Deadfall Traps: Figure-4 and Promontory Peg Construction

TL;DR

Deadfall traps kill through impact rather than restraint. They require no wire, no cordage, and no manufactured parts — just sticks, stone, and a knife. The limitation is the trigger mechanism: building one that is stable enough not to drop from wind but sensitive enough to release from an animal's touch takes practice. Practice before you need to use it.

What Makes a Deadfall Work

Every deadfall has three components:

The weight — a flat rock, log section, or heavy slab that falls and kills the animal. Must be heavy enough to kill quickly and flat enough to fall level.
The trigger mechanism — holds the weight up in an unstable equilibrium that releases under light pressure.
The bait — attached to the trigger so the animal cannot take it without releasing the trap.

The critical failure mode in most beginner deadfalls is one of two things: too stiff (the trigger doesn't release when an animal touches it) or too sensitive (the trap drops from wind, falling debris, or nothing at all). Both failures mean no food.

Finding the Right Rock

What to look for:

Flat, stable resting surface on top (so it balances reliably on the trigger)
Flat bottom surface (so it falls and kills cleanly, not rolling off)
Weight appropriate to target animal (see FAQ above)
Free of holes, severe irregularities that would make it roll unpredictably

Flat-bottomed shale, sandstone, or granite slabs work well. Avoid rounded rocks — they roll instead of falling flat.

Figure-4 Deadfall (Full Construction Detail)

The figure-4 uses three interlocking carved sticks to create a tension-based trigger. The name comes from the shape the three sticks form when assembled — they look like the number 4.

Carving the Three Sticks

All three sticks should be: Dry, straight-grained hardwood. Rot-free. Dense enough to hold carved notches without crumbling.

Stick A — The Upright

This stick stands vertically and bears most of the load.

Length: 6-8 inches.

At the bottom: Carve a 45-degree diagonal cut on ONE face, cutting from front to back from bottom to about 1.5 inches up. This angled face sits flat on the ground and is the pivot point.

About one-third from the top on the SAME face: Carve a small square notch, roughly 1/4 inch deep and 1/4 inch wide. This holds the horizontal bait stick.

Stick B — The Diagonal Brace

This stick runs at a 45-degree angle and connects the upright to the deadfall weight.

Length: 8-10 inches.

At the lower end: Carve a notch that fits precisely against the angled cut on Stick A's lower end. The two cuts interlock — Stick B's notch sits against Stick A's diagonal.

At the upper end: Form a blunt point that rests under the deadfall weight. The weight presses down on this point.

On the SIDE of Stick B, facing the upright: Carve a small notch about halfway along its length. This is where Stick C engages.

Stick C — The Horizontal Bait Stick

This stick runs horizontally and connects the upright's notch to Stick B's side notch.

Length: 6-8 inches.

At the end toward the upright: Carve a diagonal cut that seats against the square notch on Stick A, hooking into it.

At the other end (Stick B end): Seat into Stick B's side notch.

At the far end: Attach the bait.

Assembly

Calibrating Sensitivity

If the trap drops too easily: deepen the notches slightly. Increase the angle of engagement between the sticks.

If the trap won't release: reduce the notch depth. Reduce friction by smoothing the contact surfaces. Reduce the weight slightly. Shorten Stick B slightly so less weight presses on the trigger.

The goal: The weight of the trigger sticks themselves holds the system barely stable. A small additional force (the animal pulling the bait) tips it over.

Promontory Peg Deadfall

A simpler design with fewer carved pieces. Effective for small animals and faster to build.

Components

Upright peg: Driven into the ground or propped against a fixed object. Has a notch near the top.
Deadfall support stick: One end rests in the notch on the upright peg; the other end supports the deadfall weight.
Bait string: A piece of cordage or plant fiber attached to the support stick, with bait at the end. When the animal pulls the bait, the support stick is pulled from the notch and the weight drops.

Construction

Upright peg: Drive a straight stick into the ground near the trap location. Or lean it against a rock. Carve a notch on one side near the top, facing horizontally.
Support stick: One end rests in the notch on the upright peg. The other end props under the forward edge of the deadfall weight. The weight rests on the support stick.
Bait cord: Tie a short piece of cordage (4-6 inches) to the middle of the support stick, hanging down. Tie bait to the end of the cord.
When an animal pulls the bait cord, the support stick is pulled from the upright peg's notch, the weight drops.

Advantage

Fewer carved parts. The notch in the upright peg is simpler to carve than the three interlocking notches of the figure-4.

Limitation: Less adjustable for sensitivity. The cordage pull must pull the support stick out of the notch — this requires a pull rather than a nudge, which works for animals that grab bait (mice, squirrel) but less well for animals that cautiously nibble.

Placement

Deadfalls work best at:

Food cache sites (animal caches: nut piles, stored seeds)
Holes and burrow entrances
Regular feeding spots (under a consistently-used mast tree, near a water source)
Along runs, but positioned to the SIDE of the main travel path (forcing the animal to step slightly out of its path toward the bait)

Position the trap opening so the animal must reach INTO the trap to take the bait — not just snatch it from the edge. The trigger must be under the weight when the animal accesses the bait.

Camouflage the trap perimeter with natural materials — leaves, small sticks, bark — so the trap does not look like an alien structure. A well-camouflaged deadfall catches more.

Multiple Traps and Returns

Set as many as time and materials allow. Check every 12-24 hours. Reset immediately after a successful catch. Move unproductive traps to new locations after 48 hours of no activity — the location may be wrong, not the trap.

A trap that drops but the animal is not there: the trigger was too light (wind or debris set it off). Adjust sensitivity and reset.

A trap that shows disturbed bait but did not drop: the trigger is too stiff. Reduce friction and notch engagement.

Sources

U.S. Army Survival Manual FM 21-76
Tom Brown Jr. - Tom Brown's Field Guide to Living with the Earth
Mors Kochanski - Bushcraft: Outdoor Skills and Wilderness Survival

Frequently Asked Questions

What weight deadfall is needed for different animals?

The weight must be sufficient to kill the animal quickly, not just pin it. For mice and chipmunks: 1-3 lbs. For squirrel: 5-10 lbs. For rabbit: 10-20 lbs. The rock or log must drop flat and hit the animal on the back of the head or spine — placement and weight balance both matter.

Is a deadfall trap more effective than a snare?

Snares are generally more effective and easier to build well. Deadfall traps require more precise construction and placement, and the trigger must be calibrated for the target animal. Deadfalls are valuable when wire is unavailable, or as supplementary traps near bait sites where animals pause and investigate rather than running through.

What is the best bait for deadfall traps?

Use food the target animal is actively seeking. During nut season: acorns, hickory nuts. For squirrel in winter: stored seeds. For rabbit: apple, carrot, or dandelion root. For mice: grain, peanut butter, bread. The bait must be attached so the animal must interact with the trigger stick to access it.