MUSE | Natural Selection | Unit Overview and Materials | Section 4: Extending the Natural Selection Model... | 4B: The Pheasant Case | Student Handout #1
Student Handout #1
Case Three: Ring-Necked Pheasants
As you can see, the male ring-necked pheasant is brightly colored. The white ring at the base of the red and green head stand out against the dull, brownish colors of the fields in which they live. The female, on the other hand, appears well camouflaged in this habitat.
As with the previous cases, your primary goal is to explain the trait in question from a Darwinian perspective. However, in this case the final product will be a research grant proposal which will have two parts.
Remember: this is a competition so you need to provide compelling reasons for the research program you are proposing.
Miscellaneous Pheasant Information
The role of predation is extremely difficult to determine in influencing bird distribution and abundance. One study tracked birds using radio transmitters and found that among 105 deaths of such birds, 80 percent of the total were attributed to predation. Of these 76 deaths, 46 were believed to be the result of mammalian predation, 19 caused by birds, and 11 of undetermined cause. It is believed that foxes are responsible for the majority of mammalian predation cases, while smaller numbers were considered to result from cats, minks, dogs, and weasels. Among the bird predators, the most significant source of mortality is due to both the great horned owl and the red-tailed hawk. The table below lists the major pheasant predators, the majority of which detect their prey by sight during daylight hours.
Courtship season for pheasants is a noisy and colorful time of year. It occurs in early spring and typically lasts for several weeks. During this time male pheasants show increased aggression toward one another and distribute themselves throughout the habitat range into relatively small territories within which they remain for the duration of the courtship season. During this time females move freely within the entire habitat range and encounter many males. Sexually mature males, upon seeing a female, will begin a series of mating displays. Tow characteristics of the male mating display are called waltzing and wing-flapping. In the waltzing display the male presents on wing by lowering it as he advances past or around his partner. The wing-flapping courtship display involves the male holding the head and body in a vertical position while noisily flapping his wings in short repeated bursts. If the female is receptive to mating with a male she will assume a crouched posture as the male displays.
Females only respond to a small fraction of male courtship displays. During the courtship season females generally spend more time in the territories of males with bright plumage than in the territories of males with less brightly colored plumage (including juvenile males). Nearly all mature females mate during every breeding season. On the other hand, only a fraction of the males will successfully mate during a particular year.
As the branching diagram below shows, pheasants are closely related to partridges, quail, and grouse. The table shows how various characters differ between these groups of birds.