eDNA vs traditional wildlife surveys: strengths and blind spots

Wildlife biologists have spent a century refining ways to figure out what lives in a place. Camera traps, mist nets, cover boards, point counts, small-mammal grids, electrofishing, acoustic recorders — each has a niche. eDNA is the newest tool on the shelf, and it is complementary to those methods rather than a wholesale replacement. Here is where each shines and where each falls short.

Where eDNA wins

eDNA excels at cryptic species: fossorial mammals, secretive reptiles, larval amphibians, elusive fish, and everything nocturnal. A single water sample from a small stream can reveal salamanders that would take a herpetologist a full weekend of turning cover objects to confirm.

It also excels at breadth. A metabarcoding run with a broad primer set returns dozens or hundreds of species at once — an inventory that would take a traditional team years to compile.

Where traditional methods win

Anything requiring behavior, body condition, individual identity, or exact location favors direct observation. Camera traps show you a bear rubbing a tree, its age class, whether it has cubs. Mist netting a bird gives you weight, wing chord, and a band to track migration.

Traditional methods also produce absolute counts. eDNA read counts can suggest relative abundance under careful conditions, but they do not tell you 'seven wood thrushes are nesting in this stand' the way a point count can.

The hybrid future

Increasingly, professional surveys use eDNA as a fast, wide-net first pass, then follow up on the interesting hits with traditional methods. eDNA might reveal an unexpected salamander species; the herpetologist then goes back to characterize the population.

For land managers and homeowners without a team of specialists, eDNA is often the only practical way to get a real species inventory. It replaces guesswork and iNaturalist scrolling with actual data.

Frequently asked questions

Can eDNA replace camera traps?

For inventory questions, often yes. For behavior, body condition, and individual identification, no — cameras and eDNA answer different questions.

Is eDNA cheaper?

Per species detected, almost always. A single kit can return dozens of species; getting the same list from cameras and trapping would take weeks of field time.