T09 導航機制 (Mechanisms of Orientation and Navigation)

1. 動物行為學 (通識) 國立臺南大學 通識課程 2011年春 T09 導航機制 (Mechanisms of Orientation and Navigation) 鄭先祐(Ayo) 國立 臺南大學 環境與生態學院 生態科學與技術學系 教授 Ayo NUTN Web: http://myweb.nutn.edu.tw/~hycheng/

2. 09 導航機制 • 導航能力的層級 • 導航與辨識方向的cues • Visual(視覺) cues • Magnetic(磁場) cues • Chemical(化學) cues • Electrical(電場) cues and electro-location Ayo 教材 (動物行為學 2011 通識)

3. Animals depend on oriented movements Both within and between habitats Animals respond to a complex and changing environment by positioning themselves correctly in it And by moving from one part of it to another Animals depend on proper orientation to key aspects of the environment For migration, seeking a suitable habitat, looking for food returning home, searching for a mate, or identifying offspring Ayo 教材 (動物行為學 2011 通識)

4. 導航能力的層級 Animal strategies for finding their way fall into threelevels Piloting (引導) Compass orientation (羅盤定位) True navigation (真領航) Ayo 教材 (動物行為學 2011 通識)

5. 1. Piloting(引導) The ability to find a goal by referring to familiar landmarks The animal may search randomly or systematically for landmarks The guidepost may be any sensory modality Magnetic cues guide sea turtles during their oceanic travels Olfactory cues guide salmon during their upstream migration Ayo 教材 (動物行為學 2011 通識)

6. 2. Compass orientation(羅盤定位) Animals head in a geographical direction without using landmarks Use the sun, stars, and earth’s magnetic field as compasses If they are displaced before beginning migration Animals can end up in ecologically unsatisfactory places Compass orientation is indicated if an animal is moved to a distant location and does not compensate for the relocation Ayo 教材 (動物行為學 2011 通識)

7. Compass orientation Displaced birds did not reach their normal destination and ended up in ecologically unsatisfactory places Ayo 教材 (動物行為學 2011 通識)

8. Uses for compass orientation: vector navigation Compass orientation can be used in Short-distance and long-distance navigation Vector navigation: an inherited (innate) program that tells juveniles in which direction to fly and how long to fly Birds in the laboratory flutter in the direction in which they would be flying if they were free Captive birds cease their activity at the same time as free-living birds have completed their migratory journey Ayo 教材 (動物行為學 2011 通識)

9. Animals can change compass bearing Many species (i.e. that fly from central Europe to Africa) change compass bearing during their flight Garden warblers and blackcaps in the laboratory change the direction in which they flutter in their cages At the same time free-flying members change direction Migratory direction is inherited Offspring of crossbreeding two populations of blackcaps that had different migratory directions oriented in a direction intermediate between their parents Migratory direction is inherited by additive effects of genes Ayo 教材 (動物行為學 2011 通識)

10. ←The Blackcap, Sylvia atricapilla, is a common and widespread sylviid warbler which breeds throughout northern and temperate Europe. the Blackcap's closest living relative is the Garden Warbler which looks different but has very similar vocalizations. • →The Garden Warbler, Sylvia borin, is a common and widespread typical warbler which breeds throughout northern and temperate Europe into western Asia. This small passerine bird is strongly migratory, and winters in central and southern Africa. Ayo 教材 (動物行為學 2011 通識)

11. Uses for compass orientation: path integration Path integration: the animal integrates information on the sequence of direction and distance traveled during each leg of the outward journey Then, knowing its location relative to home, the animal can head directly there, using its compass(es) Ayo 教材 (動物行為學 2011 通識)

12. Path integration Information from the outward journey is used to calculate the homeward direction (vector) Path integration may be a type of vector navigation Estimates of distance and direction are adjusted For displacement due to current or wind Close to home, landmarks pinpoint the exact location of home Ayo 教材 (動物行為學 2011 通識) Desert ant

13. Many animals use path integration While foraging, a desert ant wanders far from its nest After locating prey, the ant heads directly toward home The ant knows its position relative to its nest Each turn and the distance traveled on its outward trip To determine the direction and distance of its outward route Direction is determined using the pattern of polarization of skylight, which is caused by the sun’s position Distance integrates the number of strides and stride length (a “pedometer”) At home, cues in the nest reset the path integrator to zero It is set again by the next outward journey Ayo 教材 (動物行為學 2011 通識)

14. 3. True navigation(真領航) The ability to maintain or establish reference to a goal, regardless of its location, without use of landmarks The animal cannot directly sense its goal If displaced while en route, it changes direction to head again toward its goal Only a few species (i.e. homing pigeons) have true navigational ability Oceanic seabirds and swallows (燕子) Sea turtles and the spiny lobster Ayo 教材 (動物行為學 2011 通識)

15. An animal that finds its way by using true navigation can compensate for experimental relocation and travel toward the goal. Ayo 教材 (動物行為學 2011 通識)

16. Astounding feats(令人驚奇的事蹟) of migration Different species use different navigational mechanisms An arctic tern circumnavigates the globe A monarch butterfly flutters thousands of miles to Mexico A salmon returns to the stream in which it hatched Orientation systems include: multiple cues, a hierarchy of systems, transfer of information among various systems A species can use several navigational mechanisms If one mechanism becomes inoperative, a backup is used Navigational systems may use multiple sensory systems Ayo 教材 (動物行為學 2011 通識)

17. 導航與辨識方向的cuesVisual cues: landmarks An easily recognizable cue along a route that can be quickly stored in memory to guide a later journey Based on any sensory modality, but is most commonly visual The digger wasp relies on landmarks to relocate its nest after a foraging flight A ring of 20 pine cones was placed around the nest’s opening When a female wasp left the nest, she flew around the area, noting local landmarks, and then flew off in search of prey When the ring of pinecones was moved, the returning wasp searched the middle of the pine cone ring for the nest opening Ayo 教材 (動物行為學 2011 通識)

18. Orienting with landmarks Homing pigeons wearing frosted contact lenses did not see well Their flight paths were still oriented toward home Pigeons do not need landmarks to guide their journey home But they may use landmarks when they are available Ayo 教材 (動物行為學 2011 通識)

19. Models of landmark use Species use landmarks in different ways One model of landmark use: the animal stores the image of a group of landmarks in its memory, almost like a photograph Then it moves around until its view of nearby objects matches the remembered “snapshot” A series of memory snapshots might be filed in the order in which they are encountered Desert ants use path integration to return to the nest They also use landmarks, especially when they have almost reached the nest Ayo 教材 (動物行為學 2011 通識)

20. Desert ants use memory snapshots of landmarks Close to the nest entrance, they search systematically to find the nest’s opening The search strategy varies with the species and number of landmarks If available, ants use landmarks If the direct path is unfamiliar At a clearing, it uses path integration Ayo 教材 (動物行為學 2011 通識)

21. Visual cues: sun compass Many animals use the sun as a celestial compass Determining compass direction from the position of the sun The specific course that the sun takes varies with the latitude of the observer and the season of the year But it is predictable Ayo 教材 (動物行為學 2011 通識)

22. The sun follows of predictable path through the sky that varies with latitude and season. Ayo 教材 (動物行為學 2011 通識)

23. The sun can be used as a compass If the sun’s path and the time of day are known The sun appears to move at about 15° an hour Species that take short trips do not adjust their course An animal traveling for long periods compensates for the sun’s movement It measures the passage of time and adjusts its angle with the position of the sun After 6 hours of travel, an animal switches from having the sun 45° to its left to a 45° angle, with the sun on its right Time is measured by using a biological clock Ayo 教材 (動物行為學 2011 通識)

24. Daytime migrants navigate by the sun Orientation (directionality) of migratory restlessness is lost when the sun is blocked from view Caged starlings are daytime migrants They lose their directional ability under an overcast sky When the sun reappears, they orient correctly again Birds orient to a new direction of the “sun” when a mirror is used to change the apparent position of the sun Starling (歐掠鳥) Ayo 教材 (動物行為學 2011 通識)

25. Experiments using migratory restlessness An orientation cage has 12 food boxes encircling a birdcage Birds were trained to expect food in a box in a certain compass direction As long as the birds could see the sun, they approached the proper food box They compensate for the sun’s movement Ayo 教材 (動物行為學 2011 通識)

26. Visual cues: star compass Many species of bird migrants travel at night Steering their course using stars Caged warblers housed in a planetarium oriented themselves in the proper migratory direction for that time of year When the star pattern of the sky was rotated, the birds oriented according to the sky’s new direction When the dome was diffusely lit (光線擴散), the birds were disoriented Ayo 教材 (動物行為學 2011 通識)

27. Star compass orientation in indigo buntings In planetarium(天象儀) studies, these birds rely on the region of the sky within 35° of Polaris (北極星) Ayo 教材 (動物行為學 2011 通識)

28. Indigo Bunting • It is migratory, ranging from southern Canada to northern Florida during the breeding season, and from southern Florida to northern South America during the winter. • It often migrates by night, using the stars to navigate. • The Indigo Bunting, Passerina cyanea, is a small seed-eating bird in the family Cardinalidae. Ayo 教材 (動物行為學 2011 通識)

29. Stars rotate around Polaris (北極星) Polaris provides the most stationary reference point in the northern sky Other constellations rotate around it Birds learn that the center of rotation of the stars is in the north Which guides their migration northward or southward It is not necessary for all constellations to be visible at once Ayo 教材 (動物行為學 2011 通識)

30. The stars rotate around Polaris, the North Star. The positions of stars in the northern sky during the spring are shown here. Ayo 教材 (動物行為學 2011 通識)

31. The axis of rotation gives directional meaning Once their star compass has been set, birds do not need to see the constellations rotate Simply viewing certain constellations is enough The star compass has been studied in only a few species Garden warblers and pied flycatchers also learn that the center of celestial rotation indicates north Ayo 教材 (動物行為學 2011 通識)

32. Young birds were oriented to Betelgeuse(參宿四，位於獵戶座) Birds that had experienced Betelgeuse, not Polaris, as the center of rotation interpreted the position of that star as north And headed away from it for their southern migration Ayo 教材 (動物行為學 2011 通識)

33. The orientation of indigo buntings to a stationary planetarium sky after exposure to different celestial rotations. Ayo 教材 (動物行為學 2011 通識)

34. Visual cues: polarized light Many animals orient correctly even when their view of the sky is blocked Another celestial orientation cue is available in patches of blue sky Light consists of many electromagnetic waves vibrating perpendicularly to the direction of propagation Ayo 教材 (動物行為學 2011 通識)

35. The nature of polarized light Unpolarized light: light waves vibrate in all possible planes perpendicular to the direction in which the wave is traveling In polarized light: all waves vibrate in only one plane Sunlight passing through the atmosphere becomes polarized by air molecules and particles The degree and direction depend on the position of the sun Ayo 教材 (動物行為學 2011 通識)

36. The sky viewed through a polarizing filter to show the pattern of skylight polarization at (a) 9am (b) noon, and (c) 3pm. The diagrams below show the pattern of polarization. Ayo 教材 (動物行為學 2011 通識)

37. The pattern of polarized light Is related to the sun’s position One aspect of this pattern is the degree of polarization The light at the poles is unpolarized Becoming more strongly polarized away from the poles The e-vector: the direction of the plane of polarization also varies according to the position of the sun It is always perpendicular to the direction in which the light beam is traveling The pattern moves westward as the sun moves Ayo 教材 (動物行為學 2011 通識)

38. Uses of polarized light in orientation Polarized light reflected from shiny surfaces (i.e. water or a moist substrate) Attracts some aquatic insects to suitable habitat Horizontally polarized light reflected from the surface of a pond helps the backswimmer locate a new body of water Ayo 教材 (動物行為學 2011 通識)

39. Backswimmers • Backswimmers get their common name from their characteristic habit of swimming on their backs. Although they must surface for air, they often swim around below the surface of the water. • Backswimmers or Back-swimmers (Family Notonectidae) are common in ponds and other still waters here in southeastern Arizona and throughout most of the rest of North America. Ayo 教材 (動物行為學 2011 通識)

40. The plane of polarization is an orientation cue Polarized light is used as an axis for orientation Salamanders living near a shoreline use the plane of polarization to direct their movements toward land or water It can determine the sun’s position when blocked from view And provide orientation cues at dawn and dusk, when the sun is below the horizon Ayo 教材 (動物行為學 2011 通識)

41. Magnetic cues Magnetic sense helps an organism locate a preferred direction i.e. when bacteria swim toward the muddy bottom The earth’s magnetic field may also orient nest building In the Ansell’s mole rat, or roosting place of bats A magnetic compass evolved in non-migratory birds first Optimized paths to and from nest, feeding, and drinking sites Advantages to using the earth’s magnetic field as a compass: Used where visual cues are limited or absent Unlike celestial cues, it is constant year round, night and day Ayo 教材 (動物行為學 2011 通識)

42. Cues from the earth’s magnetic field The magnetic poles are shifted slightly from the geographic, or rotational, poles The earth’s magnetic declination: the difference between the magnetic pole and the geographic pole Small in most places (< than 20°) Magnetic north is usually a good indicator of geographic north Polarity, inclination, and intensity of the earth’s magnetic field vary with latitude to provide three potential orientation cues Ayo 教材 (動物行為學 2011 通識)

43. The earth’s magnetic field. Ayo 教材 (動物行為學 2011 通識)

44. The magnetic field provides orientation cues Spiny lobster and certain fish and birds, rats and bats respond to polarity Most birds and sea turtles use the angle of inclination They distinguish between “poleward” (steep lines of force) and “equatorward” (lines of force parallel to the earth) The horizontal component of the earth’s field (the polarity) indicates the north-south axis The vertical component (the inclination of the field) tells whether it is going toward the pole or equator Ayo 教材 (動物行為學 2011 通識)

45. Birds orient using the inclination angle In the laboratory, European robins oriented in the proper direction even without visual cues Ayo 教材 (動物行為學 2011 通識)

46. Homing pigeons On cloudy days, pigeons rely on magnetic cues instead of their sun compass Orienting as if north is the direction where the magnetic lines of force dip into the earth • Birds that were misdirected by reversed magnetic information • Headed away from home Ayo 教材 (動物行為學 2011 通識)

47. The Earth’s magnetic field serve as a magnetic compass Animals respond to the intensity of the geomagnetic field Bees Homing pigeons Sea turtles American alligator If changes in magnetic intensity can be sensed The gradual increase in strength between the equator and the poles could also serve as a crude compass Ayo 教材 (動物行為學 2011 通識)

48. The magnetic compass of sea turtles Sea turtles travel tens of thousands of kilometers during their lifetimes Continuously swimming for weeks With no land in sight Loggerhead sea turtles are guided by the earth’s magnetic field Ayo 教材 (動物行為學 2011 通識)

49. A hatchling sea turtle’s magnetic compass Is based on the inclination of the magnetic lines of force Similar to a bird’s compass • Hatchlings swim toward magneticnortheast in the normal geomagnetic field • And continue to do so when the field is experimentally reversed Ayo 教材 (動物行為學 2011 通識)

50. A sea turtle’s journey begins after hatching Using local cues to head toward the ocean When they first enter the ocean, they swim into the waves To maintain an offshore heading, taking them out to sea In the open ocean, waves are not a navigational cue They can come from any direction Sea turtles maintain the same angle with the magnetic field that they assumed while swimming into the waves to stay on course Ayo 教材 (動物行為學 2011 通識)