Saturday, 4 January 2014

Potential Australasian split? Masked Lapwing

Originally named Tringa miles in 1783 by Boddaert who clearly had his mind on other things at the time; any resemblance to the Tringa family is lost on me and apparently he labelled the specimen as being from Louisiana instead of Australia! The genus Vanellus was first used by Bresson in 1760 but not applied to this species until Vanellus Novae-Hollandiae by Stephens in 1819. The subspecies novaehollandiae was originally called Tringa lobata by Latham in 1802. These birds have also been allocated to other genera Lobivanellus and Lobibyx.

All that aside, the Masked Lapwing was originally confined to north and eastern Australia and spread to New Guinea and New Zealand where it was first recorded breeding in 1932. Since that time it has spread across South Island in New Zealand and reached North Island as a breeding species as recently as 1970. It was once a rare bird on Tasmania too but is now common and widespread. It's success is generally attributed to change of land use where native forest, woodland and scrub is cleared making the habitat more suitable for them.

I was alerted to the idea that this is a potential spilt by Paul Dodd long before we'd even arrived in Australia for Wader Quest. He said I should be sure to see the northern subspecies when we had a chance just in case. In fact this was not just a new bird for Wader Quest it was a lifer and so the fact that the first bird we saw was an intergrade was potentially problematical. Fortunately we did see other apparently pure birds of both races. So what about that split then? These two forms have been considered sepearate species in the past but were lumped back in the early 1990s.

There are two distinct races Vanellus miles miles which occurs in the northern edge of the range and V.m. novaehollandiae which occurs in eastern and south-eastern Australia, Tasmania (where it was formerly rare but now common) and New Zealand.

Here is the nominate V.m. miles. Note the small black cap, large triangular lappets and the yellow wattle that extends above and behind the eye.
Masked Lapwing Vanellus miles miles; Cairns, Queensland, Australia, September 2013
Here is V. m novaehollandiae formerly known as 'Spur-winged Plover' (not to be confused with Spur winged Lapwing Vanellus spinosus) which has more black on the head extending down into the ear coverts and down the nape to the shoulders and then down into the upper lateral breast area as black patches. The wattles are less extensive only reaching the eye in the form of an orbital ring at the rear side and the lappets are considerably smaller and more rounded.
Masked Lapwing or 'Spur-winged Plover' V. m. novaehollandiae; Foxton, North Island, New Zealand, October 2013
One of the reasons that a split has not occured up to now is the extensive area of intergradation between the two subspecies where they meet. This results in a mixture of plumage and bare part characteristics. This was the first example of the species that we saw on the trip while we were in Broome and according to Chris Hassell who studies the waders in thet region it is a long way from the area of overlap and quite a rare find so far north. This species is quite dispersive by nature, hence the ease and rapidity with which it colonises new suitable areas, the younger birds are reputed to be more dispersive than adults which may suggest this in a young bird.  Note the very large lappets and quite extensive wattle over and behind the eye and black cap (although a little larger than normal) which fit well with V. m. miles as does the lack of black on the nape and upper back. However the black shoulder markings are quite distinct and would suggest V. m. novaehollandiae.
Masked Lapwing V. m. miles/novaehollandiae intergrade; Broome, Western Australia, Australia September 2013
Photo: Elis Simpson
Presumably the scientific name of V. m novaehollandiae would revert to Vanellus novaehollandiae should a split be recommended by the powers that be, or perhaps it should be V. lobata after Latham which predates novaehollandiae. It'll be interesting to see what its English name will be. It clearly cannot revert to Spur-winged Lapwing, so what will it be? Black shouldered Lapwing maybe? Any suggestions?

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