Lecture 4 Adaptations. - Digestive system -Respiration -Excretion -Nervous System (Chapter 7)

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Maximilian Haynes
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1 Boreal Owls in Duluth

2 Lecture 4 Adaptations - Digestive system -Respiration -Excretion -Nervous System (Chapter 7)

3 Digestive System

4 Bill Structure Key adaptation examples for feeding: 1 Conical - seed-cracking; finches 2 Long - nectar or probing 3 Highly specialized - filtering, etc.

5 Bill Adaptations

6 Brown and Lomolino (1998) Biogeography

8 Hawaiian Honeycreepers

9 Brown and Lomolino Biogeography

10 Avian Digestive System Lack teeth Possess specialized digestive system to process unmasticated food Highly efficient & fast nutrient extraction

11 1 Oral cavity 2 Tongue 3 Esophagus 4 Crop 5 Proventriculus 6 Gizzard 7 Liver 8 Pancreas 9 Intestine 10 Caeca 11 Cloaca Digestive System

12 Oral Cavity Taste buds poorly developed Salivary glands in pharynx initiates digestive process relatively well developed in some seed-eaters traps insects building nests - noteworthy in Edible-Nest Swiftlet of East Indies; millions of nests used to make delicacy of birds nest soup Tongue usually simple but can be highly modified

13 Tongue Modifications A. Passerine general B. Nectar feeding - tubular C. Woodpecker barbed end D. Fruit-eater short/broad E. Fish-eater rear-directed hooks F. Food-straining

14 Esophagus Size related to type of food eaten; small in insectivorous species but large in herbivores Distensible in many species e.g., in seabirds Columbiformes produce pigeon milk Inflated to produce sound and/or for displaying Crop = modification of esophagus

15 Crop Softens food Stores food (true crop) especially prominent in grain feeders Regulates flow through digestive tract

16 Cropped

18 Stomach Proventriculus 2-chambered Proventriculus and Gizzard highly developed in fish-eaters and raptors secretes acidic gastric juices Northern Shrike can digest a mouse in 3 hours

20 Stomach Proventriculus Gizzard and Gizzard Functional analog to mammalian molars Striated muscle; keratinous ridges May contain grit Most pronounced in seed-eaters

22 Food Pellets Formed in gizzard Indigestible portions of food fur, bones, chitin, etc. Regurgitated Found in wide range of species Owls, Hawks, Shrikes

23 Food Pellet Useful in food analyses Found under roosts Can form in < 4 hours

24 Liver Largest gland in bird Proportionately larger than in mammals Pancreas Relatively large Secretes digestive enzymes Endocrine gland regulates carbohydrate & fat metabolism

25 Intestine Organ where most of digestion occurs Absorption Length related to food source

26 a. Granivore Longer in seed, plant and fish eaters b. Carnivore Shorter in fruit, meat, and insect eaters

27 Caeca 2 dead-end sacs at posterior end of intestine Harbors bacteria that aids in the digestion of plant material (e.g., cellulose) Well developed in ground-dwelling herbivores

28 Cloaca 1 Receives excrement from intestines 2 Receives kidney discharge & gametes 3 Storage

29 Digestion Summary Bird digestive system reflects food habitats Many highly successful species are highly omnivorous such as gulls and crows Diet varies considerably according to the season, habitat, geographic area, and physiological demands

30 More on Digestion Huge energetic and food demands during migration individuals can increase their weight by 50 % Winter-time demands for food very frequent need for food during cold and minimal daylight hours Hummingbirds need to visit flowers each day to meet energy demands in cold,mountainous regions also drop body temperature Seabirds (e.g., petrels) forage up to 600 km from breeding colonies

31 Physiology/Morphology Continued Nervous system Respiration Excretion

32 Nervous System 1. Brain complexities of flight have led to increased need for brain power Large Brain 2-9% of total body mass Enlarged cerebral hemispheres Large optic lobes eye-brained animals Large cerebellum balance and coordination during flight Hyperpallium unique in birds, associated with learning and intelligence Well developed in Passerines, Corvids, and Parrots

33 Figure 7-11 (note drawn to same relative scale) A. Lizard B. Macaw

34 Nervous System continued 2. Senses Touch overall sense is similar to man Taste generally poorly developed e.g., taste buds in tongue of most birds compared with 10,000-17,000 in mammals Smell poorly developed in most birds, but some have excellent abilities to smell e.g., vultures attracted to smell of rotting meat

35 Nervous system continued Hearing well-developed but not as good as in most mammals Hearing via a single cartilaginous bone, stapes Owls have special ability to hear long, oblong ear openings assymetric ear openings collecting and focusing device- facial disks

36 Hearing Facial Disk Opercula (ear flaps) Asymmetrical ears Size Location Auditory centers in brain

37 Hearing Sound arrival time varies Left ear higher Sounds below horizon Right ear lower Sounds above horizon

38 Hearing Pin point mouse within 1º of vertical and horizontal plane Ann Cook

39 Nervous System continued Vision most advanced of all senses Eye of man is 1 % of head weight; 15 % of head weight in the European Starling Shape of the eye varies considerably from flat to tubular Nictating membrane found among diving birds that functions like a contact lens Eye positioning monocular in many herbivores, but binocular in most raptors Enhanced color vision: high cone density, colored oil droplets, ultraviolet receptors

40 Retina

42 Raptor Vision Eyes in frontal position Eyes elongated (telescope supported by sclerotic ring) Pupils - Large range of adjustment Owls - abundance of rods (light gathering cells) See 3x as far as humans C. Toops

43 Circulatory/Respiratory System Generally this system is very highly advanced much more so than in mammals Heart size is 1.4 to 2 times larger than in mammals Resting rate is generally lower than in mammals, but peak rates are higher (e.g., heart rates are 93 beats per min in turkey, but 1,260 in an active hummingbird) Blood has high sugar content 2 x glucose as in mammals Small red-blood cells (high surface to volume ratio) 6 seconds for blood to make a complete circuit in active birds

44 Figure 6-7

45 Respiratory system continued No stagnation period in the lungs with the air sacs 20 % in mammals Air sacs 9 in most birds but varies from 6 to 14 Air flows in only 1-direction 2 full respiratory cycles are necessary for complete air passage from intake to exhale Use sternum to inflate and compress air sacs

46 Figure 6-2 Flow: trachea syrinx bronchi posterior air sacs lungs anterior air sacs trachea out

47 Two Cycles, 4 step process Figure 6-5

48 Figure 6-5 (continued)

49 Excretory System 1. Kidneys primary organ for removal of waste products from the blood Overall less efficient than in mammals 2. Urine mixed with fecal material in large intestine with high concentration of uric acid rather than urea (found in mammals) Urea CH 4 N 2 O Uric acid C 5 H 4 N 4 O 3 2 times the amount of nitrogen excreted with uric acid

50 Birds have unique physiological and sensory adaptations for specialized lifestyles Birds are great at what they do.

EXERCISE 3 Avian Organ & Organ System

BI-160 LAB REPORT #3 NAME Introduction EXERCISE 3 Avian Organ & Organ System To investigate the major avian organs and organ systems used to sustain a bird and its active lifestyle, you will complete a