Eurasian Stone-Curlew B.oedicnemus insularum |
The largest of the world’s waders are found among the
various species of Stone-curlews or Thick-knees of the family Burhinidae. These
strange birds can be found worldwide, often well away from water in grassy or
sandy areas, with the notable exception of most of North America. In Europe and
western Asia the Eurasian Stone-Curlew Burhinus oedicnemus is the native
species.
The nominate subspecies B.o.oedicnemus reaches as far north
as southern England, where there are around 300 pairs. In the northern parts of
the range they are migratory, wintering in Africa, but in Spain where we saw
them on this trip they are resident. In Spain we found a small flock in an
abandoned industrial area.
Stone-curlews get their name from their calls which resemble
those of the true Curlew, combined with their preferred habitat. They are
almost entirely nocturnal and during the day they only usually fly if
disturbed. After dark they become much more active and their large eyes give
them good vision for the nocturnal insects (plus a few small mammals and
reptiles) which are their main prey. Seen by daylight they frankly give the impression
of being hung over after a night on the tiles.
Breeding in Stone-curlews starts as soon as they return from
their wintering grounds in the spring. The usual clutch is 2-3 eggs and
incubation is around 27 days. As with other waders the young leave the nest
very shortly after hatching and fledge at a few months old. The birds may make
several nesting attempts during the season and may raise two broods. Lifespan
is unclear, but the related Bush Thick-knee B. grallarius is recorded as living
to 30 years old.
Bush Thickneee in camouflage pose |
On the whole Eurasian Stone-curlews are listed as Least
Concern by the IUCN. One of the two subspecies found on the Canary Islands, the
Western Canary Island Stone-curlew B.oedicnemus distinctus is at grave risk as
a result of loss of habitat to tourist development and is probably under 200
pairs or less. The Eastern Canary Island form B.o.insularum is doing rather
better and can usually be found on Fuerteventura where I obtained good views a
few years ago - the image at the head of this post is a photo I took then. In the UK special conservation efforts have resulted in an
increase in the breeding population, but there are still only a few places in
the south of England where you can be reasonably confident of locating them.
Great Thick-Knee |
In captivity there are several species from around the world
that may be seen in various exhibits. In Europe the Bush Thick-Knee from
Australia, Spotted Thick-Knee from South Africa, and the European Stone-Curlew
are the species most likely to be seen. Unfortunately there are no captive
populations as far as I am aware of the two Near Threatened species of Esacus,
the Beach and Great Thick-Knees, which are more similar to other waders in that
they prefer shoreline and beach habitats rather than dry land
(images from Wikipedia, my own)
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