As you read in the first column of this series, I’ve been hosting nesting bluebirds in my back yard for the past three years and have become quite fond of this beautiful and wonderful bird. Because bluebird hosts find this activity so incredibly rewarding, we hope others will become involved, not only to enjoy the experience but to help with the cause of replenishing the bluebird population, which saw declines in recent decades but is showing positive signs lately.
Because of habitat loss, natural occurrences such as heat and storms, predators, and competition from other bird species — especially the non-native house sparrow — bluebirds have a rather tough time out there. They can benefit from the help of responsible and devoted bluebird hosts: those who will take the job seriously, who will learn the basics of how to provide the safest nesting site practicable, and who will put in the time and effort to diligently monitor their nesting site.
An improperly located nest box that is seldom or never monitored is destined to fail. Nesting bluebirds will waste precious time building a nest and incubating the eggs only to have the chicks taken by a predator — a bad situation which is made even worse if the cycle repeats itself long term.
Although certainly not an expert on nesting bluebirds, I’ve done considerable research and gained first-hand experience over the past three years. Sharing our collective experiences with each other helps add to the knowledge base that we can all benefit from. Hopefully this column will help a little with that effort. If you’re an experienced bluebird host, please share your insight. If you’re new to this, there are many great online resources with excellent information, so please do your research before becoming a bluebird host. Here are a few good sites:
Sialis (a wealth of information is available here)
Bluebird Nut
The Ambassador For The Bluebirds
https://www.ambassadorforthebluebirds.net/
Avian Report
Audubon
https://www.audubon.org/field-guide/bird/eastern-bluebird
All About Birds
https://www.allaboutbirds.org/guide/Eastern_Bluebird/overview#
And here’s a quick rundown of some basics before you get started:
The Nest Box. There are several types of nest box designs, and each has its supporters and detractors. From my experience, a top-opening box has worked well. This design can be easily made at home from a single piece of 1x6x8 cedar and a couple of small scrap pieces of 2×4 pine. The accompanying diagram shows the dimensions.
Location and Mounting. Do not mount the nest box to a tree or wooden post; doing so provides easy access to climbing predators such as snakes, raccoons, squirrels and rodents. Instead, mount the nest box atop a metal pole so that it is approximately 5-6 feet above the ground. The pole should be located in an open area at least 12-15 feet from shrubs or small trees, and the ground around the pole should be completely clear of shrubs, debris, landscaping stones, or anything that predators could hide in or climb. A 3/4 inch metal conduit pipe works well as a mounting pole. The conduit pipes come in 10-foot sections, so cut it to fit. Depending on soil type (whether loose or compacted) the pole should be hammered into the ground 18-24 inches so that is is firmly anchored, leaving 5 feet of pole above ground for mounting the nest box.
The back wall of the nest box is cut 1/2 inch shorter than the side walls to allow for ventilation. When looking through the front of the box you should see a bit of daylight at the back. 
Cutting an angle in each corner of the floor allows for additional ventilation as well as drainage should water get into the box. 
This nest box design features a top swinging door, which allows for easy monitoring of the nest (without fear that eggs or chicks could fall out, as with a front- or side-opening box) as well as a good angle for photography. There are several styles of nest boxes, each with its proponents and detractors.
Predator Guard. A predator guard is essential; don’t learn this the hard way because it is a heartbreaking lesson. Like nest boxes, there are a few different designs of predator guards. While not completely failsafe, it will make it more difficult for a predator to raid the nest box. The type I use can easily be made out of 8-inch diameter metal duct and wire mesh. Putting grease on the pole and guard is recommended as a further deterrent to climbing predators.
A predator guard can easily be made using an 8-inch metal duct and wire mesh. The predator guard is mounted to the pole so that the guard sways if a predator such as a raccoon tries to climb it. 
Also, if a snake climbs the pole up inside the guard, its path to the nest is blocked by the wire mesh top. There are other types of predator guards as well. Even with a predator guard, it is important that bluebird hosts (us humans!) also visually watch out for predators as much as feasible.
Monitoring. In my area of north Florida, bluebird pairs begin scouting for nesting locations as early as January, so it’s good to have your nest box up by then. Begin monitoring your nest box even before bluebirds have expressed an interest in it, as snakes, rodents, insects or other pests might take up residency inside thus preventing the bluebirds from using it. After the bluebirds select your nest box and begin building their nest (usually in early March), continue regular monitoring for pests — and watching for the first egg to be laid!
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This is the second column in a series.
Next in the series: “The First Brood of 2019: Discovering the Special Appeal of Bluebirds”
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