birds of prey

The Crested Caracara

CaracaraThe Crested Caracara (Caracara cheriway) is a vulture-like falcon that looks like it is wearing a very bad black toupee. Wingspan is 47 inches.

Caracaras occur throughout Mexico, Central and South American and in southern Arizona, south Texas, and south Florida.

Normal habitat includes plains, savannahs, deserts and pampas, but it can be found in forests as well.

Caracaras are large birds with wingspans up to four feet. Males and females have the same plumage: a black-topped head, a bare, reddish-orange face and a white neck. The back and wings are dark brown to black; the legs and talons are yellow. The underside of the wings have white tips. The underside of the black tail has white at the rump. (See more photos here). In flight, caracaras could be mistaken for black vultures.

The manner of flight is raven-like: direct and purposeful with noisy wing beats. The long legs make caracaras agile on the ground and swift runners.

The name “caracara” is said to derive from its rasping call. Listen here to see if you agree.

Caracaras are opportunistic feeders. They are both scavengers and predators and will even eat vegetable matter. They scratch the ground like a chicken looking for insects. They hunt mice, amphibians, other birds, and reptiles, and supplement their diet by eating carrion, hence their vulture-like behavior.

And speaking of behavior, pairs of caracaras will bully other birds and steal their food.

Caracaras nest in tall trees and saguaros. Both male and female participate in nest-building, incubation, and feeding the chicks. The nest is a loose construction of sticks, leaves and dung. The female typically lays two to three eggs and the young are nurtured for two months. Adult birds normally stick to a territory, but young birds may wander over large distances.

According to the Arizona-Sonora Desert Museum, caracaras are long-lived birds. The record life-span for a captive bird is 42 years.

See the Article Index for more Natural History articles.

The Red-tailed Hawk, a varied and versatile predator

The Red-tailed hawk is probably the most common hawk in North America. Its winter range includes most of the United States and Northern Mexico, and its summer range extends into most of Canada.

Red tail portrait

Only the adults have the distinctive red tail. Tails of the juvenile birds are light brown that gradually turn red as they mature. Adults have a wingspan of about 49 inches and a body length of about 19 inches. Females are longer than males.

Red tail flying

The plumage of Red-tailed hawks is quite varied. So rather than try to describe it, I scanned page 122 from The Sibley Guide to Birds one of the best bird books available in my opinion.

Red Tail variations

 

Red-tailed hawks are versatile. They inhabit deserts, woodlands, plains, riparian areas, and open areas. Their main prey are rodents, rabbits, and squirrels. They also take other birds such as pheasants, quail, and blackbirds. They will eat snakes and carrion also. They can take and fly off with anything up to about five pounds. They often perch high and wait for prey to show up or soar on the breezes to scan their territory.

Red-tailed hawks often hunt alone, but they also hunt in pairs, especially when they are after squirrels in a tree. They will guard a hunting area and frequently chase off other hawks, eagles, and Great Horned Owls.

According to the Cornell Lab of Ornithology, “Courting Red-tailed Hawks put on a display in which they soar in wide circles at a great height. The male dives steeply, then shoots up again at an angle nearly as steep. After several of these swoops he approaches the female from above, extends his legs, and touches her briefly. Sometimes, the pair grab onto one other, clasp talons, and plummet in spirals toward the ground before pulling away.”

“Both members build the nest, or simply refurbish one of the nests they’ve used in previous years. Nests are tall piles of dry sticks up to 6.5 feet high and 3 feet across. The inner cup is lined with bark strips, fresh foliage, and dry vegetation. Construction takes 4-7 days.” They build the nests in the crowns of tall trees, on cliff ledges, and on structures such as billboards.

According to the Arizona-Sonora Desert Museum, Red-tailed hawk populations are stable and even increasing in some areas. How long do they live? Cornell claims “The oldest known Red-tailed Hawk was 28 years 10 months old.” I’m guessing that bird was in captivity, how else could they know its exact age? I suspect that average life-span in the wild is much shorter. Various sources put the life-span between 10-21 years. Among birds of prey, it is estimated that the mortality rate is as high as 80% during the first year of life due to predation, disease, and starvation. If they make it through the first year to reach adulthood, they can expect a longer life. Many of the birds I handle at the Arizona-Sonora Desert Museum are in their teens, senior citizens of the bird world.

For more photos, see the Arizona-Sonora Desert Museum digital library here. For additional photos, sound recordings, and videos, see the Cornell Lab of Ornithology page here.

Peregrine Falcons

The Arizona-Sonora Desert Museum has recently acquired a Peregrine falcon and a Great Horned owl for Docent handling and interpretation. I am excited because I will be able to handle these birds beginning in January if museum staff can get them trained. I currently handle and interpret Harris’ Hawks and Barn owls.

Peregrine falcon

The Peregrine falcon (Falco peregrinus) has a thousand-year history with humans as a hunting animal, i.e., falconry.

Adult peregrines have a body length of 14- to 19 inches and a wingspan of 39- to 43 inches and weight up to 3.5 pounds. The weight doesn’t sound like much, but try holding that weight on your hand and keeping your forearm horizontal for 45 minutes. That’s what Docent bird handlers have to do.

According to the Cornell Lab of Ornithology, “The Peregrine Falcon is one of the most widespread birds in the world. It is found on all continents except Antarctica, and on many oceanic islands.” It occurs year-round in the western U.S. Those that nest in the Arctic tundra migrate more than 15,000 miles to winter in South America.

Peregrine falcons often nest on ledges or cliff faces (and on buildings and towers). They don’t actually build a nest, just scrape a depression in the soil if they can. The male does most of the hunting while the female broods the chicks. When not breeding, a pair will hunt together.

Peregrines prey upon medium-sized birds, attacking them on the ground and snatching them out of mid-air. They initially strike prey with their feet, then return to capture the stunned bird in mid-air. Peregrines can fly at up to 69 mph in level flight and reach 200 mph in a spiral dive.

You might think that 200 mph air rushing into the nose holes (tubercles) might explode the lungs, but peregrines have a conical bony structure in the tubercles that baffles and slows the air.

Peregrines usually kill their prey by biting the neck. Most falcons (and some hawks and parrots) have a protrusion on the upper bill, called the “tomial tooth,” the purpose of which is to sever the spinal cord of the prey when the falcon bites the neck. You can see that protrusion in the photo below.

Peregrine face

Falcons have very good eyesight. Besides binocular vision, they also have a depression, or fovea, in the retina at the back of the eye which focuses light. This feature gives the bird something like telescopic vision that enables the falcon to follow objects up to a mile away. Each eye can track separate objects independently. When you see a falcon tilting its head, it is most likely using its “telescopic” vision from one eye.

See more information at the Cornell Lab of Ornithology.

See also:

American Kestrel

Barn Owls

Cactus Wren

Cardinals, Pyrrhuloxias and Phainopeplas

Cooper’s Hawks – swift predators

Creatures of the night – Nighthawks and Poorwills

Gambels Quail

Harris’ Hawks, Wolves of the Air

Observations on Mourning Doves

Parrots in the desert?

Ravens and Crows

The greater roadrunner, a wily predator

The Great Horned Owl

Vultures, the clean-up crew

Way of the Hummingbird

Western Screech Owl

 

 

 

The Great Horned Owl

The Great Horned Owls are back in the neighborhood. I hear them, but can rarely see them because they are masters of camouflage (see photo at the end of this post). They have a distinctive sound – a loud ho-ho-hoo hoo hoo, similar to, but deeper than a Mourning Dove. They are the only owls that actual go hoo-hoo. Listen to their sounds at the Cornell Lab of Ornithology here (Scroll down and click the “sound” tab). See 84 photos at the Arizona- Sonoran Desert Museum digital library here.

Great horned owl 1

The Great Horned Owl ranges from the boreal forests of Canada and Alaska to the southern tip of South America. They seem to prefer open, second-growth forest, agricultural areas, and suburban areas. The Great Horned Owl is the third largest owl (the Snowy Owl and Great Grey Owl are bigger), with a length of 15- to 25 inches and a wingspan of up to 5 feet. These owls can weigh over 5 pounds. Females are bigger than males.

Males and females have similar plumage, but that varies regionally. According to The Sibley Guide to Birds, “females average browner and more heavily marked than males. Eastern birds are richly colored. Birds in the western interior region are generally pale and grayish in tone….” The facial disk (which helps focus sound) is orange to gray and sets off yellow eyes.

The “horns” are actually tufts of feathers which can be erect or flat to the head depending on the mood of the owl. From my experience with owls, these tufts are most often erect when the owl is on the alert.

The Great Horned Owl will prey upon anything is can catch and that includes mammals, other birds, reptiles, and amphibians. In the Southwest, cottontail rabbits and jackrabbits are favored. The Great Horned Owls are the only owls known to prey upon skunks, perhaps because they have a poor sense of smell.

Great Horned Owls do not build their own nest but instead seek out the nests of other birds such as hawk nests, squirrel nests, tree holes, rock crevices and nooks in buildings. They begin nesting in January or February and will have up to 5 eggs at a time.

Typical life span in the wild is 13 years, but they have lived as long as 38 years in captivity.

Find the Great Horned Owl in the photo below:

Great horned owl 2

Harris’ Hawks, Wolves of the Air

The Harris’ Hawk (Parabuteo unicinctus) is now a common urban dweller. Its body is chocolate brown above and below and it has conspicuous rusty shoulder patches, leggings and wing linings. The base and tip of the tail are white. It is slimmer and longer-tailed than most Hawks (buteos). Wingspan is 40-46 inches.

HH21

Males and females exhibit the same plumage, but the females are up to 40% larger. Weights range from two to three pounds for adults. This size difference is common in birds of prey. And it means that the female is the alpha bird of the flock.

The Harris’ Hawk originated in Central and South America and moved north following riparian corridors. It was not common in the desert in the first part of this century. Beginning in the 1930s, however, cattle ranching and associated water holes were developed, and the hawk was able to extend it range into the desert away from riparian areas. Since the 1980s, the Harris’ Hawk has moved into the city of Tucson in a large way because of development. It apparently thrives in suburban environments, but has yet to learn about electric lines. Electrocution is its largest cause of death in the city.

Harris’ Hawks of the Sonoran desert region are apparently a different subspecies from those in other areas. Our hawks are bigger and live in cooperative packs for both hunting and breeding. Harris’ Hawks in other areas nest and hunt in pairs. The pack is led by an alpha female. Several females may lay 2 to 4 eggs in a single nest. The eggs are incubated for 33-36 days by both sexes. The young fledge about 38 days after hatching. In Arizona, the breeding period is typically from February through October. If hunting is good, they may raise more than one brood per year. The hawks favor saguaros and tall trees such as eucalyptus and ornamental pines or cedar for nesting. Immature hawks may stay with the pack for up to two years, but eventually leave to find other packs.

Harris’ Hawks eat lizards, rabbits, rodents and small birds including doves and quail. They do not take snakes nor do they attack cats or dogs. They have been observed taking Koi fish. In the Southwest, the predominant prey is the desert cottontail rabbit. The hawk’s eyesight is so good, it can spot a rabbit up to a mile away.

The Harris’ Hawk is a very adaptive bird. In hunting, the younger birds may flush the prey while the older birds keep watch from a high perch, and then swoop down on the fleeing animal. Another strategy used is tag-team chasing. This is used for large prey such as jackrabbits. The hawks will tire out the jackrabbit until it becomes easy pickings.

To feed nestlings, prey is passed up the hierarchical chain of command to the alpha female, who feeds the young.

The Great Horned Owl is the hawk’s greatest natural enemy. The owl attacks nestlings and young hawks and can take an adult male, but not the larger adult female. Great Horned Owls, frequently appropriate hawk nests as their own. This means that the hawks frequently have to build several nests in an area. Packs of hawks will attempt to drive owls from the area.

Harris’ Hawks are territorial and will defend their territory against others of their species. However, in the winter, local flocks get together and the young females form new alliances to begin new flocks.

 

The Arizona-Sonora Desert Museum maintains a breeding flock of Harris’ Hawks. These birds perform in the afternoon free flight program from late October through mid-April (it’s too hot during the summer). You can see some videos here and more images here. All during the year, Docents at the museum demonstrate Harris’ hawks and other birds of prey.

Barn Owls, Tyto Alba?

Tyto alba is a denizen of the night who stalks his prey by sound and stealth. He may have passed you close by but you didn’t notice, or maybe you felt a brief ghostly presence. On silent wings, the Barn Owl (Tyto alba) can hunt in almost complete darkness, relying only on the faint sounds made by his intended meal. Fringe-like feathers on the leading edge of the wings help make the flight silent.

The barn owl is a very adaptable bird of prey that is found in specific habitats on all continents except Antarctica. It is the most widely distributed land bird. Barn owls eat rodents, and perhaps because we humans attract such beasties, barn owls favor nesting near human habitation in barns, under bridges, in mine shafts, and in palm trees. In the southwest, barn owls also nest in undercuts in arroyos, and may be found in desert grasslands, and in trees around agricultural fields.

Barn owls often swallow their prey whole, but they can’t digest fur and bone, so they regurgitate pellets. (Dissection of pellets allows researchers to study what the owls eat.)

Barnowl-female

 

 

 

 

 

 

 

 

 

 

Barn-owl-male

Barn owls are sexually dimorphic, that is, the males and females have differing plumage as you can see in the photos. The females tend to be bigger, darker, and more speckled than the males. The birds average about 12 inches in body length and have wingspans of about 33 inches. Weights in adults vary from 10 to 20 ounces.

The feathers form a facial disk designed to focus sound to the owl’s ears. The ears themselves are not symmetrical on the skull as in other animals. Rather the left ear points downward, and the right ear points upward. Therefore, sound reaches each ear at slightly different times and allows the owl to exactly pinpoint the source. Some researchers claim that each ear hears with slightly different frequency sensitivity. That also aides in sound location. Barn owls are smart and learn all the squeaks and twitters of their prey so that they can identify not only where it is, but also what it is. Perhaps the only rodent with equally good hearing is the Kangaroo Rat.

Birds have four toes or talons. They are configured either three in front – one in back, or two and two. The barn owl can move its outer toes to form both configurations. That enables the owl to form a good web-like trap when snatching prey. The barn owl has serrations on the claw of the middle toe to aid grooming.

Barn owls have many vocalizations, some researchers count as many as 15 distinct calls as well as tongue clicking and wing clapping. Some of the sounds are for proclamation of territory, others are for alarm, and some are for courtship and mating rituals. Many of the sounds are screaming or screeching; others include hissing or wheezing, and whistling. None of the sounds are what we would call an owl hoot.

Nesting occurs in the spring in most areas, but can occur any time of year if there is abundant prey available. The female may lay up to six eggs each one to two days apart. Incubation takes 33 days and the young hatch one to two days apart. If the parents don’t provide enough food, the older chicks starve out and may even consume the younger chicks. The chicks will fledge seven to eight weeks after hatching. Barn owls typically breed at an age of one year, and there is a high mortality rate in the wild. Typical wild life expectancy is 2 years, but captive birds have lived into their high teens.

Barn owls are difficult to observe in the wild because of their nocturnal habits. I have seen them sleeping in mine shafts. If you want to seem them close up, go out to the Arizona-Sonora Desert Museum where Docents frequently have them on display.

Barn-owl-chicks