Archive for January, 2011
Bird of the week – Week 56: Common whimbrel
January 30th, 2011 | 
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Posted in The Common whimbrel is one of the many migrants who wing their way over vast distances to visit the shores of the southern African region during the summer. They arrive from the northern hemisphere around August each year and leave again around March. They don’t breed during this visit, however, preferring to breed during their sojourn in the northern half of the globe, the visitors to southern Africa possibly breeding in eastern Russia and Siberia.
Quite a large bird, with a length of about 42 cm, the Common whimbrel has a brown head and brown mottled upperparts. The underparts are also mottled, but are lighter in colour. The long, decurved bill is black, the legs are yellow and the eyes are brown. The sexes are alike in plumage, but the females are larger than the males and have a longer bill. The distribution of the birds during their months in southern Africa is almost entirely limited to the coast, where they prefer sandy lagoons and estuaries.
Common whimbrels feed by probing into the sand, particularly in the intertidal areas; probing, walking forward and probing again. They may also adopt a static hunting pose while waiting for a burrowing crab or some such delicacy to emerge, darting forward at the crucial moment to secure the unfortunate prey. They feed mainly on crustaceans and molluscs.
The call of the Common whimbrel, most commonly given while the bird is in flight, is a loudly uttered “upupupupu” that can be heard from quite a distance.
The scientific binomial for the Common whimbrel is Numenius phaeopus; Numenius from the Greek for a new moon (presumably a reference to the curved bill) and phaeopus from the Greek for brown-footed. Thus we have a bird with brown feet and a bill shaped like a crescent moon. Not very accurate and not very helpful, but there you are.
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Sociable weaver’s nests – Nature’s condominiums!
On our first trip from South Africa to Namibia, we drove through the dry region of the Northern Cape and it was there that I first came across the fascinating nests of the Sociable weaver (Philetairus socius). They had taken up residence on virtually every telephone pole in sight and their bulky nests laid claim to their space along the highway. It was a foretaste of what was to come in Namibia and the Kalahari, where these enormous nests are the order of the day. They are nature’s version of the condominium – complete with their own air-conditioning system!
Sociable weaver’s nests are the biggest nests built by any bird and a single nest can accommodate up to three hundred birds, including their chicks.
The nest consists of several chambers, each built by a breeding pair, and it is not uncommon to see the birds busily flying to and from the nests with bits of grass in their beaks adding even more to what looks like a haystack in a tree or on a pole. Often the nest gets so heavy that the branch breaks, sending it tumbling to the ground.
Although it looks like new chambers are randomly added on, the nests are cleverly structured to provide different areas for shelter and roosting. The inner chambers are well insulated, being warmer, and are used for nighttime roosting, whilst the outer ones are used for shade during the day and are much cooler. When outside temperatures rise to uncomfortable levels, the outer chambers can maintain temperatures as low as 7oC.
The nests face a number of dangers. They can catch fire in summer and, if built on electricity poles, can cause short circuits in rainy weather. Their main predators in trees are Cape Cobras, which have a voracious appetite for the eggs and chicks. Whenever we’re in the Kgalagadi Transfrontier Park, we always stop and look out for cobras on these nests – so far we haven’t seen any! Lizards, insects and honey badgers are also a threat to Sociable weavers. The Pygmy falcon, which cannot survive harsh variations in temperature, uses the weaver’s nest and assists with guarding it from predators.
I love the different shapes and sizes of these nests and am always on the lookout for them when we are traveling through the countryside.
Bird of the week – Week 55: Diderick cuckoo
At that time of the year when spring is moving towards summer, a new bird call, familiar from last year, is heard with growing frequency throughout most of southern Africa, excluding the really arid regions. A loud and persistent deed-deed-deed-deed-er-ick. This is the striking and distinctive call that gives the Diderick cuckoo its onomatopoetic name, which you may sometimes find written as “Diederik” or “Dideric”. It is the male who does the calling, energetically declaring his territory and no doubt letting the females know where he can be found.
Like most cuckoos, the Diderick cuckoo is heard more often than it is seen, although it is not quite as retiring as some of its relatives. It is a one of the smaller cuckoos, with a length of about 20 cm; green above and with whitish underparts. They have a broken white eyestripe, a green moustauchial stripe, and green outer tail feathers adorned with white spots. Eyes are red; the bill black and legs and feet grey. Â Females differ slightly in plumage and are slightly larger than males.
It is generally a solitary bird and is found singly in open woodland and savanna, eschewing forests and plantations. In keeping with other cuckoos, the Diderick cuckoo is a brood parasite, although it is perhaps less discriminatory in its choice of host than some, and has been known to parasitise at least 24 other species. The most common amongst these are the sparrows, weavers (including the bishops) and the wagtails, all of which are significantly smaller than the Diderick cuckoo, and are thus faced with an extremely challenging task when it come to feeding the hatchling.
Diderick cuckoos are intra-African migrants and arrive in southern Africa from central or east Africa in September/October and depart again in March/April. They feed mainly on caterpillars and insects.
Being a brood parasite is not a totally idyllic life, and while the males are letting the world know who and where they are with their characteristic call, the females must locate a suitable nest which is at the right stage in the breeding cycle, locate a male to mate with (this is the easy part!) and then enter the well guarded host’s nest undetected to lay her egg amongst the host’s clutch and then leave again. Not an easy task in view of the heightened alertness of all birds during the breeding period.
The scientific binomial of the Diderick cuckoo is Chrysococcyx caprius; Chrysococcyx from the Greek for a golden cuckoo, in reference to the metallic sheen of the plumage and caprius from the Latin for like a goat – a careless error as the spelling should have been cupreus from the Latin for like copper. By the time the error was realized, cupreous had been given to the African emerald cuckoo (Chrysococcyx cupreus) and so the inappropriate goat-reference was left . Thus we have a metallic cuckoo that looks like a goat. Oops! A metallic cuckoo that has a coppery sheen – that’s better.
The Bishops of Avis
The summer rains arrived in Windhoek, Namibia, during December and the transformation that these showers wrought to the landscape was both immediate and spectacular. With the greening of the vegetation, the insects, the animals and the birds all become enthused with new vigour, not least amongst them being the gorgeous Southern red bishops (Euplectes orix).
We went for a walk to a reed bed located not far from our home in the Windhoek suburb of Avis, to find that the reeds had sprouted to well over two metres in height, and that an enthusiastic breeding population of Southern red bishops had taken up their annual residence. We dashed back home for cameras and binoculars and returned to spend a delightful hour or so watching the antics of the little birds.
The reeds in this small area are densely packed and in consequence the birds are very difficult to photograph clearly as there is invariably some vegetation obscuring at least part of the bird. But as always, patience is rewarded by the occasional clear sighting.
The males in their splendid red and black plumage flitted amongst the reeds like oversized bumble-bees, fluffing out their feathers and putting on a wonderful display for any passing females. The females, although pretty birds in their own right, lack the impressive colours of the males and are quite easily overshadowed as a result. Of course, come the end of the breeding season, the males will lose their present spectacular plumage and take on the comparatively drab plumage presently sported by the females. During this period the birds can be quite difficult to identify correctly as they blend in with many other LBJs.
The majority of the birds, both males and females, seemed to be very active during the time that we were there, in the early part of the morning, and spent very little time actually perched.
Numerous woven nests are tucked away in the reeds, surprisingly well hidden from casual view. The males weave several nests from grass and other plant material at the start of the breeding season in an effort to attract females and, as they are polygynous, each male would hope to mate with several females before the season is over.
Incidentally, the Southern red bishop is found throughout most of the southern African region; but there is also a Northern red bishop, which is generally similar in size and plumage, and which is found only north of the equator.
Bird of the week – Week 54: Cape glossy starling
A Cape glossy starling seen in bright sunlight reflects a particularly striking colour – an iridescent dark blue that shimmers vividly as the bird moves and the sun dances off its feathers. If it should move into the shade, though, the iridescence is lost and the bird becomes rather dull by comparison. It is the bright sunlight that brings the “glossy” to its name. The bird’s conspicuous orange-yellow eyes are a sharp contrast to the dark blue whatever the light, and its black bill, legs and feet complete the picture. The sexes are alike in plumage, with the males being slightly larger than the females.
Common residents throughout most of the southern African region, with the exception of Mozambique, the Cape glossy starling is about 23 cm in length and is quite gregarious by nature, often being found in pairs or small flocks. It prefers wooded savannas and in the drier regions is often to be found in the riverine bush, where there is easy access to the more common items in its diet – fruit, nectar and a variety of insects. It is also frequently found in suburban gardens, being well adapted to the presence of people and quite content to feed on easy handouts.
The song of the Cape glossy starling is a warble that may be sustained for quite long periods and may include sounds picked up from the bird’s local environment (telephones, burglar alarms), while its call is a loud “turreeu”, which points to the origin of its common Afrikaans name – spreeu. Its official Afrikaans name is Kleinglansspreeu which can be translated as “small glossy spreeu”.
Cape glossy starlings are monogamous and usually nest in natural cavities in trees, or the holes made by woodpeclers or barbets, where they are sometimes parasitized by the Great spotted cuckoo (Clamator glandarius). The female Cape glossy starling lays a clutch of two to four pale blue eggs.
The scientific name of the Cape glossy starling is Lamprotornis nitens; Lamprotornis from the Greek for a bright or shining bird and nitens from the Latin for shining. Thus a bright and shining bird, and it couldn’t be more accurate than that.
