Animal Navigation Point toward your home ?? ? ? The red star represents the capture location of this eel in the SLE while it was performing its downstream migration. The magenta triangle represents the release location after tagging. The black dots are the mean reconstructed daily locations and the magenta line is the corresponding mean trajectory. A colour gradient is used to show the temporal dimension of the reconstructed trajectory (each day is represented by a colour). The range of potential daily locations is lowest for days 1933. Bguer-Pon M. et al. (2015) Direct observations of American eels migrating across the continental shelf to the Sargasso Sea. Nature Communications 6, 8705 Early displacement experiments Leachs Storm Petrel ? ? ? ? Gagliardo A et al. J Exp Biol 2013; 216: unmanipulated control birds birds with magnets anosmic birds Homing paths of Corys Shearwaters Manx Shearwater 3200 miles in 12 days (250 mi/day) Manx Shearwater Small birds feed by day and migrate at night Small birds feed by day and migrate at night Small birds feed by day and migrate at night White-crowned Sparrow ADULTS JUVENILES White-crowned Sparrow spiny lobsters walk home How about Cataglyphys desert ants ? Dancing with the stars Are we better than ants? Animals have compasses Outdoors No stars Planetarium (no motion) Planetarium Reversed Planetarium Reversed Planetarium star donut Polarized light at sunset on a cloudy day suns location behind clouds suns location behind clouds Polarized light at sunset on a cloudy day (yes with sky stones) Vanishing bearings on an overcast day HOME LOFT Homing pigeons can find home without seeing the sun on an overcast day, MAGNETISM matters! Sunny dayOvercast day HOME LOFT HOME LOFT Magnetic Coil (azimuth compass) Understanding the Earths magnetic field (azimuth compass) Animals sense the dip angle maximum dip = North Magnetite-coupled nerves in beaks of pigeons 1) Knock out the magneto-receptive neurons 1) Knock out the magneto-receptive neurons 2) See how they orient 1) Knock out the magneto-receptive neurons 2) See how they orient Magnetoreception.The lagena in the inner ear is a candidate site of the magnetic sensory organ in the pigeon. M Winklhofer Science 2012;336: Published by AAAS Fig. 2 Recording site verification and c-Fos expression in response to magnetic field stimulation. L Wu, and J D Dickman Science 2012;336: Published by AAAS Seeing magnetism with CRYPTOCHROMES Red Green + Flavin cycle of cryptochrome. Niener C et al. J Exp Biol 2014;217: 2014 by The Company of Biologists Ltd Orientation behaviour of European robins in light of different wavelengths after being kept in total darkness for 1 h. Wiltschko R et al. J Exp Biol 2014;217: 2014 by The Company of Biologists Ltd Sunset direction (polarized sky) Star + clock compass Magnetic inclination compass Birds cross-calibrate their multiple compass systems at sunset magnetite or cryptochrome Normal Didnt see sunset Night 2 Multi-compass cross-calibration sunset x stars Birds smell Orientation requires more than a simple compass You have to know where you are relative to where you want to be Dodging the Virtual Mediterranean Pied Flycatcher Natural Magnetic Field of Germany Dodging the Virtual Mediterranean Natural Magnetic Field of Germany Simulated Magnetic Fields Simulated Magnetic Field of Germany Dodging the Virtual Mediterranean Natural Magnetic Field of Germany Simulated Magnetic Field of Germany Simulated Magnetic Fields these birds are clueless Dodging the Virtual Mediterranean Natural Magnetic Field of Germany Simulated Magnetic Field of Spain Simulated Magnetic Field of Germany Simulated Magnetic Fields Dodging the Virtual Mediterranean Natural Magnetic Field of Germany Simulated Magnetic Field of Spain Simulated Magnetic Field of Germany Simulated Magnetic Fields requires both a magnetometer and a calendar ! Bicoordinate sensory gradients Map Sense Magnetic cues: 1. inclination 2. intensity 3. declination Magnetic & axial poles are slightly different (local angle = declination) Magnetic inclination angle varies with latitude magnetic dip angle (azimuth compass) Understanding the Earths magnetic field Magnetic inclination (2 dip) Magnetic Intensity (1 T) Bivariate Grid Even better grid in the Indian Ocean, along the east coast of Africa. Magnetic dip angle (1 inclination) Magnetic Intensity (1000 nT) Magnetic map sense in spiny lobsters simulated Daytona simulated Jamaica Magnetic map sense in green sea turtles simulated Savannah simulated Key Largo Lohmann K J et al. J Exp Biol 2007;210: Young green sea turtles know the magnetic grid of the North Atlantic gyre How do over-sea migrants cope with wind drift? The problem of drift Wind flight angle The problem of drift Wind flight angle actual track Drift compensation Wind flight angle actual track Drift recovery flight angle actual track Actual satellite track our Loch Moss Nester always finds its nest Diagram illustrating potential problems in attempting to infer mechanisms of navigation from the tracks of animals. Lohmann K J et al. J Exp Biol 2008;211: