What May Have Killed My Duck? Evidence Matcher

Something got in last night and you want to know what, because the fix for a raccoon is not the fix for a fox, and the fix for a weasel is not either. Five university extension services publish tables matching the evidence at the scene to the animal that leaves it. This tool puts those tables together: tick what you found and it lists the predators the sources say are consistent with it, what each one does, and what stops it.

Key takeaways

• Headless birds point to raccoons, hawks and owls; several dead birds not eaten point to a weasel or mink; birds mauled and left point to a dog.
• Eggs gone without a trace is a snake; eggs eaten with shells left is a skunk, rat, opossum, raccoon or crow.
• Hawks hunt by day, owls by night, and both are federally protected in the United States.
• Whatever it was, the two measures that stop most of it are shutting the ducks in at dusk and half-inch hardware cloth on every opening — quarter-inch where weasels or snakes are about.

Where the tables come from

The clue list is built from eXtension’s predator management article, the University of Kentucky’s ID-245 table, the University of Maryland’s FS-1132 table, Virginia Tech’s APSC-192P table and Ohio State’s VME-22 fact sheet. They were written for chicken keepers as much as duck keepers, and the predators do not distinguish. Each clue in the tool carries the sources that list it, and each predator’s description and prevention advice is drawn from those same pages.

The tables agree on most things and differ on a few. All five put missing adults with no disturbance down to dogs, coyotes, foxes, bobcats, hawks and owls. All put missing heads down to raccoons and birds of prey. Maryland adds detail the others do not — the lingering smell of a skunk, digging under the run as a coyote sign — and Virginia Tech adds the most useful non-clue of all: a dead bird with no injury at all usually means disease or piling, not a predator.

How the matching works

Each clue you tick adds a point to every predator the sources list for it, with a second point where a clue is close to diagnostic — the musky smell, the bird eaten on the spot with feathers plucked clean, the pile of bloodied uneaten birds. The predators are then ranked. The top of the list is the animal most consistent with everything you saw, not a verdict, and if two are tied the tool says so and asks for the time of day, which usually breaks the tie.

What you get for each is what the sources say it does, and what stops it. A raccoon reaches through wire and pulls a head off; the fix is hardware cloth and a latch a child could not open. A fox takes the bird away and leaves a few feathers; the fix is a shut house at night and buried wire, because foxes dig. A weasel fits through a quarter-inch gap and kills far more than it eats; where weasels are about, the fix is quarter-inch mesh, because half-inch mesh does not stop the smallest.

Day and night

The time of the attack is often the best clue you have. eXtension is explicit: hawks typically take birds during the day, owls at night. Bobcats hunt mainly at dawn and dusk. Coyotes are primarily nocturnal but are often seen in daylight. Raccoons, opossums, skunks, foxes and weasels are night animals; dogs work in daylight. If you know when it happened, tick it.

What stops all of them

The two measures that appear in every source are the two that cost least. Shut the ducks in at dusk, every day, without exception — eXtension calls a secured house at night the single most effective measure, and ducks go in on their own once they have the habit. And use half-inch welded hardware cloth on every opening — vents, windows, gaps under the eaves — and quarter-inch where weasels or snakes are about. Chicken wire keeps chickens in; a raccoon puts its arm straight through it.

Below that: bury the wire at least 12 inches — eXtension and Kentucky — or lay a skirt outward from the base of the fence, which Maryland describes as a foot down and then 8 to 10 inches out; remove feed from the run overnight so nothing is drawn in; remove sick and dead birds at once; and for hawks and owls, cover the run or string wire or even fishing line across it, and take out the perches within a hundred yards. Hawks and owls are protected under the Migratory Bird Treaty Act in the US and may not be shot or trapped.

The whole subject — what each predator is, what it wants, how a duck house is built to keep it out — is in protecting ducks from predators, and the house itself in the duck house guide.

A note on certainty

These tables are good and they are not proof. A trail camera on the run for a week costs less than the ducks you have lost and settles the question. If you have found a dead bird with no wound and no sign of an intruder, the predator tool is the wrong tool — common duck health problems is where to look, and an avian vet is who to call.