Wednesday, 24 July 2013

Oystercatchers of the world. Pt 2: The black ones.

The black oystercatchers are generally denizens of rocky coastal habitats unlike their black-and-white counterparts that tend to inhabit areas with a softer substrate. For the most part they are resident within their respective ranges, displaying little seasonal movement.

Typical black oystercatcher habitat, Point Lomas, San Diego, California, USA. The birds you can see in this picture are cormorants and pelicans, not oystercatchers. However on the dark, smaller rocks behind there are two American Black Oystercatchers (see below).
In the Americas there are two species within this group, both are typically sedentary but unlike all the other species around the world they do show some movement outside the breeding season.

The American Black Oystercatcher H. bachmani of North America ranges from the Aleutian Islands, along the Pacific coast as far south as Baja California. During our Wader Quest we have only seen them in San Diego, California at the Cabrillo National Monument on Point Loma.

American Black Oystercatcher: Cabrillo National Monument, Point Lomas, Californis, USA, November 2012. This is a huge enlargement, hence the poor quality, but you can still see the brownish hue of the backs of these birds. 
The Blackish Oystercatcher H. ater of South America ranges south from northern Peru to Tierra del Fuego along the Pacific coast and south from central Argentina to Tierra del Fuego on the Atlantic coast and the Falkland Islands.  Some movement north on both coasts occurs outside the breeding season. We saw them at Pucusana in Lima.

Blackish Oystercatcher: Pucusana, Lima, Peru, June 2013. This species is, to all intents and purposes, identical to the American Black Oystercatcher above in bare parts colouration (yellow eye with red orbital ring and pale fleshy legs) and plumage (black underparts and head, brown upperparts).
At Pucusana we witnessed this joint aggression between a Blackish Oystercatcher pair and a Belcher's Gull Larus belcheri who didn't get the best of the encounter being driven off by the oystercatchers.

The pair begin to display, the Belcher's Gull takes on the role of voyeur.
The pair then turn to face the gull who immediately looks nervous and turns away.
One of the oystercatchers takes a lung at the intruder, who makes his getaway.
The pair watch the vanquished foe take to the air looking much satisfied with their work.
In Europe and Africa the species pairing involves the now extinct Canarian Black Oystercatcher from the Canary Islands and the African Black Oystercatcher in southern Africa. The Canarian Black Oystercatcher H. meadewaldoi has been considered conspecific with the African Black Oystercatcher and indeed with Eurasian Oystercatcher lumping all three together. Obviously we have not seen these birds alive in the wild, but we did get the chance to look at skins of the species at the British Natural History Museum, London, bird collection at Tring.

Canarian Black Oystercatcher: BNHM London (Tring).
The African Black Oystercatcher H. moquini breeds along the Atlantic coast of southern Africa south from northern Namibia to the Cape of Good Hope and from there east to eastern Cape Province. We have, as yet, to see this species, but we have high hopes of seeing them when we visit Cape Town in September of this year.
African Black Oystercatcher: Tzaarsbank, West Coast National Park, Western Cape, South Africa. April, 2010. Photo Peter Sharland. Note yellow orbital ring and red eye, black back concolourous with head and underparts.

African Black Oystercatcher: Cape Recife, Port Elizabeth, Eastern Cape Province, South Africa. April, 2011. Photo Sue Oertli.

African Black Oystercatcher: Cape Recife, Port Elizabeth, Eastern Cape Province, South Africa. May, 2011. Photo Owen Oertli.

African Black Oystercatcher: Cape Recife, Port Elizabeth, Eastern Cape Province, South Africa. May, 2011. Photo Owen Oertli.
There are no black oystercatcher species that occur in Asia, but in Australasia there is the Sooty Oystercatcher H. fuliginosus and the 'foot-in-both-camps' with the black-and-white oystercatcher species the Variable Oystercatcher H. unicolor, its scientific name being somewhat ironic I feel.

The Sooty Oystercatcher breeds around the entire Australian coastline except for a few small sections in the north and south-west. Unique among 'black oystercatchers' this species has been divided into two subspecies. H. f. fuliginosus occurs along the southern coasts from the Abrolhos Islands in the west round to Queensland in the east and H. f. opthalmicus around the northern coast from Shark Bay in the west to Queensland in the east. The difference in the two subspecies is easiest to see in the orbital ring colour which is yellowish to orange in H. f. opthalmicus and red in H. f. fuliginosus. We hope to catch up with this species in Australia in September when we visit. We may get the opportunity to see both subspecies.

Sooty Oystercatcher: Roebuck Bay, Broome, Western Australia, Australia, March 2009. Photo Adrian Boyle. This is of the northern race with a large yellow orbital ring.

Sooty Oystercatcher: Date and exact location unknown, southern Australia. Photo Paul Dodd. This is the southern race with the red orbital ring.
Variable Oystercatcher is so called because this species displays a variable amount of white on the underparts. In its most extreme form it can resemble the South Island Pied Oystercatcher but the division between the black and white on the breast is mottled and not clean cut. It is not only the variation in colouration that differs from other 'black oystercatchers', it also chooses to breed on sandy beaches and dunes and only visits rocky shores outside the breeding season. Its range is coastal New Zealand on both north and south islands.

Variable Oystercatcher: 

2 comments:

  1. Nice synopsis of the Oystercatchers. I consider myself fortunate to have seen eight species: Magellanic, Blackish, Black, American, African, Eurasian, Pied and Sooty. They really are enigmatic birds. I'll probably never see Chatham Island Oystercatcher but the others are still possible.

    David Gascoigne
    Waterloo, ON
    www.travelswithbirds.blogspot.com

    ReplyDelete
  2. Thanks David.

    We think that Chatham Island Oystercatcher is one that we will never get a chance to see too, but you never know. We certainly won't be seeing it during Wader Quest's present project although we hope to catch you up with all the birds you mentioned. Blackish, Black, American and Eurasian we have already seen, Pied we hope to catch up with again in Australia but most excitingly, for us, Magellanic, African, Sooty, Variable and South Island Pied are all new and on the cards within our planned itineraries.

    Rick.

    ReplyDelete