Forest and Woodland Foragers.

This review is work in progress at present.

A feature about Starlings and Grackles has attracted quite a lot of attention by website visitors in the past weeks and months. I am now including it in a wider review of Forest and Woodland birds including Thrushes, Mockingbirds, Thrashers, Catbirds, Starlings, Grackles and Meadowlarks.

Origins.

This group of birds almost certainly originated in forest habitats probably a little later than 30 million years ago. They eat a variety of food including insects, seeds, fruit, invertebrates, worms, snails etc which they sometimes take from the trees but more usually from the ground. They are very adaptable and have spread into a wide range of habitats.

The IOC listing has a total of 329 species:-

Turdidae, Thrushes – 170 species – I place Bluebirds & Alethes with Chats.
Mimidae, Mockingbirds, Catbirds and Thrashers – 34 species.
Sturnidae, Starlings – 114 species - Oxpeckers (2) I place these birds elsewhere.
Icteridae, Grackles and Meadowlarks – 11 species.

Apart from the similarity in habitats my other reason for grouping these birds together is that evidence suggests that they appear to have evolved at about the same time. Family Mimidae is closely related to Sturnidae.

The limited information I have found so far indicates the following times of evolution expressed in millions of years ago:-

MYA EVENT
30? Passerines evolving
20-25 Sturnidae and sister family Mimidae evolving about now or perhaps just a little later.
15+? Turdidae Genus Zoothera diverged from ancestral stock.
11 Turdidae Ancestor of Neocossyphus, Sialia, Myadestes diverged.
10 Turdidae Genus Cichlherminia Forest Thrush diverged, followed by species of Turdus genus.
7-8 Turdidae Genus Catharus diverged and started radiating in the Americas.
3.5 Turdidae Genus Sialia diverged – probably the most recent.
2- present Icteridae family evolving

Thrushes.

Thrushes are widely distributed throughout the world with the exception of the polar regions and the hottest deserts. Many species are still deep within thick forest cover. Those which have moved to inhabit the edges of forest or woodland forage for invertebrates on open ground but usually have tree cover available nearby.

The listing shows 23 genera of which Turdus has about 75 species but Zoothera with 36 species is considered to be the most primitive.

Turdus species are widely distributed with about 35 in the Americas (North, Middle and South), 18 in Europe, 12 in Asia and 10 in Africa.

The Common Blackbird, Turdus merula, has adapted to the easier picking to be had around houses and gardens. The Ring Ouzel, Turdus torquatus, which is found on rocky moorlands in Europe is perhaps representative of what the Common Blackbird might have been.

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Thrushes in genus Zoothera, which are found throughout the world but mainly in Africa and Asia, are called Ground Thrushes. I photographed the Bassian Thrush (right), Zoothera lunulata, on a walk-way in the forest at O’Reilly’s, Brisbane, Australia.

A recent molecular study indicates that the Song Thrush's closest relatives are the similarly plumaged Mistle Thrush and the Chinese Thrush; these three species are early offshoots from the lineage of Turdus thrushes before they diversified and spread across the globe. The Fieldfare and the Redwing are also close relatives.

Catharus genus has 12 species (including 7 Nightingale-Thrush and the Veery) confined to the Americas.

Myadestes genus has 13 species (including 10 Solitaires) distributed throughout the Hawaiiian archipelago.

Mockingbirds, Thrashers and Catbirds.

These birds, known as the Mimids, are now only found in the Americas. However it seems possible that they may have originated about 25-20 mya - somewhere in East Asia and at the same time as the Starlings. The most basal Starling is found in the Asian-SW Pacific and the basal Mimids are found in North America.

Mockingbirds.

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Best known for the habit of some species mimicking the songs of other birds. They are omnivorous ground foragers. There are about 17 species in three genera. Mimus and Nesomimus are quite closely related; their closest living relatives appear to be some Thrashers, such as the Sage Thrasher. Melanotis is more distinct; it seems to represent a very ancient basal lineage of Mimidae. I photographed the Northern Mockingbird (left) in Stone Harbor, New Jersey USA.

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Thrashers

Thrashers are related to Mockingbirds and New World Catbirds. There are 15 species in one large and 4 monotypic genera.

These birds appear to be the closest living relatives of the Mockingbirds. The name describes the behaviour of these birds when searching for food on the ground: they use their long bills to "thrash" through dirt or dead leaves. It is possible that the Sage Thrasher is a basal lineage among a group consisting of Mockingbirds and Thrashers.

I photographed the Curve-billed Thrasher (right) in Arizona.

Catbird.

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Two species are found in North and Middle America where they favour dense thickets, often near water.

Their breeding habitat is semi-open areas with dense, low growth; they are also found in urban, suburban, and rural habitats.

Among the Mimidae, they represent independent basal lineages probably closer to the Caribbean thrasher and Trembler assemblage than to the mockingbirds and Toxostoma thrashers.

I photographed the Grey Catbird (left) on South Padre Island, Texas.

Starlings.

In the UK most people are aware of the Common Starling (right) - Liz M photographed this group during a Bird Group trip to Spurn.

But what do people know about over 100 other species which make up family Sturnidae and what do Grackles have to do with it?

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Family Sturnidae, lists 114 species found mainly in Africa and Asia with a few in Australia. In Australia and Asia some members of the family are called Mynas rather than Starlings.

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During a visit to Australia the Common Myna (left) was as common in urban areas as the Common Starling is in the UK. One species called the Coleto is a forest bird endemic to the Philippines.

Habitats are many and various. In general terms Starlings are found in open country, favouring woodland, forest and areas of human activity. Some species like rocky hills and are cliff nesters.

That is probably why they have taken to nesting in tall buildings in urban areas. They eat insects and fruit and can be seen either perched in the canopy or feeding on the ground.

Starlings are very much birds of the Old World. In Africa 32 species are found in open woodlands and savanna with about 13 further species being forest birds.

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The Superb Starling (right) was photographed during our trip to Kenya in November 2009. In Asia the position is reversed with 39 species found in evergreen forests and 24 are found in open areas often close to human activity. These birds have proved to be very adaptable and species have found their own niches at different elevations ranging from sea level to about 5000 metres.

Grackles and Meadowlarks.

In the New World, with the exception of the Common Starling and a few species of Mynas present by introduction, no other species of family Sturnidae are present.

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But, sure enough the same habitat and behaviour is home to another group of birds, the Grackles. Ten species spread across North, Central and South America are listed in family Icteridae.

Family Icteridae is interesting. Firstly it is one of the most recent families to evove - perhaps in the last 2 million years and secondly because the species in this family, although only found in the New World regions, seem to exploit the niches which all the other Passerines taken together are found in.

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The Great-tailed Grackle (left) photographed in Texas, has a glossy, iridescent body like the Starling. They walk around lawns and fields on their long legs or gather in noisy groups high in trees, typically evergreens.

Five other species listed in family Icteridae are also of interest here. They are the Meadowlarks. These birds can open their beaks whilst probing the ground in the same way that Starlings do when they take leatherjackets. The image on the right is the Eastern Meadowlark (right) which I photographed in Arizona in 2006.