Ornithology Is the Study of Birds

Ornithology is the study of birds. Ornithologists may study the behavior, physiology, and conservation of birds and bird habitats. This work often involves surveying, recording and reporting on bird activity. Ornithologists may either generalize, or specialize in a particular species or bird group. Most ornithologists work for wildlife agencies at the federal or state levels, or conservation organizations. They may also teach or conduct research at universities. Some work at zoos, wildlife parks, or veterinary clinics and research labs. a. Zoologists have long recognized the similarity of birds and reptiles. Birds & Reptiles Mammals The skulls of birds and reptiles Mammals have two border against the first neck occipital condyles. vertebra by a single occipital condyle (a small bony knob). Birds & Reptiles Mammals The skulls of birds and reptiles Mammals have two border against the first neck occipital condyles. vertebra by a single occipital Mammals have three condyle (a small bony knob). middle ear bones, the Birds and reptiles have a single malleus, incus, and middle ear bone, the stapes. stapes. Birds & Reptiles Mammals The skulls of birds and reptiles Mammals have two border against the first neck occipital condyles. vertebra by a single occipital Mammals have three condyle (a small bony knob). middle ear bones, the Birds and reptiles have a single malleus, incus, and middle ear bone, the stapes. stapes. Birds and reptiles have a lower The lower jaw of jaw composed of five or six mammals has one bones. bone (the dentary). Birds & Reptiles Mammals The skulls of birds and reptiles Mammals have two border against the first neck occipital condyles. vertebra by a single occipital Mammals have three condyle (a small bony knob). middle ear bones, the Birds and reptiles have a single malleus, incus, and middle ear bone, the stapes. stapes. Birds and reptiles have a lower The lower jaw of jaw composed of five or six mammals has one bones. bone (the dentary). Birds and reptiles excrete their Mammals excrete nitrogenous wastes as uric their nitrogenous acid. wastes as urea. Birds & Reptiles Mammals The skulls of birds and reptiles Mammals have two border against the first neck occipital condyles. vertebra by a single occipital Mammals have three condyle (a small bony knob). middle ear bones, the Birds and reptiles have a single malleus, incus, and middle ear bone, the stapes. stapes. Birds and reptiles have a lower The lower jaw of jaw composed of five or six mammals has one bones. bone (the dentary). Birds and reptiles excrete their Mammals excrete nitrogenous wastes as uric their nitrogenous acid. wastes as urea. Birds and most reptiles lay Most mammals do not yolky eggs with similar lay eggs. structure and cleavage Mammals lack scales. divisions. Birds have scales on legs. b. Biologists refer to birds as “feathered dinosaurs” because they are believed to have evolved from small, two-legged dinosaurs called theropods. i. Theropods share many derived characters with birds, the most obvious of which is the elongate, mobile, S-shaped neck. Some also had feathers. c. Fossil Evidence: d. The earliest known bird is Archaeopteryx lithographica (meaning “ancient wing inscribed in stone”) from about 150 million years ago. i. The fossil was approximately the size of a crow and demonstrated the connection between theropods & birds. 1. It had several reptile characteristics such as a long bony tail, clawed fingers, abdominal ribs, and bony teeth. 2. The skull, beak, and feathers resembled that of today’s birds. a. Flight i. Over 150 million years of evolution, birds evolved into flying machines. A bird’s entire anatomy is designed around flight. Only four groups Bats of animals have Birds ever conquered the air by the ability of flight: Pterosaurs Insects b. Feathers i. The single unique feature that distinguishes birds from other living animals is their feathers. ii. Feathers are homologous to reptiles’ scales, both made from the protein keratin. iii. The covering of feathers on a bird is called the plumage. iv. Feathers are lightweight, yet tough. They have 2 primary functions that are essential for flight: 1. They expand the wings’ surface area to provide lift. 2. They insulate and prevent excessive heat loss. v. Accessory functions: 1. Feathers are also important in courtship, incubation, and water proofing. vi. Structure of a feather 1. A hollow quill emerges from tiny pits in the skin called follicles. 2. From each quill develops a shaft, which gives rise to a vane. 3. Each vane has many braches called barbs, which may also branch off into barbules with microscopic hooks called hamuli. 4. These feather structures interlock to keep feathers firm and smooth. vii. Types of feathers: 1.Contour feathers cover and streamline a bird’s body. a.These are also called flight feathers if they extend beyond the body. 2.Down feathers are soft and have no hooks on barbules; used for insulation. 3.Filoplume feathers are hair-like and used for sensory. 4.Powder-down feathers disintegrate as they grow, releasing powder that aids in waterproofing. viii.Preening 1.Birds rub their beak or bill over their feathers, keeps the feathers smooth, clean, and in place. 2.Secretions from the uropygial gland, informally known as the preen gland, at the base of the tail of many birds are spread over the feathers during preening to keep the plumage water repellant ix. Molting 1.All birds periodically shed and replace their feathers in a process called molting. 2.Usually feathers are discarded gradually to avoid bare spots. 3.Flight feathers & tail feathers are lost in pairs to maintain balance. 4.Many water birds, such as ducks, coots, and rails cannot fly during molt periods and will hide in thick marsh grasses. Penguins have more feathers than most other birds, with about 100 feathers per square inch. Most penguin species go through one complete molt each year, usually after the breeding season. x. Feather Color 1.Color patterns are involved in cryptic coloration, species and sex recognition, and sexual attraction. 2.Colors in birds may be due to pigments or structure. a.Red, orange, & yellow are colored by pigments called lipochromes. b.Black, brown, & gray are produced by the pigment melanin. c. Blue is created structurally by the scattering of shorter wavelengths of light by particles within the feather. Himalayan monal Volcano Hummingbird (Lophophorus (Selasphorus flammula) impejanus) c. Skeleton i. A light yet strong skeleton is a requirement for flight. 1.Hollow bones, like the humerus (forearm), have large air spaces and internal strutting (reinforcing bony bars), which helps increase strength. ii. All birds have forelimbs modified into wings (although not always used for flight) iii. All have hind limbs adapted for walking, swimming, or perching; structure of bird feet shows considerable variation. iv. Flying birds have a keeled sternum that provides area for the large well- developed pectoral muscles to attach. v. Fusion of the thoracic, lumbar, and sacral vertebrae helps maintain the proper flight posture, and supports the hind appendages during landing, hopping, and walking. vi. The posterior caudal vertebrae are fused into a pygostyle, which helps support the tail feathers that are important in steering. d. Diet i. The keratinized beaks of birds are strongly adapted to specialized food habits. 1.Short and thick - seed cracking (robin) 2.Long and thin, slightly curved - eating nectar (hummingbird) 3.Strong, chisel like - drilling (woodpecker) 4.Sharp, curved and pointed - tearing flesh (hawk) 5.Long and flattened - straining algae and plants (ducks) 6.Spear shaped - spearing fish (heron) ii. Some birds are euryphagous (generalists), feeding on a wide range of food items. 1. While there is more competition for food, there is less danger of something happening to the food source. iii. Others are stenophagous (specialists), only feeding on one type of food. 1. There is less competition but more danger of losing the food source. iv. Early birds were carnivorous, feeding mostly on insects. 1. Many birds are still insectivores. 2. Other foods include nectar, seeds, berries, worms, crustaceans, mollusks, fish, frogs, small birds, and mammals. e. Digestion i. Birds digest food quickly; they can't afford the extra weight. ii. Birds have specialized bills to help them take bites, but they do not chew as humans do. iii. At the end of the esophagus of many birds is the crop, a stretchy organ used to store excess food so the bird can digest it more slowly. iv. The bird stomach has two compartments: 1. The proventriculus, the first part of the stomach, softens food with gastric acid, mucus and other digestive juices. 2. The second part of the stomach, the gizzard (or ventriculus), has muscular walls and grinds the food into smaller pieces, often with the aid of sand or small stones the bird has swallowed earlier to help this internal ‘chewing’ process. v. Once the food is sufficiently broken down, it moves into the small intestine, where the liver and pancreas help with absorbing nutrients. Most digestion occurs in the small intestine. vi. Next is the large intestine, which is very short for most birds. vii. Where the small and large intestines join are the ceca, two pouches that help absorb any remaining water from the food and finish the digestive process. viii. After digestion, any remaining material, both liquid and solid, food passes through the cloaca to be expelled from the bird's body. 1. For many birds, waste products can also be expelled from the gizzard in the form of pellets. 2. Owls, hawks, eagles and other raptors can’t digest the bones, fur, or feathers of their prey so these materials are bundled together to form a bolus and are regurgitated. Owl pellets can be used to determine what the owls in a particular area have been eating.

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