Deadfall Traps: Construction and Principles for Large and Medium Game
The deadfall is the oldest trap in the human toolkit. Its principle — a heavy weight suspended by a trigger mechanism that releases when an animal disturbs it — has been used on every continent for thousands of years. Gibson's 1881 guide documents the deadfall in several variants, from the massive bear deadfall requiring a 15-foot log, to the portable figure-four deadfall deployable from any three sticks. All share the same mechanical logic, and mastering that logic is more valuable than memorizing specific designs.
The Physics of the Deadfall
A deadfall trap stores potential energy in a suspended mass and releases it via a trigger that is destabilized by the animal. The weight provides the killing or capturing force; the trigger mechanism is the heart of the trap's design. Gibson's detailed illustrations and descriptions show that the trigger does not need to be complex — it needs to be balanced on the edge of instability, requiring only slight force to collapse.
The critical performance variables are:
Drop weight: Heavier is more certain but harder to set and more materials-intensive to build. For small to medium game (squirrels, rabbits, mink), a 10-15 pound rock or log is adequate. For beaver, raccoon, or porcupine, 20-30 pounds. For bear, Gibson specifies logs 6 inches in diameter and 15-20 feet long — weights that can only be achieved with large timber in the right forest.
Drop height: The weight must fall far enough to develop lethal or immobilizing force. Gibson's designs use the full available height — 2-3 feet of drop for small game, 4-6 feet for large. A weight dropped from 6 inches will rarely kill cleanly; the same weight from 3 feet becomes reliable.
Trigger sensitivity: The trigger must require enough force to avoid false trips from wind, falling debris, or light contact, but little enough that the target animal will trip it while reaching for bait. This balance is achieved by practice — building and testing the same design repeatedly until the trigger geometry is understood intuitively.
The Figure Four: One Design to Learn First
Before attempting any other deadfall, master the figure four. It requires only three notched sticks and can be built in five minutes with a knife. The completed trigger assembly — when viewed from the side — forms the shape of the numeral 4. It can be scaled from mouse-sized to raccoon-sized by adjusting stick dimensions. It works in any environment with available wood.
The Bear Deadfall: Gibson's Primary Design
Gibson's flagship large-game deadfall is designed for bear and uses a construction method that any trapper with an axe and time can deploy. The design requires a pen enclosure that forces the bear to approach from a single direction, ensuring contact with the treadle.
Construction sequence:
First, build the pen. Select young trees or straight branches about 3 inches in diameter. Drive them in a row to create two side walls and a back wall, with an open front. The pen should be approximately 3 feet wide, 4 feet deep, and 4-5 feet high. Roof the back portion with crosspieces to prevent bait theft from above. Leave the front open — the deadfall log will cover this opening.
Next, prepare the trigger system. Four wooden components work together:
- A vertical post with a notch cut on its lower face, driven into the back left corner of the pen
- A second post with a reversed notch (flat side up), planted outside the pen on the right
- A third post with a crotch at the top, placed outside the pen on the right front
- A treadle piece: a forked branch about 3 feet long with a flat board across the fork ends, and an upright stick inserted at the junction
Two poles approximately 4 feet long complete the mechanism. One passes through the pen stakes, resting in the interior notch at one end and held under the exterior notch at the other. The second pole's ends rest in the exterior crotch and beneath the first pole's projecting end.
The heavy log — 6-8 inches in diameter, 6 feet long — rests on the front end of this second pole, balanced by the entire trigger assembly. The treadle sits at the entrance of the pen, raised in front, with its upright stick engaged under the latch pole.
Setting the trap: Bait with honey placed at the back of the enclosure, or honey-smeared meat. Weight the elevated end of the deadfall log with additional timbers. When the bear enters and presses the treadle while reaching for bait, the upright disengages the latch, releasing the entire mechanism. The log falls across the bear's back.
Deadfall Logs Are Dangerous to Set
A deadfall log under tension can release unexpectedly during setting. Never place your body under the suspended weight while adjusting the trigger. Approach the trigger from the side, not from beneath the log. Have a method to safely abort if the trigger is accidentally tripped during setup. These traps have injured and killed trappers throughout history.
The Figure Four Deadfall: Universal Small Game Trap
The figure four is the most portable and reproducible deadfall trap ever devised. Gibson describes it in detail, but its design is documented in survival manuals worldwide because it is genuinely the best all-purpose deadfall for small game.
Three sticks are required. All must be reasonably straight, of a diameter appropriate to the game being targeted (pencil-diameter for mice, thumb-diameter for squirrels, finger-diameter for rabbits), and long enough to support the weight while keeping it elevated.
The upright stick: Cut a notch near the top of this vertical stick — a square notch on the side facing the weight. This is the primary support for the weight.
The diagonal stick: Cut two notches — one near the top that engages with the upright's notch, holding the two together at an angle; one about one-third up from the bottom that catches the horizontal stick.
The horizontal stick (bait stick): One end supports the weight (resting under the diagonal stick's lower notch). The other end is sharpened or baited. When an animal disturbs the bait end, the horizontal stick is pulled, disengaging the diagonal from the upright, collapsing the assembly and dropping the weight.
Bait for common game: peanut butter, apple, carrot, or grain for squirrels and rabbits. Fish guts or meat scraps for mink and weasels. The bait must be secured to the stick, not merely placed on it — an animal that can remove bait without entering the trap's strike zone will repeatedly rob a poorly set figure four.
Practice Before You Need It
Build a figure four deadfall before a survival situation. Set it without a weight and practice achieving consistent trigger sensitivity. Most beginners make their triggers either too loose (trips in wind) or too tight (won't trip). The correct balance is a trigger that holds reliably under its own weight but collapses when the bait stick is pushed from one end with roughly 2 ounces of force.
Selecting Deadfall Sites
Gibson dedicates significant attention to site selection, noting that a perfectly constructed trap in the wrong location catches nothing. For bears, select well-used game trails near berry patches, streams, or areas with visible evidence of recent feeding. Bears return to productive food areas reliably.
For small game, look for:
- Runway marks — small paths worn through ground cover by repeated animal movement
- Droppings, tracks, and gnaw marks that indicate recent activity
- Natural funnels: gaps in brush, fallen logs, stream crossing points that animals use repeatedly
Set traps at right angles to runways rather than directly in them. Animals are more likely to investigate a new object at the edge of their path than to step directly over an obvious obstruction in their route.
Conceal the unnatural elements of your trap. Gibson recommends using natural materials to blend the pen structure with the surrounding environment, and disguising steel components with mud, leaf litter, or local forest debris. Scent concealment is also important — handle wooden components with clean hands or gloves, and allow the completed trap to weather for 24-48 hours before baiting if time allows.
The Downfall: A Simple Weighted Trap
For medium game in locations without suitable deadfall logs, Gibson documents the downfall — a flat rock or heavy board suspended at an angle by a simple notched stick. The bait is placed under the slanted weight, and when the animal reaches under it, contact with the notch releases the weight.
This design is less mechanically reliable than the figure four but requires only one shaped component (the notch stick) and any available flat heavy object. In rocky terrain without suitable wood, a flat stone slab can substitute for the log. The trap is most effective for ground-feeding birds and small mammals like rabbits and squirrels.