The Problem:  House Sparrows can be terribly destructive of Tree
Swallows, Bluebirds, Purple Martins, Chickadees and other native birds.

Many people feel, and we agree, that:

These non-native birds, also called English Sparrows, were introduced from Europe
roughly 150 years ago.  They now number over 80,000,000 in North America, occurring
almost everywhere people live, and wherever House Sparrows are found they compete
with native cavity-nesting species for nest sites.  Sadly, each year House Sparrows kill
thousands of native birds, trapping them in their nests and pecking them to death.  The
photo below, taken by Joni James, shows graphically what a House Sparrow did to an
adult Tree Swallow in Indiana.

And it's not just adult songbirds that are victims of House Sparrows attacks.  The photo
below, from Dick Stauffer, shows four nestling Tree Swallows that were killed inside their
nest box in Alberta.    

Although native birds try to defend their nests from destruction and usurpation by House
Sparrows they usually lose the battle, and sometimes their lives, in the end.  Photo
below of a House Sparrow (left) and a Tree Swallow (right) by Tom Beattie.

An excellent summary of the House Sparrow problem, written by Kathy Freeze of the
Purple Martin Conservation Association, can be found by clicking

You need to be able to identify House Sparrows so you can prevent
injury or death of swallows and other native birds.

Study the photos above or check a field guide if you aren't sure what House Sparrows
look like.  Note that males and females appear different, and also remember that not all
small brownish birds are House Sparrows

What can be done to stop House Sparrow destruction?

The best source of information concerning the House Sparrow problem is the bluebird
hobbyist web site
Sialis.  Click Here for its comprehensive presentation of issues and
tactics of House Sparrow control.  We will not try to restate this material.  Instead, we will
consider two House Sparrow versus Tree Swallow situations:

  • How to avoid sparrow destruction of swallow nestings in the FUTURE.
  • What to do if sparrows are threatening your swallow nests NOW.

IF House Sparrows destroyed PAST Tree Swallow nestings,
and you're worried it could happen again IN THE FUTURE:

  • Consider relocating your boxes.
  • The best way to avoid house sparrow competition is to place swallow
    boxes far from houses, barns, and other buildings where House
    Sparrows congregate, at least 100 yards away, preferably much more.  
  • Don't add more boxes to "give everyone a chance to nest."  More is not better.

NO box or entrance design will keep House Sparrows out!
  • Many people have tried to design nest boxes that would prevent House Sparrow
    damage, with little or no success.
  • Boxes with small interiors will not deter House Sparrows, despite claims,
    and small interiors can be detrimental or even fatal for young swallows
    and bluebirds.  Click Here for a page containing a discussion of nest box size.
  • Very small entrance holes will prevent House Sparrows from entering boxes
    intended for chickadees and some wrens, but will also prevent bluebirds and
    swallows from using the boxes.
  • Slotted entrances, like the one below from Duncraft, do NOT stop all
    House Sparrows from taking over swallow and bluebird boxes.  Tree
    Swallows, with their slender bodies and small heads, enter these boxes easily.  
    But, although House Sparrows are generally bulkier, in most populations there are
    individual sparrows that can also squeeze through even narrow slots.

  • Slotted entrance restrictors like the one below, have also failed in many cases.

  • Therefore, since the destruction of swallows and bluebirds by House Sparrows
    has not been solved through box design, we continue to recommend that
    boxes intended for these songbirds should be located far from buildings.

IF you have Tree Swallows trying to nest NOW, and House
Sparrows are attempting to take over their box

  • Odds are the sparrows will not leave, and it's only a matter of time before they
    destroy the swallow nesting.  
  • Your options are limited: You can kill the House Sparrows, or try non-lethal
    alternatives such as Sparrow Spookers or Hironbec Pendulums.

  • House Sparrows are considered non-native pests and are not protected by law.  
    They can be trapped and killed, or killed outright.  
  • Methods for doing this can be found on the Sialis page Here.
  • The same Sialis page explains why you should not relocate House Sparrows.

  • If you don't want to kill House Sparrows you might try a Sparrow Spooker.  

  • Spookers are simple, cheap, easily made devices that, when used correctly, can
    successfully protect bluebirds according to bluebird experts.
  • They utilize flexible flashing strips, often made of mylar sold at garden stores, that
    flutter over box lids, frightening House Sparrows enough to prevent intrusions.
  • Some other birds, including bluebirds and Tree Swallows, are more accepting.

  • We found spookers did deter House Sparrows from intruding on Tree
    Swallow boxes in a very small-scale test we conducted in 2017.
  • Spooker plans and guidelines for use can be found Here on Sialis.

  • Another non-lethal option is the Hironbec Pendulum (below), invented and sold
    exclusively by Rene Lepage of Quebec, who designed them specifically to protect
    Tree Swallows from House Sparrows.  Click Here to visit his web site.
  • Pendulums attach over nest box entrance holes and take advantage of the weight
    difference between Tree Swallows, average about 20 grams, and House
    Sparrows, average about 28 grams, to prevent the latter from entering boxes.
  • We tested pendulums successfully for several years and offer our own
    recommendations for their use (see below).

  • If you consider buying a pendulum please read this entire section carefully, being
    sure to follow all links so you will have an understanding of what's involved.
  • Click Here to view our video:  "How to Use Hironbec Pendulums to Protect
    Nesting Tree Swallows from House Sparrows."
  • And click Here for our instructional pdf:  "Suggestions for Using Hironbec
    Pendulums to Protect Tree Swallow Nests from House Sparrows."

  • When adjusted correctly a swallow can land at a pendulum entrance and pass
    through it into the box.  But if a sparrow lands its heavier weight causes the
    pendulum to pivot, blocking the box entrance (see below).
  • Click Here  to learn more about Pendulum design and operation.

Our Pendulum Trial Results:  
  • During the 2014, 2015 and 2016 seasons we placed pendulum-equipped boxes in
    a total of eight locations we thought were at high risk for sparrow intrusions.
  • Despite this small sample we learned much regarding pendulum use, and found
    they did protect Tree Swallow nests from House Sparrows when
    introduced and adjusted correctly, and then monitored daily.
  • Box design, box location, and timing of box presentation were very important.
  • It was crucial that Tree Swallows were helped to learn pendulum use first, before
    House Sparrows did, because the first species to learn possessed the box.
  • Therefore, it was necessary to wait to present pendulum-equipped boxes
    for several weeks after Tree Swallows had arrived in spring, until female
    swallows were highly motivated to enter boxes to build nests.

  • Females ready to build learned to pass through pendulums very quickly,
    especially if we assisted during a female's "lesson" by supplying nest grasses,
    making weight adjustments, and chasing House Sparrows away.
  • Once a female Tree Swallow mastered a fully-sensitized pendulum, its tippiness,
    plus the swallow pair's nest defense, prevented House Sparrow takeovers.
  • After a few days House Sparrows ignored pendulum-equipped boxes, perhaps
    because they had found these boxes were unattainable.

  • Male swallows learned pendulum operation later while carrying feathers into nests
    and when feeding nestlings.
  • Click Here to see a YouTube video showing skilled parent Tree Swallows passing
    through a Pendulum.  
  • We worried older nestlings near fledging might climb into Pendulums to wait for
    parents bringing food, and be tipped out onto the ground.  However, nestlings
    adapted to Pendulum movements, and backed into the box when necessary.

  • Pendulums did not reduce reproductive performance.  Nest construction, eggs
    laid, eggs hatched and nestlings fledged did not differ significantly from 32 nests
    in a control group of boxes without pendulums.
  • However, Pendulums were not something one could set and forget.  They needed
    daily monitoring to make sure they were correctly positioned and not jammed with
    feathers or stems (see below).

  • In summary, despite some initial skepticism, we are now optimistic
    regarding the Hironbec Pendulum's ability to protect nesting Tree
    Swallows from House Sparrow intrusions.  
  • We also predict these devices should shield other cavity-nesters like the light-
    weight Violet-Green Swallow (14 grams) in Rob Robinson's photo below, and we
    encourage folks in western North America try pendulums with this species.

Learn About Birds at Tree Swallow Nest Box Projects
House Sparrow Damage
to Tree Swallow Nestings
It is better not to have a nest box at all
than to have a nest box that raises House Sparrows!