Birds, Birds, Birds

Features

• Feathers, some scales

• Warm blooded

• 4 chambered heart

• Very light skeleton

• Two chambered stomach (crop, gizzard)

• Toothless beak

Some Amazing Bird Facts

• There are about 9,703 species of birds divided up into 23 orders, 142 families and 2,057 genera (Sibley and Monroe 1992).

• Birds can be found on all major land masses from the poles to the tropics as well as in or over all our seas and oceans and their accompanying islands.

• The total number of birds on the planet is very difficult to estimate because their populations fluctuate seasonally, but scientists have suggested that there may be between 100,000 and 200,000 million adult or near adult birds on the planet at any one time. Of these the most common or populous wild bird in the world is the Red-billed Quelea (Quelea quelea) from south of the Sahara in Africa. These birds are so prolific that they are serious pests of grain and millions are killed at roost sites every year in a vain attempt to control their numbers.

Name the most common bird

The most common

The most common bird in the world is the Red Junglefowl (Gallus gallus) most regularly seen as the common domestic chicken. The most widespread commonly seen wild bird in the world is probably the European House Sparrow (Passer domesticus) which has been transported all over the world by European settlers and can now be found on 2/3 of the land masses of the world including New Zealand, Australia, N. America, India and of course Europe.

Name the largest bird

The Largest

There are 3 possible ways of measuring largest in birds; heaviest, tallest and or longest wingspan, however, whatever way you choose, the records are all held by extinct species. The heaviest bird ever was probably the extinct Dromornis stirtoni from Australia. This flightless giant lived between 1 and 15 million years ago and probably stood nearly 3m/10ft tall and weighed in at a massive 500kg/1100lb. The tallest bird ever was, as far as we know, Dinornus maximus, a Giant Moa from New Zealand. This giant though only half as heavy as the Australian Dromornis stood an incredible 3.7m/12.1ft tall. Another extinct bird, this time from S. America, has the record for largest flying bird and longest wingspan. The Giant Teratorn (Argentavis magnificens) had a wingspan of at least 6M/19.5ft and could possibly have been as large as 7.5m/25ft.

Largest living bird

• The largest living bird is without doubt the Ostrich (Struthio camelus). This ever popular bird stands a magnificent 2.74m (9ft) high and can weigh as much as 160kg (353lb).

• The heaviest flying bird is the Kori Bustard of Africa (Ardeotis kori), a number of specimens have been scientifically recorded weighing 19kg (42lb) and heavier specimens have been reported but not confirmed. Close runner-ups are the Eurasian Bustard (Otis tarda) and the Mute Swan (Cygnus olor) both of which have been recorded at 18kg or (40lb).

The title of 'Bird with the Longest Wings' also has several close contenders with the Andean Condor (Vultur gryphus) with a well recorded wingspan of 3m (10ft) and the Maribou Stork (Leptoptilus crumeniferous) with a know wing span 2.87 m (9ft6ins) and an unconfirmed report of a specimen with a 4.06 m (13ft 4ins) are undoubtedly the longest winged birds on land. However real record holders are birds that live at sea. The Royal Albatross Diomedea epomophora has been regularly recorded with a wingspan of 3.5 m (11ft 6ins). However the Wandering Albatross, (Diomedia exulans) which has a similar average wingspan holds the scientific record for wing length. A male caught and measured by the Antarctic research ship USNS Eltanin in the Tasman sea in 1965 had a wingspan of 3.63m (11 ft 11 ins) and so holds the crown for having the longest officially recorded wings in a living bird.

The Smallest

The smallest bird in the world is generally agreed to be the Bee Hummingbird (Mellisuga helenae) from Cuba which weighs a mere 1.6g or 0.056oz. Shortest wings and body length are not really appropriate measurements because they are disproportionately affected by whether or not the bird is flightless or not and its beak length respectively. Another major contender for smallest bird is the Little Woodstar (Acestrura bombus) from S. America. Both these tiny miracles of life fly very competently. The smallest flightless bird is the Inaccessible Island Rail (Altantisia rogersi). Reaching a mere 12.5cm/5inches in length and weighing 35g/1.45oz this little beauty can only be found in the southern Atlantic Tristan da Cunha Islands.

Nests and Eggs

Largest Egg - living = Ostrich Largest Egg - ever = Elephant Bird Aepyornis maximus From Madagascar 39cm/15.4in long = 12 litres/2.6 gallons, 220 chicken eggs Smallest Egg - living = Vervain Humming bird Mellisuga minima = the size of pea Largest individual nest = Mallee Fowl Australia Leipoa ocellata builds a mound 5 m (16.5ft) high and 11 metres (36ft) wide. Smallest nest - many seabirds do not make a nest at all, nest on ground or in case of fairy tern on a branch of a tree otherwise the award goes to the hummingbirds for their thimble sized (1cm squared) nests.

Organs of digestion

Feet

                                           

  

                                         

 

                                           

  

                                           

  

                                       

                                         

  

                                            

                                         

Skeleton

The Bird Bill or Beak

• One of the most notable things about birds is their jaws and the fact that they have beaks properly called a bills.

• The bird's bill is a remarkably adaptable and useful instrument.

• Different shaped bills serve different ecological purposes and are a good indication as to the bird's feeding habits.

Tongues • Yes most birds have tongues though unlike ours a bird's tongue has 5

bones in it that support and strengthen it. In some birds however the tongue has become highly evolved.

• In some fish-eating birds such as Penguins the whole tongue is covered in backwardly pointing spikes which help in swallowing the fish. In other fish-eating birds such as Cormorants, the tongue has been almost completely reduced.

• In Woodpeckers the tongue has become greatly elongated and is stored deep in the birds skull when not extended. Woodpeckers' tongues also have a sharp pointed top to spear wood-boring insect larvae. The end of the tongue has backwardly directed barbs to help in drawing the food items out of their holes in the wood.

• Brush-tongued lories, as their name implies, have a tongue with a small brush at the tip. The brush is used to collect nectar form the various flowers which these birds visit. Other primarily nectar-feeding birds such as Hummingbirds, Sunbirds and Honeyeaters have evolved tubular tongues. These effectively give the bird a straw with which to suck up the nectar.

• Finally, in parrots the tongue has become thicker and more swollen - more like ours. This helps parrots to manipulate their food in their mouths, but it also makes it possible for them to make all the sounds that so endear them to us.

Heart and Circulation

The possession of four pulmonary veins, along with the fact that a bird's heart is generally larger and more muscular per pound (or kilogram) or body weight than ours, explains why a bird's circulatory system is more efficient than ours. The left ventricle in a bird's heart is by far the largest chamber and has to work exceptionally hard in small birds which have hovering flight such as humming birds.

FeathersFeathers are one of the most prominent features of

a bird's anatomy, and they are unique to birds. Every bird has feathers and everything that has feathers is a bird .

Feathers perform a number of functions for a bird. Firstly, they provide insulation, this is very important in a warm blooded animal It is believed by most scientists that this insulating effect was the primary force driving the evolution of feathers, i.e. ancestral birds developed feathers to keep themselves warm. Feathers also protect birds from UV light.

Secondly, feathers allow for flight. Scientists believe that flight evolved in birds as a result of their possessing basic feathers and that this added selective pressure to the evolution of feathers making them larger, stronger and refining their structure.

Thirdly, feathers control what a bird looks like. Feathers supply the bird with colors allowing for camouflage and secondary sexual characteristics and sexual display. Consider the tail feathers of a peacock.

Closer look at feathers

Feathers have a basic form of a central hollow supporting shaft called a 'rachis' and a number of fine side branches. These side branches have even finer sub-branches in contour feathers. The side branches in these are called barbs and are linked together by a set of barbules and their hooklets sometimes called 'Hamuli'. Barbs have side branches of their own called barbules. The upper ones containing a series of hooklets and the lower ones without hooks but slightly convex in form to catch the hooklets of the barbules from the next barb along the shaft.

Contour feathers The largest feathers are

contour feathers. These give the bird its shape and color and include both the flight feathers, and the tail feathers.

Scales= Feathers

• Feathers evolved from reptilian scales, and in fact birds still possess scales in the lower parts of their legs and feet.

• Feathers grow quickly and are then sealed off at the base. Once fully developed a feather is a dead matter like your finger nails, though there are still muscles attached the base of each feather which can move each individual feather to help keep it in place. Feathers do not last for ever, they become worn and battered and are replaced regularly by the bird once or twice a year depending on species. This replacing of old feathers is called molt or molting.

Down feathers The next most important

feathers on a bird are the down feathers. These are smaller and lack the barbules and their accompanying hooklets, so they are not zipped together and do not look so neat. In fact hey are soft and fluffy. They provide most of the insulation and are so good at this that mankind for many years used to collect the 'down' from various birds to put into sleeping bags to help keep us warm at night. In down feathers the side branches are longer than the rachis.

Semiplumes; Filoplumes; Bristles and Powder feathers

Semiplumes are half-way between a contour feather and a down feather. These occur between the contour feathers and help to supply insulation and a certain amount of form as well.

Bristle

Bristles have practically no barbs at all and are stiff. They occur around the eyes and mouths of some birds and are protective in function. They are particularly evident in the honey buzzard (Pernis apivorus) for instance, which feeds on the nests and young of social bees and wasps and needs protection around its beak from the stings of the adult bees and wasps.

Filoplume

Filoplumes have only a very few barbs at their tips and are believed to have a sensory function, helping birds keep their feathers in order.

Powder feathers

The fourth main types of feathers are Powder Feathers. These are unusual in that they grow continuously and that they disintegrate at the tip. The barbs breaking down into a fine powder in Herons is useful in mopping up the slime and dust that gets on their fronts during feeding. Thus they help keep the plumage clean. Powder feathers occur scattered throughout the plumage of most birds, but their function is not well understood.

Breathing in Birds

• Air is breathed in through two nostrils situated at the base of the bill This air enters the 'trachea' then passes down the throat until it reaches the syrinx (a bird's vocal chords). Here the trachea divides into two 'bronchi' before passing through the lungs. This freshly inhaled air goes first, not to the lungs, but to the abdominal air sacs. These are the largest and most important of a bird's air sacs. Some of this inhaled air goes to the posterior air sacs also.

Bird Brain… A bird's brain is different to a mammalian brain in

that the complex folds found in the cerebral cortex of mammals are missing and the cerebral cortex itself is much smaller proportionally than in mammals. Instead the corpora striata is the portion of a bird's brain which is used to control instinctive behavior - feeding, flying, reproduction etc. The mid-brain is also well developed as this is the part of the brain primarily concerned with sight, while the olfactory lobes are reduced as would be expected given that bird's in general have little use of the sense of smell.

The Avian Eye and VisionA bird's eye is very similar in its basic structure to a human eye. The eyes make up a much larger percentage of the weight of the head in

birds than in man-15% for a common Starling but only 1% for man. A bird's eye is very tightly fitted into its skull and it is capable of very little

movement, therefore birds can often be seen moving their heads in order to change their visual relationship to something. In most birds the eyes are placed much nearer the sides of the head than in humans. This gives the bird a greater overall field of view, but greatly reduces its binocular vision (the area in which both eyes can see an object).

In man, binocular vision is about 140 degrees out of a total of about 180 degrees. In a pigeon though the binocular area is only 20-30 degrees out of a total field of vision of 300-340 degrees. In many raptors and owls the situation is different. In these birds, as in many insectivorous birds, binocular vision, important in making judgements of distance, is more necessary and so these birds have their eyes more towards the front of their heads. This is most evident in owls where the total field of view is reduced to about 110 degrees with a binocular vision of 70 degrees. This is why owls turn their heads to watch you walk past. An owl can turn its head through over 200 degrees but cannot move its eyes in its head at all.

Hearing and the Bird Ear

Some birds have hearing much more sensitive than ours. Owls not only are more sensitive to small sounds but have asymmetrical ears (one ear being lower on the skull than the other) this means sounds from a single source reach the ears at slightly different times. This gives the owl the equivalent of binocular hearing, allowing them to pinpoint the source of a sound extremely accurately. Barn Owls, Tyto alba, can locate and catch small mammals in complete darkness using only their hearing. Finally, a number of species of owls have tufts of feathers which look like ears and give rise to names like 'Long Eared Owl' and 'Short Eared Owl'. These 'ears' are not ears at all, however, and have nothing to do with hearing.

The Sense of Smell and Bird Noses Whether birds have a sense of smell or not has been a much

debated question by ornithologists. Modern data based on experiments and anatomy of both the nasal cavities and the olfactory lobes of the brain suggest that most birds have practically no sense of smell.

The exceptions are Kiwis which have poor eyesight and hunt worms using their sense of smell. Several species of tubenoses which can detect the smells of fish oils floating on the surface of the sea, allowing them to find schools of fish or anchovies because their messy feeding causes an oily scum to form on the surface of the sea. The third group of birds definitely known to use smell to locate food are the vultures - both old world and new world species have been shown to find carcasses by smell to varying degrees. Other groups of birds with well developed olfactory lobes, but for which the actual evidence of the use of smell to locate prey is lacking, include various waders, many water birds, nightjars and swifts.