Skip to content

Oystercatchers at Malibu Lagoon (and nearby)

March 13, 2020

Oystercatchers have become almost regular visitors to Malibu Lagoon in recent months. This is – in and of itself – unusual, but perhaps even more unusual are some of the individual oystercatchers themselves.

Three Oystercatchers (Grace Murayama 2-28-20 Malibu Lagoon)

Surfrider Beach and Malibu Lagoon do not have permanently exposed rocks, tide pools or stony jetties, the primary habitat for Black Oystercatcher. Yet Black Oystercatchers do visit from time to time. Occasionally we get an oystercatcher – perhaps not always the same individual – who looks like an American Oystercatcher, with white belly, breast, thighs, undertail coverts and perhaps a white band in the wings and across the top of the tail. Birders eager to tick off a new bird for the area, or for their life list, may tend to call it an American Oystercatcher, and look no further. But there’s a problem with that.

Black Oystercatcher f (Lu Plauzoles 2-27-11 Surfrider Beach)

 

Rangewide population estimates number of individuals for Black Oystercatchers
Figure by Brad A. Andres, ResearchGate.com

Ranges Overlap: American Oystercatchers (Haematopus palliatus) are found on the eastern seaboard of the Americas from southern Maine to central Argentina and on the western seaboard from southern Chile to (roughly) Santa Barbara County, including the shores of Baja California and the Sea of Cortez (Gulf of California). Black Oystercatchers (Haematopus bachmani or H. bachmani) are found only on our west coast from the Aleutians to mid-way down the west coast of Baja California. These two oystercatcher species breeding ranges overlap on the west coast of Baja (see maps below). The American Oystercatchers breeding on Baja California and around the Sea of Cortez are of the Haematopus palliatus frazari subspecies (H. p. frazari.)

Black Oystercatcher (Randy Ehler 3-23-14 Surfrider Beach)

So far, so good. Complicating the issue is the fact that H. p. frazari (American) and H. bachmani (Black) breed with each other in their west Baja California common breeding area, they produce hybrids, H. p. frazari itself looks a lot like such a hybrid, and both the hybrids and H. p. frazari fly up to Southern California. SoCal birders are having a difficult time telling them apart.

Distribution of Black and American Oystercatchers

Breeding area of American Oystercatcher H. p. frazari (Baja Pub-Articulo-3618)

 

North American Shore Birds by Daniel Giraud Elliot, 1895.
biodiversitylibrary.org

Link to complete (downloadable) PDF article on Frazar’s Oyster-catcher from the above book.

H. p. frazari (American Oystercatcher) breeding on the shores of the Sea of Cortez do not interbreed with H. bachmani (Black Oystercatcher). Only H. p. frazari breeding on the west coast of Baja California, within the southern portion of the H. bachmani breeding range, have the opportunity to breed with H. bachmani. It is possible, but uncertain, if the nominate American Oystercatcher H. p. palliatus will occasionally fly across Mexico from the Gulf of Mexico and visit SoCal. (See photo below.)

SoCal can therefore get:

  • (possibly) nominate American Oystercatcher H. p. palliatus from the Gulf of Mexico
  • “clean” individuals of American “Frazar’s” Oystercatcher H. p. frazari from the Sea of Cortez
  • hybrid Haematopus palliatus x bachmani from Baja California west coast
  • Black Oystercatcher H. bachmani from its Baja to Alaska range

Simple, eh?

American Oystercatcher at the Salton Sea Aug. 14-30, 1977.
(WFOPublications.com Figures Tab)

Not so fast. Here’s a comment from an article on the Rare Birds of California (WFOPublications.org) website about American Oystercatchers in California:

Roberson (1993) noted that three different people assigned scores of 26, 27, and 29 to the 1863 specimen—values at the upper end of Jehl’s hybrid range (10–29). Jehl himself scored the specimen a 27, exemplifying the predicament faced by anyone attempting to judge the acceptability of borderline individuals.

[The WFO article also has a lengthy table of American Oystercatcher and/or hybrid sightings, and two photos (one hybrid; two American Oystercatchers, reproduced above). Read the article and check the photos.]

“Seagull Steve,” in his excellent posting Americanish Oystercatchers: Hybrids vs. frazari, has a similar comment when discussing the bird below.

American (or hybrid) Oystercatcher bird B (Seagull Steve)

Scoring Bird B 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.

Even with the Jehl Scale in hand it’s not as straightforward as one might hope. I recommend that you read Steve’s entire posting. It’s well illustrated and succinct.

“Jehl,” refers to Joseph R. Jehl, Jr. Jehl did field research on American Oystercatchers breeding on the Mexican west coast and published his results in 1985 (Hybridization and Evolution of Oystercatchers on the Pacific Coast of Baja California. Joseph R. Jehl, Jr. Ornithological Monographs, No. 36, Neotropical Ornithology (1985), pp. 484-504). This paper is widely cited but is currently behind a paywall. [See abstract at the bottom of this posting, following the Jehl Scale.] He created a 42-point scale, now known as the “Jehl Scale,” to help differentiate the various oystercatchers. The complete scale is near the bottom of this posting. The scale certainly helps, but as the WFO citation and Seagull Steve’s comment above note, it is difficult for two observers to arrive at the same Jehl Scale score on simultaneous observations of the same bird.

You can print or download your own Jehl Scale and start separating these birds as uncertainly as do the experts. There are two options: either one page or two pages which you can print doublesided.

Oh, I almost forgot – there’s another complication. The Jehl scale lists ten plumage areas to look at: Upper Tail Coverts, Tail, Chest, Belly, Under Tail Coverts, Thighs, Greater Secondary Coverts, Extent of Primary Wing Stripe, Underwing Coverts, and Axillars.

Don’t count on being able to see them all. Perhaps the best you can is to end up with a partial score such as 17 out of 26 or 28 out of 38, instead of  31 out of the perfect world 42.

Following is a collection of frazari and/or hybrid photos taken at Malibu Lagoon/Surfrider Beach, plus one at nearby Las Flores Beach. Give it a go and rate them yourselves. I’ll give you my ratings below each. Most are incomplete; “skip” represents areas I couldn’t see. (Use my ratings for comparison purposes only; reliability unlikely.) I’ve also included some Haematopial factoids for your edification.

Bird #1 (Grace Murayama 12-9-15 Surfrider Beach)

Bird #1 12-9-15: Overall – 17 of 26. Upper Tail Coverts – skip, Tail – 0, Chest – 3, Belly – 6, Under Tail Coverts – 2, Thighs – 4, Greater Secondary Coverts – 2, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Factoid #1 – Etymology. Haemotopus: Linnaeus. Greek haima “blood”; Greek pous “foot”; hence blood-red foot. H. backmani Audubon: after Audubon’s friend Reverend John Bachman 1790-1874. Audubon’s two sons married Bachman’s daughters. Also namesake of Bachman’s Warbler. Oystercatcher: Elliot Coues said, “Oyster-opener would be a better name, as oysters do not run fast,” a sentiment echoed by most other ornithologists familiar with the family. Name attributed to Mark Catesby, 1731.

Bird #2 (Bill Crowe 4-2-19 Surfrider Beach, eBird.com)

Bird #2 4-2-19: Overall – 19 of 26. Upper Tail Coverts – skip, Tail – 0, Chest – 3, Belly – 6, Under Tail Coverts – 4, Thighs – 4, Greater Secondary Coverts – 2, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Factoid #2 – Etymology. H. palliatus Temminck: Latin palliatus “wearing a cloak” from the dark feathering of the back. H. p. frazari: citation from Brewster, 1888, for the collector of the first three specimens from the Baja California shore of the Sea of Cortez, north of La Paz.

Bird #3 (Grace Murayama 1-20-20 Surfrider Beach)

Bird #3 1-20-20: Overall – 17 of 26. Upper Tail Coverts – skip, Tail – 0, Chest – 3, Belly – 6, Under Tail Coverts – 2, Thighs – 4, Greater Secondary Coverts – 2, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Factoid #3 – American Oystercatcher food & foraging. Coastal habitats including sand or shell beaches, dunes, salt marshes, marsh islands, mudflats, and dredge spoil islands made of sand or gravel. During migration and winter, they are found feeding in mud, salt flats or shellfish beaches exposed by the tide. They feeds almost exclusively on shellfish and other marine invertebrates. Oysters are a staple of their diet, as their name suggests, but they also eat mussels, clams, limpets, sea urchins, starfish, crabs, and worms. In general, they use their bills to catch shellfish. [Wikipedia]

Bird #4 (Chris Tosdevin 2-01-20 Surfrider Beach)

Bird #4 2-01-20: Overall – 29 of 42. Upper Tail Coverts – 1, Tail – 0, Chest – 3, Belly – 6, Under Tail Coverts – 3, Thighs – 4, Greater Secondary Coverts – 3, Extent of Primary Wing Stripe – 2, Underwing Coverts – 3, and Axillars – 4.

Factoid #4 – Black Oystercatcher food & foraging. Restricted in its range, never straying far from shores, in particular favoring rocky shorelines. Perhaps seen mostly on coastal stretches which have quieter embayments, such as jetty protected areas. Forages in the intertidal zone, feeding on marine invertebrates, particularly molluscs such as mussels, limpets and chitons. It also take crabs, isopods and barnacles. It hunts through the intertidal area, searching for food visually, often so close to the water’s edge it has to fly up to avoid crashing surf. It uses its strong bill to dislodge food and pry shells open. [Wikipedia]

Bird #5 (Ryan Terrill 1-20-20 Surfrider Beach, eBird.com)

Bird #5 1-20-20: Overall – 20 of 30. Upper Tail Coverts – 1, Tail – 2, Chest – 2, Belly – 5, Under Tail Coverts – 4, Thighs – 4, Greater Secondary Coverts – 2, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Factoid #5 – Word Hyphenation progression. In English, the progression is from a phrase or two separate words, to a hyphenated word, to a single word. Examples: Road of rails, Rail road, Rail-road, Railroad; Catcher of oysters, Oyster catcher, Oyster-catcher, Oystercatcher. [LonelyPlanet.com]

Bird #6 (Grace Murayama 2-07-20 Surfrider Beach)

Bird #6 2-07-20: Overall – 22 of 26. Upper Tail Coverts – skip, Tail – 1, Chest – 3, Belly – 6, Under Tail Coverts – 4, Thighs – 4, Greater Secondary Coverts – 4, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Factoid #6 – Family Systematics. There are four world bird checklists: International Ornithological Committee / Union (IOC), Clements/eBird, Howard & Moore (H&M), and Handbook of Birds of the World (HBW). Each of them handles the species of the Oystercatcher family Haematopodidae differently. IOC and Clements list the same twelve species within the Oystercatcher family Haematopodidae, although in different sequences. H&M has the same twelve in the same sequence as IOC, but adds the Ibisbill. HBW lists only ten species.

Bird #7 (David Youmans’ friend 2-09-20 Las Flores Beach)

Bird #7 2-09-20: Overall – 23 of 26. Upper Tail Coverts – 3, Tail – 3, Chest – 4, Belly – 6, Under Tail Coverts – skip, Thighs – 4, Greater Secondary Coverts – 3, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Factoid #6 – Species & Ranges. The twelve species in the IOC order and their ranges are: Magellanic Oystercatcher, Haematopus leucopodus, sc. Chile to Falkland Is.; Blackish O., H. ater, n. Peru to Falkland Is., winters to Uruguay; Black O., H. bachmani, w. Aleutians to c. Baja Calif. & Los Coronados Is.; American O., H. palliatus, coasts & is. of  N&S America, West Indies, Galapagos Is.; Canary Island O., H. meadewaldoi, Canary Is. extinct 1950; African O., H. moquini, coasts of s. Africa; Eurasian O., H. ostralegus, Iceland to e. Kamchatka Peninsula, winters to s. China & Africa; South Island O., H. finschi, highlands of South I. (New Zealand), winters to North I.; Pied O., H. longirostris, coastal Australia, Tasmania and s. New Guinea; Variable O., H. unicolor, coasts and is. of New Zealand; Chatham O., H. chathamensis, Chatham Is. e. of New Zealand; Sooty O., H. fuliginosus, coasts and is. of Australia-Tasmania.

Bird #8 (Steve Hampton 2-15-20 Surfrider Beach, eBird.com)

Bird #8 2-15-20: Overall – 20 of 30. Upper Tail Coverts – 1, Tail – 1, Chest – 3, Belly – 6, Under Tail Coverts – 3, Thighs – 4, Greater Secondary Coverts -2, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Factoid #8 – Checklist exceptions. The IOC lists the twelve oystercatcher species in the sequence given in Factoid #6 above. Clements’ sequence starts with the final three IOC species, then the preceding three, then the initial six. Howard & Moore uses the IOC sequence but at the end adds Ibisbill Ibidorhyncha struthersii, a long-legged long-billed bird restricted to stony areas of Himalayan mountain streams; the other three checklists put Ibisbill in its own monotypic family Ibidorhynchidae. Handbook of Birds of the World uses the IOC sequence, but considers Black Oystercatcher H. bachmani as a subspecies of Blackish O. H. ater of s. S. America, and South Island O. H. finschi as a subspecies of Eurasian O. H. ostralegus of Eurasia.

Bird #9 (William Box 2-24-20 Surfrider Beach ebird.com)

Bird #9 2-24-20: Overall – 20 of 30. Upper Tail Coverts – 1, Tail – 1, Chest – 3, Belly – 6, Under Tail Coverts – 3, Thighs – 4, Greater Secondary Coverts – 2, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Factoid #9 – Species Distribution Pecularity. Five of the twelve species live only in Australia, New Zealand and nearby islands, a large diversity for a relatively small area. Four species inhabit only the Americas. One species covers all of Eurasia, one has southern Africa, and one species, now extinct, lived only in the Canary Islands off the NW coast of Africa.

Bird #10 (William Tyrer 2-28-20 Surfrider Beach, eBird.com)

Bird #10 2-28-20: Overall – 18 of 26. Upper Tail Coverts – skip, Tail – 0, Chest – 3, Belly – 6, Under Tail Coverts – 3, Thighs – 4, Greater Secondary Coverts – 2, Extent of Primary Wing Stripe – skip, Underwing Coverts – skip, and Axillars – skip.

Some of the photos above are certainly of the same bird, but I’ll leave it to you to draw your own conclusions on that. My overall vote is a firm uncertainty.

Following the Jehl Scale below, at the bottom of this posting, is the abstract for Jehl’s 1985 paper Hybridization and Evolution of Oystercatchers on the Pacific Coast of Baja California.

[Chuck Almdale]

You can print or download your own Jehl Scale and start separating these birds as uncertainly as do the experts. There are two options: either one page or two pages which you can print doublesided.

Jehl Scale – Score Total as Follows
0 – 9:      Characteristic of Black Oystercatchers
10 – 29: Characteristic of Hybrids
30 – 38: Characteristic of American Oystercatchers
Jehl
Scale Upper Tail Coverts
0 Black, as in bachmani
1 Black, a few white mottling
2 Nearly equally black and white
3 White, a few black mottlings
4 White, as in palliatus
Tail
0 Black, as in bachmani
1 Mainly black, trace of white at base of vanes
2 Basal quarter of rectrices white
3 Basal third of rectrices white
4 Basal half of rectrices white, as in palliatus
Chest
0 Black with black chest band extending smoothly onto midbelly, as in bachmani
1 Black chest band extending onto upper third of belly
2 Black chest band extending onto upper quarter of belly
3 Black chest band bordered by ragged edge on upper breast
4 Black chest band sharply delimited from white of upper chest, as in palliatus
Belly
0 Blackish, as in bachmani
1 Blackish, with traces of white on a few feathers
2 Blackish, white area around crissum
3 3/4 black, 1/4 white
4 Nearly equal black and white
5 3/4 white, 1/4 black
6 Entirely white, as in palliatus
Under tail coverts
0 Entirely black, as in bachmani
1 Mainly black with slight white mottling
2 Nearly equally black and white
3 Mainly white
4 Entirely white, as in palliatus
Thighs
0 Entirely black, as in bachmani
1 Black with grayish underdown, NOT noticeable externally (skin)
2 Puffs of grayish down noticeable
3 Mainly white
4 Entirely white, as in palliatus
Greater Secondary Coverts (width of white edging in folded wing)
0 White lacking, as in bachmani
1 Less than 2 mm
2 2-5 mm
3 6-15 mm
4 More than 15 mm
Extent of white wing stripe
0 Lacking, as in bachmani
1 White markings confined to inner half of secondaries
2 White markings extend to outer secondaries but not to primaries
3 White present on some or all of inner five primaries
4 White present on a least one of primaries 6-10
Underwing Coverts
0 Entirely black, as in bachmani
1 Mainly black, some white mottling
2 Nearly equally black and white
3 Mainly white
4 White, as in palliatus
Axillars
0 Black, as in bachmani
1 Mainly black, some white mottling
2 Nearly equally black and white
3 Mainly white
4 White, as in palliatus

_______________________________________________________________________________________________

Hybridization and Evolution of Oystercatchers on the Pacific Coast of Baja California
Joseph R. Jehl, Jr.
Ornithological Monographs
No. 36, Neotropical Ornithology (1985), pp. 484-504
https://www.jstor.org/stable/pdf/40168300.pdf?seq=1

ABSTRACT

The ranges of the Black Oystercatcher (Haematopus bachmani) and the American Oystercatcher (Haematopus palliatus frazari) overlap for approximately 480 km along the Pacific coast of Baja California. Phenotypes are variable, especially in coloration, and hybridization has long been known. Yet, at most localities parental morphs predominate, hybrids are uncommon, and assortative mating occurs when possible. The historical record is sufficiently detailed to allow demonstration of changes in the hybrid zone. At the turn of the century–or whenever they were first studied–most populations were composed largely of parental morphs. After intensive collecting, resulting in the virtual extermination of some populations, recolonization occurred from both north and south. The reconstituted populations differed from the original ones, and by the 1920s and 1930s the frequency of hybridization was high. Recently, however, many populations have returned to their original composition. The prevalence of parental forms, a demonstration of assortative mating, and the resumption of stability in the zone of hybridization after a period of dynamic change, all show that there is selection against hybridization in this zone of secondary contact and that the two forms are specifically distinct. The nature of the selective forces remains to be determined.

2 Comments leave one →
  1. Connie Brekke permalink
    March 13, 2020 9:24 pm

    Thank you!

    Sent from my iPhone

    >

    Like

  2. Lynn Bossone permalink
    March 13, 2020 7:51 pm

    Chuck, About a year or so ago, maybe even longer, there was a hybrid Am/Bl Oystercatcher in Ballona Creek just East of the Pacific bridge. I assume Walter Lamb included it in his eBird list at the time. Maybe you knew about this occurrence already. Interesting that they interbreed in the Baja! Lynn Bossone Culver City

    Sent from my iPhone

    >

    Like

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: