Swallow nests are mud nests built by barn swallows and other swallow species on the exterior of buildings and structures. While swallows themselves are harmless and even beneficial insect-eating birds, their nests can sometimes cause damage to houses. This article will examine whether swallow nests actually damage houses, look at the potential types of damage they can cause, and provide recommendations on dealing with swallow nests on your home.
Do Swallow Nests Damage Houses?
The short answer is swallow nests can potentially cause damage to houses, but the damage is usually minor or cosmetic in nature. The mud nests are built using mud and grasses gathered by the swallows, then cemented onto a vertical surface using the bird’s saliva. The nests are cup-shaped structures attached to the sides of barns, sheds, bridges, and houses.
When attached to homes, the main way swallow nests cause damage is by eroding building materials as the birds build the nests. The mud and constant moisture from the saliva can wear away at wood, stucco, brick, and mortar over time. The nests also leave behind stains from the mud and droppings. In some cases, large nests built up over successive seasons can cause more extensive damage. However, in most situations the damage caused by swallows nesting on homes is minor.
Some potential types of damage include:
– Staining or streaking on walls or siding from mud or droppings
– Erosion of wood, stucco, brick, or mortar over time
– Nest debris clogging gutters or downspouts
– Spoiling of external paint or finishes
– Structuralweakness if heavy nests are left in place for years
So in summary, swallow nests can technically cause damage, but not typically any major structural or expensive damage. The harm is usually limited to cosmetic issues that can be remedied with cleaning or refinishing. Preventative measures can be taken to minimize any damage that does occur.
Why Do Swallows Nest on Houses?
To understand the potential for swallows nesting on houses, it helps to know a bit about swallow behavior and nesting preferences. Here are some key reasons swallows frequently nest on homes and buildings:
– Ideal vertical surface – Swallows prefer vertical surfaces like walls to attach their mud nests to. The eaves and walls of homes or other structures provide perfect nesting spots.
– Protection from weather – The overhangs of roofs provide shelter and shade for nests. Being tucked close to buildings helps protect the nests from heavy rain or wind.
– Near open areas – Swallows hunt for insects on the wing, so they like nesting sites adjacent to open fields, water, or lawns where flying insects will be abundant. Houses provide both vertical walls and adjacent open space.
– Height above ground – Swallows like nesting high up, 10 feet or more above ground, to avoid predators. The height of homes suits this need.
– LED lights attract insects – Many modern porch and security lights use LED bulbs, which attract more night-flying insects than older bulbs. More insects mean more food.
– Lack of natural nest sites – Deforestation and development reduces cliffsides, caves, and trees suitable for nests. Manmade structures substitute for disappearing natural sites.
So in many ways, human homes frequently provide an ideal substitute nesting habitat for swallows that have lost natural options. This draws the birds to settle on houses, despite not being designed for them.
Types of Swallow Nests on Houses
There are a few common species of swallows known to nest on residential buildings in the United States and Canada:
– Barn Swallow – This is the most common species to nest on homes. They build distinctive cup-shaped mud nests on ledges or beams.
– Cliff Swallow – Makes gourd or jug-shaped mud nests clustered together on walls. Favorite spot is under eaves.
– Bank Swallow – Digs burrows into soil banks, but may nest in gaps or crevices on homes. Nest is a mud cup attached to the hole.
– Northern Rough-winged Swallow – Nests in cavities including spaces under roof tiles or shingles. Likes barn-shaped nests.
– Purple Martin – A larger swallow that nests in birdhouses or gourds. May occupy apartments on a special “martin house.”
Here is a visual guide to the different common swallow nest types and locations:
Barn Swallow
Barn swallow nests are mud cups attached to vertical walls or beams. Favorite spots include eaves, porch ceilings, garage doors, and window sills. Multiple nests are often clumped together.
Cliff Swallow
Cliff swallows build dense clusters of gourd-shaped nests together on walls or under eaves. The nests have a tunnel entrance at the top.
Northern Rough-winged Swallow
These swallows nest in cavities like spaces under roof tiles, shingles, or flashing. The nest is a mud cup attached to a vertical surface.
Bank Swallow
Bank swallows dig burrows in dirt or sand banks, but may also use gaps or crevices in buildings. The nest is a mud gourd-shape attached to the cavity.
Purple Martin
Purple martins nest in bird houses or multi-chamber “martin apartments” installed by homeowners who want to attract this bird.
Potential Damage Caused by Swallow Nests
As discussed previously, barn swallow nests do not generally cause major damage to homes, but their mud structures can lead to some cosmetic or nuisance issues such as:
– Staining on walls, siding, or finishes
– Eroding wood, stucco, masonry
– Nest debris clogging gutters
– Droppings collecting on walls or decks
– Spoiling exterior paint before time
– Making a mess during nest demolition
– Bird mites infesting nearby areas
Structural damage would be very unlikely except in cases of a very large nest stack built up over many seasons. Nests are generally less than 1-2 pounds. Risks come from the mud eroding materials or moisture being held against surfaces. Wood rot is unlikely unless combined with another moisture source.
The mess, staining, and required cleaning are the most common damages. These can be prevented or controlled quite easily. Serious damages requiring siding replacement or stucco repair would be rare.
Severity of Damage
Here is an approximate guide to the severity of damage swallow nests may cause:
– Mild – Staining, streaking, minor erosion of paint or finishes
– Moderate – Noticeable erosion and crumbling of mortar or wood, minor staining
– Severe – Major erosion and structural weakening, extensive staining, costly repairs needed
Most homes will only experience mild to moderate damage at most. Only in extreme long-term cases would damage reach a severe level.
Should You Remove Swallow Nests From a House?
Homeowners have a few options when it comes to dealing with barn swallow nests on their homes:
1. Leave them in place
2. Remove nests after nesting season
3. Prevent nest building
Here are considerations for each approach:
Leave Swallow Nests in Place
Advantages:
– No work removing nests
– No risk of swallows rebuilding in same spots
– Enjoy watching the birds raise their young
Disadvantages:
– Nests may slowly damage building
– More droppings build up over years
– Messy remains after birds leave nest
– Nests can obstruct lights or cameras
Leaving swallow nests in place requires minimal effort, but damage may worsen over time. Only recommended if damage is already very minor. Should check nests annually.
Remove Nests After Nesting Season
Advantages:
– Minimizes building damage
– Fresh start each year
– Can enjoy watching young fledge
Disadvantages:
– Difficult to remove old nests
– Risk birds will rebuild in same spots
– Must avoid disturbing nests in season
Removing nests annually reduces damage but requires work. Best done in winter when nests are abandoned. Avoid removing active nests during breeding season.
Prevent Nest Building
Advantages:
– Eliminates damage from start
– Maintains building appearance
– Discourages annual nesting
Disadvantages:
– Deters desired wild birds
– Ongoing prevention required
– May be considered inhumane
Blocking nest building stops damage but prevents enjoyment of swallows using your home. Requires vigilance each spring.
Tips for Preventing Swallow Nesting
Here are some tips to stop barn swallows from building mud nests on your house:
– Install plastic owls or hawk decoys nearby – Swallows avoid areas patrolled by predatory birds
– Hang wind chimes or reflective ribbons – Movement and reflections deter swallows
– Apply gels or pastes – Non-drying gels make surfaces too slick to attach nests
– Place wooden boards with spikes – Spikes stick out and prevent nest adhesion
– Hang fishing line in grid pattern – Ciss-crossing line blocks nest attachment sites
– Use sound devices – Speakers with predator calls or alarm sounds scare off swallows
– Keep lights off at night – Darkness reduces insect prey attracting swallows
– Remove food sources – Fix leaks, manage pet waste, and drain standing water to limit insects
– Maintain clear sight lines – Prune landscaping so swallows feel exposed and unsafe
– Apply repellent chemicals – Bird repellent pastes or sprays create an unfavorable roosting surface
– Seal gaps and cavities – Plug spaces swallows could use to access sheltered nesting spots
Persistence is key, as swallows are highly motivated to rebuild nests each spring. Ongoing vigilance and reapplication of deterrents is often needed.
When to Remove or Discourage Nests
It’s important to know when during the swallow breeding season certain actions are legal or ethical:
– Discouraging nest starts – Use deterrents in early spring before breeding begins
– Removing old nests – Take down empty nests after breeding season ends (late summer)
– Blocking partially built nests – Can carefully remove new nests before eggs are laid
– Leaving active nests – Cannot disturb occupied nests with eggs or young
– Letting fledglings leave – After young can fly, nests can be removed
So the key times to remove nests are early spring before breeding and late summer after young have fledged. Active nests must be left undisturbed during summer breeding season.
Conclusion
While messy and occasionally causing minor cosmetic damage, barn swallow nests on homes are generally harmless to enjoy from a distance. Many people like seeing the aerial acrobatics and young swallows being raised. Limited damage can be mitigated by cleaning and refinishing affected areas annually. Extensive damage is rare, and there are humane ways to exclude or dissuade swallows when needed. With some seasonal maintenance and awareness, the birds and homeowners can peacefully coexist.
