Nest Box Monitoring Protocol
Why We Monitor:
We put up nest boxes to attract native cavity nesting birds, especially bluebirds. In doing so, we assume responsibility for the following:
The progress and success of nests and fledglings
The health and safety of the birds we have attracted
Preventing non-native invasive house sparrows from using the nest box.
Monitoring for signs of vandalism, predators and pests.
Keeping detailed records of the history of each box.
Submitting our recorded data to our state and national organizations.
How to Monitor:
Before you open the box, make sure the box number and the data page in the book are the same. Read all the previous week’s entries in the notebook before opening the box.
Approach the box quickly but quietly, make a little noise (talk) so the bird knows you are coming.
When you open the box, keep your head back from the opening in case the female is in the box and flies out the opening.
Take note of the species of adult birds present and any activity you observe.
Open the box, being careful to not stand in front of the opening in case the adult flies out. Do not open the box if nestlings are 13 days old or older. This may cause them to fledge prematurely. When in doubt about the age of the young, do not open the box.
Note the number of eggs or nestlings and the approximate age of nestlings (see page in field notebook.) Get accurate count of nestlings.
Close box, tighten screw, walk away quickly.
Write your findings on the correct page corresponding to the box number in the field notebook. Check appropriate spaces and include any comments that will help next week’s monitor know about box’s tenants. Be as clear as possible.
Note and record species of any cavity nester — not just bluebirds using the box.
Occasionally, the female will stay on the nest when you open the box. Do not disturb her. Close the box and come back later to check.
Predators, Competitors, & Pests:
Wasps – scrape out nest, crush it on the ground, rub non-perfumed soap on inside roof and/or sides of box to discourage them.
Snakes – usually the eggs or nestlings disappear but the nest remains intact. The snake guard deters most snakes, but others easily drop off trees on to the box.
Cats, squirrels, raccoons, opossums – the nest is destroyed and eggs and young are missing. Use of the raccoon guard cuts down on these predators.
Native Competitors - House wrens and tree swallows compete with bluebirds for nest boxes, but they cannot be removed. If wrens are a problem, move boxes at minimum 50 ft. and as much as 200 ft. from brush and trees. If swallows are taking over the box, install a second (paired) box 15-30 ft. away from the first for the bluebirds.
Ants – use Vaseline in a thick ring on the pole up inside the snake guard to discourage ants. Be sure to put the Vaseline up under the guard so bluebirds or other wildlife do not get it on their feathers or fur.
Blow flies - use 100% food grade diatomaceous earth as a deterrent. Any time after the first egg is laid but before hatching takes place, determine location of bottom of egg cup. Insert tip of squeeze bottle about one inch below where eggs are, and point tip slightly down (not straight), and apply about two small puffs under egg cup, and a puff at same level on either side of egg cup. This is where the blow fly larvae hide during the day. See detailed instructions on the Virginia Bluebird Society website. Alternatively, an infested nest can be changed out if a clean nest is available. See http://sialis.org/nestchange.htm for instructions.
House sparrows [HOSP] - adult and/or young bluebirds have head pecked in and are dead. Often a sparrow nest has been started on top of the dead birds.
House sparrows are not a native species and are not protected by law. They kill our native cavity nesters at an alarming rate, often displace them and take over available cavities.
The best way to deal with house sparrows is to use a series of passive controls. The most important of these is to monitor weekly and remove HOSP nest and any eggs. Place removed nest and eggs in a plastic bag and dispose of far removed from the nest box in a trash can or in a natural area where it will not attract predators and will not be available for nest rebuilding.
House sparrow nests are sloppy and fill the entire cavity. Nests are made of coarse grass, trash and other fibers, haphazardly woven together, is often tall (arcing up the back of the nest box) with a tunnel-like entrance.
House sparrow eggs are white or beige with brown spots; sometimes greenish.
House sparrows will rebuild every week, all summer long, so be persistent; they are hard to discourage. It is the male that bonds to the box and builds the nest.
If weekly removal of the nests or addling of the eggs doesn’t discourage the HOSP, move that box to another location away from buildings.
Bluebird Nest Building:
Bluebird nests are made of dried grasses or pine needles or a mixture of both, and sometimes have a feather or two mixed in. They are very neat and tidy with a cup in the middle.
Bluebird nest building takes an average of 4 to 5 days but can easily range from a week to six weeks or more, depending upon the weather. Don’t clean out a nest box because there is no activity for a while. The birds may leave and then come back.
Bluebird eggs are clear pale blue, not spotted. 4-6% of bluebird eggs are white with no spots. Very infrequently, the eggs can be pale pink.
If you see the number of eggs fluctuate it may be a snake, another predator or a competitor bird removed the eggs, and then the female started laying again. Or it may be that the adult bluebirds removed infertile eggs.
Nests of Other Native Cavity Nesters:
Do not remove the nests of any other birds including carolina chickadees, tufted titmice, tree swallows, prothonotary warblers or house wrens. These are all native birds and are protected by federal law.
Monitor the box as you would for bluebirds. Report the data at the end of the season just as you would for bluebirds.
Tree swallows have nests of grass with large feathers arched over the nest or mixed in the top. Eggs are usually a very pure white, and sometimes pinkish.
Chickadee nests are made of moss with a layer of plant and animal hairs on top. Eggs are tiny, and white to creamy white with brown dots or spots.
Titmice nests are made with mosses mixed with natural materials such as leaves, bark, hairs, snakeskin. Eggs are creamy white with reddish-brown spots.
House wren nests are made of sticks piled to the top of the box, with smaller sticks on top with an indentation cup inside, usually on the back side and lined with grasses or other finer natural materials. Eggs are white, pink-white, or grayish, speckled or blotched with reddish brown.
Carolina wrens have nests mostly of dead leaves and sometimes moss lined with fine grasses and hairs. The eggs are small and white with heavy brown spots concentrated in a darker ring of spots at the larger end.
Keep good records in order to keep the other monitors on your team well informed, and to ensure accuracy in end of season data reporting.
Try to know the day the last egg was laid - this way you can know when the incubation started.
Bluebirds typically lay 5 eggs, one a day every morning for 5 days. The female begins to incubate the eggs the morning after the last egg was laid (or sometimes that same day) so they will all hatch at once. Average incubation is 12 to 18 days.
Use a calendar in the trail notebook and count backward to get accurate dates for hatching and fledging.
Never open the box after the 13th day. If the birds leave the box before they are fully mature, they may fly to ground and become lunch for some predator.
After they hatch, the young will fully develop and fledge between 17 and 21 days, depending on the weather, the number of hatched young and the availability of food.
Watch the nest for feeding activity – the adults are actively feeding the young during their last few days in the nest up to and including fledge day. On fledge day, the adults will continue to feed the young from outside the box every 10-15 minutes, luring the young to leave the nest.
After the Bluebirds Have Fledged:
Listen to make sure nestlings have left the nest (fledged). Stand by the nest box and look for nervous parent birds, dive bombing, beak clicking. That is a sure sign at least one fledgling is inside.
When you are sure the nest is empty, open the box and check for any unhatched eggs. Note it in your records.
Check for dead babies. Try to account for all eggs that were counted in the nest. This gives you a more accurate fledgling count.
Check under the nest for blowfly larvae. If you find larvae or any mites present, record that on the data sheet. Remove the nest and sweep any remaining bits of nest or droppings into a plastic bag and dispose of far removed from the nest box, either in a trash can or in a natural area where it will not attract predators. The female may start a new nest within a week of the young fledging and start laying eggs immediately. Usually there is one less egg in the second clutch, but not always.
Bluebirds often play musical boxes, and occasionally will lay a second clutch somewhere else. If the bluebird are not banded, we can never be sure it is the same pair.
After the second clutch there may be a third. Follow as above.
After the last clutch, winterize your boxes. See the instruction on the VBS website. By mid-March, clean out the grasses or pine needles you placed there, but leave the box winterized until the warmer weather arrives. It helps keep things cozy during a cold spring and will help ensure the first clutch survives.
Equipment List:
5-gallon bucket, to carry the supplies listed here.
Field notebook with all necessary monitoring sheets.
A pencil or two, with eraser in case a mistake is made.
A mirror, to check nest for eggs and chicks inside the box.
A Phillips screwdriver or small pliers for opening the side of the box.
A small container of Vaseline to discourage ants
Disposable gloves, to wear when applying Vaseline or when cleaning out old nests.
Plastic bags, to carry away old nests. Don’t drop nesting material on the ground near the box – this will attract predators.
Paint brush, to sweep out box. Many of us carry toothbrushes for tough spots and corners.
Scraper of some sort (putty knife) to get the guano off the wood.
Plastic condiment bottle with tip, containing 100% food grade diatomaceous earth (DE).
Unscented bar of soap for wasp control.
You may also want to bring a flashlight and a camera and especially a pair of binoculars for your own use.