Invertebrate Eaters

These birds eat a variety of invertebrates and many have become omnivorous. Some of them eat fish and frogs but I have not placed them with the carnivorous flesh eaters because the feeding technique rather than the food they eat is the characteristic which I want to highlight. I have defined two sub-groups:-

Aquatic Pluckers and Probers.

Shallow water feeders - these long-legged, long-necked birds favour shallow water. Sub-habitats can be defined geographically to some extent. The nature of their beaks is the most significant feature of these birds. It enables various different species to feed together, even side by side in some cases, because they are able to access potential foods in such a variety of ways:-

  • Flamingos were once quite widespread. They hold their bent beaks upside down to filter feed on algae and small crustaceans in the water. They favour saline or highly alkaline coastal waters and are mainly found in Africa and the Americas.
  • Spoonbills like fairly open waters where they take crustaceans and molluscs with their spatula shaped beaks. They are quite widespread.
  • Avocets favour estuaries, coastal lagoons and lakes where they feed on small aquatic animals.
  • Stilts like fresh or salt-water margins where they take aquatic insects and invertebrates from the water surface.
  • Railsand Crakes are secretive foragers which have dagger beaks. They take aquatic insects, invertebrates, seeds, plant materials and small creatures.
  • Plovers and Lapwings are found on coastal beaches, around inland waters and even on high moorland where some of them breed. They pluck insects and invertebrates from the ground surface.
  • Dippers are specialised feeders. They are found exclusively in fast flowing streams and rivers where they swim and walk under water in search for insect larvae and crustaceans.

Terrestrial Foragers, Pursuers, Pluckers, Probers and Borers.

Scrub-land - Ground foragers.

There is a small group of large to medium sized birds in small families, with just a few species in each, which are only found certain regions of the world:-

  • Kagu is a single species, ground dwelling bird found on forested mountainsides and undergrowth of New Caledonia. They probe the ground for worms and small creatures. They lack the musculature for flight but can glide downhill to escape predators.
  • Lyrebirds have astonishingly long tails and are incredibly good mimics. They are ground dwelling birds of Australia which fly little. They scratch the ground to reveal insects and invertebrates.
  • Mesites, which are only found in forest and scrub land in Madagascar, forage and probe the ground for insects and seeds. They are thrush sized birds rather like the Tinamou in appearance.
  • Hoopoes have long, de-curved beaks which they use to probe the ground for worms, small snakes and frogs. They are found in open, cultivated areas in Africa and Europe. Hoopoes bear a resemblance to the Crested and Spinifex Pigeons of Australia both in appearance and ground probing behaviour.
  • Rockjumpers in family Chaetopidae are very specific in their choice of habitat. We found them on the rocky hillside near to the coast in South Africa. They have short wings and fly little. They scratch and probe the ground for insects, larvae and invertebrates.
  • Ground Hornbills are ground foragers which have evolved to become quite fearsome carnivorous predators which often work together in small groups and will take an animal as big as a hare. They are only found in Africa and may well have evolved from fruit eating Hornbills.

Forest and Wooded country.

Two main families are predominant:- Turdidae the Thrushes and Sturnidae the Starlings. Both are omnivorous probing the ground for invertebrates. They also take fruits and berries. The difference between the two families is habitat in which they are found and the probing technique employed. Thrushes favour wooded country whereas the Starlings prefer open country. Additionally Starlings are able to open their beaks once in the ground and this enhances their ability to take larger invertebrates.

  • Thrushes were originally forest dwellers but many have adapted to more open habitats so long as cover is available when danger threatens. They forage for invertebrates and larvae on the ground and are known by a variety of common names including Blackbird, Ring Ouzel, Fieldfare, Redwing and the American Robin. They have all established their own niches. Some are birds of the deep forest whereas others have adapted to life in parks and gardens.

Ground Thrushes in genus Zoothera, found in the deep forests of Australasia, Africa and Central and North America, are thought to represent early evolution of our modern Thrushes. Altitude is an important factor in the niche separation particularly for the African species. Evidence suggests that genus Turdus probably evolved in the last 10 million years and that genus Geomalia should perhaps be reclassified as a Babbler.

My interest in respect of Thrushes lies mainly with species which have not adapted to habitation. I highlight below one or two species which interest me especially:-

Fieldfares and Redwings breed in the Scandinavian mountain birch forests where they eat berries. When they make landfall in the UK they feed up on berries and then move to fields and meadows where they forage for invertebrates.

Ring Ouzels have not adapted to habitation and are counterparts of the Blackbirds found on rocky moor-land hillsides.

Forest Robins, Akalats and Alethes are small Thrush-like birds in family Turdidae. They favour the dense forest undergrowth in Africa.

Rock Thrushes favour high rock cliffs and ravines. They eat insects, small reptiles, berries and seeds.

Open country birds.

  • Starlings are mainly birds of Australasia and Africa with a few in Europe. They are found in open areas where they are very effective ground probers taking invertebrates. When fruits and berries are available some of these birds forage in the canopy. They have the ability to open their beaks when probing the soil for invertebrates. This helps them to take leather-jackets and the like.

Meadowlarks are the New World counterparts of Starlings. They are very adaptable and have powerful beaks which they can open whilst probing in the ground like the Starlings. The Long-tailed Meadowlark found in the Falkland Islands forages for invertebrates and is known locally as the Military Starling.

Mynas belong to the same family as the Starlings and are only found in Australasian region. They have adapted well to life in towns and villages where forage for insects, worms, household scraps and berries which have fallen to the ground.

Ground pursuers and pluckers.

This is a group of medium to small birds which have evolved in the Eastern Hemisphere and has some counterparts in the Western Hemisphere:-

  • Eastern hemisphere birds of the fields and meadows – Wagtails, Pipits, Longclaws.
  • Eastern hemisphere birds of dry stony areas – Wheatears, Coursers, Larks.
  • Birds endemic to the Americas some of which appear to be the counterparts of the Wheatears –Mockingbirds, Thrashers, Catbirds, New World Blackbirds.

Tree probers and borers.

These birds can be described as extremely arboreal. Woodpeckers and Creepers especially have a world-wide distribution. They include Wood Hoopoes, Woodpeckers, Flickers, Sapsuckers, Woodcreepers, Treecreepers, Sittellas and Nuthatches.

Undergrowth and Ground Foragers.

These birds like the protection offered by dense undergrowth where they forage in the foliage and on the ground for insects, invertebrates and fruit. In Europe and particularly East Africa Babblers tend to forage in chattering groups.

Catbirds, Mockingbirds and Thrashers are listed in family Mimidae and found exclusively in the Americas. They favour habitats where undergrowth can provide protection while they forage for insects, invertebrates and fruits. They tend to use their wings (thrashing) to disturb large insects and invertebrates. The Curve-billed Thrasher searches for food by digging holes in the ground.