The issue, of course, is how to control crows. Regrettably there are no easy answers but here are few ideas. Before any crow control program can be instituted, readers should understand that crows are a federally protected bird. Under the North American Migratory Bird Act (a treaty between the U.S., Mexico and Canada) you have to have permits to use lethal control on crows. (note, some agricultural states have an exemption from this law in order for farmers to protect crops). Thus in light of the law, you must use harassment and other non-direct contact control methods.
1. Effigies. Crows are remarkably nervous birds. They hate effigies of owls and scary eyes. Understand, however, that these effigies only work on the short term. Once the crows realize that they aren't alive, they may return. Moving them around will help extend the length of their effectiveness.
2. Distress calls. Using a tape recorder of a crow in distress or hawk etc, can help you disperse crow roosts. Again, effectiveness may be short lived.
3. Trimming tree branches. This is a drastic approach, but if you have fewer branches, then you will by definition have fewer crows who can roost there. This method may not be economically feasible.
4. Bangers. Bangers are devices shot from shotguns and emit a loud bang. Be sure to follow all local shooting laws as well as prudent safety principles. They are a pyrotechnic device so areas in drought conditions should be especially careful. But the result of their use will be immediate. (I also suggest getting police permission before using also).
First, I need to warn everyone again that crows are a federally protected species. One that requires particular attention is the North American Migratory Bird Act aka Migratory Bird Act. If you view the list of protected birds, you will see crows are on it. However, states have been given some latitude with this law. For example, some agricultural states have exemptions that allow farmers to kill crows at will. Others only allow crow killing during certain seasons and there are other exceptions. The key is that you must know the laws of your state before starting on any lethal crow control program. Ignorance is no excuse.
If you have permission from your state to kill crows and know the various laws you have to follow to legally kill them, then you are ready to learn about the various methods available to you. Just a note, some states may forbid some of these methods. Be sure you know all laws and safety rules before implementing any crow control program.
Hunting is by far the most common lethal crow control method. The weapon of choice is a shot gun. You can hunt in a couple of different ways. One is to put up an owl effigy and shoot the crows as they bomb the fake owl. Remember, that in order for crow hunting to work you must not be seen. Crows are a very cautious bird. If they see you, they will leave in a hurry. Using blinds or cover are a must in crow hunting. Another method is to find a tree or blind and call them using crow calls. Finally, you can use what is called the duck hunting method for crow control. This technique relies on calls, crow effigies and a blindkl visit http://www.thecrowroost.com/ You can learn about hunting crows at various web sites but one that I would recommend visiting is http://www.crowbusters.com/index.htm
Of course the trouble with hunting is the amount of land you need in order to hunt safely. Nevertheless, hunting is a quick and effective method.
A second method is to trap the crows. If you have a lot of crows you will need to use a trap like the Australian Crow Trap. This is a large box (6-7 feet cubed) with a V in the top that allows the birds to fly in through the wide portion of the V and then traps them inside because they can’t close their wings and keep moving upward through the narrow portion of the v. If you have single crow problems then you can catch them using foothold traps. (Warning though these traps have been unfortunately banned by many U.S. states because of public ignorance of these traps).
Finally, there are no poisons registered for crows from what I have read. Probably, given the size of the birds, it was too dangerous to use poisons due to concern that the poison might kill smaller birds that might feed on the poison also.