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ADVANCED. LEC 14. University of Rio Grande Donald P. Althoff, Ph.D . ORNITHOLOGY. Migration & Navigation – Part II Reference Chapter 10. Learning About Migration & Navigation.

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slide1

ADVANCED

LEC

14

University of Rio Grande

Donald P. Althoff, Ph.D.

ORNITHOLOGY

Migration &

Navigation – Part II

Reference Chapter 10

learning about migration navigation
Learning About Migration & Navigation
  • Pfeilstorch = German for “arrow stork”. Name given to storks injured by an arrow while wintering in Africa…then returning to Europe. Most famous Pfeilstorch found in 1822 in a German village—it was carrying an arrow from central Africa in its neck. This specimen was stuffed and is in a collection at the University of Rostock…and is known as the RostockerPfeilstorch.
homing navigation
Homing & Navigation
  • German study of storks: a) held back juvenile storks until adults had migrated b) RESULTS: juveniles traveled stork’s migration route. Therefore, for this species, ______________ to navigate/ migrate.
  • English study of mallards: a) took eggs from mallards that nested in England and were non-migratory popnb) hatched the eggs 1,500 miles to the north c) hatched mallards __________ even though they were non-migratory.
manx shearwaters homing studies
Manx Shearwaters: Homing Studies
  • Displaced 338 individuals returned home from long distances with remarkable promptness—i..e, displayed remarkable _________ ability
  • One bird, displaced from Skokholm, Wales, UK and taken to Boston returned in 12 ½ days…averaging 250 miles per day…traveling minimum of 3,050 miles
laysan albatrosses homing studies
Laysan Albatrosses: Homing Studies
  • 18 adults shipped via air from nest sites in Midway Atoll to 6 different locations around the North Pacific Ocean
  • 14 of 18 (representing at least 1 from each release location) returned to Midway Atoll—the farthest was 4,120 miles in 32 days
penguins homing studies
Penguins: Homing Studies
  • Adelie penguins breed on exposed rock all around the Antarctic continent. At least 177 separate sites = rookeries.
  • Adelie penguins were displaced long distances in all directions from natal rookeries
  • All returned home, even if it meant swimming around large areas of land mass
how do these birds navigate
How Do These Birds Navigate?
  • Sun
  • Influence of topography and/or landmarks
  • Magnetic field / Geomagnitism
  • Celestial bodies = sun, stars, moon, planets…known collectively as celestial cues
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Sun
  • Greater efficiency of homing with clear skies—during cloudy conditions, random homing
  • Clock shifting: depends on bird’s innate knowledge of where sun will be. Experiments show if off 6 hours, homing off 90o
  • More recent study of yellow-faced honeyeater suggest that sun is usually used as a “__________ ______” in combination with the magnetic field

See: Munro, U. and R. Wiltschko. 1993. Clock-shift experiments with migratory yellow-faced honeyeaters, Lichenostomuschrysops (Meliphagidae), an Australian day-migrating bird. Journal of Experimental Biology 181:233-244. (available on email request)

topography or landmarks
Topography or Landmarks
  • _______________ birds get back home better than inexperienced birds
  • Best homing at distances of _____ miles. For these same birds homing success increased at 30-40 miles away…perhaps then using sun and electromagnetic fields.
  • _______ routinely follow highways, railways, and rivers—even if not the most direct route.
  • Waterfowl known to follow watercourses and coastlines—but reluctant to cross large, open bodies of water unless favorable winds.
some celestial cue theories handouts
Some Celestial Cue Theories (handouts)
  • _________ Azimuth Theory—studied starlings in caged environment. On cloudy days, no directional tendencies…but clear days focused correct direction for spring migration
  • _________ Sun Arc Theory—studied homing pigeons released from unfamiliar sites…under varying weather conditions. When birds could see sun, they flew directly home.
  • _________ Navigation by Northern Stars Theory—planets least likely cue, moon only visible part of month…so fixed on stars.
  • …then Steve Emlen’s classic studies!
ph d studies at cornell university
____________: Ph.D. studiesat Cornell University
  • Examined orientation behavior of ______________ my manipulating the location and movements of stars and constellations in a planetarium.
  • Determined they derived ______________ information from the pattern of constellations relative to each other and the celestial pole
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Emlen’s studies of indigo buntings…con’t

Birds viewed the ‘_____’ through the screen… the stars

were “set” both aligned and inproperlyalignend

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Emlen’s studies of indigo buntings…con’t

Effects of _______________…restlessness!

Resulting Vector Diagram

“Footprint” record

celestial cue theories
Celestial Cue Theories….
  • Despite some “challenges”, the earlier theories (i.e., work) by Kramer, Matthews, and Sauers remain plausible to varying degrees
  • There is evidence—especially based on Emlen’s research—that birds ____ orient by sun, by stars…even using some of both
  • Magnetism, as proposed by Keeton, could serve as a backup system to sun or star navigation when neither of the later are “available”.
magnetic field orientation
Magnetic Field Orientation

Evidence:

  • Pigeons disoriented wearing bar magnets
  • Robins in steel cages, when magnetic field is reversed , reversed Zugunruhe
  • Pigeons with “electric cap” fly in opposite direction
  • Iron-rich sensory neurons found in pigeon’s skull

http://www.livescience.com/33889-pigeons-gps-cells-strange-snapshots.html

magnetic field orientation con t
Magnetic Field Orientation…con’t
  • Conclusion on MAGNETIC orientation: bird’s can and do judge compass direction by sensing the Earth’s magnetic field. However, this is more important in young birds and…. …as they mature, celestial cues (sun and stars) become the more important compass reference
in summary
In Summary….
  • Billions of birds migrate every fall and spring to exploit a) _______________ opportunities and b) ____________ opportunities
  • Exactly why some species migrate and others do not is somewhat still an unresolved question
  • Flights of many long-distance migrants require extraordinary ___________________
  • Conservation of migrant species is of concern—as many populations are declining. The problem can be due to loss of suitable a) ________ habitat in Central and the Caribbean and b) ________ grounds in North America
  • Birds use different sources of info to navigate