General information and Description
Crows are scavenger birds of the genus Corvus in in the Cirvidea family, which also includes magpies, ravens and about 120 other bird species. Crows thrive in pairs, and are territorial. Their main mode of attack is vulture-like in nature. Unlike hawks that carry away hens, crows are known to attack prey in droves. As opportunistic feeders, they often just hover around an area, waiting for their prey to die. Crows seldom bother adult chickens that can defend themselves. They favor young hens, growers, chicks, and eggs. It is common for crows to perch themselves on rooftops and electric poles overlooking poultry farms and learn the routine movement of your fowl. At the right time, they invade chicken coops to kill chicks and growers, and cart away eggs. This can reach up to a dozen or more depending on the flock of crows that invade your poultry farm. A successful attack will prompt them to return again and again. They usually make a pest of themselves during the months of May and June.
The 40 plus members of this genus can be found on all temperate continents, except South America and several islands.
Method of kill
Said to have the intelligence of a 2-year-old, crows have been known to think or strategise when observing their prey. They may sometimes attack in pairs or packs while making their distinct noises. A few species of crow, including the New Caledonian Crows, are known to use their claws and thick, pointy beaks to force tools for use in sourcing their foods. They also pluck and bend grass stems and twigs and effectively fashion "knives". They prefer letting other animals do the kill and wait for leftovers, which explains their penchant for dropping tough nuts on streets and waiting for speeding cars to crush them.
Prevention and Treatment
Crows can be a blessing and a curse for chicken owners. If given the opportunity they may attack chicks, but, ironically, they can also act as flock guardians and chase other birds of prey, such as hawks, away. To keep your flock safe from possible crow attacks you should follow the same precautions as for hawks and other birds of prey. Keep especially younger chickens and smaller breeds, such as bantams in a covered run and chicks in a secure brooder. Crows seldom attack mature large fowl, but they are opportunists who will steal eggs if they can, so collect eggs frequently and discourage your hens from laying outside the coop. CDs hung in various places around your coop and run will reflect light and can help to scare crows away, but they will get used to them being in certain positions after awhile, so move them around from time to time.
Do keep in mind that killing and/or relocation certain birds of is considered a felony under the Migratory Bird Act. For more information see here.
For more information on crows and how to deal with them visit the Predators and Pests section of the forum.