Merlin or the Audubon Bird Guide: scanner against field guide

Merlin offers three routes to a name: a photograph, five questions about size, colour and behaviour, and Sound ID listening live and naming several species singing at once. Its identifications are weighted by what eBird checklists say is plausible in your county this week, which is much of why it works.

Audubon is a complete North American field guide in an app, built on the Society's own species accounts. It has a step-by-step filter — size, colour, region, habitat, activity — that you work through yourself, which is a very different exercise from pointing a camera.

Working through Audubon's filter teaches you what to look at, and that is worth something a scanner cannot give you. Merlin's five-question wizard does the same job faster and with less depth.

Audubon includes recordings you can play. Merlin listens, which is a different capability entirely.

Sound ID identifies species as they sing, several at once, drawing a live spectrogram with each name labelled against the part of the recording that produced it. Standing in a wood at dawn with it running finds birds an experienced birder in the same spot had not registered.

This matters because most birds are heard before they are seen. A warbler in a canopy is a sound long before it is a photograph. No field guide, however good, is available in that moment.

The reason no one else matches it is institutional: the Macaulay Library of expert-verified recordings, plus eBird's record of what is actually present near you. That is a century of ornithology, not a feature.

Merlin gives you a name and a short account. Audubon gives you the species treatment: nesting behaviour, diet, migration timing, habitat preference, conservation status and detailed range maps, written by an organisation that has been publishing bird references for over a century.

That is the difference between knowing what it was and understanding what it was doing. If you have just identified a bird behaving oddly — a heron in a field, a hawk being mobbed, a warbler in the wrong month — Audubon is where the explanation is.

It also works fully offline once installed, which for a reference is exactly what you want.

On 2026-09-03, both listed no in-app purchases at all. Merlin is published by the Cornell Lab of Ornithology and Audubon by the National Audubon Society — a university research programme and a conservation non-profit, both membership-funded.

Neither app is a loss leader for a subscription because neither organisation sells software. They are outreach, and the quality reflects institutions with something to prove about birds rather than about retention: Merlin holds 4.9 from 112,000 reviews, Audubon 4.3 from 4,518.

The commercial bird identifiers have to justify a subscription against this, which is a hard position to be in.

• Download Merlin's regional bird pack over wifi. It cannot identify offline without one, and the packs are large.
• Download packs for where you are travelling, not only where you live — a pack for the wrong continent produces confident nonsense.
• Allow microphone access and test Sound ID before you need it.
• Keep location services on. Merlin's accuracy leans heavily on knowing what is plausible where you are.
• Let Audubon finish its initial download, so the guide and range maps work with no signal.

Then leave Sound ID running while you walk and open Audubon when something needs explaining.

Neither identifies a feather, an egg or an empty nest, and all three are ordinary finds. Those are identified from characters you list rather than photograph, which is why we built free browser keys for feathers and eggs.

In the United States it is illegal to possess the feathers, eggs or nests of almost any native bird under the Migratory Bird Treaty Act, including items found on the ground. Photograph them and leave them.

Both apps make you better at this if you let them, and the mechanism is the same: they ask the questions a field guide would ask.

Merlin's five-question wizard — where were you, when, how big, what colours, what was it doing — is a classic identification key in app form. Audubon's filter walks the same ground more slowly. Answering either honestly forces you to notice things you would otherwise skip: relative size against a familiar species, whether the bill is thin or conical, whether it foraged on the trunk or at the branch tips.

Those are the characters experienced birders actually use, and they work when the bird has already flown. A scanner does not teach them, because the photograph does the noticing for you.

Two habits worth building alongside the apps. Learn the ten commonest species where you live properly, so everything else becomes 'not one of those' rather than 'unknown' — that is most of what expertise looks like early on. And check what eBird reports near you before going out, because identifying against twenty plausible candidates is a different task from identifying against four hundred.