Nest Box Research

Danielle Takacs ‘23, SUNY New Paltz Biology Department

Tree swallow nestlings in the Millbrook Preserve

Native Cavity Nesters

If you’re a frequent visitor of the Millbrook Preserve, you might have noticed the wooden bird houses placed along the trails. They may look purely decorative, but these houses play a vital role in ongoing research conducted by Biology students at SUNY New Paltz. They are “nest boxes”, providing habitat for many different animals during the breeding season. One group of particular interest is birds. We study birds to give ourselves a better understanding of how to conserve them. Birds face many threats, all of which are often chalked up to “habitat destruction”. With this, we often picture clear cutting of healthy forests. What is not often considered as habitat, however, is the dead trees. Also called “snags”, standing dead and dying trees actually provide more habitat for wildlife compared to when they are alive. We humans tend to remove them from our landscapes, as they appear to be useless, dangerous, and visually unpleasant to us. Yet they are essential for the survival of many different wildlife species; particularly cavity-nesting birds.

“Nature has introduced great variety into the landscape, but man has displayed a passion for simplifying it. Thus he undoes the built-in checks and balances by which nature holds the species within bounds.”

― Rachel Carson, Silent Spring

More than 80 species of North American birds rely on snags for nesting. Primary cavity nesters such as woodpeckers, nuthatches and chickadees excavate the nesting holes. Secondary cavity nesters, as well as many non-avian species, use these holes for foraging, nesting, raising young, storing food, roosting or perching. When we clear all the dead trees from our backyard, we are directly contributing to this habitat destruction. When forest management removes snags from their landscape, they are reducing the available nesting sites for birds such as owls, ducks, woodpeckers, swallows, martins, nuthatches, chickadees, titmice, wrens, bluebirds, warblers, and sparrows, among others.

It is important to realize that a tree’s value does not end with its life. Next time you visit the Millbrook Preserve, try to spot nest cavities in the trees. If you see holes made by woodpeckers, that is a dead tree; perhaps a small animal has made its home inside.

What do the nest boxes tell us?

In addition to providing habitat for a variety of bird species in the preserve, these nest boxes are ideal for studying an array of behaviors in birds that are otherwise extremely difficult to observe (picture yourself in the middle of an expansive forest, tasked with finding several tiny bird nests!). Through this research, students, such as myself, have been given the rare opportunity to become intimately involved with the life of many cavity nesters. Watching them build their nests and raise their young is almost like peeking into a secret world. This experience is unlike any other; it has allowed me to share a new connection with nature, gaining a life satisfaction from its beauty and complexity. But with life, there is always a balance. If you have a nest box of your own, you may notice one frequent visitor is a small brown bird with a black patch on its throat. These guys are social, curious, and quite entertaining to observe. But unless you are a birder, you may not know that to some, they are sworn enemies. This cute little bird is a dominator of nest boxes, oftentimes pushing native cavity nesters out.

Passer domesticus, otherwise known as the house sparrow, is an old-world sparrow in the family Passeridae, originating from Europe and parts of Asia. It was introduced to South Africa, South America, Australia, New Zealand, and North America, perhaps as pest management strategies, but has since taken over. They are the picture-perfect invasive species. They are vigorous breeders, often producing up to four broods where other species produce only one. They are not picky eaters, feeding on seeds, bugs, or the crumbs from your muffin. And finally, they thrive in human environments, nesting in warehouses, factories, garages, porches, and other man-made structures- most notably- our nest boxes. Well-intending citizens put up nest boxes near their homes to observe and support birds, but often end up with a much larger issue. House sparrows are quick to dominate these boxes--occupying them before natives can--or even violently removing established birds. The more habitat we provide them, the more their population grows, escalating the problem exponentially.

If these invasive birds thrive in human-made structures, how can we keep them out of our nest boxes? Biology professor Dr. Kara Belinsky began to tackle this question in 2017, by installing a small nest box network of 18 boxes on the SUNY New Paltz campus. In the first year, a variety of native birds used the boxes farthest from buildings along the forest edges, painting a picture of hope for our campus. In the next year, house sparrows dominated nearly the entire network. But perhaps there is a safe distance from human structures where the nest boxes can be placed that would limit their dominance by house sparrows? The nest boxes along the trails in the Millbrook Preserve this were intended to test this idea. Throughout The Preserve, we placed 60 standard Eastern bluebird nest boxes located at varying distances from the closest human-made structure. Myself and other students from Dr. Kara Belinsky’s lab at SUNY New Paltz have been monitoring these boxes for house sparrow usage every spring and summer. Since the construction of the nest box network in 2020, no house sparrows have nested in any of the boxes, despite having been observed near nest boxes at the edges of The Preserve. Instead, the boxes have been homes to native birds such as tree swallows, house wrens, tufted titmice, black-capped chickadees, and eastern bluebirds, as well as mice, flying squirrels, fishing spiders, wasps and moths. So why aren’t house sparrows occupying the nest boxes in the Millbrook Preserve? It may have to do with nearby population sizes. Perhaps there are not enough sparrows to spill over into The Preserve, while the large population on campus compelled some sparrows to occupy nests at the forest edge there. Future research may focus on expanding the Mill Brook Preserve nest box network into suburban areas surrounding The Preserve in hopes to gain a more thorough understanding of how to best support native cavity nesting species with appropriately placed nest boxes both near and far from large house sparrow populations and small nature Preserves.  

More information about House Sparrows

Summer research students Danielle Takacs and Sam Mustafa checking a nest box