Improve Your Flock with Trapnests

Use this traditional method to help you select the best hens for your breeding program.

nest drilling

Harvey Ussery installs trapnests in his coop. The nest-trapping technique traps a hen in the nest with the egg she has laid, so the breeder can identify her and mark her egg for his records.

Photo by Harvey Ussery

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Time-honored indicators of “who’s laying and who’s lying” in a flock include wide, moist vents; generous space between pelvic bones; and expansive, pliable abdomens. But when you’re selecting the best-laying breeders for your flock, you should know precisely which hen is laying which egg. Yes, those hens with the “wide, moist vents” are the ones in active production. But is such a hen laying five eggs per week, or six? Do these eggs have an average weight of 57 grams, or 64? Knowing those answers with certainty is essential if you’re to select for daughter hens that lay even more eggs of larger size.

Targeting other egg traits might be important to you as well, such as intensity of shell color in breeds known for unusual hues — Ameraucanas, Marans, and Welsummers, for example. And what about egg shape? Or shell texture, thickness, and integrity (absence of flaws that weaken the shell)? Like the rate of lay and average size, such eggshell qualities are heritable, so breeding for production of more-desirable eggs in future years requires removing the layers of less-desirable eggs from your poultry breeding program now. And that requires trapping the hen in the nest with the egg she has laid

, so you can identify her and mark her egg for your records before releasing her.

Trapnest Design

Serious poultry breeding management by small-scale producers is in decline, and that has resulted in a dearth of information about nest-trapping. But you can find a few trapnest designs from the older farming and homesteading literature online. (See the compendium of older designs at The Trap Nesting Thread on BackYard Chickens.) Familiarity with those designs might suggest a model which best fits your management style, henhouse layout, and skill set. Many designs are effective so long as they feature the following elements: 1) A door which allows the hen to enter, but which 2) is triggered to drop or swing into blocking position by the movement of the hen into the nest.

Whatever design you choose, its most essential requirement is that it works 100 percent of the time. Data from nest-trapping will help you determine which hen becomes the foundation of your stock through future generations — and which one goes to the stewpot. Each failure of your trapnests to capture a laying hen results in unidentified eggs, undercutting the information you need to make informed, critical decisions.

The following is a brief description of trapnests I have used, their essential design elements, and potential problems to avoid.

Purchased Wire Fronts

The only option I know for buying trapnest fronts, available in two sizes and made from heavy-gauge wire, is actually designed to fit onto purchased sheet-metal nest units. The only such nests I ever used were pretty junky, and I scrapped them long ago. I prefer my sturdier homemade versions. However, some breeders mount purchased fronts onto their homemade trapnests, so I decided to try this by making a set of my own (left and center boxes pictured above). I cannot recommend them. The problem is the amount of force the hen has to exert on the door — folded into the “set” position — to trigger release. Numerous times I watched as my hens entered the nest, brushing the edge of the wire door but failing to trigger release. I added wood strips to reduce the distance between the wire and the edge of the nest, and to require more forceful contact by the hen as she squeezed through. This netted a capture rate of about 50 percent — not nearly good enough.

Perhaps you’d have better results with heavier hens — my Icelandics are on the small side. But I’ve abandoned the commercial trapnest in favor of less fiddly versions made and fine-tuned here at home. Consider this as well: After building your trapnest, you can either spend an additional $21 to $39 per wire front for each nest, or you can get your doors for free by using scraps from your project and building them yourself.

Swinging Door Variations

For simplicity, it would be hard to beat the swinging-door design. The basic idea is simply to hinge a door above the entrance to an ordinary nest box, as shown in the illustration above. Swing the door into the nest and suspend it in a set position with a prop stick from below, an overhead wire bent at its end into a short hook, or any number of ingenious options (illustrated in slideshow). Unlike the purchased wire fronts that require a significant push from the hen, the door’s support can be set to “hair trigger,” in which the merest nudge from the hen’s back as she enters the nest will knock it off its prop, releasing it to swing into blocking position behind her. This design’s advantage is that it’s easy to build. The biggest challenge is spacing the suspended door at just the right distance over the edge of the nest to offer easy and inviting access while ensuring that the hen can’t enter without making contact. The precise size of the opening requires experimentation and modifications for your specific design — and even for the average size of the hens you’re trapping.

Look again at the drawing in the slideshow. Obviously, when building this trapnest you’ll need to allow greater nest depth if the hen is to clear the door and allow it to swing shut. However, if you intend to make a unit of several nest boxes and mount it on the wall, adding much nest depth makes for a rather clumsy unit indeed. And the hen might simply settle into the middle of the nest space, causing the door to drop directly on her. This would cause her to become “nest shy” if it boots her out or, in the worst case scenario, traps her between the door’s edge and the nest floor. Finally, if the door is indeed set to hair trigger, might the hen jostle its release prematurely if she flies into the entrance, wings aflutter?

My modifications to the basic swinging-door design resolve these problems, as illustrated in the slideshow. When I make a swinging-door nest box, I cut the door in two and hinge the halves, so the door unfolds to full blocking length as it falls. With these changes, the radius of the door’s swing is cut in half, reducing the depth required. The swinging-door units I’ve made are 16 inches deep, only a few inches deeper than the typical 12-inch depth.

I add a retaining strip a few inches past the entrance to hold the nesting material and define the nesting space deeper inside. The resulting empty vestibule discourages settling-in near the entrance and draws the hen deeper inside before the door is triggered. Finally, I mount an external perch for the hen to land on first, ensuring her entrance into the nest itself is more sedate, and avoiding premature release of the door.

My Granddaddy’s “Rabbit Box” Design

When I asked my father to help build my first trapnests, he suggested a design based on the “rabbit boxes” his father used to trap wild rabbits, featuring a notched, baited “trigger stick” as the release for a sliding door. In my version, the hen knocks the trigger loose as she settles into the nest for laying. (Step-by-step construction is discussed and illustrated on my website at Making and Using Trap Nests and in my book The Small-Scale Poultry Flock.)

In this design, I also add a few extra inches to create an empty vestibule (as described above) to tempt the hen deep into the capture space. The door is suspended in the open position via a string through an overhead hook to the trigger stick at the other end — and drops only when the hen’s settling-in ritual knocks loose the stick’s notch. This design is more complicated to build because of the added tracking strips that guide the door’s drop. But it’s the only design I’ve found to be 100 percent effective — it always traps the hen if properly set up. It cannot be otherwise, given that the hen is fully in the capture space (not just in the process of entering it as with the swinging-door design) before the door is triggered. Failure to knock the trigger stick free as she settles in is simply not possible.

Note that with any design, you can dampen the noise and impact of the closing door by stapling in place a bumper made of scrap inner tube. You should always provide ventilation for the hens trapped inside the nest, and design doors that are easy to install and remove for storage, because the trapnests will be used as ordinary nest boxes most of the year.

Managing Trapping

Now that you have a number of options for building your own trapnests, let’s consider how to use them. Nest-trapping all the time would be wildly impractical. You should schedule trapping periods of several days at strategic points in the laying cycle, depending on the information you’re trying to capture — in summer to track peak production; in fall for precise onset of lay dates for pullets; in winter to discover who best holds production then; or in late winter/early spring to tag hens that lay best in those shorter days (likely to be the best layers the rest of the year). Avoid nest-trapping during the molt, when hens’ varying drops in production will invalidate comparative data.

Nest-trap only when you can check the nests frequently — as often as every 15 minutes in the hours when hens are most likely to lay. And be sure to have enough trapnests in proportion to the number of tested layers — about one trapnest for every six hens. Remember, integrity of the data depends on trapping every hen that lays an egg until you can make a record. If urgent hens blocked from the nests lay in the litter, there goes an irreplaceable swath of your data.

Even the best-laying hen has a periodic “reset” day when she lays no egg. If her off day falls within the test period, she’ll show as less productive than a hen whose reset happens not to occur in those days, even if actual production of the two is the same. You should average out your results by scheduling two tests in the basic target period — say, four days each and three weeks apart.

Given the time commitment, you might think nest-trapping is a drag on efficiency. I’d argue that it actually could increase efficiency. Let’s say you have 25 hens in your poultry breeding program. You don’t nest-trap, but it’s obvious that one hen lays a chronically small egg; another hen lays lopsided eggs; and three other hens lay eggs with shells that are thin or have wrinkles or fracture lines. Knowing these traits are heritable, you always discard those eggs when selecting for incubation. Problem solved, you think, regarding selection against those undesirable traits. But how many breeding hens do you have again — 25? I don’t think so: You have 20, plus five freeloaders on your poultry breeding program! A set of well-designed trapnests can identify those freeloaders.

Using Trapnest Data

Nest-trapping data require permanent identification of hens using, for example, plastic leg bandettes or metal wing bands, available in various colors and sequentially numbered lots. Check the trapped hen’s identification before release, and mark her egg in pencil with ID and date. Your specific use of this raw data depends, of course, on the characteristics you want to target — how you use yours will differ from how I use mine. If you use digital spreadsheets, design one to automate and analyze your data.

The egg traits listed above — for level of production and quality and size of egg — are obvious targets for selection in an improvement breeding project. During four years of breeding here, I’ve aggressively targeted the sorts of flaws in egg shape and eggshells discussed, such as lopsidedness, bulges, fracture lines, being too round, and the like. Already, I’m close to eradicating those flaws.

But there are other ways nest-trapping can advance your specific breeding management goals. Maybe you want to breed for greater longevity (genetically linked to vigor, health, and hardiness) while keeping egg production high as hens age. Nest-trapping to the rescue: If Hen 106 and Hen 141 trap at the same level of production, but the former is a year older than the latter, which is the obvious candidate for breeder?

I hatch with broody hens exclusively, so I nest-trap for hatching eggs from known broodies to ensure mothering traits remain strong in a portion of their daughters. Though the cock doesn’t lay eggs, he carries his mother’s genes for production traits. So, choice of a breeding cock can boost future performance of layers — if nest-trapping has proved that his mother has the egg traits you’re looking for.

There’s no other method that comes close to nest-trapping when it comes to the specificity and breadth of selection data made available. If you’re serious about poultry breeding, you really should be using this tool!


Harvey Ussery is the author of The Small-Scale Poultry Flock. Visit his website for a bounty of information on poultry management.