AY Honors/Raptors - Advanced/Answer Key

1. Have the Raptors Honor.

For tips and instruction see Raptors.

2. Breeding / Offspring:

a. What are the mating and breeding habits of raptors?

• Smaller species begin breeding at an earlier age than larger species.
• Small hawks, falcons, and harriers usually start to breed at one to two years.
• Soaring hawks, kites, and large falcons breed at two or three years.
• Ospreys begin breeding at three or more years.•
• Large eagles usually start to breed at four to nine years, and vultures up to 12 years

About 90% of raptors are monogamous (one male mating with one female) and forming a “pair bond”.

Larger raptors keep the same mate for several years. They tend to require larger territories and if they must make efforts to attract new mates annually, they would be unable to defend the amount of space they need for feeding.

• Bald Eagles
• Osprey
• Barn Owls
• Re-tailed Hawks

Being monogamous doesn’t mean they mate for life. Other raptors have a different mate each year. Some raptors have different nest threats that make long term bonds and multiple broods a necessity if their species are to survive. A few species of raptors are polygynous (when a male mates with more than one female at a time or a female mates with more than one male. Some polygynous raptors are:

• Harriers
• Boreal Owl

For breeding pairs that stay on their territory year round the breeding season is marked by an increase in aerial displays and the male and female spending more time together around the nest site.

Diurnal birds of prey breed during the time of the year when food is most available for raising young. They usually lay eggs in spring or early summer but the actual months differ depending on geographic location.

Each species usually lays its eggs at the same time each year.

Most diurnal raptors establish territories and breed in the same general area where they were hatched and raised.

Most owl species, especially those found in temperate or sub-Arctic regions, breeding occurs during the spring. Variations of breeding schedule may correspond to the weather, food abundance, and competition from other owls, disease and availability of a mate.

b. What are some facts about the incubation period of raptor eggs and birth of raptor chicks?

Most raptors raise one brood per year. If the first clutch (group of eggs) fails, the raptor pair may lay another replacement clutch.

Most species lay from one to four eggs, but if food is plentiful, some owls may lay as many as a dozen. The larger Raptors seldom lay more than two eggs. The Black Vulture lays only one. Eggs are laid over several days. Small species lay an egg once every two days while large species lay an egg once every three to five days.

Small falcons, hawks and harriers usually lay 4-6 eggs in a clutch. Large falcons and hawks lay three to four eggs. Small kites lay three to five eggs. Large kites, hawks, caracaras and ospreys lay two to three eggs. Eagles and small vultures lay one to two eggs. Large vultures and condors lay only one egg per clutch.

Owls lay 1-13 eggs depending on the species, usually 3 or 4 are more common. The eggs are rounded and white. During incubation eggs are rarely left alone. Incubation of eggs usually begins when the first one is laid and lasts, in most species, about 30 days.

• Raptor eggs vary greatly in size, shape, color and texture.
• The female keeps the eggs warm until they hatch while the male does the hunting for both of them.
• Incubation period can last 23, 45 or even 60 days. There is usually a longer incubation time for the larger birds like the eagle and vulture.
• The chicks break the shell with the help of a tooth on the tip of their beak that they lose soon after being born.
• The babies are born covered with a fine, soft down. Feathers do not appear for a few weeks. They are defenseless and depend on their parents for a long time. Baby vultures stay in the nest the longest time and do not take flight until they are four months old.

c. Baby raptors can be called by what names?

Baby raptors

may be referred to as chicks or hatchlings.

Baby owls

are owlets

Baby eagles

are called eaglets

Baby hawks and falcons

are eyas (ahy-uhs)

d. Are raptors good parents?

Raptors are excellent parents. So other predators won’t find their chicks, eagles carry eggshells and food debris away from the nest. Owls vigorously defend their nests.

4. Migration:

a. Discover some facts about the migration of raptors.

Raptors are birds and most birds migrate. As with all birds, each species has variations. Twice a year, many raptors migrate, especially the diurnal raptors. Some owls, such as the snowy owl, migrate south in the winter

The Short-eared Owls living in cold regions are migratory but their migration is irregular and nomadic. Short-eared owls appear to concentrate where prey is abundant.

In the extreme northern portions of their range, Great Horned Owls will migrate if there is a shortage of prey in winter, but if food is available, migration is minimal.

Migratory raptors spend the spring and summer in northern areas where they nest and rear their young. During the winter, the raptors fly to more southern latitudes where food is more abundant. They spend the fall and winter there before returning to the north.

How do raptors migrate? Migrating raptors depend on thermals and updrafts to help them in their migration.

Thermals

The sun heats the surface of the Earth unevenly and warm air rises like bubbles in boiling water. Raptors gain altitude by soaring up in a thermal.

Updrafts

In mountainous areas, wind blows across the earth's surface and then upward giving raptors enough lift to soar for many miles.

Diurnal Raptors migrate during the day. The raptors that rely mostly on soaring do not start their migration until strong thermals begin to form after 8 am. Most migrate south from July through January. To spot hawks and eagles during migration put yourself in the raptor’s roadway (leading lines).

Leading Lines

Raptors often follow geographical features such as coastlines and mountain ridges as they migrate.

Obstacles

Raptors do not like to fly over water because there are no thermals

For more information on thermals, updrafts, leading lines and obstacles, see hawkwatch.org.

5. Complete a project, not previously done, from the list in the basic Raptor Honor #6.

See requirement 6 of the standard level for more information.