Storks - Long-beaked Predators

Storks - long-beaked predators

Storks are large, long-beaked and long-legged birds with wonderful soaring abilities. Although they bear a superficial resemblance to herons, they are not related to them, nor to ibises. In fact, recent analysis supports the view that the closest relatives of storks are the condors and other New World vultures (in addition to skeletal similarities which suggest a common ancestor, both groups of birds share the habit of defecating onto their legs as a cooling mechanism).

High Speed Snappers

Although lacking talons and sharp beaks of true raptors, storks are predators which feed on all manner of living and dead animals. Most stork species are specialised fish eaters, and some possess a unique trigger mechanism which allows them to snap their bill shut in 0.025 seconds (one of the fastest reaction times recorded for any vertebrate). The Yellow-billed Stork typically wades or stands in shallow water with its beak submerged and agape, while it shuffles its feet or spreads it wings, in a bid to disturb hiding prey.

Storks and Man

Of the world's nineteen species of stork, fifteen are regionally threatened, but some have fared reasonably well alongside mankind. Eight species occur in Africa. The fabled European White Stork has long been protected by superstition (related to its supposed delivery of newborn babies in white nappies!) and traditionally nests on roof tops in several parts of the continent. Many, however, run a gauntlet of hunters on their annual migration across the Sahel and North Africa. The indefensibly grotesque Marabou Stork has a penchant for carrion and offal, so has thrived in and around human settlements in Africa, possibly occurring in greater numbers now than ever before.

Many storks are gregarious and either breed colonially or forage in large flocks. Almost all are either migratory or nomadic, moving large distances to take advantage of fluctuating food availability. Wherever they occur, storks are fascinating and often entertaining birds to watch.

European White Stork

This distinctive bird visits Africa as a non-breeding migrant (although a small breeding colony of a dozen or so pairs has established itself in the south-western Cape, where a Mediterranean-like climate prevails). The birds move south in flocks of up to 10 000 birds, using the warm air of thermals to cross the Sahara desert. Some individuals may notch up 20 000km a year as they travel from Scandinavia to southern Africa, and back. From October to March, flocks of White Storks can be seen to follow rain fronts which promote the emergence of locusts, grasshoppers and ‘army worms' (Spodoptera). Foraging in large numbers is no doubt advantageous when dealing with relatively small prey as each bird serves as a ‘beater' for the next. They can be common in agricultural lands where most farmers welcome them for their ‘pest control'. In its European breeding grounds (including Spain, Portugal, Poland and Russia) the White Stork feeds primarily on rodents and amphibians. This species has no doubt benefited from the methodical deforestation of western Europe over the centuries which has provided suitable open habitat.

Saddle-billed Stork

The tallest and arguably most handsome member of the family, this elegant bird lives in monogamous pairs which are attached to a large home range. The Saddle-billed Stork does not adapt well to alteration of its habitat, so is today restricted to large wilderness areas and wildlife reserves. Fishes (up to 500g), crabs, frogs and large water-beetles are the favoured prey, and it is known to pirate fresh catches from cormorants and other aquatic birds. The pair nest in a tall tree, where up to three young may be raised in the large stick nest.

Abdim's Stork

This small, gregarious stork is an intra-African migrant which visits the grasslands of eastern and southern Africa from November to March. It breeds north of the equator, with colonies in trees or on cliffs. Pairs form for the breeding season only and there is no evidence of long-term bonding (as, for instance, exists in the Saddle-billed Stork). Flocks are often seen soaring in thermals, where they are sometimes mistaken for vultures and frequently join groups of White Storks. Like this bigger bird, they are partial to grasshoppers. The bird is named after Bey Al-Arnaut Abdim (1780-1827), the one time Governor of the Wadi Halfa area of northern Sudan.

African Open-billed Stork

A slender, chocolate-brown stork with an extraordinary pincer-like bill. This is a completely aquatic stork which feeds almost exclusively on snails and freshwater mussels. Contrary to popular thought, these shelled molluscs are not smashed in nutcracker style (which the stork's bill strongly suggests) but are extracted from their intact shell by the razor sharp lower mandible which slices off the strong attaching muscle, while the upper mandible holds the shell fast. The snails and mussels live in sediment or mud, so have to be searched for by the storks which have been observed to follow in the wake of hippos (and even to ride on the backs of these huge mammals) which habitually churn up the mud and expose the birds' preferred prey.

Marabou Stork

Many different birds - kingfishers, trogons, sunbirds and others - might contest the title of 'most beautiful in Africa', but the Marabou stands uncontested as the least so. While it might be unfair to call the bird grotesque or ugly, its pockmarked, scabby face and ashen plumage render it less than lovely to the human eye. The bird's behaviour hardly helps its case for it is primarily a scavenger and pirate, typically associating with vultures at carrion, or picking up human rubbish in scruffy towns and settlements. Large numbers occur on the outskirts of cities such as Kampala, Kigali and Nairobi, where they attend rubbish dumps and often perch on tall buildings. The Marabou's strange pendulous throat sack is both a cooling device (a mass of blood vessels lie just below the skin) and a means of displaying status or sexual readiness.

Yellow-billed Stork

With its bright sulphur-yellow bill and mask of bare cherry-pink skin, set off by pied plumage, the Yellow-billed Stork is an attractive bird. Small flocks typically forage in shallow water, especially the drying pools in wetlands or sandy rivers, where fishes and frogs are readily captured. the birds are rarely in one place for long, except when they settle to breed. Pairs (sometimes several to a large branch) build a small stick nest in the canopy of a large tree, frequently in the company of herons, cormorants or pelicans.

Black Stork

This is the most cosmopolitan of all storks, although it appears to be declining throughout its vast range. In Africa, it breeds in mountainous areas, where solitary pairs build their nests on cliff faces, or sometimes take over the nest of an eagle or Hamerkop. The bulk of the world's population occurs in the palearctic, ranging from Spain to Japan; many of these birds migrate to south-east Asia after breeding. Crabs, frogs and small fish make up the bulk of its diet and it favours shallow streams rather than pools of standing water.

Woolly-necked Stork

This is a typically solitary species, but flocks will gather at sources of abundant food. One population ranges throughout sub-saharan Africa (except for the dry west), while others are found on the Indian peninsula and Indonesia. Woolly-necked Storks are often attracted to bush fires, where they snatch up large insects and small vertebrates escaping the flames; it is not uncommon to see them feeding in this way alongside European White Storks and Abdim's Storks. Locusts are a favoured source of food, and the birds may follow rain fronts which promote the emergence of these plague-forming insects.

andBEYOND's Stork Hotspots

A variety of stork species can be seen in the vicinity of virtually all andBEYOND lodges, and on guided safaris. All eight African species have been recorded at Klein's Camp, Grumeti, Lake Manyara Tree Lodge, Ngorongoro Crater, Kichwa Tembo and Matetsi.

- Duncan Butchart -

Posted: Birds by CC Africa, Date: 21 November 2006