Monitoring A Trail

Once your trail or boxes are up and ready, it is important to monitor them. This will allow the bluebirds to thrive in the best possible conditions.

Bluebirders are urged to monitor all nest boxes under their care on a weekly basis.


Monitoring Forms

Multiple Nest Box Weekly Field Record Monitor’s Short Form 

Individual Nest Box Weekly Field Record

The Annual Bird Nesting Survey Summary EZ Form

More Tips by Kent Hall, Ph.D.

Nest, Egg & Chick Removal for bluebirds, chickadees, Tree Swallows (1, 2, 3, 4) and House Wrens (4): What are the Procedures approved by USFWS in Dec., 2006

Partial or complete nests w/o eggs: 1st week; 2nd , 3rd weeks no change, then remove; restart week count if more building occurs; if wet, remove, replace with dry, fine grass or pine needles (white pine preferred). Touch eggs each week; if they are warm, they are being incubated; if they then turn cold, they have been abandoned and are dead; to test your judgment, remove a single egg and crack it open. If the egg is viable (has a moving embryo), leave the remaining eggs—but if the embryo does not move (= dead) or the egg is empty, remove cold eggs and nest. It is also possible for dead eggs to be incubated well after they should have hatched (up to four weeks), and are warm to the touch. Leaving eggs in a nest this long simply “robs” the nesting pair of precious time in the season when they could be rebuilding a productive nest. To prevent this problem, estimate the date for the last egg being laid (one egg is laid/day). Add 19 days to that date (14 for incubation; 5 for a delay in incubation) and when the monitoring date hits the 19 days or beyond, remove a single egg and repeat the procedure in #2). Chicks starving/lethargic: foster into nests with chicks of similar age, + or – 2 days [place with slightly younger, if possible]: 85% reared by adoptive parents in a 4-year study by the ALAS in central WI. House Wrens Only: If a partial nest of sticks is in your nest box the 1st week, remove them; the 2nd week, remove them and tape the opening. In two weeks, open the box and repeat. The 2nd taping should be left until the end of the season because no other species can nest in the box in the territory of a wren or you can choose to allow the wren to complete its nesting. If egg cup or eggs are found at any time, you should allow the natural cycle to continue.

Where should you put the nest boxes to avoid predators?

Do not put boxes on wooden fence or electrical posts. The cheapest and most convenient mounting system uses 3/4” electrical conduit.

  • Cut 10’ conduit to 6’-8” lengths.
  • Flatten 4” at end bury 18” of conduit.
  • To the remaining 5’ conduit attach two 3/4” clamps and screw to box.
  • Two 3/4” pieces can be joined with a coupler to make a 6’-8” post.
See more…


In the summer of 2012, Leif Marking and assistants videotaped raccoons climbing fence posts covered with PVC tubing. Previously, it was thought that such protected posts not be climbed by them. It was also thought that one detect raccoon predation raids by nesting materials being pulled from boxes. The Marking team found that raccoons remove eggs and pop them into their mouths like we do M & M’s without removing nesting materials. Numerous monitors ask me what causes the loss of eggs with the nest left perfectly intact. We must now suspect that many of these losses are due to raccoons. To prevent raids of your nest boxes by raccoons, two preventive measures are suggested:Use wool or a wire brush to smooth off oxidized PVC and/orSmear car wax paste on the post.

House Sparrows

House Sparrows are exotic, introduced species from Europe. They have no legal protection from the USFWS in North America. They have a strong, seed crushing beak that easily out-competes the slender/weaker insect-eating beak of other. The best way to prevent these pests from occupying your nest boxes is to keep them away from livestock (especially cattle) or homes with feeders using millet and/or cracked corn as these locations attract large numbers. But these pests can fly up to ½ mile to occupy a box, so considerable habitat is lost nest boxes unless another alternate is used. And the best alternative is a Van Ert trap (VanErt Sparrow traps: 22684 US 69, Leon, Iowa 50144, 641-446-6471, fvanert@grm. net, (cost is about $10 + S&H) Van Ert are easy to insert and highly effective when used properly. should be set only when the sparrow is building a nest or has already constructed one. Then, all nesting materials should be removed from the box (including eggs). Usually, the male is trapped and that is a good thing because he is the “enticer” of the female. Trapping a female is not as effective as the male will attract another female. Rarely, both are trapped together. Dispose of the sparrow, put a clear, plastic sack (held tight at the bottom) over the nest box. Open the door and the sparrow will fly out and can be penned against the side of the box and disposed of. In 60-75% of the time, only one trapping is necessary to clear up the nest box for protected songbirds. In two years of ALAS studies, almost 100% of boxes with removed sparrows have produced young from other songbirds, mainly bluebirds. The major problem faced by trapping sparrows is how long to leave the traps in place. I use two approaches: Set trap and return after monitoring the rest of my boxes or Set trap and return the next day. By that time, the sparrows are dead, but if you have trapped a swallow or bluebird, they will still be alive and can be released unharmed. My experience is this: “Leaving traps in nest boxes rarely leads to the deaths of accidentally trapped but protected songbirds, if the trap is left no longer than 12 hours”. See also this PDF made by a bluebird lover.

Black Flies

Black flies are a menace like no other to cavity nesting song-birds. In Wisconsin, blackflies are limited mainly to the south-drift less areas of the state. The counties there have many slow-moving but low-pollution streams that are ideal for of black flies. Female black flies are the real culprit of this insect. Like female mosquitoes, they are attracted by CO2 given off by incubating hens or immobile chicks and bite them for a blood meal. Females are driven off their eggs by the persistent biting of black flies but chicks can’t get away from black flies and are killed by dozens of black fly bites. Anyone who finds a brood of chicks killed by black flies will not soon forget it. But we now have a way to prevent black fly deaths:

  • Use Permethrin-10 poultry insecticide.
  • Dilute it to 0.50% concentration and place it into an aspirator bottle such as a “Windex Bottle”.
When you find black flies around your nest box (swarms hover like a large fruit fly) use this protocol to prevent the hen from abandoning the nest box and the death of the chicks:
  • Spray the opening and all cracks on the box, both inside and out
  • If there are eggs in the nest, put a small, clear jar over the eggs and spray the nest thoroughly
  • If there are chicks in the nest, make sure they are at least 3 days of age—mist thoroughly (spray does not harm the eyes)
The 2nd week:
  • Spray the hole and cracks on the outside of the box only, again plus the nest if the eggs have not hatched and spray the chicks for the 2nd and final time.
  • If you recognize that black flies are being attracted to your boxes, you can almost eliminate black fly problems entirely, if you use these techniques.


Woodpeckers can cause great destruction to nest boxes as they use them as roost-sites in fall, winter and early spring. Hairy Woodpeckers occupy boxes the most followed by Downy Woodpeckers. We have tried to keep woodpeckers out of our boxes by placing thin wafers of aluminum or ¼” plastic over the damaged holes. Nothing has worked well as woodpeckers have the striking ability to “chisel” materials used to patch the damage. Heavier metal can be used, but is too costly to be useful for large trails. The only practical solution is to leave the boxes open in the winter to keep woodpeckers out (even then, they sometimes do damage). We use wire to keep the doors open as “good Samaritans” walking past boxes completely open, sometimes close them as an act of good will during the winter. Wires can be unwrapped and boxes closed on March 15 to accommodate early arriving bluebirds. These wires can also be used to keep lids open for a week after the first bluebird has fledged to increase the likelihood that the bluebird will produce a 2nd brood. Another advantage to keeping the boxes open during the winter is that chickadees and House Sparrows do not use the boxes for roost sites during the winter. This approach levels the playing field for bluebirds coming to nest in the early weeks of the season.


Useful Resources

Bluebird Chick Development

The First 14 Days
By Jack Bartholmai and Pat Ready


Life Cycles

Eastern Bluebirds
Photos by Jack Bartholomai

Tree Swallows
Photos by Pat Ready and Jack Bartholmai

Photos by Pat Ready and Jack Bartholmai

House Wren
Photos by Pat Ready and Jack Bartholmai

Nest Guide to Cavity Nesters

Eastern Bluebird, Tree Swallow, Black-capped

Chickadee, House Wren, House Sparrow

Species Identification of Cavity Nesters


The Monitoring Program

at Discovery Park, TN

This short educational video provides an example of what a Bluebird Monitoring Program is all about.