Can we sex crows? (7)

These differences were also seen in the Hooded Crows which I got a chance to observe in Rome two years ago. The smaller one was observed to solicit courtship feeding from the larger individual, which indicates almost with certainty that the smaller one was a female. As you can see, the female has the thin neck line and less massive wing musculature. Although not a good shot, the male's upper bill had a small hook, while the female's upper and lower bill tips meet like a pair of forceps.

You may not always be able to tell the sexes of crows. But in many cases you can, by looking at the combination of all or parts of the following characteristics: body size, wing musculature, the neck size, bill structure/size, plumage coloration/sheen and of course behavior.

Note: These differences between sexes may pertain only to the crow species which I have had the chance to observe. Thus, they are not necessarily applicable to the other species, although I have the impression that they are, at least in some aspects.

Can we sex crows? (6)

The previous 5 posts were of the Carrion Crows (Corvus corone). The male and female characteristics seem to hold true with other species. This photo is of a known pair of the Jungle Crow (Corvus macrorhyunchos). As indicated by the arrows, the upper bill of the male is hooked and longer than that of the female.

Can we sex crows? (5)

Unfortunately, I couldn't find the best shots of a typical male. The above two photos are of the same known individual. He looks miserable due to molting. He is a much nicer-looking guy in breeding season. Despite his condition, I think you can see the shoulder muscle is well developed.

As indicated by an arrow, his upper bill is slightly hooked and typically longer than that of the lower bill.

Can we sex crows? (4)

This is another photo of a female crow, indivicually recognized by the leucostic primaries. The reason why we can tell it is a female is that she does the incubation. Though not a very good capture, I think you can see that the bill and the wing musculature are typical of females.
It is impossible sometimes to tell the sex of a lone crow without any background information about the bird. But it is often possible if you get used to spotting the male/female characteristecs. Furthermore, the plumage of females is duller than that of males.

Can we sex crows? (3)

This is the closeup of the female I mensioned in the previous photo. From the ruffed-up nostril feathers and partial leucostic tail feathers, we can tell that this is the same female.
Female crows tend not to have a hook on the upper bill. The lengths of upper and lower bills tend to be the same, or with very little difference. This is one of the characteristic of a female crow. A typical male crow has, on the other hand, a "hooked" upper bill, or the upper bill considerably longer than the lower one. But again, you have to be aware of the fact that there are individual differences.

Can we sex crows? (2)

This pair is the one I've been observing for a few years. Despite the general impression that all crows look alike, individual crows are all so different with unique physical characteristics, only if you observe them closely. For example, in the female of this pair, her tail feathers are partially leucostic. And, the feathers covering her nostrils are ruffed up and looking like a rump probably because they have curles. These characteristics seem to be genetic and do not change from year to year.
From this photo, you can see that the male is larger and has more developed wing muscles than the female.
There are of course individual differences in body size and considerable overlap between sexes, so that you may not be able to tell apart a large female from a small male. Size alone is not a good indicator. However, the well-developed wing musculature and thicker neck line are good indictors that it is a male.

Can we sex crows? (1)

As most birders know, only female crows incubate. That is, if a crow is sitting in a nest incubating, it is almost invariably a female. A female corvid stays very close to the nest often brooding over the nestlings, probably until the young gains sufficient thermoregulation ability. The male brings food to his mate and nestlings in addtion to that for himself during this period. Thus, it is presumed that the work load of a breeding male is considerably large. (This is also true with other corvids like magpies and jays)
Based on the observation of a number of breeding crow pairs, I have found it possible to tell apart sexes of crows to a considerable extent. I understand very well that the accuracy has to be limited depending on observation and photographing conditions and that I have to keep in mind that I shouldn't make premature identifications if sufficient observation and supporting evidences/data are not available.
Bearing the above-mentioned limitations in mind, I would like to show you how crows can be visually sexed (with supporting behavioral observations) in some cases.
The photo is that of a female Carrion Crow incubating.