Birds do not hibernate in winter. While some migrate, some birds like chimney swifts and grackles will need to find warm places around Minneapolis-St. Paul. The warmth from chimneys and furnace vents are two common places we find birds in Minneapolis homes during the winter.

Exhaust vents and chimneys both offer dry, warm shelter for birds.

Why Birds Choose Your Furnace Vent

To a bird, an unprotected PVC or metal exhaust pipe looks like a cozy tree hollow. During late winter and early spring, birds search for warm spots to escape the chill and build nests. Your furnace exhaust emits rising heat, creating an ideal microclimate. Unfortunately, once a bird hops or falls inside the smooth vertical pipe, it cannot spread its wings to fly back out.

The Danger of Blocked Exhaust Vents and Carbon Monoxide

The primary job of your furnace exhaust pipe is to pump deadly combustion gases—including carbon monoxide (CO)—safely out of your home. When a bird or its nesting debris clogs this pipe, those odorless, colorless gases have nowhere to go except back into your living space. Running your furnace with a blocked vent creates an immediate, life-threatening carbon monoxide hazard for your household.

How Nesting Materials Damage Your Heating System

Birds don't just get stuck; they bring dried twigs, straw, grass, and feathers. This debris creates a double threat. First, highly flammable nesting materials sitting near the furnace's heat exchanger or draft inducer motor create a direct fire hazard. Second, the added resistance forces your furnace motor to work overtime, causing internal components to overheat, break down, or shut off completely in the dead of winter.

Birds in Chimneys

Several bird species, in their natural habitat, gravitate toward nesting in the nooks and crannies of cliffs. The most common of these are chimney swifts, swallows, and pigeons.

Signs of Birds in Chimney

Whether you have chimney swifts, swallows, or pigeons in your chimney, they share signs. Small, gray birds with cigar-shaped torsos and long, curved wings, chimney swifts soar through the air, making loud chattering noises. To figure out if you have birds in your chimney, look for these signs of birds:

Sights

• If chimney swifts live in your chimney, they will fly out to feed in the early morning and return in the evening. Swifts are easy to mistake for bats. Unlike swifts, bats have an opposite schedule. Bats are nocturnal. If you see flights out of your chimney at sunset, it’s most likely to be bats. Another way to know whether you have bats or birds is that birds will fly in and out all day to feed their young.
• Looking into your chimney, you should be able to see one or more nest-like structures clinging to the chimney walls.
• You might see nesting materials such as leaves and twigs that have fallen into your fireplace. This happens not only with swifts but also when other species of birds nest in your chimney.

Bird Sounds

• During nesting season, which runs from about March or April to October, you will hear chirping and begging calls from baby swifts. Chimney swifts are vocal birds. You can hear chimney swift noises inside your home near the chimney. If the bird in your chimney is a pigeon, you’ll hear cooing sounds. With any bird, you may also hear wings flapping and scratching.

Smells

• As bird droppings accumulate along chimney walls and in your fireplace, you will notice a foul odor.

Problems Birds in Chimney Causes

While birds are a welcome sign of spring and may seem harmless, when nesting in your chimney, they pose a risk to your health and home.

Fire Hazard

Most bird nests are built with twigs, leaves, and grass, all of which are quite flammable. If you light a fire when birds are nesting, even the tiniest spark can cause a fire. During summer, when these materials become dry, the risk increases. In addition, using your fireplace with a bird nest in the chimney can partially block the release of smoke. This can trap carbon monoxide in your home.

Structural Damage

Over time, bird nests can cause long-term and costly damage to the structure of your chimney. The accumulation of moisture, debris, and droppings can weaken your brickwork. Bird droppings contain high levels of uric acid. This acid is potent enough to damage brick, stone, cement, and many other materials we would normally think of as strong.

This is especially important if you have chimney swifts in your chimney. These migratory birds often return to the same place to nest year after year.

Health Risks

Birds in chimneys pose health risks and spread disease, infections, and parasites.

Bird droppings contain bacteria, parasites, and allergens affecting the lungs. Dried bird droppings grow fungi that cause respiratory diseases such as histoplasmosis and tuberculosis and can also worsen existing respiratory illnesses such as asthma.

The parasites they carry include fleas, mites, lice, and ticks. Once in your home, they are difficult to eradicate and will cause you and your pets discomfort.

Bird Control Solutions

Birds are federally protected by the Migratory Bird Treaty Act. It is unlawful to kill, capture, or harm them in any way. When you need bird removal from your chimney, the professionals at Wildlife Management Services are your best solution. We have over 40 years of experience in the humane and lawful removal of any nuisance animal in and around homes.

Deterrents

Chimneys are not the only places in your home where birds cause harm. Many backyard bird species will nest in gutters, soffits, vents, and attics, too. The most effective way to keep them away from your home is with bird deterrents your house a less attractive roosting and nesting spot.

Sonic and ultrasonic devices emit sounds that imitate predators such as owls, hawks, and eagles. Some devices sound like gunshots, screeching, clapping, and shouting. Sonic devices emit sounds humans and birds can hear, while ultrasonic sounds are only audible to birds.

Sonic devices can produce positive results quickly but can annoy people. Birds can also get used to the sound, making them less effective over time. Ultrasonic devices have multiple frequencies, so the birds don’t get used to the sounds. Also, humans can’t hear them, so they aren’t annoying.

Visual deterrents can also be useful. These include decoys of bird predators—owls, hawks, and snakes—that scare birds away. Non-animal examples of visual deterrents include shiny objects that sway in the breeze, reflective devices, and bright balloons with large eyes or targets on them.

Exclusions for Bird Control

Bird exclusions are physical barriers that keep birds out or away from certain areas. Use exclusions after you've eradicated birds from your chimney to keep them from returning. Exclusion is a more permanent solution.

Chimney caps are protective coverings that fit on top of your chimney. In addition to keeping birds out, they will keep other wildlife, such as raccoons and squirrels, out. Made of metal, they come in different sizes and will keep rain and snow from damaging your chimney’s bricks and dampers, prevent downdrafts, and keep embers from flying out onto your roof.

Install a chimney cap in the fall, after chimney swifts have left on their migration south. When they return in the spring, they will not be able to enter the chimney to take up residence again.

Repairing and sealing around your chimney keeps chimney swifts from finding an alternate entrance.

Chimney swifts are beneficial birds to have around the yard when nesting outside and away from your home. When you see them soaring back and forth high in the air, they are catching bugs mid-flight, eating as many as 12,000 insects—mosquitoes, wasps, and aerial spiders—daily. Chimney swifts are declining, and many supporters build chimney swift towers in their yards or advocate for them in parks.

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