A Guide to the Orders of Birds

There are approximately ten thousand or so species of birds, this while not a large number compared to some Classes, nevertheless presents many headaches in classification. In many ways the birds have by their very nature taken evolutionary paths that to this day - and probably far into the future, cause much confusion.

That means that classification is constantly changing as new results are found, and new ideas are accepted. In particular many new and often interesting results are coming from Biochemical classifications, compared to traditional morphological classifications. The Ciconiiformes are a case in point.

For the sake of completeness here are mentioned all of the currently "used" Orders and possible revisions.

To further put things in perspective here is a geographic breakdown of how many bird species there are distributed worldwide:

South America 3200
North America (From Panama and the Caribbean) 2000
US and Canada Only 925 recorded
Europe 1000
Asia 2900
Australia, Oceania 1700
Africa 2300
Antarctica

To be more technically accurate, a quick review should also be made of the Class Aves. The Class Aves encompasses all birds - both living and extinct, for this reason there are some further divisions. Which might in some ways seem academic, but can be very important in their own right. The Class Aves therefore includes everything from Penguins to Archeopteryx with many similar evolutionary branches such as the Confuciusornis spp. all of which seem to be very much extinct these days.

What we would know as modern birds are grouped into what is known as the Ornithurae. These are distinguished from all of the other ancient birds - by their tail. The ancient birds have a characteristic tail. Essentially not that much different anatomically to say a cat or dog's tail. although to be precise a Theropod Dinosaur's tail may be a better example.

This is not to say modern birds don't have a tail - they do. Only it is modified. The bones are fused and compressed into what is called a Pygostyle. This (just to be difficult) is not the only type of Pygostyle to have existed, Oviraptorosaurs to name one example. So it is further defined by being "plough" shaped.

So we are almost at modern birds. The Ornithurae are divided two ways into two subclasses, one a group of extinct birds that had teeth - Hesperornithes, and finally the modern birds subclass Neornithes.

And as one final complication before we get to the Orders, all of the bird Orders are divided into two superorders, Palaeognathae and Neognathae. These comprise of all the birds we know, the birds in your garden, in the wild, and at the zoo. They are divided into two groups on the basis of the palate. The Palaeognathae have a palate that is quite different to all the other birds. A more primitive or so called "reptilian" palate structure.

In case your now thinking the jaws and anatomy of bird beaks and skulls is boring, an interesting article from Nature 2004 can be found here. Obviously there is still much to learn.

Confining ourselves to the living Orders, the Palaeognathae comprise the following Orders:

Order Struthioniformes - Emus, Ostriches, Cassowaries
Order Lithioniformes
Order Tinamiformes

This is the traditional and simplest way of arranging things, however the more modern approach splits the Struthioniformes, so we have:

Struthioniformes - Ostrich
Rheiformes - Rhea
Casuariiformes - Cassowary, Emu
Apterygiformes - Kiwi
Tinamiformes - Tinamous

So the above Orders make up the belong to the superorder Paleaognathae, all other orders belong to the Neognathae.

The above tends to make more sense, although many have concerns about Emus being placed in the Casuariiformes.

Now for a quick run through of the Orders.

Struthioniformes

Credit: Douglas Media

Comprising of well, just the Ostrich, Struthio camelus. The others all being ancient. The classic definition being the lack of a keel, hence the name Ratite used for these types of birds. Essentially being flightless the need for strong pectoral muscle attachments vanished, so the breast is actually flat, or "raft" shaped, giving the Latin Ratite.

Of note is that it is the males that do the parenting. In fact the biology is quite interesting with single roaming females being allowed to deposit their eggs in the clutch. These eggs are kept to the outside of the "paired" parents eggs, in many ways being sacrificial to Hyaenas and similar predators.

Rheiformes

The Rheas are two species of ratites as mentioned above in the Family Rheidae and the genus Rhea. They are native to South America. There are two existing species: the Greater or American Rhea and the Lesser or Darwin's Rhea. The genus name was given in 1752 by Paul Mohring and adopted as the English common name.

Again these birds are what we would think of as the typical flightless birds. It is not that uncommon to see them at a zoo or similar and here people get them mixed up with Emu's of Australia in particular. Another interesting feature of these birds is the ability to store urine in an expansion of the cloaca. They also have quite large wings for a flightless bird, holding them out while on the run.

Casuariiformes

Credit: Douglass Media

This Order comprises of the Cassowaries, of which there are three species. One in the remnant tropical forests of Far North Queensland, Australia, and the other two species across Papua New Guinea through to the Eastern Indonesian Islands.

Also this Order encompasses the Dromaiidae, or Australian Emus. There is one Species, but the number of subspecies varies depending on who you ask. They are sufficiently related to the Cassowaries to be placed in the same Order. My own (personal opinion) is that they might deserve an order of their own, based on the available fossil evidence.

Like all large animals, these birds can be dangerous, in particular the Cassowary. My own personal experience with them was while living in Cairns, Far North Queensland, Australia. A Cassowary easily killing a neighbours dog, as anyone who has seem them kick would realise. During the breeding season they also produce and home in on low frequency vibrations. This seemed to cause confusion for the birds on a popular running trail in breeding season, with many a runner being charged. The explanation being that the pounding feet of a runner on a forest path sounded a bit too close to the breeding "boom" "boom" sounds.

Apterygiformes

Credit: Glen Fergus

Kiwi are flightless birds endemic to New Zealand, in the genus Apteryx and family Apterygidae. They are the smallest of the ratites, and perhaps the most peculiar. There are five recognised species all of which are highly endangered, being absolutely unadapted for life alongside small mammals.

Of all birds, they have a very long "odd" feature list. For example they lay the largest egg in relation to body size of all known birds, being only approximately the size of a domestic chicken.

They are nocturnal, not that this in itself is unusual for birds, however they do have a highly developed sense of smell and are the only birds to have nostrils on the end of their beak. This seems to help them probe in sand and grass tussocks with a minumum of visual aid.

In many ways because of New Zealands isolation these birds (and others) seem to have filled the ecological role that mammals would fill in other places in the world.

Image Courtesy Maungatautari Ecological Island trust.

Tinamiformes

Credit: Patrick Colin

The tinamous are a family comprising 47 species of birds found in Central and South America. One of the most ancient living groups of bird, they are related to the ratites. Generally ground dwelling, they are found in a range of habitats.The family Tinamidae consists of about 47 species in 9 genera. although they look similar to other ground-dwelling birds like quail and grouse, tinamids have no close living relatives, and hence are placed in their own order, Tinamiformes. These taxonomic names are based on the Galibi word for these birds, "tinamu".

Of Gondwanan origin, tinamids are related to the ratites. although the fossil record in South America is generally poor, the known tinamiform fossil record goes back 10 million years. Together with the ratites, they make up Palaeognathae, while all other living birds are members of Neognathae. Along with the other palaeognathes, tinamids have no keel on their sternum and a distinctive palate.

We now come to the Neognathae

Anseriformes

Credit: Pascal Alexandre

The Anseriformes are one of the oldest orders of birds, they include what everyone would know as Ducks and Geese and are highly adapted to their aquatic life. Many are also great travellers performing huge annual migrations.

Anseriformes are also unusual in many ways, often having complex reproductive social systems, not to mention anatomies. Many also are unusual among birds in feeding on low nutrition grasses and vegetation, which also involves further ecological adaptations such as in the Geese.

Galliformes
Credit: Der Ibris	Galliformes are an order of birds containing turkeys, grouse, chickens, quails, and pheasants. More than 250 living species are found worldwide. Common names are gamefowl or gamebirds, landfowl, gallinaceous birds or galliforms. "Wildfowl" or just "fowl" are also often used for Galliformes, but usually these terms also refer to waterfowl, and occasionally to other commonly-hunted birds.

Charadriiformes

Credit: Jason Finch

Charadriiformes are a diverse order of small to medium-large birds. It includes about 350 species and has members in all parts of the world. Most Charadriiformes live near water and eat invertebrates or other small animals; however, some are pelagic (sea birds), some occupy deserts and a few are found in thick forest.

This Order includes what are known as commonly known as Gulls, Auks and Waders. although there is a fair amount of disagreement over this Order with the Sibley-Ahlquist taxonomy lumping all of what are the Charadriiformes into the Ciconiiformes. although recent evidence suggests the Charadriiformes are a distinct bird lineage in their own right. Perhaps more demonstrating the pitfalls of taking DNA hybridisation studies to extremes. (My personal opinion: It seems to me that while Biochemical taxonomy is useful, it should not be see as the holy grail and there are many potential issues. In short I have no problem with the Charadriiformes and even more so the idea of a distinct lineage seems to make sense to me.)

Gaviiformes

The loons (North America) or divers (UK/Ireland) are a group of aquatic birds found in many parts of North America and northern Eurasia (Europe, Asia and debatably Africa). All living species of loons are members of one genus, Gavia, family, Gaviidae, and order Gaviiformes all of their own.

The loons are the size of a large duck or small goose, which they somewhat resemble in shape when swimming. Their plumage is largely black-and-white, with grey on the head and neck in some species, and a white belly, and all species have a spear-shaped bill.

At the present time the Gaviiformes are very much up in the air, with no clear concensus. This is one of those Orders that is very much in the wait and see category. Every Ornithologist seems to have a different opinion on them and "all" the available data seems confused and often contradictory.

Podicipediformes

The Grebes are another Order - or "ah hmmm" grouping which nobody really seems to know where they belong. They are a group of freshwater diving birds, however they have a very different anatomy to most other birds. It gets worse since biochemical results essentially show them not belonging anywhere other than making it quite clear that they are not Loons.

This is another Order where only time and further research will resolve some of the open problems. The latest evidence seems to indicate that they are most closely related to Flamingos. Still to be a bit cynical here, then we get on to the question of Flamingos...

Procellariiformes

Procellariiformes are an order of seabirds that comprises four families: the albatrosses, procellariids, storm-petrels and diving petrels. Formerly called Tubinares and still called tubenoses in English, they are often referred to collectively as the petrels, a term that has been applied to all Procellariiformes or more commonly all the families except the albatrosses. They are almost exclusively pelagic, feeding in the open oceans.

Sphenisciformes

Credit: Ken Funakoshi

Penguins make up the order Sphenisciformes, family Spheniscidae, and are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers. Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend about half of their life on land and half in the oceans.

Pelecaniformes

Credit: Geoff Penaluna

The Pelicaniformes comprise the familiar Pelicans and a number of other families - most of which are disputed (as usual). To start with the less controversial through to the worst. The pelicans, seem ok, although Sibley and Ahlquist seemed to want to move the whole lot into the supermassive Ciconiiformes (thank goodness this idea never gained ground) as part of their Ciconiiforme obsession. It is general accepted that the Balaenicipitidae - the Shoebill, Balaeniceps rex is part of the Pelicaniformes - if for no other reason than somewhere to put them.

Beyond that it gets murky and convoluted. Sibley and Ahlquist originally wanted to throw a whole bunch of stuff into the Ciconiiformes, that idea has been generally dismissed. So now what has happened is a whole bunch of Ciconiiformes are being snuck into the Pelicaniformes. (If you cant beat them join them?).

So now the Order Pelicaniformes includes the Ibises and Spoonbills - Threskiornithidae, which has some arguments for. However it has opened the door to shifting the lot now to Pelicaniformes, the Cormorants, Phalacrocoracidae are now here also. Not to mention the Frigate Birds - Fregatidae and Darters, Anhingidae. And some others

The latest seems to be the Herons - Ardeidae, this seems to be really pushing things and is almost bizzare. In essence the whole of the Ciconiiformes are being shifted over to the Pelicaniformes...based on the fact that nobody originally accepted moving the Pelicaniformes into the Ciconiiformes...

(Personal Opinion: There seems to be a modern confusion over what Taxonomy is meant to achieve, compounded with confusion over cladistics. Not to mention alot of egos involved. So until I see something better the Herons can stay in Ciconiiformes.)

Phaethontiformes

Credit: Mila Zinkova

tropicbirds are a family, Phaethontidae, of tropical pelagic seabirds now classified in their own order Phaethontiformes. Their relationship to other living birds is unclear, and they appear to have no close relatives. There are three species in one genus Phaethon. They have predominately white plumage with elongated tail feathers and small feeble legs and feet.

In other words...another vague Order.

Ciconiiformes

Credit: Ryan Cheng

traditionally, the order Ciconiiformes has included a variety of large, long-legged wading birds with large bills: storks, herons, egrets, ibises, spoonbills, and several others. As mentioned in the Pelecaniformes are large number of these families have now been moved there, with pressure on the remaining families. Essentially leaving only the Storks in the Ciconiiformes.

To paraphrase "...and influential Sibley-Ahlquist taxonomy greatly enlarged the Ciconiiformes, adding many more families, including most of those usually regarded as belonging to the Sphenisciformes (penguins), Gaviiformes (divers), Podicipediformes (grebes), Procellariiformes (tubenosed seabirds), Charadriiformes, (waders, gulls, terns and auks), Pelecaniformes (pelicans, cormorants, gannets and allies), and the Falconiformes (diurnal birds of prey)."

Which must be noted as one of the wonders of modern science, in essence proving birds are related to birds. On the plus side the Ciconiiforme obsession seems to be waning (although Pelecaniformes are still expanding.)

(Personal Opinion: Commonsense seems to be prevaling with many seeming to ignore what can only be described as strange pushes into the Ciconiiformes, as far as I know most are happy to keep New World Vultures out of the Ciconiformes along with many others. As mention before I think much of this is confusing morphological taxonomy with Cladistics, not to mention placing too much emphasis on DNA hybridisation techniques. "Every tool has it's place".)

Cathartiformes

Credit: Eric Kilby

This is a possible Order, or maybe even as I write a discarded Order. It "may" contain the New World Vultures, which were traditionally in the Falconiformes, as they are really quite different to the Old World Vultures. Then "suprise" there was a push to put them in with the Ciconiiformes, when that didn't work commonsense seemed to prevail and they are now either back in the Falconiformes or in the new raptor Order of Accipitriformes.

This Order can be taken as entirely provisional and I expect it will probably fade into history. ( Well for at least a while, till someone comes up with the idea again.Expect to see them moved to Accipitriformes.)

Phoenicopteriformes

Credit: John Harrison

The Flamingos, essentially another "basket" of we don't know where these go, so make another order. Actually the Flamingos are an Ornithological sensitive issue - "...don't mention the Flamingos". To give a brief idea of what I will call the "Flamingo Problem", and just how complex (and messed up this is).

The Flamingos were traditionally in the Ciconiiformes (...they have long legs), and were seen as most closely related to the Ibises and Spoonbills, which seems to make sense so far. However the Threskiornithidae are now in the Pelecaniformes and over the years a number of relationships have been found with the Anseriformes. Essentially Flamingos have the same lice as Ducks.

It doesn't end there however since the Grebes come up as the Flamingos relatives. (Which of course nobody knows where the Grebes go also.) Anyway some recent genetic evidence seemed to push the Grebe hypothesis indirectly. Essentially all of these odd Orders actually seem to have some genetic markers in common. So the idea is to split the birds into two big groups.

The weird Orders on one side, Metaves, and the less weird Orders the Coronaves on the other, which would be two subgroups of Neoaves. (Sound complicated yet?). For now it is probably best to let the Flamingos remain in Phoenicopteriformes until further research sheds more light on the issue.

(Personal Opinion: For what it is worth, there does seem to be some sense to Metaves and in many ways would explain a lot - or at least bring a bit of clarity. Clearly some groups of birds are very difficult to figure out taxonomic relationships for. The interesting thing is that this research shows that all of these weird groupings actually do have something in common.)

Falconiformes

Credit: John O'Neil

"Ah at last an easy one", I hear you say. "Falconiformes, must be Falcons and Eagles and similar right?". Well not quite, compared to some Orders the Falconiformes are relatively easy. However there are some problems and issues.

The first being that well, Eagles and Falcons are actually quite different when you begin to look closely. And recent genetics have confirmed this to a further degree. This essentially means the Eagles are shed off into the proposed Order of Accipitriformes, (Which is one new Order I happen to agree with.)

So far it doesnt sound too bad, still there is the New World Vulture problem, which at least for now sees them placed back in here - compared to being in the Ciconiiformes, (which had the push for leaving Ciconiiformes to the Storks, so either they are closely related to the Storks - or are in with the Pelecaniformes). So after all that New World Vultures can stay in the Falconiformes for now.

But wait there is more, just to make this thoroughly confusing, there seems to be mounting evidence that the Falconiformes nearest relatives are - you guessed it - the Psittaciformes, the Parrots. This is not as silly as it sounds for anyone who has spent time among birds. There are many similarities when one starts to dig deeper. The New Zealand Kea, Nestor notabilis, comes to mind.

The Falconiformes seem to me at least an exciting area to watch for the future.

*Accipitriformes

The Accipitriformes are an order that has been proposed to include most of the diurnal birds of prey: hawks, eagles, vultures, and many others, about 225 species in all. For a long time, they have been included with the falcons in the Falconiformes, but because of recent DNA research that suggests falcons are more akin to parrots and passerines as mentioned elsewhere.

(This is a proposed order that I happen to agree with, the falcons are quite different birds and deserve an Order to themselves. At the same time the Accipitriformes would neatly solve a number of problems.)

Gruiformes

Credit: Wing Chi Poon

The Gruiformes comprise of essentially the Cranes, Crakes and Rails. although this Order seems to attract less controversy than many of the other Orders, it was in many ways from the outset a hodge podge grouping. Over the years a number of Families were added "incertae sedis", meaning "uncertain placement", perhaps due to this more open approach from the start is the explanation for less controversy.

In recent years with newer research more correct homes have been found for some of these Families, for example the Pedionomidae into the Charadriiformes. Essentially there is still much to be sorted in the Guriformes though, with a fair number of them being more related to other Orders.

Pteroclidiformes

Credit: Marie de Carne

The sandgrouse are a family, Pteroclididae, of 16 bird species, the only living members of the order Pteroclidiformes. They are restricted to treeless open country in the Old World, such as plains and semi-deserts. They are distributed across northern, southern and eastern Africa as well as Madagascar; the Middle East, India through to central Asia; and the Iberian Peninsula. Sandgrouse are traditionally placed in two genera. Two central Asian species in Syrrhaptes, and the rest in Pterocles, but recent research casts some doubt on this division.

Coloumbiformes

Credit: Tom Tarrant

The Order Columbiformes includes the very widespread and well known doves and pigeons, classified in the family Columbidae, and also the extinct Dodo and the Rodrigues Solitaire, long classified as a second family Raphidae. There are 313 species, found worldwide making up the Columbiformes order. Like many birds, all Columbiformes are monogamous. Unlike most other birds, however, they are capable of drinking by sucking up water, without needing to tilt the head back.

This was the original reason for including the Sandgrouse - Pteroclididae here. Until it was realised that they can't actually suck up water, hence moving them to their own Order.

In many ways Columbiformes are perhaps one of the simplest and stable of Orders. And as a group of birds display some remarkable characteristics, much much more than what many people would think of as boring pigeons.

Psittaciformes

Credit: Luc Viatour

The Psittaciformes comprise of the well known Parrots, also known as psittacines. There are roughly 372 species in 86 genera found mainly across the warm and tropical regions - with some interesting exceptions. For example New Zealand, Patagonia and Tasmania, Australia.

The Order is subdivded in three families: the Psittacidae or true parrots, the Cacatuidae or cockatoos and the Nestoridae. As an Order there are not that many problems. The issues seem to be more to do with internal relationships and the overall relationship of the Order, as mentioned a growing hypothesis is that the Parrots are most closely related to the Falconiformes. Parrots also have an interesting feather structure to distinguish them, called Dyck texture, this through optical interference creates the spectacular colourations we see in the Parrots. although this is not found in the Cacatuidae.

Cuculiformes

Credit: Ebvan Parker

Another dubious Order, the Cuculiformes traditionally included three families of; Musophagidae - turacos and allies, Cuculidae - cuckoos, coucals and anis, Opisthocomidae - Hoatzin.

So here is another Order causing trouble. The Sibley-Ahlquist taxonomy raises the Musophagidae to an order Musophagiformes which may or may not be warranted. The Hoatzin continues to be enigmatic; it is probably best regarded as a distinct, monotypic order, especially if the turacos are also considered one. The coucals and anis are sometimes considered subfamilies of the Cuculidae, or otherwise assigned to families of their own, the Centropodidae and Crotophagidae respectively.

Another one in the category of watch, wait and see.

*Opisthocomiformes

Credit: Linda De Volder

A new proposed Order just for one bird. The very peculiar and interesting Hoatzin, Opisthocomus hoazin, perhaps one of the most enigmatic of all the birds. A leaf eating bird of South America, which feeds on leaves and amazingly has claws on it's wings when young enabling it to climb trees. Obviously a bird such as this is not going to fit in well anywhere, hence this new proposed Order.

The essential problem here is that the genetic evidence is completely contradictory and the best "guess" at the moment, as wild as it may seem is some sort of relationship with the Doves and Frogmouths. Basically a very weird animal.

Strigiiformes

Credit: Avecida

The Owls make up the Order Strigiformes, they are divided into two families, the typical owls, Strigidae, and the barn-owls, Tytonidae. The only real issue with the Strigiformes seems to be that of where they are most closely related. Either to the Falconiformes or more likely to the Caprimulgiformes - Nightjars. This seems more likely if the Falconiformes and Psittaciformes are closely related.

The Sibley-Ahlquist approach of placing the Nightjars and Owls in the Order Strigiformes and hence the Owls as a Family Strigidae seems to be increasly remote as more modern genetic evidence is used. Rather giving them all there own Order seems to be the most sensible approach.

Caprimulgiformes
	The Caprimulgiformes comprise of the Nightjars - Caprimulgidae, Eurostopodidae and the Frogmouths - Podargidae. The other two families seem much more controversial and uncertain, that is the Potoos - Nyctibiidae, which seem ok for now. And lastly the Oilbirds - Steatornithidae, which by all accounts of the available evidence seem to deserve their own Order.

Apodiformes

traditionally, the bird order Apodiformes contained three living families: the swifts, Apodidae, the tree swifts, Hemiprocnidae, and the hummingbirds, trochilidae. In the Sibley-Ahlquist taxonomy, this order is raised to a superorder Apodimorphae in which hummingbirds are separated as a new order, trochiliformes, but this has been refuted by subsequent research. With nearly 450 species identified to date, they are the most diverse order of birds after the passerines.

This Order is actually fairly steady, the main issues seem to be around nearest relatives which is increasingly looking like the Owlet-nightjars. In case anyone is wondering the swifts and Hummingbirds are actually similar in many ways anatomically. Perhaps the most obvious is the feet, hence the name of the Order, interestingly none of the Apodiformes have scales or scutes on their legs or feet like other birds, instead having only bare skin.

Coraciiformes

Credit: Christian Svane

The Coraciiformes are a group of usually colourful near passerine birds including the kingfishers, the Hoopoe, the bee-eaters, the rollers, and the hornbills. They generally have syndactyly, with three forward-pointing toes (and toes 3 & 4 fused at their base), though in many kingfishers one of these is missing.

The Kingfishers in themselves seem to be reasonably robust, perhaps the only controversy is the trogons and Hornbills, which many think should be elevated to their own Order.

Piciformes

The Piciformes are a fairly standard Order with no real issues. This Order encompasses the well known woodpeckers.

Six families of largely arboreal birds make up the order Piciformes, the best-known of them being the Picidae, which includes the woodpeckers and close relatives. The Piciformes contain about 67 living genera with a little over 400 species, of which the Picidae (woodpeckers and relatives) make up about half.

Trogoniformes

Another Order with an unusual toe arrangement, the trogoniformes comprise of the the trogons and quetzals. The trogoniformes which contains only one family, the trogonidae. The family contains 39 species in eight genera. The fossil record of the trogons dates back 49 million years to the mid-Eocene.

The trogoniformes issue seems to revolve around their nearest relatives, this is most probably an ancient linkage with the Coraciiformes, although at the moment this is probably too soon to tell.

Coliiformes

Credit: Jerry Freidman

The Coliiformes are composed of the sub-Saharan mousebirds and are a small group of birds which have no real close affinities to other groups. Though they and the parrots and cockatoos, Psittaciformes, may be closer to each other than to other birds. The mousebirds are therefore given order status as Coliiformes. This group is confined to sub-Saharan Africa, and is the only bird order confined entirely to that continent. They had a wider range in prehistoric times and apparently evolved in Europe.

In many ways this Order seems to be a relic, and in past times was much more widely dispersed. At the present time their relationship to other Orders is hardly clear.

Passeriformes

Credit: Gabriel Buissart

The Passeriformes, make up what are commonly known as the perching birds, that is they can actually perch on a branch (which when you think about it, not all birds can do). The Passeriformes are incredibly diverse making up more than half of all bird species. They are actually one of the most diverse of all vertebrate Orders.

The name comes from the latin for "sparrow" - passer, and that is what these birds essentially are. When someone mentions bird, this is the type of bird most people will think of.

The main controversies are internal and most especially over the superfamily Corvidae (essentially the crow type birds - of which there are many), and also the Meliphagoidea - the honeyeaters, which could probably be elevated to their own Order or Orders.

There are also a number of families which need some serious revision or it is currently underway, such as the warblers. And a number of families which are lumped into the Passeriformes which could probably be moved. Only time will tell.