Bluebird and Small Cavity Nester Conservation
Sialis - Bluebirds and other small cavity nesters

eggsManaging House Sparrows - EXPERIMENTS

Warning: This webpage deals with both active and passive means of managing House Sparrow (HOSP) populations. These methods are experimental (i.e., unproven.)


Also see: Proven HOSP control methods (active and passive), HOSP Photos, History, Attacks (warning: graphic photos), photos and descriptions of other brown birds that look like HOSP, Biology, Population Proliferation, Video Clip of HOSP Attack, information on euthanizing captured birds, HOSP advisory handout for people with boxes used by HOSP and one for commercial facilities allowing HOSP to breed/roost/feed, trap review, and essay "Are HOSP Evil?" Separate webpages with drawings and photos on sparrow spookers, Magic Halo, and How to Trim Wings and Links for more information and DIY drawings.

It's possible neophobia (fear of novel objects) may be a factor with HOSP being deterred by sparrow spookers, monofilament, magic halos, and different box styles. However, a HOSP will readily investigate a new wooden box that is put up.

Nestbox Type (Also see Nestbox Styles, Pros and Cons) No nestbox suitable for bluebirds is HOSP-proof. HOSP are smaller than bluebirds, and thus can enter any hole a bluebird can fit through.
  • Be aware that even though HOSP may not "prefer" to nest in certain types of nestboxes, they may still enter them for the purposes of attack, and may use them if nesting cavities are limited or competition for sites is fierce. They may also enter them if they are being used by another bird, due to their competitive nature.

Type of boxes HOSP MAY avoid or not prefer: Again, despite claims you may read, no one has invented a nestbox yet that HOSP will not use. One of the reasons HOSP are so widespread is that they are very adaptable. HOSP tend to be wary of change, and may initially avoid a new type of box. But over time (or due to nest site competition) they may become accustomed to it, and use these boxes.

  • A square hole 1.25 x 1.25" has been suggested (Terres 1953) to allow the slender bluebird access but prevent the "pudgier" HOSP from entering.
  • A "K" box (designed by Terry Glanzman) was reported by some BRAW monitors to be quite effective in deterring HOSP. It is shallow, but has no side ventilation, and the design looks similar to a Gilwood box.
  • A thicker, slick PVC box is being tested by Keith Radel of MN to see if HOSP have trouble hanging on to the entrance.
  • LIGHT: Some speculate that HOSP prefer a dark, deep cavity. Others believe that light is not a significant factor, as HOSP will nest in the open (e.g., on top of a sign), although these nests tend to have a tunnel-like entrance. Varner (1964) felt that bluebirds also prefer darkness inside the box, so a design that lets light in might also deter bluebirds somewhat. The main concern is designs that let in so much light that the interior can overheat, or let in nasty weather.
    • Open-top "Bauldry" boxes are no longer recommended by NABS. They have a 3" hole in the top, covered with hardware cloth. Supposedly HOSP don't like a wet nest. Unfortunately, it is not healthy for bluebird nestlings either, and can increase the likelihood of fatal hypothermia. These boxes may still be used by HOSP.
      • One birding store owner tried covering the 3" hole with plexiglas (on the theory that light deters HOSP), but the heat killed the eggs and nestlings. However, he did indicate that bluebirds appeared to prefer these boxes (Zimmerman personal communication, 2004)
    • Boxes with 1/2 of the roof made of Plexiglas (covered during warmer weather to prevent overheating) do not appear to deter HOSP long term.
    • Boxes built with extra light entering the box (vents, slots, two holes, plexiglas) are all used by HOSP. HOSP have been known to use a nestbox that has no roof at all. I don't know whether they are really not PREFERRED by HOSP.
    • Removing most of the wood bottom of the nestbox and covering it with circles of Plexiglas, or with 1/4" hardware cloth so that the bottom looks open to a bird looking inside the nestbox does not work long-term (Kridler on Dick Walker experiment).

Experiments with light continue:

  • We know that HOSP WILL use a box that lets more light in (see above.) The question is, will they AVOID a box like this, or PREFER a box that is darker over a lighter one when given a choice? And will Loren Hughes slot box.  Photo by Hughes.native cavity nesters use a box with a lighter interior?
  • The bigger entrance hole in the Gilwood (which HOSP tend not to prefer) or a 2-hole box does let in more light.
  • Loren Hughes experimented with drilling a 2" hole in the side of the nestbox near the top. Then he stapled a 3" square piece of plastic cut from a milk jug over the hole on the outside of the nestbox. Note that the plastic may become brittle over time, and need to be replaced. He tested coating it with KRYLON Crystal clear acrylic spray to see if it lasted longer. Initially, HOSP seem to lose interest in the box (possibly due to neophobia - fear of something new). Some HOSP packed grass against the acrylic to block out light. He discontinued this experiment.


Unfortunately passive methods have limited effectiveness. Active management includes rendering eggs infertile, egg and nest removal, HOSP trapping, shooting, etc. Since House Sparrows are classified as pests and are not protected by U.S. federal law, they may be quickly and humanely euthanized.

  • Playbacks (recordings): Some folks have suggested using a plastic/stuffed decoy + tape recording of a call - I'd be interested in knowing whether this is an effective lure for HOSP. Elizabeth Farley (who has worked on projects where birds were target netted) suggested that songs or calls would work best at the beginning and during the height of the breeding season when testosterone levels are high. Calls, especially alarm calls, will often attract members of both sexes, and sometimes individuals of other species as well. If several songs from several different birds are used, it may take longer to become desensitized, depending  on how often you play the recording(s). Try playing the recording for about 30-60 seconds, then stop for several minutes before playing it again. This works especially well if you have detachable speakers with really long cords, so you can hide them near your box, and control the player from a distance. You can also record the tape/CD so there is several minutes of silence between songs and just set it up, push play, and watch from a distance. Birds will tend to "fly-by" back and forth over wherever the speakers are first, and then sometimes go right up to them directly when they fail to see another bird. If the bird is released, it is unlikely that you can recapture it using this method.


I'm including this because I've seen it proposed more than once - some homemade method to electrify a feeder or birdhouse to "zap" HOSP. Putting aside the difficulties of targeting HOSP only and the technical challenges of properly designing a circuit, this approach is fraught with dangerous possibilities, including seriously injuring or electrocuting yourself, especially for a person who is not a skilled electrician. Apparently there are commercially available feeders "designed to train squirrels and raccoons to stay away from it by giving them a mild electrical shock" that are supposedly ASPCA approved. But as one bluebird landlord said "A combination of selective feeding (or no feeding), in-box trapping, repeating traps, and spookers have proven themselves to be effective and safe methods for HOSP control. I doubt that any electrocution device would prove the same." Personally, I don't want to see ANYONE get hurt, or to accidentally injure or kill a native bird, which would be illegal under the Migratory Bird Treaty Act.


  • Garlic (in a feeder or nestbox) has not been found to repel House Sparrows. It might work on vampires though.
  • Thick wood block hole guards like the one shown on the box below are not thought to deter House Sparrows, and may even be attractive to them. They MAY (according to Bluebird Love) also deter Tree Swallows, although many trail monitors have not had this experience. Boxes without blocks may be accepted more readily by bluebirds (Musselman 1934). They do not deter raccoons. The only purpose they serve is to make it harder for avian predators (jays, etc.) to reach eggs and nestlings, and for squirrels or woodpeckers to widen the entrance hole.
  • A Carrier (slant) box, which looks like a nestbox turned on its side with the hole facing the ground is not effective in deterring HOSP - it may even be preferred by them. It is almost impossible to trap HOSP in this box, and contents may spill out during monitoring. It is probably best suited for flying squirrels.
  • Hanging/swinging nestboxes do not effectively deter HOSP. However, Linda Violett in CA has had success with large hanging two-holed boxes. See more.
  • Starling Extruder Doors used in Purple Martin gourds do not effectively deter HOSP.
  • HOSP adapt quickly to sound frightening devices (fireworks, shell crackers, acetylene exploders, and cymbals, alarm or distress calls).
  • Nixalite (pointy wire generally used to repel pigeons) will simply be used to hold nests in place.
  • Fake plastic snakes inside a box. Some HOSP have incorporated them into their nest.
  • Putting a baseball in the nest cup. Kenneth Y of NY reported that the House Sparrows proceeded to construct a new nest directly on top of the baseball.
  • Nestbox Color: It has been suggested that painting a nestbox a sky blue color might deter HOSP. Several folks who had tried it did NOT find that it helped. There is also a concern that boxes painted any color but white will get too hot inside.
  • Frightening Noises: (fireworks, shell crackers, acetylene exploders, cymbals): They move HOSP from an area short term, but the birds become accustomed to them over time unless the sounds are diversified and locations are shifted periodically.

References and Links for more information

Sparrow Trap and Other Supply Links - also see page on Retail Suppliers

The information provided here is for informational purposes only and users of the information do so at their own risk. The reader must consult state/federal officials to determine the legality of any technique in the reader's locale. See remainder of disclaimer.

All solutions to HOSP control have drawbacks, but not controlling them at all has the greatest drawback.
- Cherie Layton, The Bluebird Nut, 2006




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