Nestbox Monitoring and Wildlife Husbandry: The Basics
If you've ever joined us out at Robin Hills Farm for a hike, tour or event, you may have noticed the little wooden nestboxes, set high on T-posts, that dot the property—by the ponds, around the pasture, in the Wetland Loop of our nature trail, or peeping out from the woods near the garden.
These boxes make up our Bluebird Trail, and are the pride and joy of our Education Team. Like most of what we do out here, they are multifaceted in purpose, bridging conservation, education and a healthy dose of outdoor recreation. Nestbox monitoring not only helps us to increase the biodiversity of our beautiful site, but is also one of the easiest DIY conservation projects to get involved in, and a great way to get up close and personal with wildlife. And, since the reward of seeing and hearing these lovely little birds around the Farm is enjoyment that everyone can share in, what's not to love?
Why bluebirds? Bluebirds are a beautiful, beneficial native songbird, well-adapted to living alongside humans but threatened by declining populations in recent years. This is due to the hand-in-hand problems of habitat destruction and increased competition by invasive species. Bluebirds are cavity nesters, meaning that they require enclosed spaces to nest—think dead trees and wooden fence posts, both of which are hard to find in highly developed areas—but they are not well-equipped to fight for these increasingly rare, specialized habitats. Aggressive European species like the starling and house sparrow have a nasty habit of crowding out bluebirds, in some cases even destroying their eggs and killing the parents. Back in the '70s, this sad state of affairs drew the sympathy and activism of a small group of Audubon Society members, and the North American Bluebird Society (NABS) was born. Since then, NABS has made it their mission to educate and empower the common citizen—not scientists, not wildlife rehabilitators, not veterinarians, but the average layperson with a few spare minutes a week and a desire to make a difference—to join the fight to save the bluebirds. Their website gives the amateur conservationist everything they need to set up and monitor their very own Bluebird Trail, asking only that they share their data at the end of the year.
As we've found out here at Robin Hills Farm, there are few things more rewarding than watching a nest form from the first few blades of grass, fill up with eggs, and then, in just a few weeks' time, host the hatching and fledging of impossibly, exquisitely tiny and delicate baby birds. It is a timeless cycle of life and renewal, played out in real time just a few feet off the trail; it's a longstanding part of the pageant of springtime here in the eastern United States, which just needs a little help here and there to run smoothly and endure well into the future. By enlisting backyard birdwatchers and novice naturalists, bluebird organizations like NABS (as well as local chapters, like the Michigan Bluebird Society) have created a national network of bluebird population data, which monitors all three of the US's native bluebird species and is entirely supplied by volunteers. This conservation effort, fueled by pure passion and excitement, has been quite successful; in the past 10 years, bluebird numbers have markedly increased, as have those of the enthusiasts who keep tabs on them. It's a difficult hobby to feel ambivalent toward; with just a little effort and engagement, most find a daily source of wonder and inspiration that keeps them setting up boxes and filling out monitoring forms year after year.
Setting Up Nestboxes
Most of the work of constructing a bluebird trail lies on the front end, in the earliest days of spring. Nestboxes may be purchased at gardening stores or online—or, if you're handy with some basic tools, designs are freely available on the Internet. This is also a good time to check your expectations. Though it is natural for "bluebird landlords" to feel somewhat protective of their tenants, the first rule of wildlife husbandry is to let nature be nature. Keep an eye out, lend a hand when strictly necessary—but make the effort to know what is necessary. It is our role as conservationists to facilitate and support natural processes that are faced with threat, which requires us both to be informed and to respect that wildlife understand these processes better than we do. In other words, the primary experts in bluebird matters are bluebirds! We may foster their success by providing habitat, but they must be given the space to succeed on their own terms. No amount of good intention will stand in for the ancient force of their age-old, finely honed survival instincts.
Therefore, when choosing where to place nestboxes, be mindful of the bluebird's natural tendencies and needs. Bluebirds prefer "edge" habitats, with clear open spaces and scattered trees, and are therefore perfect for fencerows, golf courses, yards and parks, farmland, fields, et cetera. However, close proximity to buildings can increase the risk of competition from house sparrows, and too much woody or brushy cover will discourage bluebirds from establishing. Preventative management is key to avoiding the need to step in later, so select locations with care, mount boxes on posts at least five to six feet tall, and install obstructions on the posts to deter predators such as raccoons and snakes (knowing what predators are likely to be around, looking for trouble, is helpful). The entrance hole should face an open area, and have ready access to water and places to perch within a forty-foot radius.
Checking a Nestbox
Next begins the game of watching and waiting. This, in our experience, is an excellent time to practice patience in the face of nature's unpredictability. Boxes should be checked every week (or twice a week once an active nest is established), preferably in the afternoon and only in mild weather, and carefully logged on the NABS monitoring forms. The thrill of finding the first scattered twigs or stray feather takes a little time, in some cases; it's best to be ready for it, with a working knowledge of which cavity nesters might come calling. Starlings should be easily kept at bay with a properly sized entrance hole, but house sparrows may need to be evicted several times—their forceful persistence and drive exceed those of the gentle bluebird, and a poorly monitored nestbox will ultimately only increase their number. Sparrow nests may be removed by hand and disposed of, but do not leave the remnants close to the box, lest they draw predators and pests. House sparrows' haphazard nests are fairly easy to recognize, often incorporating scraps of trash and built with a tall canopy. Their eggs are pale, usually whitish, and speckled with brown.
However, the bluebird is only one of several native, beneficial cavity nester species, and though NABS has a clear favorite they advocate for these other birds as well (and, in fact, displacing any native cavity nester is illegal). Here at Robin Hills Farm, we currently host several tree swallow and house wren nests, in addition to three families of bluebirds. Chickadees and tufted titmice are also potential nestbox tenants. Each has a unique style of nest, which can be recognized with fairly little practice; for example, tree swallow nests closely resemble the finely woven grass structure of a bluebird nest, but with a shallower cup luxuriously lined with feathers. Male house wrens, on the other hand, build rickety towers of twigs and spider egg sacs in every viable cavity their territory covers, which female wrens may then choose to line with feathers and other insulation. (Wrens can also outcompete bluebirds, but prefer brushier areas, so we like to give them their own box or two in woody margins that bluebirds will avoid.)
Monitoring a Nestbox
When monitoring nestboxes, a footstool is helpful and a businesslike pace is best practice, hard as it may be to tear oneself away from a nest of perfect blue eggs or tiny, brand-new hatchlings. We've found avian parents to be quite tolerant of well-meaning intrusion, though they will at times vocalize their distress if one lingers too long. It is, however, pure myth that human scent will drive parents away from their nest; bluebirds are devoted parents, but moreover, songbirds have little to no sense of smell. Still, touching the eggs or hatchlings should be avoided except in a handful of extenuating circumstances, which will usually make themselves quite apparent—if the nest is wet, for example, or if the young seem weak and the parents have been missing in action for at least half a day. The Michigan Bluebird Society provides a comprehensive overview of nestbox troubleshooting; the focus, notably, remains on prevention rather than remediation.
Of course, anyone who chooses to form a close acquaintance with the wild will at times witness the grimmer side of things—such is the nature of, well, nature; at times, nests will fail, whether by harsh conditions, parasites or predators. This is not a personal failure, and understanding that such tragedies are sometimes the inevitable way of things is yet another lesson of nextbox monitoring. Most of us are sheltered from the hard truth of mortality, in this day and age, and accepting these seemingly cruel whims of circumstance as a lesson will not be an easy or immediate process. But, difficult as it may be, the best means of recovery is cleaning out the box for a fresh start, and hoping for a kinder turn of fate the next time around. More likely than not, nature will oblige; in the springtime, at least, odds tend to be stacked in favor of life and renewal.
Though we can't overstate the importance of being informed in this venture, no amount of research can capture the surprise and delight that inevitably come with each new nest built, egg laid, or sleepy little pile of hatchlings discovered. Noble as the cause of conservation may be, it is these rare sensations of awe that form the true allure of nestbox monitoring—and which, arguably, this grassroots effort to save the bluebirds was built on. Human passion, though small in the face of life and death and survival instincts, is nonetheless a powerful thing.