Tuesday, 11 March 2014

Single species wader families.

The suborder Charadrii i.e. waders or shorebirds are dominated by two very large families. The largest is the Scolopacidae with around 90 species and the Charadriidae with getting on for 70 species. However there are three families that have but 1 species within them; Dromadidae (Crab Plover); Ibidorhynchidae (Ibisbill); Pedionomidae (Plains Wanderer). In addition there are two species that on the Wader Quest list are in a family of their own Pluvionidae (Egyptian Plover); Pluvianellidae (Magellanic Plover) - in the Handbook of Birds of the World they are lumped in with Glareolidae (Pratincoles and Coursers) and Chionidae (Sheathbills) respectively.

The Crab Plover Dromas ardeola is a curious looking beast. It seems to be a cross between an avocet by colouration and a thick-knee in stature. It is considered to be of Least Concern with regard to its conservation status.

Crab Plovers Dromas ardeola; Khor al-Beida, Umm al-Qaiwain, UAE. November 2012.
Its breeding range is around the Arabian Peninsula on the Red Sea, Indian Ocean and Persian Gulf coasts. Non breeding birds occur south along the African coast and Madagascar, with a few reaching as far as South Africa, and east to southern India , Indian Ocean islands and at one site in south-west Thailand. There are no estimates for the population size but it is large and there are few threats to it, the major one being potential oil spills. However the birds we saw in the UAE were on a site that is apparently destined to become a marina, so they may be under threat.

Crab Plovers Dromas ardeola; Khor al-Beida, Umm al-Qaiwain, UAE. November 2012.

The unique thing about these birds is that they nest colonially in burrows, close together. Many wader chicks are able to leave the nest very soon after hatching (nidifugous) but Crab Plover chicks are dependent on their parents staying in the burrow for some time (nidicolous) and even after that depend to some extent on their parents.

Crab Plovers Dromas ardeola; Khor al-Beida, Umm al-Qaiwain, UAE. November 2012.
The Ibisbill Ibidorhyncha struthersii is another unique looking bird and looks, as the name suggests, much more like an ibis than a wader. Again the population size is unknown and it is categorised as being of Least Concern. It has a large range from south-east Kazakhstan to Kashmir to the south and east to north-west China, Tibet and north-east India, which is where we saw it, and across to east-central and north-east China.

Ibisbill Ibidorhynchus struthersii; Kosi River, Garjiya, Uttarakhand, India. January 2014. 
These birds are one of the birding world's iconic species, much sought after partly due to the inaccessible places that they live, stony river beds at higher altitudes. When they remain still in this habitat they can be very difficult to find and only give themselves away if they move.

Ibisbill Ibidorhynchus struthersii; Kosi River, Garjiya, Uttarakhand, India. January 2014.
There are two birds in this picture showing how well they blend into the background.
The Plains Wanderer Pedionomus torquatus is even more difficult to see than the previous species. It lives in remote areas of Australia and depends on native grasslands which have largely been converted to arable crops or introduced grazing meadows causing the population to decline. For this reason, and due to the fragmented nature of the remaining populations, this species is considered to be Vulnerable. Birders are very unlikely to just stumble across them and even in the right places will find it hard without a professional local guide.

This is another of those species or families that one wonders why they are considered waders at all, such as sheathbills, jacanas and seedsnipe. They look as if they should be better placed with the buttonquails, but then there is a move afoot to include those within the waders also.

Egyptian Plover Pluvianus aegyptius lives across sub saharan Africa from Senegal and The Gambia to Uganda and Ethiopia and down to Zaire and northern Angola. It used to occur along the River Nile north as far as Egypt, hence the name. It is considered to be of Least Concern due to its large range, but overall it is probably decreasing in numbers.

Egyptian Plover Pluvianus aegyptius; Basse Santa Su, Upper River Division, The Gambia. January 2014.
Most birders probably catch up with this species in The Gambia where birding trips are cheap due to the tourism industry, but a trip up river is required to see them. We did not buck this trend seeing ours at Basse Santa Su. These birds migrate away from The Gambia to breed, retreating from the country from January onwards. Their biggest threat seems to be the damming of rivers raising water levels to cover sand bars and open river banks.

Egyptian Plover Pluvianus aegyptius; Basse Santa Su, Upper River Division, The Gambia. January 2014.

The last in our little subset of waders is the Magellanic Plover Pluvianellus socialis. Again a bird of one of the remotest regions of the world, commonly known as the world's end, the tip of south America. This bird is thought to be Near Threatened as it has a small population and its habitat is threatened although there seems to be no evidence to show the population is declining. However, birders in the region have expressed to us their concern that they are seeing much smaller aggregations of these birds in recent years.

Magellanic Plover Pluvianellus socialis; Adult Laguna Verde, Tierra del Fuego, Magellanes y Antarctica Chileno, Chile. November 2013.
Their breeding distribution is confined to the extreme southern parts of Chile and Argentina but in the Austral winter they can be found as far north as the Valdés Peninsula in south-central Argentina. This species was certainly on our list of highlights during our quest. We had struggled to get useful information about where exactly to look for these birds until literally the day before we arrived in Punta Arenas and to keep costs down as always we had cut the time available to look for them to a bare minimum.

Magellanic Plover Pluvianellus socialis; Juvenile, Laguna de Los Cisnes, Punta Arenas, Magellanes y Antarctica Chileno, Chile. November 2013. This was the first of this species we saw.




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