Raptors
INDEX
WHAT ARE RAPTORS?
TYPES OF RAPTORS
RAPTOR FEATURES
RAPTORS, MAN AND CONSERVATION
RAPTORS OF THE BAHAMAS
RAPTORS OF ARDASTRA GARDENS
WHAT ARE RAPTORS?
The word raptor comes from the Latin word “rapere” which means to seize or plunder. Today, it is loosely used to describe a particular group of carnivorous (meat-eating) birds also known as the birds of prey. They are found throughout the world except for Antarctica and a few remote islands.
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TYPES OF RAPTORS
There are approximately 482 species of raptors in the world. They are broken down into 2 main groups, the diurnal (active in the day) raptors and the nocturnal (active in the night) raptors.
- Diurnal raptors
The diurnal raptors consist of five different families of birds that are referred to as true raptors and are within the order Falconiformes.
- Secretary bird – Sagittaridae – contains one species. Unusual looking for a raptor as it has many crane-like features.
- Osprey – Pandionidae – contains one species. This is the only raptor that only feeds on fish.
- Kites, old world vultures, harriers, hawks, eagles and buzzards – Accipitridae – the largest group containing 217 species.
- Falcons and caracaras – Falconidae – contains about 60 species.
- New world vultures – Cathartidae – contains about 7 different species.
- Nocturnal raptors
These are the owls. They are not considered true raptors but because they have similar features and habitats we will refer to them as the raptors of the night. There are 2 different families of owls that all belong to the order Strigiformes.
- Typical owls – Strigidae – contains 123 different species. Mainly found in woodlands.
- Barn owls – Tytonidae – contains 10 species. Mainly inhabit open areas including farmland.
RAPTOR FEATURES
True raptor features
Despite their differences, all raptors are exceptional at catching live prey and all share at least three features that are well adapted for this: keen eyesight, eight sharp talons (claws) and a hooked beak.
Raptors rely on their keen eyesight to find their prey. The size of their eyeball is relatively big when you compare it to the size of their head; the eyeball has attached eye muscles designed for rapid focus and the retina enables high resolution. The diurnal raptors have full color vision (higher numbers of cones on the retina) and their eyes are excellent for accurate depth perception, making it easier to catch moving objects.
The owls on the other hand do not see colors very well (less cones and more rods on the retina) but instead can see very well in low light conditions. The shape of the eyeball in raptors is quite different from humans. The human eye is typically round, making it easier to rotate the eye when the person is looking around. The eye in raptors is tubular in shape, allowing for a larger lens to fit inside. Because of its shape, it cannot rotate and therefore they cannot look around without moving their heads. To compensate for this, raptors have very flexible necks that can nearly turn all the way around.
The talons are long, curved, powerful grasping claws, attached to very strong toe and leg muscles. The length and size of a raptor’s toes, and the curvature and thickness of its talons are related to the type of prey it pursues. Most birds of prey will have three toes pointing forward and one pointing backward. These toes can apply an extremely powerful grip on their prey, literally crushing it to death. The talons may also be used to pierce a vulnerable spot, such as the back of the neck, to quickly kill the prey. Eagles and hawks kill their prey by dislocating the neck. Ospreys have two toes facing forward and two facing backward. This allows them to hold the fish they catch with four claws, two on each side, for a secure grip. Ospreys also have spiny scales on their feet that help them hold the slippery fish more securely. Owls also have four toes. However, one of the toes is very flexible, and can be rotated forward or backward for a two plus two or a three plus one toe arrangement.
All raptors have a characteristic beak, hooked at the tip with sharp cutting edges which is used to cut and tear meat. Many raptors will either catch live prey or scavenge for carrion (flesh of dead animal). Some species will only eat live prey whereas others prefer dead prey (for example the vultures).
Raptors tend to be sexually dimorphic (males and females differ in appearance), with the females being larger than the males. This apparently enables the pair to be able to hunt for different sized prey and expanding the range in food source for the young.
Vulture features
Unlike the other raptors, vultures have flat footed talons as they feed on dead prey. They also do not rely on keen eyesight to find their food but they have a very keen sense of smell to located decaying flesh.
Owl features
Owls rely very heavily on their hearing for pinpointing prey and there are many features that help to increase their ability to “hear” them out:
- Owls have softer feathers than most birds and so their feathers make virtually no noise as they sneak up on animals. This also makes it easier for the owl to hear its prey.
- The feathers on the face of owls are in the shape of a disk and this funnels sound waves directly into the ears just behind the eyes.
- The ears of owls are also located at different heights. This makes it easier for the owl to determine which direction the sound is coming from.
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RAPTORS, MAN AND CONSERVATION
Many species of raptors are disappearing world-wide and there are many reasons for this, making it difficult to help save these amazing birds.
As with most animals, habitat loss is the number one reason why raptors are vanishing around the world. Land is being cleared making it hard to find appropriate nesting sites, and food. The majority of raptors tend to nest in cavities inside old dead trees and these are often removed from properties as they are seen as “unsightly”. Unfortunately, this means that raptors have a harder time finding nesting sites and sometimes trees are taken down while chicks are still inside.
For hundreds of years raptors have been killed by hunters and farmers as they believed that these birds were competing with them for food or taking livestock. This has been a misconception that has reduced populations around the world. Today, many farmers have realized their true potential in controlling the populations of crop pests like rats and rabbits and now they are encouraged and nesting boxes are built to attract them into farmlands.
Like all animals that are at the top of the food chain, raptors are also vulnerable to pesticides, insecticides and human-made toxic chemicals. Chemicals are passed up the food chain from plant to herbivore and on to the carnivores. Many of these chemicals dissolve in fat and so they get stored in the fatty tissues of many animals. The top predators tend to accumulate these toxic chemicals because they eat a large number of animals that are often exposed to these types of chemicals. This is known as bioaccumulation. Examples of chemicals that have been blamed for the disappearance of birds of prey are the organochlorines such as DDT and PCB. These chemicals can cause chronic illness and even death of both the adults and the young birds. Even if the chemicals are not at high enough concentrations to actually kill the birds it tends to cause the thinning of eggshells, which brake easily when the mother sits on her eggs. The poisoning of rats and seed eating birds by farmers has also lead to poisoning birds of prey.
Today, there are many organizations trying to educate the public about the vulnerabilities and usefulness of the birds of prey. There are also many dedicated organizations that take in sick or injured raptors to rehabilitate them back to health and release them back into the wild. Some of these organizations have also begun breeding programs for some of the birds most at risk of extinction.
All of these efforts are vital in helping to save these amazing birds but without a habitat to go home to, it will all be in vain.
RAPTORS OF THE BAHAMAS
There are many birds of prey that are year-round residents in the Bahamas. Additionally, many raptors are migrant visitors to the Bahamas, flying from North America during the winter months. Below is a table of the different raptors found in the Bahamas.
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Family
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Species
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When found in the Bahamas
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True Raptors
Falconiformes
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Swallow-tailed Kite (Elanoides forficatus)
Northern Harrier (Circus cyaneus)
Sharp-shinned Hawk (Accipiter stiatus)
Red-tailed Hawk (Buteo jamaicensis)
American Kestrel (Falco sparverius)
Merlin (Falco columbarius)
Peregrine Falcon (Falco pereginus)
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Southern Bahamas, August-October
October-April
February-April
On larger islands year-round
Common all year round
October-March
Rarely visits during October-April
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Owls
Tytonidae
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Barn Owl (Tyto alba)
Burrowing Owl (Athene cunicularia)
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Year round
Year round
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Osprey
Pandionidae
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Osprey (Pandion haliatus)
Resident race and migratory race
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Resident race common in Southern islands
Migratory race in Northern islands, Oct-Apr
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American Vultures
Cathartidae
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Turkey vulture (Cathartes aura)
Black vulture (Coragyps atratus)
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On larger islands year round
Very rarely passes through
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RAPTORS OF ARDASTRA GARDENS
Ardastra gardens has a variety of raptors; an American Kestrel, Red-tailed Hawk, Barn Owl and a Great horned owl.
American Kestrel
(Falco sparverius)
The American Kestrel belongs to the fastest moving birds in the sky known as the Falcon family. The American kestrel is also known as the Sparrow Hawk and it is the smallest and most colorful of American Falcons and is the second smallest falcon in the world. There are about 20 subspecies found throughout North and Central America, the Caribbean and the Bahamas. American Kestrels are quite common in the Bahamas, but go unnoticed as they are shy of humans. These birds spend a lot of time sitting on top of tall trees in search of small prey such as lizards, insects and small rodents.
Often kestrel chicks are brought into Ardastra gardens by concerned citizens because it had “fallen out of its nest”. Unfortunately for these birds, even when they have fallen out of their nest, removing them causes more harm than good as the parents would normally still feed and defend their fallen chick. Once they are removed from the nesting area, the chick will no longer have its parents to teach it how to survive.
Ardastra gardens has an American Kestrel that has been kept for this very reason: to educate visitors that collecting fallen chicks is not a good practice.
Great-horned Owl
(Bubo virginianus)
The Great Horned Owl was first seen in the Virginia Colonies, which is where it derived its species name. The common name refers to the tufts of feathers, called Plumacornes, on top of the head that resemble "horns". The fact that these are the largest owls in the southern United States makes them the "Great" Horned owls.
They occuur in wooded areas in the continental United States throughout the year and though they are not considered threatened or endangered, they are limited by suitable nesting sites. These birds mainly hunt by sitting atop a high branch and wait to ambush prey but they are also known to walk on the ground to capture small prey and wade in shallow water to snatch frogs. The Great-horned owl has an extremely wide variety of prey species, of which 253 different species has been identified.
These birds nest in January and February and do not build their own nests, they prefer to utilise the nests of other birds such as hawks, crows and herons.
Most Great-horned owls live about 13 years in the wild but some have lived into their 30's in captivity. Ardastra has a Great horned owl that is about 17 years old. His name is Shadow and he came to Ardastra from a rehabilitation center. In the 1980's he was shot in the wing by a hunter and had to have his right wing amputated and therefore will never be able to be released back into the wild. He will live out the rest of his life here at Ardastra Gardens to hopefully show the general public what effects human activites have on these amazing birds.
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