Daily crow migration???

Question

Every day lately around 4:00 about 100,000 crows fly over my house all heading in the same direction. Are these the same crows everyday or are they different crows heading to a meeting ground? And it always seems like it happens this time of year.
If anyone could explain why they do this, that would be great.

Answer 1

Crows sometimes form communal roosts in fall and winter, it is interesting to note that where I live they do it in the spring and summer opposite to all other information about communal roosts.

Excerpt from Crows.net....

ROOSTS
Whenever one speaks of crows, its wisest not to be too definite. The behavior of crows can vary widely from place to place. However, we can say that in many places, crows will gather in fall and winter to spend the night in large communal roosts containing several hundred to many thousand birds. Roosts as large as 200,000 or more birds have been reported. Communal roosts may remain in one location for a number of years or may shift from place to place in response to changing conditions.

During the day, the crow population may be spread out over a very wide area, but perhaps an hour or more before dusk, birds will begin to fly towards the roost, collecting together into ever larger flocks as they get nearer. Generally, it seems as though most birds do not fly directly to the communal roost, but stop at nearby "staging areas".

In some cases there may be several staging areas fairly near the roost. Often staging areas are in cemeteries or other areas where fairly open areas are surrounded by or interspersed with trees. Birds will fill the surrounding trees, hunt for food on the ground, and engage in general socializing. A roosting area may be virtually empty while nearby thousands of crows mill about in a staging area.

As dusk approaches, the birds will abandon the staging area and gather in the communal roost. Often every suitable branch on every tree for a considerable distance will have a crow occupying it and there are constant alarms and mass flights and continual interactions of birds both in flight and in the trees. The noise level can be tremendous. As it grows dark the birds settle down and remain quite until dawn when they disperse again.

Almost nothing is known about why crows form these communal roosts or of the dynamics of the populations involved. It appears that crows will travel considerable distances to a roost, but that not necessarily every crow in an area will travel to a particular roost every night. There is some indication that some individual crows may go to a roost some nights but not others.

Answer 2

They are flying to their roosting site after feeding all day.
" In winter they gather at night by thousands in communal roosts."
http://www.answers.com/topic/crow?method=26&initiator=answertip:more

Answer 3

Pretty good arguments here.