What are Tree Swallow nest box grids?
  • What's better than one pair of nesting Tree Swallows?  Lots of swallows nesting
    in one place in a nest box grid!
  • You'll find nest box grids mentioned elsewhere on this web site, but since grids
    are one of the neatest things you can do with Tree Swallows we think the topic
    deserves a short page of its own.
  • We define a Tree Swallow nest box grid as a group of pole-mounted swallow
    boxes, spaced at regular intervals, out in an open field.  To us Tree Swallow
    "grids" are synonymous with Tree Swallow "projects."

  • Grids take advantage of the fact that Tree Swallows don't defend large feeding
    territories around their nests the way many other songbirds do.  Since Tree
    Swallows defend only their nest site and a small area immediately around it you
    can attract many nesting pairs to a single field.
  • So, if you can find a suitable site, setting up a nest box grid for Tree Swallows is
    an option you may want to try.  See Finding a Good Site.

How far apart should Tree Swallow boxes be spaced in grids?
  • Boxes for Tree Swallow ought to be at least 100 feet or 28 meters apart.  
    Farther apart is even better if you have the space.  
  • Closer spacing tends to increase squabbling among adult swallows, which may
    interfere with nesting success.
  • The thumbnail diagrams below show approximate box spacings in feet (at left)
    and meters (at right).  Click on images to enlarge view.

How can you measure distances out in the field?
  • At home, determine your average pace or footstep length, so you can use
    number of paces to measure rough distances in the field.

How far from field borders should Tree swallow boxes be placed?
  • Boxes placed far out in fields are less apt to be found by mammalian predators.
  • Try to keep swallow boxes at least 150 feet or 45 meters away from field edges.

How many boxes can be put in a Tree Swallow grid?
  • Quality of the habitat for Tree Swallows and size of the field are the most
    important factors limiting the potential number of boxes in your grid.
  • In general we think it's best to start with a relatively small number of boxes and
    observe swallow nesting success over a couple of seasons.  If the results are
    good you can consider expansion.
  • Over the years we've operated five swallow box grids, with from six to eighteen
    boxes each.  Our current grid (see below: boxes as red dots) starts each year
    with 8 boxes, with additions as needed to accommodate competition.
  • The grid is in excellent habitat and could easily be expanded to 50 or more
    boxes, but we've chosen not to exceed 20.  
  • To view a YouTube video of our Salmon Creek Tree Swallow Grid click here.
  • Our grid can also be viewed by satellite at 43.308N by 77.736W.

  • Tree Swallow grids of 100 boxes or more are often established for scientific
    research, where large data samples are required.  See Tree Swallow Research
    to learn about the many valuable contributions of this species to our knowledge
    of birds in general.

Will other kinds of birds nest in Tree Swallow grids?
  • It's not unusual for bluebirds to claim boxes, even in very large swallow grids.
  • If House Wrens show interest in boxes in a grid the boxes are too close to trees
    or shrubs and should be relocated.  See House Wren Damage.
  • If House Sparrows show interest in boxes in a grid the boxes should be moved
    farther from houses, barns, or other buildings.  See House Sparrow Damage.

Doesn't grouping nest boxes make them more vulnerable to predators?
  • Yes, it can, if you don't place your boxes carefully and don't protect them.
  • If predators, especially raccoons, find and predate one nest box in a grid there
    is a real danger that they will search for other boxes, killing and eating young
    and adult birds as they go.  Entire grids can be wiped out in this way.
  • Please use caution locating boxes and use predator guards with all your boxes,
    whether placed alone or in grids.  See Predator Protection.

Click here for Next Step: Protecting Boxes from Predators.

Tree Swallow Nest Box Grids
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