Merlin Bird ID app

Merlin Bird ID by Cornell Lab of Ornithology is a brilliant app to help you identify birds when outdoors.

Designed for beginner and intermediate birdwatchers, Merlin Bird ID is a smartphone app available for Android and iOS. I’ve been using it for a couple of months and I think it’s absolutely brilliant. (Thanks Iris for introducing me to Merlin!) So let’s have a look at its main features.

Free – and no ads

This is a good starting point! The app is free to install, and does not contain those annoying pop-up ads you usually get in free apps.

Globally available

Also great is that the app can be used anywhere in the world! Currently it has content for over 8,500 birds! Obviously you won’t need all that info, so the makers offer Bird Packs, each of them tailored to the birds that may visit your neighborhood.

Easy to start

Upon opening the app for the first time, you are prompted to download your relevant country or region’s Bird Pack (list of birds). There looks to be over one hundred packs, ranging from specific countries like Iceland, Uruguay or Kenya to regions like US Northeast, North Africa or South East Asia. I selected Europe: Western, which says it includes “frequently encountered species found in France, north to Germany and east to Austria” so that includes Belgium where I live. It lists 381 birds in this region.

The opening menu displays “Start Bird ID” and three other options: Photo ID, Sound ID and Explore Birds:

The opening menu of Merlin

The best: Sound ID

I’m going to start with what I consider the best feature of Merlin, which is Sound ID. This is the feature of Merlin that I use the most and is absolutely brilliant! Sound ID listens to the birds around you and shows real-time suggestions for what’s singing or calling!

When you are outdoors and you hear a bird, you simply open Merlin, press Sound ID and then the big microphone icon. The app then “listens” to the bird and tells you what it is! Yes it really is that simple – and it works marvellously. Here’s an example when it identified five different species in a four-minute recording:

5 bird species were calling in the woods!

Highly accurate

After two months of using Merlin in the field, I reckon that it will match a call/song of a bird with the name of that bird 90% of the time. There are a few occasions when something is singing or calling and Merlin doesn’t identify the bird. But nine times out of ten it will respond with an identification.

But has it identified the right bird? Can we trust it? Well, I am pretty well acquainted with the calls and songs of most common birds that I am likely to hear in my neighborhood, having learned them as a young boy from two LPs I had: Bird Sounds in Close-up Volumes 1 & 2. So I have been putting Merlin to the test. Very occasionally Merlin gives me a questionable identification. I would place its accuracy at something like 95%.

Visual identification

To get Merlin to identify a bird you have seen, press “Start Bird ID” and the app asks where you saw the bird, when you saw it, the size of the bird, its main colors, and what the bird was doing. It then creates a list of possible birds. You can scroll through the possibilities until you recognize the bird you have seen. If you can’t find your bird you can adjust your answers – adding another color for example, or more accurately defining its size.

The main questions asked by Merlin.

ID from a photo

You can also press Photo ID. This is when you can take a photo or choose a photo from your library, and the app identifies it.


It’s not really a drawback of this app, more a personal opinion of using any app while I am outdoors enjoying nature. Basically, I don’t want to be on my phone a lot when walking in nature. For this reason I do not use the “Start Bird ID” mode as I don’t want to be spending time scrolling through the questions. if I see a mystery bird I prefer to take notes – or if I have my camera and telephoto lens with me, take a picture – and then look it up either in Merlin or in a bird book back home.

But that’s just my personal way of working. I do however use the Sound ID mode a lot. That involves no scrolling, just one button to press.

More useful bird info

The app also provides a lot of useful information on birds. If you enter the “Explore Birds” mode you can scroll through all the birds in your Bird Pack, pick out the bird you wish to know more about, and find out lots of details such as photographs, sounds, maps, and ways to identify it in the future. The photos include males, females, as well as juvenile photos of each species. It really is very comprehensive.

An example from “Explore Birds”

Where do I use it?

Personally, for me its great strength lies in its ability to identify bird sounds in real-time. This is how I use the app as it’s fun and it really improves my ability to identify birds. Birds have such a range of calls. One type of call, and one which I am not so familiar with, is the flight call. Birds in a flock keep in contact with each other by chirping to each other. Flight calls of finches and buntings, for example, are quite similar, and I am not very good at identifying them. Merlin, however, has no such problem. So I was delighted when it identified a flock of small birds passing quickly overhead as containing chaffinches, linnets and reed buntings!

Another example is a mixed winter flock of tits working through the tops of trees in a forest. These often contain various species. Again, Merlin comes up trumps. It identified a recent small flock of about 30 tits as containing at least one blue tit, great tit, coal tit and a marsh tit.

I am also impressed by Merlin’s “ears”, which pick up bird sounds from quite a distance away. I was in my local woodland the other day, listening to the birds while using Merlin, and a Jay came up on the Merlin screen. I know what a Jay sounds like and I had not heard a Jay. But then way in the distance I heard … a Jay! It must have been half a kilometer away or more. Merlin had picked it up before I had.

Overall conclusion

I think that the developers over at Cornell University have done a fantastic job compiling such a great app and making it available for free. I highly recommend it.

If you download and use it, let me know how you get on with it. I would be especially interested to hear from readers using Merlin in different regions of the world.


  1. I’ve not been happy with sound ID on Merlin. Perhaps they just haven’t got to my part of the world yet. Good to know that it works well somewhere, because that means it is just a matter of time before they train it for other places.


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