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Birds

Freshwater Birds

Nazool Ali

           -Gaviiformes: divers or loons

           -Podicipediformes: grebs

           -Anseriformes: screamers, ducks, geese and swans
    

 

Sharma Dwarka

Order: Tinamiformes
           -Paleontology and Classification
           -General features
           -Natural History
           -Species found in Guyana

 

Freshwater Birds

Nazool Ali (1998)

The orders Gaviiformes, the divers or loons and Podicipediformes, the grebes, contain relatively primitive birds. The divers may not be far removed from the Cretaceous Hesperornis (an early flightless toothed bird).

Order Gaviiformes, Family Gavidae - Divers or Loons

1. The members are relatively large aquatic birds (66-95 cm) and dive to feed on fish.
2. They have dense compact plumage, with the upper parts mainly black and under parts white.
3. They have long and pointed bill used for spearing fish.
4. The legs are short and very posteriorly placed so that walking is not graceful. The three (3) front toes are full webbed with the fourth one being backwardly directed and vestigial and the tarsi is laterally compressed.
5. They have small pointed wings. They have strong flight but have to patter over the surface of the water before take off.
6. The nest is poorly constructed and is a slight depression in the ground at the water's edge.
7. When the young are small they ride on their parents' back. They depend totally on their parents for food until almost fully grown.
8. Loons live in the Northern Hemisphere.

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Order Podicipediformes, Family Podicipediae - Grebes

1. The members are small to medium sized aquatic birds (22-60 cm) and dive to feed on a mixed diet of plants and invertebrates.
2. The plumage is satin like, with black, white and rufous patterns. A conspicuous head tuft is seen in some species.
3. They have a sharp and pointed bill, of medium length.
4. The legs are short, very posteriorly placed and the tarsi is laterally compressed. The three (3) forward toes are lobed with flat claws, the rear toe vestigial.
5. Their wings are short and rounded, the flight is weak. Paradoxically some species are migratory, others tend to colonise man-made lakes.
6. Their nest is usually a floating mass of decaying vegetable matter.
7. The members are distributed world wide.

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Order Anseriformes

The members comprise of two very different birds the screamers (Anhimidae) which are large marsh birds (70-90 cm) and the more aquatic ducks (Anatidae) which range in size from 29-152 cm.

1. The plumage is dense and waterproof but very variable.
2. The screamers have chicken-like bills but the Anatidae has typically broad beaks.
3. The legs are short and heavy, the front toes partially webbed (Anhimidae) and fully webbed (Anatidae)
4. Their wings are typically large and their flight is fast and direct.
5. The nest is typically on the ground and lined with feathers.
6. The members of the Anhimidae is confined to the warmer parts of South America and the members of Anatidae have a world wide distribution.

Suborder Anhimae, Family Anhimidae - Screamers

Screamers are turkey-sized birds with a loud trumpeting call. They have long slender toes with the three front toes only partially webbed and the hind toe is long and level with the front toes. They have no defined apteria and their bills are slender, slightly decurved and chicken like. They have rounded wings with spurs on bend of wings. Their ribs lack uncinate processes. The most peculiar feature of the screamers is a skin filled with small bubbles of air which gives a crackling sound when pressed. The functions of these bubbles are not yet known.

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Order: Tinamiformes

Sharma Dwarka (1998)

Family: Tinamidae
Members: Tinamous
Distribution: Neotropics
No. of Genera: 9
No. of species: 47

Paleontology and Classification

1. Tinamous represent one of the oldest stock of birds of South American continent.
2. To date three genera of fossil Tinamous, of one species each has been described from a single deposit from Miocene of Argentina (about 10 000 000 years ago.)
3. Many anatomical and biological resemblances have been noted between Tinamous and rheas or nandus (Rheidae).
4. Though the bony palate, quite clearly links the two groups, most authorities prefer to maintain them as separate orders, Rheiformes and Tinamiformes.

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General Features

1.They range in size from about 15 cm- 50 cm and weigh from about 150g-2kg.
2. A rather uniform body is evident.
3. Their head is small with a medium sized bill and their neck is long and slender and clothed with short features.
4. They have a quite heavy body with a high rump outline.
5. Tinamous have short, rounded wings which are inconspicuous on the standing bird.
6. A rudimentary tail is present in these birds.
7. The plumage coloration is highly concealing in spotted or barred patterns of brown gray, rufus or tan.
8. The bare legs are typically rather thick and of medium length.
9. There are three short front toes and a hind toe which is either elevated or absent.

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Natural History

Locomotion

1. Tinamous are adapted for ground dwelling.
2. they can walk rapidly and can run with amazing speeds.
3. They rise in flight only when almost stepped upon.
4. The flight of Tinamous is clumsy but swift.

Vocalization

1. Their voices are among the strongest and most pleasant.
2. It consists of loud stereotyped, but melodious whistles.
3. The calls of male and female are similar but discernibly different to the human ear.

Habit selection and food habits

1. Tinamous are adapted to a wide variety of environments that includes dense woodland, thickets, open woodland, savannah etc.
2. The food taken by Tinamous varies with season habitat.
3. They can eat termites, rodents, vegetable foods, seed, ticks, berries and fruits.

Reproduction

1. Some species display their brightly coloured undertail coverts in mating displays.
2. Multiple mating is a rule among Tinamous but there are exception with a few species.
3. They nest in a shallow depression in the ground which is constructed and defended by the male.
4. The eggs are among the most beautiful of all birds, always monochromatic and highly glazed.
5. These include yellow, green, purple etc.
6. the clutch may become quite large (about 8- 16 eggs).
7. Incubation lasts for 17 to 21 days which is done by the male who also broods and guides the chicks for several weeks.

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Species found in Guyana

1. Great Tinamous
2. Gray Tinamous
3. Little Tinamous
4. Undulated Tinamous
5. Red legged Tinamous
6. Variegated Tinamous

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