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Raptors: Nature’s Finest Hunters

Raptors: Nature’s Finest Hunters

The subtle beauty and ecological benefits of these birds of prey.

 

Article by Tamra Bolton

Photos by Larry Ditto

 

What Is A Raptor?

“Raptor” is derived from the Latin word rapere which means “to seize or to capture.” These birds are identified by distinctive features such as a strong curved or hooked beak, sharp talons and keen eyesight. They include eagles, hawks, kites, osprey, falcons, owls and vultures. Raptors hunt during the day (diurnal) or at night (nocturnal)…some do both. All raptors are federally protected species, making them illegal to harm or possess without a special permit.

Why Are They Important?

Since raptors are usually at the top of the food chain, they are good indicators of the health of their habitat.

Texas Parks and Wildlife Department Wildlife Biologist Matthew Reidy agreed, “Lots of prey…lots of raptors…that’s a healthy landscape.”

TPWD Wildlife Biologist Cliff Shackleford added, “Some Texans continue to think of all raptors as ‘chicken hawks’ that are bad for their property, but this is changing as many folks appreciate how these birds keep numbers of rodents in check Without raptors, we’d be overrun with rats and mice.”

A single Barn Owl can consume about 1,500 rodents per year and a family of Barn Owls can polish off up to 25 rodents each night.

“Barn Owls have been documented catching a rat or mouse every 15 minutes while feeding young,” said John Karger A.H.T., founder and Executive Director of Last Chance Forever, The Bird of Prey Conservancy.

Hawks and owls also help control gophers whose tunnels often cause erosion. The Cornell Lab of Ornithology reported that some adult hawks eat around 1,460 small mammals (rodents) every year, and during breeding and nesting season that number increases.

“Raptors eat the rodents that eat the eggs of quail; they eat rattlesnakes that bite the quail hunter’s $1000 pointer,” Karger said. In fact, snakes are a favorite food of the Red-shouldered Hawk.

Other species such as the Swainson’s Hawk have a diet that consists of mostly insects, eating sometimes large numbers of grasshoppers and other pests which benefit farmers and hay producers. The Great Horned Owl is the only raptor that will kill a skunk, a predator of ground-nesting bird eggs.

When considering all the positive contributions raptors make to our landscape, we are reminded of the Aldo Leopold (considered by many as the father of wildlife ecology) quote about seeing the big picture instead of just focusing on one component.

“If the land mechanism as a whole is good, then every part is good whether we understand it or not…To keep every cog and wheel is the first precaution of intelligent tinkering,” Leopold said.

Types of Raptors in Texas

One of the first steps land managers can take to understand their raptor population is identifying the raptors in their area. Michael Harris, wildlife biologist with H&T Environmental, said this is very important because raptors are prey-driven and opportunistic; some have a very limited diet and require particular habitats to mate, nest and hunt.

Raptor species found in Texas often change with the seasons due to migration. Most diurnal raptors migrate to some extent, but most nocturnal are year-round residents. These are a few of our more commonly seen species:

Buteos or soaring hawks are medium to large hawks and have stout bodies, broad wings and fan-shaped tails. They include Red-tailed Hawks, Red-shouldered Hawks and Swainson’s Hawk.

Accipiters, or forest hawks, are small to medium bodied with short, rounded wings and a long tail. They include Cooper’s Hawks and Sharp-shinned Hawks.

Bald Eagles are often spied close to water sources but can range up to 50 miles or more in search of food. Golden Eagles may be seen but are often mistaken for Turkey Vultures.

Black Vultures, unlike Turkey Vultures, can be aggressive and kill prey instead of just feeding on carrion. Sometimes Black Vultures, just like eagles, Caracaras, hawks and several other mammal predators, attack and kill weak and newborn livestock. The white wing tips on Black Vultures and the more frequent flaps in flight are the best ways to distinguish them from the more docile Turkey Vulture. All vultures do an excellent job of ridding the land of carrion and provide an important ecological service.

The only falcon that is widely distributed in Texas is the colorful American Kestrel. However, Caracaras are also in the falcon family and are growing their range into North Texas. American Kestrels eat insects, snakes, mice, and occasionally, small birds. Caracaras feed on both carrion and hunt live prey.

Kestrels are about the size of a dove and have a peculiar habit of “pumping” their tails while they are perched. Quail outweigh these raptors making it highly unlikely kestrels are a threat.

Owls are prolific in Texas. There are 11 species of owl that can be found in Texas including the Great Horned Owl, Barn Owl, Barred Owl, Long-eared Owl, Short-eared Owl, Burrowing Owl, Elf Owl, Flammulated Owl, Western Screech-Owl, Eastern Screech-Owl and Ferruginous Pygmy-Owl.

One can usually determine their presence by their vocalizations and by the owl pellets they leave behind.


Cooper's Hawk

 Harris's Hawk

Red-tailed Hawk

Northern Harrier

White-tailed Hawk

Swainson's Hawk

Barred Owl

Burrowing Owl

Eastern Screech Owl

Great Horned Owl

Bald Eagle

Black Vulture

Crested Caracara

Turkey Vulture

Aplomado Falcon

Mississippi Kite

 

What about Game Birds?

The question of quail, doves, and other game bird depredation by raptors is a subject with slightly differing findings around the state.

“In East Texas, raptors are not the largest contributors to game bird mortality, but stray house cats, raccoons, foxes and fire ants are the game birds’ worst enemies here,” Harris said.

While raptors do feed on quail occasionally, some studies show that man-made factors such as radio tagging and using pen-raised quail may alter the supposed rates of mortality due to raptors.

Dr. Clint Boal, Professor of Wildlife Ecology at Texas Tech University said that in their test trials using a trained raptor, they launched a captive-reared and a wild bobwhite simultaneously from game launchers, and the captive-reared bird was pursued eight out of 10 times. He said that they also conducted 53 trials where they presented trained raptors with a pair of bobwhites, one with a radio-transmitter and one without a radio-transmitter (from launchers) and the radio-fitted bird was pursued in 64 percent of the cases, suggesting a bias selection of radio-tagged birds.

This could lead to biased estimates of natural mortality rates of bobwhite due to avian predators, if the data is coming from radio-tagged birds. Landowners/managers might want to take this information into consideration when they are estimating their mortality numbers due to predation, especially raptor predation.

Taking a second look at some of the management practices we use can help us reach a more balanced approach to the question of raptor predation. The research team at the Rolling Plains Quail Research Ranch (RPQRR) has discovered that farm ponds, drought feed programs and supplemental feeding of deer can have unintended negative consequences for quail. Farm ponds, while mostly beneficial, impact racoons and feral hogs (both enemies of quail) more positively than quail; drought feed programs allow producers to keep their numbers up, but an overabundance of deer can result in limited grass cover for quail; and, supplemental feed meant for deer is also eaten by racoons and feral hogs and helps increase their reproductive and survival rates.

These factors are most likely to impact quail mortality than actual raptor predation. But to mitigate the raptor predation that can occur, Boal suggests keeping feeders from woodland edges and fence rows can aid in quail survival. Providing escape cover is probably the most important thing that can be done to help quail avoid raptor predation, especially in the winter.

“Have plenty of cover across the landscape…brush and a ‘quail house’ every softball throw apart,” Dr. Dale Rollins, a quail expert, said. “Know the species of cover on your property, and don’t remove plants that are useful for quail protection. That big prickly pear is important, even if it doesn’t look like it.”

Dr. Fidel Hernandez, Alfred C. Glassell, Jr. Endowed Professor of Quail Research, Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, said that studies in Georgia show that feeding grain (to Northern Bobwhite) has an indirect consequence…attracting predators to feeding sites. The study found that the Red-tailed Hawks were “almost three times closer to feeding sites than expected,” an example of “a common management practice having an unintended influence on a top predator.” The study suggests that the grain draws in a higher density of other animals, such as rodents, which are the primary prey of Red-tailed Hawks.

“Conservation-minded landowners should always strive to take a pulse on their wildlife (big and small),” Rollins said. “Who’s increasing? Who’s decreasing? This will give landowners a better idea of how to approach a solution.”

Additional questions include: Are some of my practices causing an imbalance? What can I change or stop doing that will be more beneficial to the whole habitat?

An interesting Florida Fish and Wildlife Commission research study conducted in the Tall Timbers in northern Florida gives us some good numbers to reflect on when considering the raptor predation, Boal said. This research on the Cooper’s Hawk was very enlightening concerning the subject of quail predation. Even though the Cooper’s Hawks’ diet is mostly comprised of birds, the study showed that “Northern Bobwhites accounted for only 2 percent of the hawks’ diet for the males and 6 percent for the females, which translates into only 18 bobwhites per hawk annually,” a surprisingly low number.

Raptor Depredation Permit

In very rare cases, federal law allows for the killing of the birds with a special permit, but only after every other avenue has been exhausted. To apply for a Migratory Bird Depredation (MBD) permit, you have to first prove that the bird or birds are a hazard to human health and safety or personal property.

Then you are required to prove that you have used deterrents to discourage the depredating migratory birds such as horns, pyrotechnics, propane cannons etc. and provide photographic proof of the damages by the birds; and you must also have a recommendation from the USDA Wildlife Services Department that addresses your particular problem. It also asks about your habitat management measures to discourage migratory bird use, and your application must include any required state permits/tribal permits or approvals associated with the depredation.

This type of permit is considered a short-term solution only and you must provide a long-term plan you are going to implement “to eliminate or significantly reduce the continued need for the killing or removal of birds and/or destroying eggs/nests.” As one might expect, emotions run high in the area of MBD, with valid concerns on both sides. A valid federal permit is the last resort, but it provides the help property owners/land managers sometimes need.

Future of Raptors in Texas

At present, raptors are thriving in spite of urban creep and other factors. Some species are even adapting to city life. While the numbers of some species are down due to habitat loss, populations of others remain stable and/or are growing. To ensure the health of our diverse Texas landscape, we must be ever mindful of the overall ecological picture. Ongoing education about the beauty and benefits of our birds of prey is important.

For now, we must use wisdom in applying current knowledge to manage the land for the good of the entire habitat.



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