Bird #1. A rather haggard black and white oystercatcher with a low black bib, with a lot of black "dripping" down its bib onto the upper belly. Although some many would be tempted to call this a frazari American Oystercatcher, it is a hybrid American X Black Oystercatcher. Ventura Harbor, Ventura, CA.
On much of the continent, ID of oystercatchers is a carefree and stressless task. You either have Black or American, or none at all. Simple. Enter Southern California, which has moderate numbers of Black Oystercatchers, and occasionally American Oystercatchers, which allegedly occur so often that they aren't even a review species anymore. The two species hybridize frequently, primarily in Baja California, but those birds regularly move north into California...giving us Black, American and hybrid oystercatchers to find. This is complicated enough, right?
No. No it is not. It needs to be more complicated. Because the subspecies of American Oystercatcher here (frazari) is thought (by some) to look exactly what a hybrid American X Black Oystercatcher would be expected to look like. They are not really expected to look like the clean cut, palliatus Americans of the east coast. They are sloppy, smudgy, and have tons of black bleeding in to their white parts...or so some have been lead to believe.
So how can you tell a hybrid from a frazari American Oystercatcher? Is there even a difference? Are frazari oystercatchers just hybrids, and nothing more? Well, with the way some birders think of frazari as appearing, there really isn't a difference (i.e. in the latest edition of the National Geographic guide, which is quite unhelpful in this instance). But if one is a bit more conservative in their approach (i.e. not stringy), the differences begin to appear.
This is where I am obliged to mention the vaunted "Jehl Scale", which birders take very seriously. If you're not familiar with it, go take a peek. I think it's a good idea and is widely accepted by high-ranking birders, but it is just begging to be misinterpreted. Stringers love using the Jehl Scale, because they can magically turn hybrids into pure birds while sounding like an expert. Put a bunch of birders together and you will likely get all sorts of different Jehl scores for the same damn bird. You also need very good looks/photographs of the bird in order to score it accurately.
My opinion? To put it simply, many so-called frazari in California should simply be called hybrids. The birds with a high black "bib", little to no black in strange places, and only a little smudging on the sides of the bib are good for frazari. It should be noted that other populations/subspecies of American Oystercatcher, such as those in the Galapagos Islands (galapagensis), have a slightly uneven bib as well, so this is not just something to be expected in hybrids.
Yeesh, what a mess. Let's just look at some birds, shall we?
Bird #2: A typical hybrid oystercatcher, albeit a whiter one than Bird #1. The Ventura Harbor has been one of the easiest places to see hybrids in California the last couple years. That said, the Ventura Harbor has been one of the easiest places to string an American Oystercatcher the last couple years, if you get my drift. Photographed at Ventura Harbor.
Note dark mottling under the wing and under the tail, dark flecking on the belly, extensively dark uppertail and black rump...all strong hybrid marks. By the way, I want to give props to the diligent eBird reviewers who have kept misidentified "Americans" from the Ventura Harbor off of eBird.
So how can you tell a hybrid from a frazari American Oystercatcher? Is there even a difference? Are frazari oystercatchers just hybrids, and nothing more? Well, with the way some birders think of frazari as appearing, there really isn't a difference (i.e. in the latest edition of the National Geographic guide, which is quite unhelpful in this instance). But if one is a bit more conservative in their approach (i.e. not stringy), the differences begin to appear.
This is where I am obliged to mention the vaunted "Jehl Scale", which birders take very seriously. If you're not familiar with it, go take a peek. I think it's a good idea and is widely accepted by high-ranking birders, but it is just begging to be misinterpreted. Stringers love using the Jehl Scale, because they can magically turn hybrids into pure birds while sounding like an expert. Put a bunch of birders together and you will likely get all sorts of different Jehl scores for the same damn bird. You also need very good looks/photographs of the bird in order to score it accurately.
My opinion? To put it simply, many so-called frazari in California should simply be called hybrids. The birds with a high black "bib", little to no black in strange places, and only a little smudging on the sides of the bib are good for frazari. It should be noted that other populations/subspecies of American Oystercatcher, such as those in the Galapagos Islands (galapagensis), have a slightly uneven bib as well, so this is not just something to be expected in hybrids.
Yeesh, what a mess. Let's just look at some birds, shall we?
Bird #2: A typical hybrid oystercatcher, albeit a whiter one than Bird #1. The Ventura Harbor has been one of the easiest places to see hybrids in California the last couple years. That said, the Ventura Harbor has been one of the easiest places to string an American Oystercatcher the last couple years, if you get my drift. Photographed at Ventura Harbor.
Note dark mottling under the wing and under the tail, dark flecking on the belly, extensively dark uppertail and black rump...all strong hybrid marks. By the way, I want to give props to the diligent eBird reviewers who have kept misidentified "Americans" from the Ventura Harbor off of eBird.
The same bird as above. A very striking individual; the dark blotches on the axillaries and breast band extending well into the belly (among other things) put this bird firmly into hybrid territory.
Bird #3, at rest. This is on the heavily-marked side of Americanish oystercatchers that show up in California, many are not as striking.
Bird #4: Morse Point, Santa Cruz Island. At first I thought it was the same American Oystercatcher that I had located at the same site previously (see Bird #5) until I noted that it was an adult (adults have all orange-red bills, immatures have a dusky-tipped bill). The breast band was somewhat lower on the breast as well, and less white was visible above the folded wing.
Bird #3 is on the left, Bird #4 on the right. Note the more white on the tail/rump of Bird #4, and wider white wing stripe.
Scoring Bird #4 very conservatively (using other photos as well), the Jehl Scale gives it a 31. That's a pure American Oystercatcher right there, despite the suspiciously narrow wing stripe and narrow tail band infused with dark feathering. At least, that's what Jehl thinks it is. Me? I'm not convinced. I have no doubt that many birders (including good ones) would tick this as an American, but I personally feel like there are too many Black Oystercatcher genes getting expressed.
Meet Bird #5. The bird on the right had been present near Morse Point on Santa Cruz Island since early April, and appears to be staying for the summer. It has the high breast band typical of American Oystercatchers (sitting higher on the breast than birds 1-4), with a very limited amount of smudging near the bend of the folded wing, as expected in frazari. It closely resembled American Oystercatchers I have seen in the Gulf of California, which do not have a mysterious genetic makeup; hybrids do not occur there.
This angle shows the high and unragged black bib line, as well as the clean white flanks, axillaries and underwing expected in frazari. The undertail coverts are a pristine white as well.
Note the broad width of the wing stripe and tail stripe compared to Bird #4. This bird has a little bit of dark mottling in the white of the tail band, but it is limited and does not bisect the tail/rump. Out of the many American Oystercatcher candidates I've seen in California over the years, this is the only one that I feel really fits the frazari bill. And if you are wondering...this bird scored a 39 on the Jehl scale.
So do all American Oystercatchers in California have Black Oystercatcher genes? It's possible; there is no concrete evidence either way. The American Oystercatchers at the Salton Sea in the 1970's most likely came from the Gulf of California, where hybridization does not occur (a photograph of a couple of those birds is on Don Roberson's page here). I think that's something we should accept though; frazari birds that show up here likely have some Black Oystercatcher genes, but that doesn't mean we should count all hybrids as American Oystercatchers, or not count American Oystercatchers at all.
If you would like to learn practically everything there is to know about American Oystercatchers, the American Oystercatcher Working Group is an excellent resource. And if anyone knows where to find Jehl's classic paper online, please let us know!