The Wrybill (Anarhynchus frontalis)

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We decided that it would be nice for us to give you some information on the chosen #BeakoftheWeek, so we are kicking things off with last week’s…

wrybill 1

Figure 1. Wrybill beak bend

Being amongst the strangest beaks that we have encountered during our scanning escapades, the wrybill, or ngutuparore, is a charismatic species endemic to New Zealand.   You’ll notice straight away from this picture and Fig 1 that there is something slightly awry with the morphology of this birds beak.  It is unique in being the only species of bird that has its beak always bent laterally, and exclusively to the right.  This specially adapted beak is used to sweep under stones in its hunt for invertebrates, such as mayfly and caddisfly.

The internet bird collection has a nice video of some wrybills in action.

The wrybill is a pale plover, of about 20cm in length, from the charadriidae family, which consists of about 60 species including dotterels and lapwings.  Similar species include the sanderling and banded dotterel.  Its breeding grounds are found solely on the braided riverbeds of New Zealand’s South Island, from where it migrates to over wintering grounds in the North Island.   They are known to form dense flocks at their wintering grounds (see Fig.2).

 

Figure 3 A sketch of the Wrybill from A History of the Birds of New Zealand (1888)

Figure 2 A sketch of the Wrybill from the A History of the Birds of New Zealand (1888)

This monogamous, ground nesting species has a life expectancy of about 5 years.  Chicks are precocial and clutch size consists of two eggs on average.  There is slight sexual dimorphism, with males having a black bar above their foreheads and a black breast bar.  Females have a slightly browner and narrower breast bar and lack the bar above the forehead.

 

 

 

The wrybill employs a few techniques to avoid predation.  As you can see from this picture of their eggs they blend nicely into the background of the riverbed, similarly to the pale appearance of the adults.  Camouflage is not the only method used as parents will also perform distraction displays to entice predators away from their nests.

This is a species in decline, with the IUCN redlist describing them as vulnerable since 1994.  Before the 1940s hunting was a cause for a major drop in their population, which has since recovered.  However, threats from predation by introduced mammals and native birds, as well as the flooding of nests and the loss and degradation of breeding grounds, are further putting this species under threat.  Population estimates from winter counts lie at about 5,000 individuals.

To fully immerse yourself in the world of the wrybill you can check out a distribution map and listen to some wrybill calls on Xeno Canto.

References:

BirdLife International (2015) Species factsheet: Anarhynchus frontalis. Downloaded from http://www.birdlife.org on 05/05/2015.

Dowding, J.E. 2013. Wrybill. In Miskelly, C.M. (ed.) New Zealand Birds Onlinewww.nzbirdsonline.org.nz

Hay, J. R. 1984. The behavioural ecology of the wrybill plover. Dissertation. Ph.D., Auckland University, Auckland.

The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 05 May 2015.

Wiersma, P. (1996). Wrybill (Anarhynchus frontalis). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2014). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/53856 on 5 May 2015).

Images

Sketch of Wrybill” by A History of the Birds of New Zealand, 1888 is licensed under Public Domain Mark 1.0.

Wrybill bill bend” by A History of the Birds of New Zealand, 1888 is licensed under CC BY-SA 3.0.