territories during the breeding season, but join the roosts afterward.

For an interesting account of a large urban roost in central New
York (pictured above), check out the website dedicated to the roost in Auburn, NY <http://com-site.com/savethecrows/>.

Just why birds congregate in such large groups is still largely a
matter of conjecture. A number of hypotheses have been constructed to explain it:

  • One is that the birds simply are congregating in the most favorable
    spot (protection from predators, protection from the elements, the only trees suitable for
    roosting, etc.), and they don’t mind doing it with a bunch of other birds. This idea is
    kind of analogous to a crowded hotel: everyone has the same needs being met at the same
    place, but no one is really interacting with anyone else.
  • Another idea is that the birds get some protection from predators by
    being in a large group. This is the “wagontrain” analogy: safety in numbers.
    Crows are most afraid of large owls, and sleeping with a bunch of other crows could afford
    some protection for an individual crow.
  • Another idea is the information center hypothesis, where information
    about profitable foraging areas is transmitted. The idea is that an individual that did
    poorly foraging for itself on one day can watch for other individuals coming in to the
    roost that look fat and happy, that obviously found some rich source of food. Then the
    hungry individual can either backtrack the happy ones’ flight paths, or follow them out
    first thing in the morning to the good food source.
  • Another food related idea is the patch-sitting hypothesis. This
    theory is similar to the first one mentioned, in that roosts congregate around a large,
    non-defendable, reliable food source. So, first thing and last thing in the day, food is
    available. It need not be the best food, but it is something to eat to get them going. The
    birds can then disperse out and do whatever they need to do, having had some kind of
    breakfast first. Roosts, then, will form in suitable roosting habitat near these large
    food sources. For crows, such abundant sources might be landfills, commercial composting
    facilities, or certain types of agricultural fields.

Crows have been congregating in large roosts in the fall and winter
for as long as there have been crows. Crow roosts can range from small scattered roosts of
under one hundred individuals to the spectacularly large roosts of hundreds of thousands,
or even more than a million crows! A roost in Fort Cobb, Oklahoma was estimated to hold
over two million crows (Gerald Iams, 1972, State of Oklahoma Upland Game Inventory
W-82-R-10). Most roosts are much smaller, but roosts of tens of thousands are common.

Before heading to roost, crows will congregate in some area away
from the final roosting site, usually an hour or two before complete darkness. Here the
crows spend a lot of time calling, chasing, and fighting. Right at dark the main body of
the group will move toward the final roosting spot. Sometimes this final movement is
relatively quiet, but usually it is still quite noisy. I have seen crows coming together
from several separate congregation areas, heading to one final staging area where they all
coalesce, then everyone heads to the final roost. The final roost can be a cohesive group
in a single woodlot, or it can be rather diffusely spread out over quite a wide area of
suitable trees.

Many, perhaps most, people who witness large roosts or the flight
lines to them are reminded of Alfred Hitchcock’s movie “The Birds.” I think this
association is unfortunate. It makes the allusion that somehow what we are watching is
sinister, unnatural, and threatening. In fact, it is none of the above, but one of the
most natural things in the world. I would prefer to replace this association with the idea
that such roosts are something to be marveled at. To me they always bring up the idea of
Passenger Pigeons. When Europeans first came to North America, the Passenger Pigeon (Ectopistes
migratorius
) was the most abundant bird on earth. Migrating flocks were said to
darken the sky for hours as they passed. Despite their incredible abundance, they are
completely gone now, driven extinct by the early years of the 20th century. A combination
of habitat destruction (the complete devastation of the eastern hardwood forests) and
hunting for sale as meat in commercial markets destroyed one of the greatest natural
spectacles on earth. Not a single Passenger Pigeon remains on earth today, nor do any
people that remember seeing their massive flocks. I would like for people to look at the
large congregations of the similarly-sized American Crows going to roost and think that,
despite how impressive they might be, they are but the slightest hint of what the
Passenger Pigeon flocks must have been like.







Why have these roosts
recently moved into cities?


A number of possible explanations exist for the relatively recent
influx of roosting crows into urban areas. The birds are not making drastic shifts in
behavior; crows have been gathering into winter roosts for as long as there have been
crows. We know, for example, from work done in the 1930’s by John Emlen at Cornell
University that approximately 25,000 crows were gathering in a roost near Auburn, NY in
the winter of 1932-33, and that a large roost was present in 1911-12 (Emlen, J. T., Jr.,
1938, Midwinter distribution of the American Crow in New York State, Ecology 19: 264-275).
The big difference is that they were roosting 3 miles south of town then and are roosting
smack in downtown Auburn today. Any increase in size of the roost would be imperceptible,
compared to the change of locale.

A couple of things may have worked together to get crows into town
(both for nesting and roosting):

1) The 1972 extension of the Federal Migratory Bird Treaty Act of
1918 to cover crows. At this point the hunting of crows became regulated. No longer could
anyone anywhere take shots at crows, but had to do so (theoretically) within proscribed
guidelines and hunting seasons. It is possible that this change may have resulted in the
decrease of shooting pressure on crows, allowing them to become more tolerant of the
presence of people.

2) A prohibition on the discharge of firearms within city/village
limits. It is conceivable that crows somehow stumbled across the fact that they could not
be shot in cities because of local ordinances against shooting in town. So, in fact crows
might have somehow figured out that the best thing to do to live with their enemy was to
get as close as possible, not stay away. Many crow hunters do most of their hunting along
flight lines of crows moving to roost. These flight lines through urban areas are
protected, those in rural areas are not.

Once crows overcame the urban barrier, a number of possible
advantages could extend to them:

a) Cities are warmer than rural areas. In most places a difference
of 5-10 degrees F exists, sometimes referred to as a “heat bubble” over cities.
Because roosting is a winter phenomenon, warmer spots could be important.

b) Great Horned Owl (Bubo virginianus) populations should
be lower in urban areas. Next to people with guns, Great Horned Owls pose the largest
danger to an adult crow. Great Horned Owls take adults as well as nestling crows with
great regularity. (That is why crows hate them so much!) Owls probably are regular
attendants at crow roosts, as owls wake up as the crows are heading into the roosts, and
sleeping crows should be pretty easy picking.

c) Artificial light assist crows in watching for owls. I have
noticed that many urban crow roosts are not located in nice dense trees where the crows
would have microclimate advantages, such as protection from wind or cold. Rather, the
crows perch out on the tips of bare branches of leafless deciduous trees. I was quite
surprised by this at first, but then I noticed that many (most?) roosts are located near
sources of bright illumination, such as streetlights and parking lot lights, like the
lights at the Auburn prison and Syracuse University. It makes sense for crows to like
“nightlights” to protect them from their biggest bogeyman, the Great Horned Owl.
Crows don’t see well at night; owls do. Crows near street light could see approaching
owls. Also, if a crow gets scared out of its roost in the middle of the night (presumably
by an owl taking crows), in lighted urban areas the crows can see where the predator is,
and perhaps more importantly, can see to find another perch. You can imagine that flying
blindly into the dark is not something any bird would choose to do. I was surprised at the
amount of activity at the Auburn roost well after dark. The crows were still making a lot
of noise and even flying from tree to tree. In other roosts I have watched that were in
darker locations the crows quieted down rather quickly and no movements between trees were
seen shortly after complete darkness.

d) Urban areas provide large trees for roosts. In many places some
of the largest trees to be found are in urban areas. Many trees in parks and cemeteries
were protected from the severe logging of the end of the last century, and are some of the
oldest trees around. These large trees may be especially attractive to crows.







Do crows migrate?



Crows breeding in upstate New York are partially migratory.
Breeding birds, and most of the tagged individuals in my study, appear to remain all
winter. The breeding pair appears to visit their breeding territory every day of the year,
although they will roost and forage in other places. Non-breeders may spend significant
periods on the home territory, or may spend time away. Many individuals wander around the
local area joining different foraging flocks on subsequent days. They may or may not visit
the home territory during this time. Other non-breeders leave the area entirely for
several months. Several of the birds I have tagged in Ithaca, NY have been recovered
(shot) or seen in Pennsylvania during the winter. One individual (less than one year old)
was seen at a compost pile in northern Pennsylvania with a flock of crows, and three weeks
later it was back in Ithaca with its parents who were starting nesting. It helped the
parents raise young that year, and remained in the area over subsequent winters.




How many
broods of young can a crow family produce in one year?


In general, American Crows have only one
successful brood a year. Figure it like this: it takes from one to two weeks to build a
nest (always a new one with each nesting attempt), 6 days to lays eggs (2-6 eggs, average
of 4.7 in my study), 19 days of incubation (begun with the penultimate, or antepenultimate
egg, i.e., next-to-last or next-to-next-to-last egg, depending on clutch size), 35 days in
the nest before fledging (30-45), and then 6 weeks to 2 months to feed the young to
independence. That adds up to nearly 4 months from start to finish. Even though American
Crows are one of the earliest nesting species in New York (laying eggs the last week of
March), they cannot hope to pull off two broods a year. In my study population if a nest
fails after the first week or two of May, the pair does not attempt to renest in most
years. On occasion in some years some pairs will renest rather late after a latest
failure. The latest young I have banded hatched 7 June.

Nest success is 50% (average in my study) or
less (other studies), and rarely do successful crows raise all the young from all the eggs
they lay. On average in my study, rural nests produce 4 young per successful nest and
urban nests produce 3. Average clutch size in both areas is 4.7.





How long
do crows live?


Most crows don’t even live a year, having died in the egg
or as nestlings. In my study population of American Crows in Ithaca, New York, just about
half of the nests succeed in producing young. Of the young I band in the nest a week
before fledging, about half are alive and with their parents the next year. Of course some
have disappeared and not died, but that’s a pretty good survival rate for birds anyway.
Once they survive that first year they have a good chance of making it for several years
more. None of my birds try to breed when they are one year old, and some are six years old
and still helping their parents. Average age of first reproduction for females is 3.3
years, and males average 4.9 years. Breeders have about 93% yearly survival. My survival
data (biased towards the short side by those that disappear) indicate that some crows
should live to be 17 – 21 years old [note this is a change in the
prediction from what I have had posted before Dec 1998, based on reanalysis of survival
data]. The oldest known wild American Crow was 29 1/2 years old (see Dilling, 1988,
Ontario Bird Banding Association Newsletter 33: 2-3.). The second oldest known, however,
was only 14 years, 7 months (Clapp et al., 1983, Journal of Field Ornithology, 54(2):
123-137).

As of
November 2010 we have 2, probably 3 crows that were banded as nestlings in 1993 that are still alive, making them currently 17 years and 7 months old. Here is a photo of one of them, AP HART93 when he was just 17. You can see that his colored and metal bands have fallen off, and the has only the remnants of his wing tags.







What is the difference
between a crow and a raven?


Crows and ravens, although in the same genus (Corvus)
are different birds. (Think of leopards and tigers; both are in the genus Panthera,
and are obviously related, but they are quite distinct animals.) The words
“crow” and “raven” themselves have little or no real taxonomic
meaning. That is, the Australian “ravens” are more closely related to the
Australian “crows” than they are to the Common Raven (Corvus corax). In
general, the biggest black species, usually with shaggy throat feathers, are called ravens
and the smaller species are considered crows.


Common Ravens can be told from American Crows by a couple
of things. The size difference, which is huge, is only useful with something else around
to compare them with. Ravens are as big as Red-tailed Hawks, and crows are, well, crow
sized. The wedge-shaped tail of the raven is a good character, if you can see it well.
Crows sometimes show an apparent wedge shape to the tail, but almost never when it is
fanned as the bird soars or banks (except for a brief time during molt in the summer).


More subtle characters include: ravens soar more than
crows. If you see a “crow” soaring for more than a few seconds, check it a
second time. Crows never do the somersault in flight that Common Ravens often do. Ravens
are longer necked in flight than crows. The larger bill of the raven can be seen in
flight, but it is actually less apparent than the long neck. Raven wings are shaped
differently than are crow wings, with longer primaries (“fingers”) with more
slotting between them. As my neighbor said, “Ravens are the ones whose wings you can
see through.” The longer primaries make the wings look more bent at the wrist than a
crow as the bird flies, and the “hand” portion can look nearly pointed.


If seen perched in a good look, the huge bill and shaggy
throat of a raven are diagnostic. The upper and lower edges of the bill are parallel for
most of their length (3/4?) in ravens, while in crows the downward curve starts somewhere
around 2/3 of the way out for males, and about halfway for females.

But remember, ravens are pretty uncommon around here
[Ithaca, NY]. If you see a “really big crow!”, chances are good that it really
is a crow. Yes, there are large crows and small ones, but you couldn’t ever tell which was
which. Any difference in size (380g – 660g is the weight range around here; 800 – 950 mm
wingspan) among individuals is not detectable, in that the range of appearance of a single
crow (by fluffing or sleeking its feathers) is greater.

American Crows make the familiar “caw-caw,” but
also have a large repertoire of rattles, clicks, and even clear bell-like notes. However,
they never give anything resembling the most common calls of Common Ravens. The most
familiar call of a raven is a deep, reverberating croaking or “gronk-gronk.”
Only occasionally will a raven make a call similar to a crow’s “caw” but even
then it is so deep as to be fairly easily distinguished from a real crow. Ravens also make
a huge variety of different notes. It has been said (attributed to native Americans) that
if you hear something in the forest that you cannot identify (assuming you know all the
common forest sounds), it is a raven.





How
do you tell a Fish Crow from an American Crow?


Fish Crows (Corvus ossifragus) are a rather small
species of crow endemic to the Southeastern United States. Typically they have been
restricted to the coastline from southern New England to Texas, but in the last few
decades have been expanding their range, especially inland up large rivers.

Visually, Fish Crows are difficult to tell from American
Crows. Unless one has a great deal of experience in close observation of the species,
identification is only safely done by voice.

The calls of Fish Crows and American Crows are readily told
apart. American Crows most frequently give the familiar “caw caw.” Fish Crows
have a much more nasal call that may be better enumerated “awh” or
“uhn.” The most diagnostic call of the Fish Crow is the double noted
“uh-uh.” I always say that if you want to tell the species of crow, ask it if it
is an American Crow. Fish Crows will deny this by their emphatic “uh-uh!”

Fish Crow calls can be confused with the begging calls of
American Crows. It should be pointed out that these begging calls are given not just by
dependent young crows, but also by adult crows in certain situations. Most prominently,
early in the breeding cycle of American Crows the females will give begging calls
frequently.

For a much more detailed discussion of this
identification problem, go to my special Fish Crow ID page.




Can crows be shot
legally?


The Migratory Bird Treaty (Weeks-McLean Migratory Bird
Law), passed in 1913-14, ratified between the United States and Great Britain (for Canada)
in 1916, went into full effect as the Migratory Bird Treaty Act in 1918. This law gave
federal protection to most birds in North America, but did not extend protection to crows,
and crows continued to be shot as “varmints” over most of their range. In 1936
Mexico was included in the treaty, but still crows were unprotected. In 1972 amendments to
the treaty extended protection to 63 families of birds common to both the United States
and Mexico, including birds of prey and crows. As a result, at least theoretically, all
native birds in the United States are protected by law, but special permits can be
obtained to deal with cases of nuisance birds causing damage or annoyances. This act makes
it illegal “to possess, transport, or export any migratory bird, or any part, nest,
or egg of any such bird.” (That means you cannot legally have feathers from any local
non-game bird!)

Crows, although not technically “migratory game
birds” (like ducks) can be hunted in similar fashion in some states. The U.S. Fish
and Wildlife Service regulations, 50 CFR Chapter 1 20.1 extends regulations to the hunting
of “migratory game birds, and crows.” The Act allows states the rights to
establish hunting seasons on crows, with the exception of Hawaii where the only species
present is the severely endangered Hawaiian Crow (Corvus hawaiiensis). 50 CFR
20.133 allows states to set their own seasons, bag limits, and methods of taking crows
subject to certain limitations, namely that “1) Crows shall not be hunted from
aircraft; 2) The hunting season or seasons on crows shall not exceed a total of 124 days
during a calendar year; 3) Hunting shall not be permitted during the peak crow nesting
period within a State; and 4) Crows may only be taken by firearms, bow and arrow, and
falconry” (so no dynamite, poison, or traps).

Many states that have crow hunting seasons, like New York,
allow hunting only 4 days per week. This action stretches the 124 days out so that the
season may extend nearly eight months. No state that I have yet seen has a bag limit on
crows.

Interestingly, the New York season violated the Federal
guidelines for several years. The season for 1997-98 ran 15 September through 14 April. In
my study of American Crows in central New York, from 1989-1995 I observed or calculated
(based on hatching date or size of nestlings) the start of incubation for 289 nests. The
range of incubation-starts in this data set runs from 24 March through 1 June. That means
that eggs can be present from 20 March through 20 June (based on an average of four days
of laying and 19 days of incubation). Bull (1974, Birds of New York State) gives New York
eggs dates for American Crows as 30 March to 14 June, in general agreement with these
dates and indicative of the overall generalizability of the data for the state. 80.5% of
all nests were being incubated before the end of the New York hunting season on crows, in
clear violation of 50 CFR 20.133. Nesting had begun at least a week or two before this
time for those nests. Nest building can begin in the first week of March, but usually is
concentrated in the last two weeks. I personally don’t consider the first few attempts at
getting a twig in a tree real nesting, but certainly the laying of eggs and onset of
incubation must be. I provided these data to the NYSDEC in April 1997, and they were going
to change the season for 1998-99 to end on 31 March (15 September – 31 March; Fridays,
Saturdays, Sundays, and Mondays only). The 1998-99 NYSDEC hunting regulations, in fact
were printed with a 31 March termination date. (Score one for the age of reason, or so I
figured.) Apparently, however, some complaint from a crow hunter resulted in a tabling of
the change and DEC personnel were informed not to enforce the printed season closure. The
1999-2000 hunt still extended into the middle of the breeding season! I recently received
word that the 2000-2001 dates will be (barring unforeseen changes) 1 September – 31 March.
So they finally got the hunt out of the main part of the breeding season, and added the
two lost weeks into the fall.

In addition to hunting, crows may be taken (i.e., shot)
without a permit in certain circumstances. USFWS 50 CFR 21.43 (Depredation order for
blackbirds, cowbirds, grackles, crows and magpies) states that a Federal permit is not
required to control these birds “when found committing or about to commit
depredations upon ornamental or shade trees, agricultural crops, livestock, or wildlife,
or when concentrated in such numbers and manner as to constitute a health hazard or other
nuisance ” Provided: a) that none of the birds killed or their parts are sold
or offered for sale. b) That anyone exercising the privileges granted by this section
shall permit any Federal or State game agent free and unrestricted access over the
premises where the operations have been or are conducted and will provide them with
whatever information required by the officer. c) That nothing in the section authorizes
the killing of such birds contrary to any State laws and that the person needs to possess
whatever permit as may be required by the State. In New York state landowners or those
cultivating lands may take without a permit “common crows when the wildlife is
injuring property or becomes a nuisance.”





Do crows taste bad? Is
that where the saying “to eat crow” comes from?


I have always been interested in how crows taste for a couple of
reasons. One is because of the old adage “to eat crow,” meaning to do something
distasteful (like admit being wrong), which suggests that crows taste bad.

The etymology of a saying like “To eat crow”
is often hard to trace. Often you will find answers that sound good, but are simply
constructed stories made far after the fact to explain something unusual. (My father was
good at these stories; usually they involved “Sam” something-or-other)

I have been made aware of the following reports of the origin of
“To eat crow” from a couple of web sites:

From the McDougal Littell web site http://www.mcdougallittell.com/, (©1999
Houghton Mifflin Company All Rights Reserved)

Idiom – eat crow

Definition – Be forced to admit a humiliating mistake

Etymology – The term’s origin has been lost, although a
story relates that it involved a War of 1812 encounter in which a British officer made an
American soldier eat part of a crow he had shot in British territory. Whether or not it is
true, the fact remains that crow meat tastes terrible.


From “Food for Thought” by James R. Watson http://www.niva.com/original/writblok/fall97/a-origin.htm
in the Fall 1997 issue of Writer’s Block http://www.niva.com/original/writblok/

“If you’re feeling defeated, you simply must eat
crow–a bird that is as tasty as it is melodious. It’s one of our domestic dishes from a
recipe allegedly discovered during the War of 1812. A Brit had caught an American shooting
a crow on the wrong side of the border. He talked the Yank into handing over his gun, then
used it to force the fellow to take a big bite out of the crow and swallow it. Needless to
say, once the American had his gun back, he forced the Brit to eat the rest of the
bird.”


I actually do not believe this story is the real origin of the
saying. It just sounds too pat and too contrived. Also, I find it difficult to believe
that a single incident between unknown and relatively unnoteworthy individuals would make
its way so pervasively into the general lexicon. (Besides, which of these guys would
spread this tale around? Neither one would want to talk about it, I imagine!) Note that
both accounts mention that crows taste bad, an unproven assumption.

I have seen two references to the edibility of crows in the
technical ornithological literature (I’ll have to look the references up; I don’t have
them on the top of my head), and they are widely divergent. One says that they are foul
(not fowl) and not worth eating. Another says that they taste just fine, as good as any
other dark-meated bird.

I have had several opportunities to sample the flesh of crows (I
will not go into detail about how this came about, but remember this is a legally hunted
species). In my opinion, crow tastes just fine. It is similar to wild duck or any other
wild bird with very dark meat. Crows have no white meat on them, as is true for most
birds. (Whenever someone says something “tastes like chicken” remember that
they’re talking about the DARK meat of chicken, not the white.) The meat of most wild
birds is even darker than the dark meat of chicken, and will have a gamy smell and flavor
to a varying extent.

New York (and most states with hunting seasons) set no daily bag
limit on crows. Most literature on hunting them tells the hunters to be considerate to the
property owner and collect the crows into one big pile instead of leaving them scattered
over the field. A few mention that crows are edible and give some recipes for cooking
them. I think if I knew people were eating the crows, crow hunting would feel more
acceptable and less like vandalism.





Do crows cast pellets
like hawks and owls?


Most birds that eat indigestible foods produce pellets. I
know for a fact that crows and jays (at least Blue and Florida Scrub-) produce pellets,
and I am certain that most other insectivorous birds do as well. I’m not sure why all we
know about are owl pellets. Perhaps it’s because they roost in recognizable spots and
produce large, cohesive pellets with lots of hair to hold them together. If anyone would
bother to look under a crow roost they would find hundreds of small lumps of grain and
gravel that represent the crows’ pellets. Not having much hair in them, they fall apart
quickly and might be overlooked if you didn’t know what to look for. In the winter of
1996-97 I was exploring under a medium to large crow roost in central Ohio (somewhere
between 14,000-50,000) and was surprised at the amount of gravel that was moved. Take
about 5 small stones (each about 2 mm in diameter), figure a pellet every other day over
the course of 5 months, and multiply by 50,000, and you come up with a significant amount
of material moved! (I figure, at a conservative 0.2 grams per load, 750 kilograms of
gravel or 1,650 pounds.)






Do male crows ever
incubate?


I have never seen a male American Crow incubate, and I have
not heard of any truly convincing cases of males incubating. My colleague Dr. Carolee
Caffrey has spent hundreds of hours watching nests of marked crows in California, and she
also has never seen anyone but the breeding female incubate. Female-only incubation is
typical of the family Corvidae. Only females get brood patches, the defeathered, highly
vascularized patches on the belly and chest that are in contact with the eggs. Any report
of males incubating needs detailed verification. (See for example, Hailman &
Woolfenden, 1985, Nest-defense of the Florida Scrub Jay and the problem of
“incubation” by male passerines, Wilson Bulletin 97(3): 370-372.)

The reports of shared incubation in popular reference
sources (like Harrison’s bird nest book) appear to be repeated quotes from the same
source: Bent’s life histories, quoting Bendire. I have read Bendire (1895, Life histories
of North American birds) and he gives absolutely no details. But you know what they say,
that if something is repeated often enough it becomes fact.

I have made a couple of observations that might explain
some reports of male incubation. Helping females sometimes try to incubate. When the
breeding female is off the nest these younger birds will slip in and sit on the eggs or
nestlings. They usually look nervous, constantly looking around, and always leave very
quickly when they see another crow approaching. Unlike the incubating female, they are
never fed on the nest and are often chased away.

A second instance is when the breeding male comes and feeds
the incubating female. Often the female will leave the nest for a while. The male usually
remains nearby to guard the nest. Most frequently he will perch near the nest or even on
the edge of it. Very infrequently he will actually step down into the nest and stand in
it. I find that male Fish Crows do this rather regularly. These males do not, however,
actually incubate. That is, they do not put their bodies in contact with the eggs and
transfer heat.






I saw crows fighting and
it looked like one was going to kill the other. Why would they do that?


Crows are very social species and live in large extended
family groups. That does not mean, however, that they are friendly with all other crows.
Just as we humans are social and love our families and friends, we also have been known to
fight and kill each other on occasion. Birds may fight for a number of reasons, such as
defending territory boundaries, protecting their mate (or sexual access to them), or
defending some other resource. Crow fights within a family are usually short and involve
only a few pecks. (Crows, in my experience, actually seem to have very few intra-family
squabbles compared to some bird species.) Fights between members of different families,
however, can be protracted and deadly. I frequently see crows locked together tumbling out
of trees in the spring. Although I have never witnessed an actual killing, I would not be
at all surprised to see crows kill another crow from outside the family group that was
trespassing.

Another possible explanation of extreme violence is that
the attacked crow was already injured. Injured, sick, or oddly acting birds are often
attacked by their own species. Crows are no exception. One explanation for this behavior
is that having an injured individual around is dangerous to others in that it might
attract predators. Not only that, but a vulnerable crow could teach a predator to hunt for
crows, which might endanger other crows. With this line of reasoning, crows would be best
served by getting rid of an odd ball. I do not know if crows would eat another crow they
killed. They might, but I rather expect they would not.






Do the
male and female crow mate for life?


More or less. In general, it appears that they do. Unless a
mate is killed or severely incapacitated, crows appear to stay with the same mate year
after year. It is possible, however, for exceptions to occur. Generally this would happen
in the case of a young pair of birds that mated but bred unsuccessfully. They might break
the pair bond and try again with someone else. I had one young male return home after an
unsuccessful first nesting attempt. Because the female was unmarked I do not know if she
died or also went home to her folks.





Are crows ever white or have white in
the wings?


Yes. Click here to find out
more



We have a
pair of crows in our backyard that use our bird bath as a depository for all of the
carcasses they find. There are various snakes and rodents in the bath right now. It is
disgusting. Why do they do that?


Crows and all members of the family Corvidae will store
excess food. Sometimes you can see crows bury things in the grass of the yard (usually
covering it up with a leaf or plucked grass; sometimes looking at it several times and
using a number of different coverings before being satisfied that it really is hidden).
They also hide food in trees or rain gutters, or whatever is a handy spot. At this time of
the year (April) crows are nesting, and the female breeder sits all day on the eggs or
young nestlings. She leaves the nest only infrequently and the male and the helpers bring
her food. Food is easy to bring (all pecked into pieces and stashed in the throat under
the tongue), but water is harder. So, crows often will dunk dry foods in water and take
the moistened food to the nest. It is likely that that is what is going on in the
birdbath. In my experience with several captive crows, some individual crows also seem
more inclined to put food in water and leave it there than others. Perhaps they want it to
rot a little to improve the flavor a bit before they eat it (just like we do when we
“age” beef).





Since the crows came we
don’t have any little birds around anymore!


Crows are predators and scavengers, and will eat anything
they can subdue. That said, the bulk of their diet (in this area, anyway) consists of
waste grain in winter, and earthworms and other terrestrial invertebrates in the spring
and summer. Crows will eat eggs and nestlings of songbirds, and in some areas might have a
significant impact of a local population of birds. Far more likely, however, is that crows
are but one of a host of species preying on the “desirable” wildlife, and
removing crows will make no change in the end result (that of most of the young birds/eggs
being eaten). A number of studies have been done, removing crows
and looking at the resulting nest success of birds the crows depredated, that illustrate
this point. Removal of crows does NOT increase nest success or survival of the bird to be
protected. Nearly always some other predator steps up to eat the same number of eggs and
young birds, or they die for other reasons.

This idea of compensatory mortality is a
very difficult one for people to believe. It is not intuitive. “Common sense”
says that if you get rid of one source of mortality that the overall mortality rate should
go down. In fact, the world does not act this way. I like to use the analogy of
handicapped parking spaces at the mall You drive up to the mall, looking for a parking
space in a crowded lot. You can’t find a parking space, but there are four near the
entrance that are reserved for handicapped permits only. You complain and think that if
only those handicapped restrictions weren’t there, you could park in those spots (common
sense). In truth, of course, if those spaces were not reserved they would have been taken
long ago, just like all the other spaces in the lot. So if one more egg hatches, that will
be one more nestling that gets eaten by a raccoon. Or if one more nestling makes it out of
the nest, that’s one more fledging for the local Cooper’s Hawk to eat. Or, if one more
young bird survives to fly to South America, that’s one more bird that falls into the
ocean during the bad storm (1001dying instead of 1000). And so on and so on. This concept
of compensatory mortality is vital to the idea of game management. What it says to the
managers is that it doesn’t matter to the population if hunters take a bunch of young that
were slated to die anyway. If you keep your take within the limits of the mortality that
normally occurs, exactly NOTHING happens to the overall population, even if you kill a
million individuals (like the million Mallards that are killed in the US every year). And
it works! Of course, if you exceed the normal mortality things go awry. Or if the sources
of mortality increase in an unusual way (huge losses in habitat, for instance, or total
loss of food supply at a staging ground) then bad things happen. But the normal
fluctuations of a stable community just absorb the small perturbations.

So, although you might see a crow eating a baby robin, that
is not bad. MOST baby robins die before reaching adulthood. That’s why the robins nest so
many times during the summer. The presence of crows in an area will not mean all the
robins and cardinals will disappear. In fact, despite a slight but significant increase in
American Crow populations in North America since the mid-1960’s, American Robin
populations have increased (nearly identically to crows) and those of Northern Cardinals
have stayed steady (North
American Breeding Bird Survey
data). The only species of bird that is decreasing in
North America in which I MIGHT be convinced crows play a significant part is Common
Nighthawk, and that only in urban areas (and as yet this is all speculation). Urban
nighthawks have such a specialized nest site selection (flat gravel roofs) that crows
might be able to figure them out and find most of the nests in an area.

In summary, crows are NOT a problem to most songbird
populations, especially not those that are likely to be found around people’s houses. When
crows move in, the other birds don’t leave. I try to encourage people to enjoy the crows
as well as the other birds. Crows are fascinating animals in their own right. I happen to
think they are aesthetically pleasing to look at too. Granted, they are not brightly
colored, they get up too early in the morning, and they are loud. No other bird in our
area, however, has such a human-like personality and social system as the American Crow.
Please see the other information on my web pages about their family lives. Try to get
people to understand that it is not a “gang” of crows in their backyard, but a
family.





We’ve got crows hanging
out in our yard. How can we get rid of these pests?


Good luck! Once crows have decided to come to your yard, it
might be hard to convince them to leave. Plastic owl decoys will work, … for about 15
minutes. A dog could be more effective, especially if it was encouraged to chase them. If,
however, something really special was attracting the crows to the yard (like readily
available food), the crows probably would figure a way how to get it and avoid the dog.
The idea is to make the yard an unattractive place for the crows. Cut down your trees if
you have to. Chase them when possible and make it obvious that you are after THEM, not
just going out in the yard for other reasons (it will make a difference, trust me, but see
below for the associated risks of this technique). Killing the crows is not a recommended
option. It can be done legally only in a few areas (out of the city, and with permits or a
hunting license). But, if one family of crows found your yard desirable, chances are
others will too. Crow society is filled with excess crows that are waiting for an
opportunity to breed (the helpers staying home and helping the parents raise young). If
you kill some territory holders off, you just create a breeding opportunity for the crows
waiting in the wings.

A far better solution is to work on your own attitudes, not
the crows’. Pests are like weeds: their status relies entirely on your point of view and
state of mind. What is a weed to one person is a beautiful flower to another. It is my
experience that if you let something bother you, it will. The more upset you get about it,
the more it bothers you, and the more it bothers you the more upset you get, and the more
upset you get the more it bothers you, and so on and so on, until you explode. Although
some measures do exist to change crow behavior, it might be easier and more effective to
attempt to change people’s attitudes about crows. (I actually have little hope of doing
either!)

Crows are not evil, and they are not purposely trying to
torment you. They are just being crows, trying to live their lives and feed their
families. Actual property destruction is one thing that might require action, but just
being annoying is something else again. Try to appreciate the crows for the fascinating
creatures they are. If you get over that hurdle, the annoying habits become much less
annoying. I have said that crows are much like my family or my dog: they do many things
that annoy me, but I love them and am willing to overlook (most) of the annoying things
because the relationship is primarily positive on the whole.

Crows do have one endearing characteristic that is
apparently not shared by other birds. They will get to know people as individuals. While
you can get chickadees to eat out of your hand, any old hand will do, and I suspect that
the chickadees do not know you as an individual. Crows will! If you toss them peanuts (I
recommend unsalted, in the shell) on a regular basis, they will wait and watch for you.
Not just any person, but you. If you do this often enough, they will follow you down the
street to get more. I have made a point of getting on the good side of a number of crow
families around Ithaca. Some will follow my car down the street, and if I don’t notice
them and toss them peanuts they will dash across the windshield to let me know they are
there. Some of these crows recognize me far from their home territories, way out of
context. (It did, however, take some of them a long time to learn to recognize my new
car.) So indulge yourself and makes some personal friends with the crows. That is the
preferred relationship, because they also are happy to turn this talent of recognition to
the darker side, and treat you as an enemy. (Again, not just all people, but YOU.) Because
I climb to crow nests to band young birds, many crows in Ithaca know me and hate me.
Whenever they notice me in their territory they will come over and yell at me. They will
follow me around and keep yelling for as long as I am there. Believe me, it’s better to be
on their good side than their bad side!



My 10 year old son keeps
having crows trying to attack him. He will be out in the
yard and they come swooping down on his head. He has done nothing to them and he is
terrified to go out side alone now. I have been out there and they have not bothered me.
Please tell me what I can do.


Since you gave no indication of where you live, I have to
guess on exactly what is happening. But, right now (late May) in most areas of the country
crow babies are just fledging (leaving the nest). In the first couple of weeks that the
young are out of the nest they cannot fly well and are very vulnerable to predation. They
hide in the trees and the parents are very protective of them. At this time the parents
will mob (attack) any potential predator in the area. Usually this means cats and dogs,
but it appears that your son elicits the same response. You are too big to risk getting
too near. Just wait a few days and the fledglings will leave your yard and the parents
will calm down. Try to keep in mind that these birds are not vicious fiends bent on your
son’s destruction, but merely dedicated parents trying to defend their own young in the
best fashion they know.



What mythologies are
associated with crows?


Lots, but they’re way more boring than the real stuff crows do! (I’m
a biologist, not an anthropologist. These things tell you lots about people, but little
about animals. IMHO) If you really must go after this material, try the links from The American Society of Crows and Ravens.



I found a baby crow that must have fallen from the
nest/been abandoned/is injured!


What should I do?

Probably you should put it back where you found it. If you
don’t like that idea, contact a licensed
wildlife rehabilitator
. For a lot more on this topic, click
here
.




We have a pair of crows
tearing our windshield wiper blades off our vehicles. We have no explanation for this
activity or how to stop it. Can you offer some advice or comments on the behavior?


This is a very odd one. I have now heard about this kind of crow
vandalism from nearly a dozen people in a dozen different parts of the country, and I am
stumped as to how to explain it. All I can say is that crows are very investigative and
curious, and it is possible that these traits have led them to investigate the wipers.
Wipers do not resemble food to me, so I cannot think of a good reason they would attract
crows. The wiper blades themselves, though, are exactly the sort of thing that young crows
might like to fiddle with: pliant yet resistant; soft enough to dismantle, but tough
enough to give a bit of a challenge. Young crows in their first and second years often
“play” with things that are not edible and do not interest older crows. Siblings
watch each other too, and often vie for the object in question (be it a feather, a stick,
or, perhaps a windshield wiper blade). So, it is possible that one young crow found out
about how fun windshield wipers were and then “taught” other family members.

What to do about this? Harassment is probably the best policy. Chase
those crows any time you see them around your cars. They will probably keep coming back,
and they will probably learn to hate you on sight. Still, it might keep them off. You
might also try adding some novelty to the vehicle or where you park them. Crows do not
like new things in an area where humans hang out. Small, but obvious changes in the area
or on the vehicles might be enough to get them worried. A tassel hanging from the radio
antenna might be enough of something new to keep them away for a while. If none of this
works, try getting a car cover like people with expensive antique cars use. It might be a
pain, but it will probably be less expensive than weekly windshield wiper replacements.




What is a group of crows
called (as in “a gaggle of geese”)?


The poetic term for a bunch of crows is a “murder.”
No scientist calls them that, only poets. Scientists would call it a flock.




Who builds the nest,
and what do they look like?


In the beginning stages of the nest both members of the
pair, as well as some helpers many times, work equally hard on building the nest. In fact,
the male can be even more active getting started. The breeding female, though, usually
does the most building at the end when they are lining the nest. She is the one who gets
everything comfortable in there, because she is the only one who sits in the nest to
incubate and brood the young.

American Crow nests are bulky things that are constructed
of three parts 1) an outer basket of sticks, 2) a filling of mud and grass (often the
grass is visible sticking out the bottom of the nest; a good clue it’s a crow nest), and
3) a thick bowl of something soft. Grapevine bark and cedar mulch, seem to be the most
popular lining materials around here, with mammal fur and twine common. Paper is unusual
but does get used, as does plastic occasionally. Perhaps the most unusual lining material
I have found were some Emu feathers.




Do crows collect shiny objects?


No. Wild crows do not like, nor
collect shiny objects. They do not hide, store, or cache anything but food. I believe that
all stories of crows and magpies taking shiny objects come from people’s experiences with captive,
hand-raised young birds.

Young corvids are very investigative, and love to handle
objects. They like to pick them up, peck at them, and then hide them. Most corvid species
hide food for later retrieval (some, like the nutcrackers in the genus Nucifraga,
are extreme, hiding and remembering thousands and thousands of seeds). Juvenile birds
“play” with inedible objects, picking them up, pecking them, and eventually
hiding them. (Play is just doing appropriate actions with inappropriate objects, just like
children playing house.) In the wild, they would play with sticks, stones, acorn caps, and
things like that. In captivity, they will do the same thing to just about anything small
and portable, and they may be attracted to shiny things, like keys, coins, or the like.
Most corvids are “scatter hoarders” and hide only one or a few things in any one
location (rather than being “larder hoarders” that store everything in one
place, like a packrat). So if your pet crow hid your keys, don’t expect to find them
in the same place that you find your diamond ring.





More on these later:


What do crows eat?


everything


Why do crows gather in flocks during the day?


to cruise the singles’ flocks


How smart are crows?


smarter than many undergraduates, but probably not as smart
as ravens


Are crows getting bigger?


no


Are crow populations increasing?


probably, but not as much as you think


How can you tell a male crow from a female?


not easily


How many different calls do crows make?


lots, but most of them still sound like “caw”


Why do crows hate owls?


many good reasons, most having to do with decapitated crows


Do crows play?


yes


Do crows make good pets?


yes, but they’re VERY illegal





INTERESTING THINGS ABOUT CROWS THAT MOST PEOPLE DON’T
KNOW ENOUGH TO ASK ABOUT (More on these later):




Cooperative breeding


Long-term pair bonds


Long-term family bonds


Sibling helping


Brood reduction


Territoriality and flock use


Urban/rural comparison


Dispersal


Age of first breeding


Caching of food


50 species of Corvus


Historical range of C. brachyrhynchos




Return to the Crow Page.


Return to Kevin McGowan’s Home Page


Last updated
09-Nov-2010





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