What is a box check?
A box check is a brief examination of a box's contents, recording what's seen
on a data sheet.  Most Box Check Record sheets (click link to see example
and also see example below) have fields for date, time, box number, species
using the box, stage of nest construction, number of eggs, number of young,
and remarks.  Using codes or abbreviations makes recording easier.











How do you check a box?
  • Approach the box quietly.
  • Unfasten the door gently and open it just enough to peek inside.
  • If there is an adult swallow inside close the door and move on to
    another box, making a note to return to this box later.
  • If there is no adult inside open the door wide enough to view the
    whole interior.
  • Note pertinent box contents data on the Box Check Record sheet.
  • Any broken eggs or dead nestlings you find should be removed and
    disposed of well away from the box.
  • Refasten the door securely and move on.










Warning!  Some types of colonial wasps build nests in birdhouses, usually
anchoring nests on the underside of the roof.  Make it a habit to check for
wasp nests so they can be removed while they are small.  Rubbing the
attachment surface with a bar of soap helps deter wasps from building.

Won't opening boxes disturb the swallows?
They clearly aren't pleased to have you poking in their nests, which is one
reason to make checking boxes the last thing you do on a project visit.
They may give alarm calls, attracting a crowd.  Some may even dive on you.  
But Tree Swallows almost never desert a box that's simply been checked.  

However, there are a few situations when Tree Swallows are sensitive to
disturbance, when you should not open boxes or do so very carefully.  
These are:
  • On mornings when females are laying eggs wait until after 9:00 A.M.
  • During incubation, open the box a crack and peek in to make sure the
    female is not inside before making a full check.   If the female is inside,
    close the box, back away and wait until she leaves before checking.
  • Don't ever check boxes at night!  Females disturbed at night may
    desert, even if they are incubating eggs or brooding small young.
  • Never open a box with nestlings 13 days old or older!  This could cause
    them to leave the nest prematurely and die.  
  • Look carefully at the wing of the 12 day old nestling below.  Note how
    the flight feathers of the wing have partly erupted from their sheaths
    and resemble little paintbrushes.  If you don't know the exact age of
    the nestlings in a box, and you find ones with wings more erupted
    than in this example, leave them alone!  Disturbing them could cause
    them to leave the nest prematurely, and die.
If you take these simple precautions your box checks should be fine.













How often should you make box checks, and how do you know when a box
has laying or incubating females, or when nestlings are 13 days old or older?
It's best to make box checks at least once a week, the more often the better
since there are some crucial events, such as last egg date and hatch date, it's
important to know.

Early in the season you would normally check every box on each visit to your
project.  However, once a female has finished laying her eggs it's best to rely
on your Control Sheet  to guide checks at that box.  The Control Sheet
displays the status of every nest so you'll know which boxes need checking
and when, so unnecessary checks and potential problems can be avoided.  
Refer to your Control Sheet at home before visits.  

Box Check data fields:
  • Date and Time:  Some people omit time.
  • Box Number:  You should have a numbering system for your boxes.  It
    helps to have numbers marked on the box doors.  Note: You may not
    need to check every box on every visit.  Your Control Sheet helps
    determine exceptions.
  • Species:  You can use the banders' four-letter code.  For instance; Tree
    Swallow = TRES, Eastern Bluebird = EABB, House Wren = HOWR, etc.
  • Nest:  Stage of nest construction measured in shape and completeness
    of cup vegetation, and amount of feathers.  For instance:
      MT = empty box
      FG = few grasses or other vegetation
      !/4 C = ring of vegetation hardly visible
      1/2 C = ring visible
      3/4 C = nest cup is shaped but box floor still visible
      CC = complete nest cup formed and box floor covered  
      FF = few feathers
      SF = some feathers
      MF = many feathers
      VMF = very many feathers  
These are all rather subjective, but let you compare nests.  
It's common to stop noting nest construction data once eggs are laid.
  • Eggs:  Number of eggs present.  Tree Swallows lay one egg per day, but
    sometimes if weather is poor females skip a day.  A skip of several days
    usually means another female has taken over the nest and has started
    to lay her own eggs.  Takeover females often lightly cover the eggs of
    the previous female.  Occasionally one or more eggs are thrown out by
    competitors, either other swallows or competing species.  Note: you
    may have to remove eggs one at a time to get an accurate count.  Lift
    them very carefully, place them in a cupped hand, then replace them
    gently in the cup.
  • Young:  Number of young present.  As with eggs you may need to
    remove young to get an accurate count.  Ease your fingers carefully
    underneath each one at a time, lift it out, and place it into your other
    hand.  If they grab nest material in their feet give them a minute to
    relax their grasp.  Older nestlings can be squirmy.  Don't drop!!!  Be sure
    to replace nestlings directly into the nest cup, not out on the edges,
    and return them to the cup very gently so they aren't injured by hard
    pieces of vegetation.
  • Remarks:  You might want to note dead or missing eggs or young,
    runted young, behavior of adults during the check, takeover concerns,
    presence of wasps, unusual nest material, weather issues, etc.






















What do you do with all this data?
You take it home and transfer it to the Nest Box Record sheets you keep for
each box.

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Box Check Records