Preparing For Nesting

Last updated: January 2023

Although the cold, wintery weather is still upon us and warm days are few, your backyard birds are probably already preparing for the beginning of their nesting season. We have had reports as early as mid-January of Eastern Bluebirds checking out nesting sites, and often Bluebirds have laid their first clutch of eggs in February.

What can we do to help ensure a strong nesting season for all of our backyard birds? Well, here are a few tips:

Understand Nesting Needs - Not all birds nest in trees as we tend to see in children's books. Backyard birds generally fall into three categories in regards to nesting behaviors: Ground Nesters, Tree and Shrub Nesters, and Cavity Dwellers.

As the name implies, Ground Nesters build their nests in or on the ground (Whip-poor-wills and Killdeer for example). These birds, and their nests, are, for obvious reasons, susceptible to predation from many critters, including domesticated animals such as cats and dogs, but other than keeping pets inside or away from nesting areas, there is little that we can do to help these birds prepare for nesting season. Tree and Shrub Nesters tend to build their nests in shrubs or trees, again, as the name implies. Common birds that do this include the Northern Cardinal and the Ruby-throated Hummingbird. Trimming trees and shrubs before nesting season begins will help to not disturb nesting habitats for these birds. Cavity Dwellers, particularly those who nest in holes in trees, fall into two basic categories: primary cavity dwellers who create their own holes; and secondary cavity dwellers who use the holes made by other animals or by the elements, typically in the trunks of trees, or other holes that may be convenient such as openings into your home's attic, shed, or other structures. This last group is the group upon which most of the rest of this article will focus.

Provide Nesting Habitat – The simplest way to provide nesting habitat is by using nesting boxes. Boxes can be simple or ornate, but for a nest box to be practical, there are three general criteria we look for. First, a box needs to have ventilation. Ventilation is important in man-made housing as to allow excess heat to escape during warm weather. Usually this is accomplished using vent holes or slots near the top of the box that will allow the warm air to escape as it rises. This isn’t so much a factor in natural nesting holes due to the density of the wood in the truck of a tree acting as an insulating layer. The second thing we look for is drainage to allow water that may seep in through cracks in the box to escape. In Since man-made nest boxes are often located on exposed fences, walls or poles, more water is likely to enter the box through the opening than might happen in a natural hole that is better protected by the canopy of leaves and branches in the tree. The third feature is a way to open the box for cleaning once the nesting season is completed. Obviously, this is not a factor with natural cavities, but in man-made boxes, cleaning out the old nesting material helps control parasites and helps keep the nesting materials from accumulating to the point where predators such as raccoons and squirrels can reach inside and raid the nest. This gives future generations using the box a better chance of survival.

Size matters: Most cavity dwellers (starlings not included!) look for nesting cavities that best suit their needs. When looking at nesting sites, potential tenants are looking at entrance-hole size, depth (particularly how deep the cavity goes below the entrance-hole, and floor size. If a cavity is too large, the effort needed to fill the cavity with extra nesting material may be too much. If the cavity is too small, there may not be enough room for the family and predation is more likely.

Location, location location: Just as size is important, so is the height and placement of the entrance hole in respect to prevailing winds. Birds nest at different heights. For example, woodpeckers tend to nest at 10 to 20 feet off the ground while Eastern Bluebirds generally use nesting sites located from 5 to 8 feet off the ground.

Nature does not always provide the perfect hole in the perfect place, so size and location are not absolutes, but observations/studies over long periods of time have helped ornithologists and birding enthusiast develop guidelines for providing the ‘ideal’ sizes and locations of man-made nest boxes. At Wild Birds Unlimited, our knowledgeable associates will help you, based upon your backyard environment, determine the best nest boxes and where to place them to help you attract the bird species you are most apt to have success with. We at Wild Birds Unlimited also try to keep a good supply of natural nesting materials in stock for those birds who use such materials. We do NOT recommend using dryer lint, pet or human hair, or yarn or string as these may contain chemicals that may become inhaled or ingested by the birds in the nest. Instead, opt for natural fiber such as llama fleece, natural wool, or natural cotton batting. Cotton batting can get wet and stay wet, so llama fleece or natural wool are our first choices.  

Feed for Success – Generally speaking, all Wild Birds Unlimited seed blends, along with the natural foods available in the area, will help provide your backyard birds with the best nutrition possible. Most all of our blends contain a high percentage of protein and fat that the birds need, and our seed blends never contain any cereals or filler seeds. However, during nesting season, nesting birds’ nutritional requirements can change with the extra physical demands of producing eggs and feeding baby birds. For this reason, Wild Birds Unlimited has a number of seed blends and other foods that are formulated to meet the increased nutritional needs of both parents and nestlings. Our nesting seed blends are designated as PLUS blends, containing higher protein through the addition of tree nuts and suet nuggets, more vitamins and minerals through the addition of fruit, and added calcium carbonate for stronger egg and bone development. In addition to these PLUS blends, WBU offers several Bark Butter products, some of which contain dehydrated mealworms and all of which contain added calcium. Some of our WBU suet cakes are also fortified with fruit, insects, and calcium. The bark butter and suet cakes provide an excellent source of high-energy food in a form that can be easily given from parent to nestling without much ‘processing’ on the part of the parents.
It is important to note, however, that food sources should usually be located a safe distance from nesting sights so that nest predation by critters is not encouraged!

Do a Little “Spring Cleaning” – We always suggest that nest boxes be cleaned out after the nesting season is complete or before a new nesting season begins (but remember, nesting season may start early so get on out there and get it done!), to help foster a healthier environment for the family and particularly for the nestlings. There are some ‘rules that should be followed though, both for your protection and for the protection of your birds. First, protect yourself! Use common-sense precautions when cleaning a nest box. Birds are wild animals and as such, they are not the cleanest! Always wear rubber gloves when handling the nest box or its contents. Wearing a paper mask may also help keep you healthy, particularly if you happen to be allergic to the dander or mites that may have inhabited the box. Be sure to wash your hands well with warm, soapy water afterwards too. To protect your birds, never use any harsh chemicals and especially nothing that contains the term ‘cide’ in the name, such as pesticide or fungicide. The suffix ‘cide’ means to kill. We don’t want any residual chemicals left behind that might affect the health of the birds. The commonly accepted cleaning solution to use is made up of ten parts water to one part common household bleach. While bleach, in strong solution, can be a ‘cide,’ when diluted with water to the proportions given above, it becomes a cleaner and disinfectant. Even still, when finished cleaning a nest box with a water/bleach solution, always rinse well and allow the box to sit, open, where it can dry for at least 24 hours before closing it up and putting it back in place. Obviously, when using any solution containing bleach, be sure to wear appropriate clothing (grubbies) that won’t be ruined if they get bleach on them.

Final Points – Providing nesting habitat for your birds is actually relatively easy, particularly if you rely on your friends at Wild Bird Unlimited to help guide you to the right nest boxes, nesting materials and foods to help you give your birds the best environment possible. However, nesting is still a fifty-fifty proposition. You may try to attract one species and wind up attracting something else. Unless it is an undesirable species such as European Starlings or English (House) Sparrows, go with the flow and enjoy what comes your way. Sometimes you won’t get any takers for a season or two, or get tenants one season but not the next. Don’t despair, experience has shown us that you will have success if you are patient. Remember, too, that the minimal effort required for seasonal preparation of your nesting habitat is insignificant in comparison to the weeks or months of joy you can receive watching one, two, three, or more broods of nestlings fledge during the spring and summer months!

Also remember that as hard as it may be to watch, the best thing you can do for your nesting birds, aside from providing nesting boxes and good quality food, is nothing. Every year we receive numerous calls from well-meaning ‘landlords’ who have picked up fledgling birds for fear they were ‘lost’ or were a target for predators. Nature takes its course and yes, some birds are lost to predation (in or out of the nest), weather, or other natural occurrences. This is just part of the natural order of things that has preceded our involvement by millennium.

Happy Birding!