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Bird Navigation

Bird Navigation. Tony Ludlow tony.ludlow@modelresearch.com www.modelresearch.com 12 th Jan 2006. Aims of lecture. Show what birds achieve Discuss views about how they do it Illustrate the way various systems interact and how birds calibrate one system from another

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Bird Navigation

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  1. Bird Navigation Tony Ludlow tony.ludlow@modelresearch.com www.modelresearch.com 12th Jan 2006

  2. Aims of lecture • Show what birds achieve • Discuss views about how they do it • Illustrate the way various systems interact and how birds calibrate one system from another • Review mistakes in the progress of research

  3. Types of navigation • Piloting • Compass sense • True navigation

  4. Piloting • Difficult to rule out, given height at which birds fly • Not possible for Bronze-winged cuckoos • Other methods can be demonstrated

  5. Compass v true navigation • Perdeck’s experiments • Tracking birds

  6. Perdeck (1958)

  7. Michener and Wallcott's pigeon harness

  8. Combination of methods Michener and Wallcott (1967) tracked single pigeons and found • A phase of straight flight, not usually towards home: compass sense • Flight heading accurately towards home: true navigation • Use of landmarks within 10 miles of loft.

  9. Michener and Wallcott (1967) tracks

  10. Sensory cues: problems in research • Circular statistics • Redundancy not understood (Pennycuick, Matthews) • Vanishing direction • Piloting cues not eliminated

  11. Kramer (1957) • Starlings --- day migrants • Circular cage – recorded from each perch • Birds showed migratory direction • Confused by overcast • Adjusted for sun movement (90 degrees in 6 hr)

  12. Sun compass: Kramer (1957)

  13. Kramer (1957) • Compensated for normal sun movement • Followed sun when it was shifted by mirrors (so not magnetism, etc.) • 6hr clock shift caused 90 deg shift • `Sun’ kept stationary; birds changed their angle to it.

  14. Stellar compass • Sauer and Sauer (1955) showed blackcaps chose correct autumn directions under a planetarium and reversed direction in spring • Emlen (1970) showed that indigo buntings respond to celestial rotation; they were taught to use other constellations as `north’ star • Bellrose (1967) used radar to show that migrants were well oriented at night, even in overcast • May be they see glimpses and keep straight using the direction of wind gusts (Nisbett, 1955)

  15. Magnetic compass • Rejected in 1960s • Evidence in bees (eg. Lindauer and Martin, 1972) • Keeton (1971) showed magnets confused pigeons under overcast (could act on compass or true navigation) • Wiltschko and Wiltshcko (1972) showed that robins responded to the angle of dip if strength of field similar to earth's • Wallcott and Green used electric coils on pigeons. NUP disoriented, SUP did not.

  16. Polarised light • Brines (1980) demonstrated that rotation of polarised light was used during day • Seems to be this rather than the sun which is used • Birds use rotation of stars to find north • Using rotation, they don’t need a clock

  17. True navigation • Perdeck's adult starlings showed true navigation • So did Michener and Wallcott's tracks • The vanishing direction is easy to measure but very often wrong.

  18. Theories of true navigation • Every twist and turn is integrated (spider, millipedes, Walraff (2000)) • Celestial cues could be used to find home direction (Board of longitude prize) • Magnetic variation across earth's surface • Odours

  19. Celestial navigation? • Requires astonishing accuracy of time sense • Requires astonishing accuracy of visual discrimination (frosted glass contact lenses) • Keeton showed that pigeons home when they cannot see the sun • After a time shift, pigeons show compass errors not errors in home direction.

  20. A magnetic map? • Pattern of magnetism over earth's surface could be used in principle • Wiltschko and Wiltschko (1996) showed this would require minute discrimination: 0.03%. Daily variations are of same order. • It is not clear how the map would work: Angle of dip; Boles & Lohmann (2003) lobsters

  21. Home direction from odours Wallraff (1967) reared pigeons in screened lofts: • Those which could see the sun but not feel the wind got lost • Those which felt the wind but never saw the sun were fine • Odour hypothesis From 1972 Papi and colleagues did many experiments on anosmic pigeons • There is a debate in the Navigation symposium. See Wallraff (1996); Wiltschko (1996) and Able (1996) • Odetti et al (2003) effects of flight experience on orientation performance

  22. Calibrating the systems • Birds are not born with a star map • Magnetic compass (angle of dip) reverses at the equator, so needs to be recalibrated • Savannah sparrows are born with a response to magnetic field • Helbig (1996) Genetics of response • Migratory song birds also respond to celestial rotation • Celestial compass updates the magnetic one during migration • But Sandberg et al (2000), 4 species calibrate star map with magnetic cues.

  23. Redundancy and balance between systems • Keeton: sun or magnets • Multiple systems • How much weight does a bird put on each • Learning two cues could mean less weight to each • Individuals may differ, based on their experience. That would make experiments hard to interpret

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