People obviously misidentify birds sometimes and there are some well-known species pairs or groups that are pretty hard to get right. My interest in this thread is not necessarily in general cases of hard identifications but in locally specific errors that regularly occur in particular places or regions. I think it can be revealing of how birders approach identification, particularly when they're starting out or are unfamiliar with an area.
I'm mainly a local patch birder at Girdle Ness in Aberdeen. I often bump into visiting birders and also check lists people post on sites like Ebird or Birdtrack from here. I think I have a pretty good idea of what birds are common here and in what sort of numbers, so I'm often curious when visiting birders seem to be seeing things that I don't tend to see or in numbers that seem really unusual. Of course, I might be missing stuff and they might genuinely be seeing things that are unusual, but there tend to be some species that fairly consistently get misidentified in the area. I'll go through a few of the commoner examples.
Black-throated Diver
Black-throated Diver is pretty rare here. I think it's maybe marginally commoner than White-billed Diver, but not by that much. Probably 95% of divers I see are Red-throated, and most of the remaining 5% are Great Northern. A fraction of 1% are White-billed or Black-throated. I think other local birders see them at the same kind of rate. But visiting birders often seem to see them, sometimes in quite good numbers. They're usually a bit surprised when I say how rare they are. I've lived in eastern Scotland for 26 years and, away from the Forth and Moray coasts where they seem regular, Black-throated Diver is pretty rare in my experience. I've probably seen fewer than 10 away from those core areas.
Lesser Black-backed Gull
LBBs are common residents everywhere in Britain aren't they? Well, no. In northeast Scotland, they're basically a summer visitor. At Girdle Ness between mid-October and late February, I've seen two in ten years. They're quite a bit rarer than Glaucous or Iceland Gulls, for example. But other people's lists frequently have LBBs on them during this time of year. I saw a list from Girdle Ness the other day that had a count of five. I've not seen one here since mid-September! This is maybe one of those cases where people just assume they're around and don't look too closely at the 'black-backed gulls'.
Goosander/ Red-breasted Merganser
Obviously these are quite similar species but there's a particular variant of their confusion that's common in eastern Scotland more generally. I think some birders assume that if they're anywhere near the sea, they're RBMs. But Goosander form large moulting flocks in summer and these are often around river mouths or in coastal waters. These are always getting mis-IDed as RBMs. We get a moulting flock of 50-100 at Girdle Ness in summer and every year, I'll see a list on Ebird or Birdtrack with a count of 50+ RBMs on it. We do get them here, fairly commonly, but not in those numbers.
Twite
You get Twite in Scotland don't you? Linnets in England; Twite in Scotland. That's how it works. Well, sadly Twite is no longer very common in most parts of Scotland and I haven't seen one at Girdle Ness for over a decade. Since then, I think there have only been one or two reliable records. Lots of claims though, usually in late summer when tonnes of juvenile Linnets are about.
Tree Pipit
Girdle Ness is good for migrants, so there must be good chances of Tree Pipit. Well, we do get them but they're surprisingly scarce and most records are flyovers. Quite often I'll see records online of Tree Pipits here, usually at odd times of the year. These aren't definitely wrong, but I suspect most of them are.
Purple Sandpiper
This is maybe the most locally specific one here and is a bit unusual in that it's a case of a species being much commoner than people think rather than rarer. We regularly get a roost of 200+. If you see a large flock of Calidris waders here, they will be Purps. We get other small waders too, but never in those sorts of numbers. Every year, I see reports of 200+ Dunlins though. Not a serious mistake but that would be a massive record count for here. We get Dunlin regularly, mostly as a passage migrant and usually in single figures. It's an interesting case where sometimes the bird apps don't help. Routine counts of 200+ Purple Sandpipers often get flagged as unusual by Ebird/ Birdtrack, while a similar count of Dunlin wouldn't, despite being far less likely. I sometimes wonder if that's a source for some of the misIDs. I also once saw an unusually high count of Redshanks from a visiting birder that I suspect were also Purps.
These examples aren't intended to belittle birders who may be inexperienced or are new to the area. It's mostly just to look at the local specifics of identification and some of the surprises and challenges this can throw up. I'd be interested in other examples from other areas. I'd also add that I've definitely casually misidentified things myself when travelling around, particularly in other countries.
