Date: 3/29/26 9:14 pm From: Eran Tomer <00001de85cdc9338-dmarc-request...> Subject: [GABO-L] eBird, Merlin and tricky IDs
Hi all,
Over recent months I have been encountering repeated issues with eBird reports so I'd like to share the concerns.
First, certain species seem to be over-reported:
* Some uncommon birds are visibly more common on eBird than in the field. * Some are reported from unlikely locations and habitats. * Some sighting notes, photos and recordings confirm misidentifications. * Occasionally some species are reported in suspiciously high numbers on single checklists. * Nearly all of these birds have visual or vocal "confusion species". * The popular Merlin app misidentifies some of these species often (see below).
eBird filters and reviewers flag rarities but many confusable species are fairly common and slip through. Apparent visual mix-ups generating over-reporting of the scarcer (per season) species:
Downy vs. Hairy Woodpecker. White-throated vs. White-crowned Sparrow (immatures confusable also with Field Sparrow and nonbreeding Chipping Sparrow). Winter vs. (Northern) House Wren, and these vs. fleetingly-observed Carolina Wren. Orange-crowned Warbler vs. drab Pine Warbler. House vs. Purple Finch, and rarely female Purple Finch vs. female Rose-breasted Grosbeak. Wood vs. Swainson's vs. Hermit Thrush. Broad-winged vs. Red-shouldered Hawk
To a lesser extent - Cooper's vs. Sharp-shinned Hawk. Greater vs. Lesser Scaup. Louisiana vs. Northern Waterthrush.
Common auditory confusions evidently generating some misreporting:
Downy Woodpecker sometimes utters an extra-loud "Pick !" approaching a Hairy Woodpecker's "Chink !", while a distant Hairy call can sound faint like Downy's. Usually Pileated Woodpecker's and Northern Flicker's calls are diagnostic but they vary and occasionally resemble each other. Pileated Woodpecker and Blue Jay (better known) have some calls resembling a Red-shouldered Hawk's. Red-bellied vs. Red-headed Woodpecker vs. Northern Flicker calls - usually distinctive but sometimes confusable. Osprey and Bald Eagle share not only habitat but also some similar calls. American Crow calls can sound close to Fish Crow's single caws (not the distinctive "UH-uh"). Trills of Chipping Sparrow vs. Pine Warbler vs. Dark-eyed Junco vs. Worm-eating Warbler. Harsh calls of Red-winged Blackbird vs. Common Grackle vs. Rusty Blackbird and sometimes Brown-headed Cowbird. House vs. Purple Finch songs. White-breasted vs. Red-breasted Nuthatch - calls not always distinctive, especially when heard faintly or just once. Red-eyed vs. Blue-headed Vireo songs. The see-saw songs of Black-and-white Warbler vs. American Redstart vs. Prothonotary Warbler, and some Cape May & Bay-breasted Warbler songs. Kentucky Warbler vs. Carolina Wren (and even Common Yellowthroat). Northern Parula has some quirky songs approximating Cerulean and other warblers. Summer vs. Scarlet Tanager songs.
Not even getting into mimicry and other tricks, e.g. Blue Jays' and Red-eyed Vireos' occasionally mewing roughly like Gray Catbird.
Enter the Merlin app. Usually it works well when:
1. The vocalization is loud & clear. 2. The vocalization is repeated. 3. The bird produces its typical vocalization (most species have multiple song and call types, some heard more commonly than others).
I use Merlin frequently with nondescript call notes, for a second opinion on confusable songs, and with any vocalization I don't recognize. But I never report any Merlin-identified species I can't confirm independently because -
* Merlin errs often, especially when the said 3 conditions aren't met, which is much of the time. It struggles differentiating similar songs, e.g. House Finch vs. Purple Finch vs. American Goldfinch when heard indistinctly. It misidentifies Pine Warbler as Dark-eyed Junco consistently, which also highlights the difference between software and humanware: unlike Merlin, we know Juncos don't sing from tall treetops in winter. Pine Warbler does. Merlin also slips with Carolina Chickadee vs. Tufted Titmouse chatter, blackbird "Check !" calls and surely many of the above-listed species, particularly when not heard well.
Sometimes Merlin corrects itself but retains the misidentification on the reporting list rather than replaces it. Example: in spring Chipping Sparrows sometimes sing a short, slow, warbler-like trill. One time Merlin decided it was American Redstart, then gave the correct ID as the bird kept singing and I moved closer. But the redstart remained on the species list. So that's something to watch for.
* Merlin also hallucinates much - it lists birds not present, common species especially. One example: recently I was birding in a heavily forested area and habitat-indifferent Merlin "found" European Starlings twice. None were actually heard (or seen) during the 4-hour hike, nor was any similar vocalization.
All this is not to discredit Merlin altogether. It's highly useful and gets most species right. But it's not fully trustworthy and therefore must be used cautiously, as a supportive tool only. Especially regarding rarities.
Finally, a few, recent checklists had durations (birding times) of 5-7 minutes yet reported 34-36 species. In March and midday / afternoon. That's hardly credible. 35 species in 5 minutes would be impressive even for a spring migration fallout morning. A handful of Piedmont checklists from March have c. 35 species in 15-30 minutes but even that's uncommon, typically involving productive habitat (e.g. aquatic), good timing and luck. Usually such tallies require at least 45 birding minutes. The figures vary among seasons, habitats and regions.
So folks, please be truly careful with visual & sound IDs and confirm independently any Merlin-reported species. Including common birds, not only rarities. If uncertain, eBird allows reporting by family as in "swallow sp.", "New World vulture sp.", "Sharp-shinned / Cooper's Hawk", "Short-billed / Long-billed Dowitcher" (talk about an ID challenge) and many others. And if reporting a rarity, please describe how you determined the ID and ruled out similar species. Holding ourselves to high reporting standards ensures our Georgia eBird data is accurate for everyone relying on it - birders, conservationists and ornithologists.
Best regards & spring migration excitement,
- Eran Tomer Atlanta, GA
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