The Merlin Story: From Field Guide to Smart Identifier

Merlin was launched as a free mobile app to bring the power of Cornell’s birding databases to everyday users. Over time, it’s grown far beyond a static “book in your hands.” It now supports identification by question prompts (size, color, behavior), by photo, and by sound (in many regions). 

A core strength of Merlin is that it is built on—and continuously informed by—the massive user-submitted observation database eBird (and the Macaulay Library of photos and recordings). Merlin’s algorithms (for photo ID and sound ID) are trained using compiled bird photos, recordings, and metadata contributed by birders worldwide. 

In short: Merlin is not just static—it learns and evolves as more data comes in.

Key Features & How They Help

Here are the major features that make Merlin powerful and enjoyable to use:

1. Bird ID by prompts (Wizard / descriptive)

You can answer a few simple questions (where and when you saw the bird, how large it was, what main colors you saw, and what it was doing) and get a likely candidate list. Merlin filters out species unlikely for your location or season, narrowing possibilities.

This is great when you see a bird but can’t snap a clean photo or record a song.

2. Photo ID (computer vision)

You can feed Merlin a photo (camera or gallery) and the app uses computer vision to suggest likely species matches. It doesn’t always get the top one right, but in many cases it gives you a plausible shortlist.

Even if your photo is far from perfect (through foliage, a bit blurry, partial view), Merlin often still gives useful suggestions.

Photo ID is powered by models trained on large datasets from eBird / Macaulay Library and collaborators like Caltech / Visipedia.

3. Sound ID / Bird Song Recognition

This is one of Merlin’s coolest features: you can press “Sound ID,” and the app listens in real time (or from a recording) to identify which birds are singing nearby. It displays suggestions as it hears them.

Behind the scenes, Merlin transforms audio into a spectrogram (a visual frequency-vs-time display) and then runs its trained neural network to match patterns to known species.

However, Sound ID is not fully global yet: in many regions (especially less-studied ones) its species coverage is limited.

You can help expand the system by submitting recordings tagged with background species in eBird checklists.

4. Explore Birds / Likely Birds lists

Rather than waiting to identify one by one, you can browse all species likely for your location and date. Merlin lets you set a location (even in advance) so you can work offline.

You can also sort the list by “most likely” (instead of alphabetical) to focus on species with the highest probability.

5. Bird Packs for regions / travel

If you're traveling, you can download bird packs for specific regions (e.g. India, Europe, Central America) so that Merlin’s identification system is tailored to that area.

6. Saving / Life List (“Save My Bird”)

Once you're confident in an ID, you can tap “This is My Bird” to save it to your personal life list—complete with date, location, and saved to your Merlin profile.

Because Merlin is connected to eBird, your saved birds (and their metadata) are visible in your eBird interface (My eBird → Manage Checklists).

7. Offline support

One essential feature: once you’ve preloaded the relevant bird pack or configured location filters, Merlin will function offline (for ID, Explore Birds, and using saved location data). This is immensely useful when you're in the field out of cellular reach.

8. Sound and Photo Libraries / Reference media

For each bird species, Merlin includes photos, recordings of songs/calls, range maps, and descriptive notes. You can play back calls for reference or compare your observations.

Utility & Real-World Use

Here’s why Merlin is more than just a fun gadget—it adds real value to birding (for beginners and experienced alike):

• Instant feedback in the field. When you come across a bird you don’t recognize, Merlin can often give you candidate names right then and there—especially helpful when the bird flies off too quickly.

• Learning & education. By comparing your observations with what Merlin suggests, you train your eye and ear over time.

• Encouraging citizen science. Because Merlin is connected to eBird, your observations help strengthen the larger database (if you choose to upload via eBird).

• Expanding audio birding. Some birds are cryptic or low in visibility, but singing. Sound ID helps you “see” via ear.

• Travel support. You don’t need to carry multiple field guides; just download the regional pack and go.

• Memory & documentation. Your life list preserves not just the bird names but when/where you saw them.

• Supporting research and conservation. More observations (with verified metadata) help researchers understand species distributions, phenology, and shifts in ranges over time.

However, Merlin isn’t perfect. In complicated cases—very similar species, tricky lighting, overlapping songs—its suggestions may be ambiguous or incorrect. Many birders treat Merlin as a companion, not the final authority. Also, in poorly documented regions, Merlin’s models might not have as strong a foundation yet.

Some users in birding forums estimate ~75% accuracy for Sound ID in their contexts (i.e. it misses some and occasionally mislabels).

Still, its strengths and ease of use make it a powerful tool.

Integration with eBird & Other Databases

One of Merlin’s biggest advantages is how it leverages and interfaces with other birding data systems.

eBird & Macaulay Library

Merlin is tightly interwoven with eBird, Cornell’s platform for community bird observations:

• The species lists and likelihood models in Merlin come from aggregated eBird observations (hundreds of millions of checklists).
• Photo ID and Sound ID models are trained on large volumes of images and recordings from eBird checklists and the Macaulay Library. 
• When you save a bird in Merlin and mark it via “This is My Bird,” the data becomes part of your eBird interface (checklists) in many cases.

This synergy means Merlin “stands on the shoulders” of the global birding community.

Export / Interoperability

If you use other platforms (such as iNaturalist or other personal bird-logging tools), there is some possibility to export your Merlin records, though integration is not always seamless.

• Some users report exporting their Merlin list (CSV or similar) and then importing into iNaturalist or other systems.

• But because Merlin’s primary observational backend is eBird, the best “native” integration is with eBird.

• Note: Some birders suggest caution about over-automated merging between Merlin and eBird, especially when automatic IDs are used without validation. (In forums, some say that automatic use of Merlin’s IDs in eBird might lead to low-quality data). 

Beyond Birding Databases?

Merlin’s design is quite domain-specific, so it doesn’t integrate broadly with non-birding systems (ERP systems, for instance). (Do note: there is a commercial “Merlin” enterprise software in other domains, but that’s not related.)

So in essence, Merlin is built to connect deeply with the birding / citizen science ecosystem (not general business systems).  

Tips & Best Practices

To get the most out of Merlin, here are some user tips:

1. Pre-download your regional bird packs before going into remote areas so you can use it offline.

2. Set location filters ahead (in the Explore Birds menu) so Merlin knows which species to focus on.

3. Use multiple identification modes. E.g. if Photo ID is inconclusive, switch to descriptive or Sound ID (if allowed in your region).

4. Use good photo / audio habits. Try to get clear views (good lighting, minimal obstruction) and clear recordings (less background noise).

5. Verify suggestions. Don’t accept Merlin’s top suggestion blindly—compare with what you see/hear and the reference media.

6. Contribute recordings / media. If you have good audio recordings or photos, tagging background (other species) in eBird helps train the models.

7. Backup or export your life list if you use multiple platforms (in case you ever switch tools).

8. Stay aware of coverage limits. In under-sampled regions, some species may not yet be well represented by the models, so treat the output as suggestions, not guarantees.

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A Birding Companion, Not a Replacement

The beauty of Merlin isn’t that it replaces field guides or human expertise—it’s how it augments them.

• For beginners, it accelerates learning and reduces the frustration of not knowing what you saw.

• For intermediate or advanced birders, it’s a second opinion, a reference, a fast lookup tool.

• For regions or species you’re less familiar with, it helps fill gaps in your knowledge.

Because Merlin is kept free and open (in the sense of leveraging eBird’s open data), it encourages broader participation in birding and citizen science. Through smart integration and continuous model improvement, it’s helping transform what once was a hobby for enthusiasts into a more accessible, data-driven experience.