Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Raptors perching on or soaring over methane burners suffer burns and singed feathers when the gas flares ignite. © Dianne Moller

Raptors perching on or soaring over methane burners suffer burns and singed feathers when the gas flares ignite.
© Dianne Moller

February 2009

Burned while getting dinner

Raptors hunting down a meal at landfills risk a hot, painful surprise.

Dianne Moller

A six-month-old red-tailed hawk soars on a breezy, warm, fall afternoon over cars, homes and people. It spies a large open area with rats and mice. Jackpot! A rodent smorgasbord. With no trees to perch on for a lookout, the hawk spots something familiar that looks like a pole. It immediately alights and keeps a watchful eye to the ground for what could be its last meal for days. Suddenly, a hot flame ignites from underneath with a raging force. Instinctively, the hawk spreads its wings to fly away, but instead, tumbles to the ground. Every feather on its body is scorched and singed away. Its feet are blistered. Its eyes sting from the heat. It canít get back in the air and doesnít understand what just happened.

Young raptors are trained to hunt from the air, and a redtail that cannot fly is a raptor that will not survive. Several burned raptors admitted to our rehabilitation center during the past decade were found by concerned citizens in their backyards very near the City of Janesville landfill. Most of these birds were young red-tailed hawks or owls. After years of investigation, weíve concluded these unfortunate raptors are getting flash burns from perching on or flying over landfill stacks where methane gases are automatically flared off.

Why is this happening? Solid wastes, particularly food wastes, contain organic matter that attracts rodents and other small mammals that are an excellent food source for raptors. Since landfills are used year-round, active landfills provide a particularly important hunting ground for raptors from late fall through the winter when other food sources are harder to find. Since landscaping near the working area of a landfill is virtually treeless, the burners that are erected to vent methane gas from decomposing wastes make attractive perches for raptors hunting rodents and other prey.

At larger landfills, the methane gas is collected from much shorter pipes and is purified and piped to supply energy. At slightly smaller landfills, the burner stacks can extend high in the air to dissipate gases. At the Janesville site, burner pipes about 30 inches in diameter at the north and south ends extend nearly 30 feet up. They make wonderful perches that give the raptor a commanding birdís-eye view.

When methane builds up in the collection system, each burner has an automatic igniter that flares off the escaping flammable gas. Methane burns hot and clean. It emits a nearly invisible flame, which can quickly burn or kill anything perched on top, flying overhead or seeking shelter inside the pipes. Some landfill burners rise as high as 60 feet.

Many landfills are located away from homes and businesses in low traffic areas, so itís likely that a relatively small percentage of raptors injured following methane flaring would be noticed, recovered or rescued. Without their protective feathers for insulation and flight, these birds likely die from exposure, starvation or predation. The average red-tailed hawk only weighs two to three pounds, and likely succumbs within two weeks.

In Janesville, the landfill is located within city limits in a high-traffic area, and thatís likely why some of the birds have been found and brought in for treatment. The recovery period for a burned raptor can be 11 months or longer depending upon the severity of the injury and time of year when the accident occurred. The birdsí feathers molt on a natural cycle beginning in spring and a new set of feathers grows in by fall. Sometimes if the feather follicles are damaged extensively, the raptor may have to complete a second molt before it has all of its flight feathers. Also if its feet are badly burned, it can develop secondary infections or a condition called bumblefoot that complicates its recovery.

A convalescing bird can spend an entire year or more in a cage, flightless. During that time its muscles atrophy, just as a person confined to a nursing facility when recovering from a serious auto accident loses muscle tone and needs to keep exercising. Once the bird molts in a new set of feathers, it must be conditioned to rebuild muscle, energy and confidence prior to release. Hunting can be difficult for a healthy bird in top physical form, let alone a bird in poor condition. Even healthy birds have to beat long odds. An estimated 70 percent of all raptors die in their first year due to starvation, harsh winters, vehicle collisions, illegal shootings or electrocution.

The first time a burned hawk was brought to my facility, I questioned if it had been electrocuted. Typically, electrocuted birds die instantly, suffer deep tissue burns, but often have little feather damage aside from the point of entry and point of exit wounds. As a licensed falconer, I have experience flying and training hawks and falcons. Three years ago, my peregrine falcon was electrocuted and the only visible external injuries were two black spots on her feet and internal injuries. These birds were decidedly different – no feathers left and extensive burns.

Most of the birds burned were young red-tailed hawks or owls. © Allison Halkey
Most of the birds burned were young red-tailed hawks or owls.
© Allison Halkey

I asked a former long-time rehabber from the Janesville area what he thought might have happened. He recalled admitting a few hawks and owls found burned on or near the landfill grounds and suspected the birds had been perching on the methane burners. That was more than 10 years ago. Another rehabilitator suggested I check with others to see if they were finding birds in similar conditions near landfill sites. I kept records, began networking and posted photos for comparison with other rehabilitation centers nationally. The raptors burned at landfills all had the same appearance.

As evidence mounted, I approached the local landfill operator and contacted the Wisconsin Department of Natural Resources about alternatives like erecting a pole higher than the top of the methane burner to encourage the birds to perch at a safe distance. We also discussed the notion of installing a tripod-like cover over the methane burner with a point over the top of the flare to discourage birds from landing. At the time, DNR permits had restrictions prohibiting obstructions or covers that might interfere with the flow of methane or the flame.

But last October, I admitted two immature hawks that had been burned within two weeks of each other. Immediately after picking up the second hawk, I drove to the Janesville landfill. Just as I was pulling in, so was the landfill operationís manager, John Whitcomb. He was quite concerned about the bird and wanted to correct the problem. From there I drove to the DNR office in Janesville and met with Brian Barbieur, our local air quality engineer, to show him the hawk. Barbieur agreed something needed to be done to prevent or lessen the occurrences of these burn injuries. He and other DNR staff would work with the landfill manager.

Whitcomb contacted an engineer and came up with a means to weld a crown of steel spikes on top of the pipes that would not interfere with the methane flaring but would discourage the hawks from perching. Protections for birds flying over the pipes as gases are flared off still need to be developed. The city has also discussed installing a large utility pole higher than the burner that would make a more attractive perch for raptors. Thatís a bit more complicated as the city needs to avoid utility lines buried underground and doesnít want to puncture the landfill liner. Ideally, other landfills might take a first step and install motion cameras near their gas flares that could provide early warning by documenting if this same problem is occurring. Such cameras are inexpensive these days and are commonly used by hunters who want to see if animals are using a path.

Red-tailed hawks and other raptor species are extremely beneficial to the environment. One redtail can consume an average of 1,800 rodents a year. Wisconsin averages 100 rodents per acre of land. In some areas, those numbers are much higher. In three years, two mice can theoretically multiply to 350 million, if the population is left unchecked. So hawks and owls are quite beneficial to the landfill and landowners who live nearby. Turkey vultures also frequent landfills, attracted by smell, and feed mostly on carrion and garbage.

Raptor burns from landfills where trapped gases are automatically flared may be more common than is realized or reported. There are no national statistics on the issue, but several prominent rehabilitation centers I contacted also have admitted similarly burned raptors that staff believe were caused by unprotected landfill methane burners. Itís unknown if the problem is greater in certain geographical areas or if it is restricted to a certain type of methane flares. Trapping and recovering methane gas for energy use could eliminate this hazard where such collection is practical.

While raptors are state and federally protected under the Migratory Bird Treaty Act, costs for rehabilitating injured birds are typically borne by the wildlife rehabilitator. My thanks to the City of Janesville landfill users who made a contribution towards the care and feeding of these hawks.

We hope our local problem has now been resolved, but I want to make other communities aware of this issue and alert to the signs that can indicate when hawks, owls and falcons in their area are getting burned on their daily hunts.

Dianne Moller is a licensed rehabilitator, educator and falconer of birds of prey. She owns and operates Hoo's Woods located near Milton, Wis. and conducts raptor education programs. She also serves as the Great Lakes Regional Direcotr for the North American Falconer's Association.