Often during an increase of the main food source will encourage raptors to form pair bonds with more than one mate. Harris' Hawk is odd, for they will form polyandrous bonds without a prey increase. Polyandry is only reported in Harris' Hawk and Galapagos hawks.
"Color Phases" is perhaps in inaccurate term; the term color phases suggests that color change is related to age, and this is not so. Often the term color morph is used to avoid confusion. Color phases are not linked to gender either; but often color phases are linked to environment. There is a theory related to this, named Gloger's Rule. The rule states that color is directly effected by climate. For example- in a dry climate the plumage may be paler, while in a wet climate the plumage would be darker. In colder climates plumage contains more creams and blues, while in hotter climates plumage has more red.
Most raptors are solitary by nature, and this usually applies to hunting also. However, many raptors will hunt cooperatively to increase their chances of catching prey. Often, when confronted by a raptor the prey will flee in the other direction. If the raptor is hunting with a partner, the partner will be waiting for this and will quickly kill the prey.
Harris' Hawk is noted for its peculiarity in breeding arangements (see above), and is also odd in the way it hunts. Often, they will travel in family groups of four and five and hunt down large prey. Their hunting tactics are sophisticated, and are noted for being very much like wolves. A hawk may flush the prey and then chase it to exhaustion, or just overwhelm it with sheer force of numbers. When juveniles are with the party, they will eat before the adults.
Size is variant on many factors- gender, family, food population and others. In raptors, females are larger, often by 1/3. This is called Reverse sexual dimorphism. Differences in plumage, size and other attributes due to gender is known as sexual dimorphism. The term "sexual dimorhpism" is also often used to convey the fact that in most animals, males are larger than the females. Raptors are just the opposite. Reverse sexual dimorphism, or RSD, is greater in faster, active bird-eating raptors, such as falcons, than in slower, more relaxed raptors such as eagles or buteos. The differences in RSD also differ from species to species.