Animal navigation
Animal navigation is the ability of many animals to find their way accurately without maps or instruments. Birds such as the
Several species of animal can integrate cues of different types to orient themselves and navigate effectively. Insects and birds are able to combine learned landmarks with sensed direction (from the
The ability of wild animals to navigate may be adversely affected by products of human activity. For example, there is evidence that pesticides may interfere with bee navigation, and that lights may harm turtle navigation.
Early research
In 1873,
With regard to the question of the means by which animals find their way home from a long distance, a striking account, in relation to man, will be found in the English translation of the Expedition to North Siberia, by Von Wrangell.[a] He there describes the wonderful manner in which the natives kept a true course towards a particular spot, whilst passing for a long distance through hummocky ice, with incessant changes of direction, and with no guide in the heavens or on the frozen sea. He states (but I quote only from memory of many years standing) that he, an experienced surveyor, and using a compass, failed to do that which these savages easily effected. Yet no one will suppose that they possessed any special sense which is quite absent in us. We must bear in mind that neither a compass, nor the north star, nor any other such sign, suffices to guide a man to a particular spot through an intricate country, or through hummocky ice, when many deviations from a straight course are inevitable, unless the deviations are allowed for, or a sort of "dead reckoning" is kept. All men are able to do this in a greater or less degree, and the natives of Siberia apparently to a wonderful extent, though probably in an unconscious manner. This is effected chiefly, no doubt, by eyesight, but partly, perhaps, by the sense of muscular movement, in the same manner as a man with his eyes blinded can proceed (and some men much better than others) for a short distance in a nearly straight line, or turn at right angles, or back again. The manner in which the sense of direction is sometimes suddenly disarranged in very old and feeble persons, and the feeling of strong distress which, as I know, has been experienced by persons when they have suddenly found out that they have been proceeding in a wholly unexpected and wrong direction, leads to the suspicion that some part of the brain is specialised for the function of direction.
Later in 1873, Joseph John Murphy
If a ball is freely suspended from the roof of a railway carriage it will receive a shock sufficient to move it, when the carriage is set in motion: and the magnitude and direction of the shock … will depend on the magnitude and direction of the force with which the carriage begins to move … [and so] … every change in … the motion of the carriage … will give a shock of corresponding magnitude and direction to the ball. Now, it is conceivably quite possible, though such delicacy of mechanism is not to be hoped for, that a machine should be constructed … for registering the magnitude and direction of all these shocks, with the time at which each occurred … from these data the position of the carriage … might be calculated at any moment.
Donald Griffin (1915–2003) studied echolocation in bats, demonstrating that it was possible and that bats used this mechanism to detect and track prey, and to "see" and thus navigate through the world around them.[6]
Ronald Lockley (1903–2000), among many studies of birds in over fifty books, pioneered the science of bird migration. He made a twelve-year study of shearwaters such as the Manx shearwater, living on the remote island of Skokholm.[7] These small seabirds make one of the longest migrations of any bird—10,000 kilometres—but return to the exact nesting burrow on Skokholm year after year. This behaviour led to the question of how they navigated.[8]
Mechanisms
Lockley began his book Animal Navigation with the words:[9]
How do animals find their way over apparently trackless country, through pathless forests, across empty deserts, over and under featureless seas? ... They do so, of course, without any visible compass, sextant, chronometer or chart...
Many mechanisms of spatial cognition have been proposed for animal navigation: there is evidence for a number of them.[10][11] Investigators have often been forced to discard the simplest hypotheses - for example, some animals can navigate on a dark and cloudy night, when neither landmarks nor celestial cues like Sun, Moon, or stars are visible. The major mechanisms known or hypothesized are described in turn below.
Remembered landmarks
Animals including mammals, birds and insects such as bees and wasps (
Orientation by the Sun
Some animals can navigate using celestial cues such as the position of the Sun. Since the Sun moves in the sky, navigation by this means also requires an internal clock. Many animals depend on such a clock to maintain their
When
Experiments with
Monarch butterflies use the Sun as a compass to guide their southwesterly autumn migration from Canada to Mexico.[15]
Orientation by the night sky
In a pioneering experiment, Lockley showed that warblers placed in a planetarium showing the night sky oriented themselves towards the south; when the planetarium sky was then very slowly rotated, the birds maintained their orientation with respect to the displayed stars. Lockley observes that to navigate by the stars, birds would need both a "sextant and chronometer": a built-in ability to read patterns of stars and to navigate by them, which also requires an accurate time-of-day clock.[17]
In 2003, the African dung beetle Scarabaeus zambesianus was shown to navigate using polarization patterns in moonlight, making it the first animal known to use polarized moonlight for orientation.[18][19][20][c] In 2013, it was shown that dung beetles can navigate when only the Milky Way or clusters of bright stars are visible,[22] making dung beetles the only insects known to orient themselves by the galaxy.[23]
Orientation by polarised light
Some animals, notably insects such as the honey bee, are sensitive to the polarisation of light. Honey bees can use polarized light on overcast days to estimate the position of the Sun in the sky, relative to the compass direction they intend to travel. Karl von Frisch's work established that bees can accurately identify the direction and range from the hive to a food source (typically a patch of nectar-bearing flowers). A worker bee returns to the hive and signals to other workers the range and direction relative to the Sun of the food source by means of a waggle dance. The observing bees are then able to locate the food by flying the implied distance in the given direction,[4] though other biologists have questioned whether they necessarily do so, or are simply stimulated to go and search for food.[24] However, bees are certainly able to remember the location of food, and to navigate back to it accurately, whether the weather is sunny (in which case navigation may be by the Sun or remembered visual landmarks) or largely overcast (when polarised light may be used).[4]
Magnetoreception
Some animals, including mammals such as blind mole rats (Spalax)[25] and birds such as pigeons, are sensitive to the Earth's magnetic field.[26]
Homing pigeons use magnetic field information with other navigational cues.[27] Pioneering researcher William Keeton showed that time-shifted homing pigeons could not orient themselves correctly on a clear sunny day, but could do so on an overcast day, suggesting that the birds prefer to rely on the direction of the Sun, but switch to using a magnetic field cue when the Sun is not visible. This was confirmed by experiments with magnets: the pigeons could not orient correctly on an overcast day when the magnetic field was disrupted.[28]
Olfaction
Olfactory cues may be important in salmon, which are known to return to the exact river where they hatched. Lockley reports experimental evidence that fish such as minnows can accurately tell the difference between the waters of different rivers.[32] Salmon may use their magnetic sense to navigate to within reach of their river, and then use olfaction to identify the river at close range.[33]
Gravity receptors
Other senses
Biologists have considered other senses that may contribute to animal navigation. Many marine animals such as seals are capable of hydrodynamic reception, enabling them to track and catch prey such as fish by sensing the disturbances their passage leaves behind in the water.[36] Marine mammals such as dolphins,[37] and many species of bat,[6] are capable of echolocation, which they use both for detecting prey and for orientation by sensing their environment.
Way-marking
The wood mouse is the first non-human animal to be observed, both in the wild and under laboratory conditions, using movable landmarks to navigate. While foraging, they pick up and distribute visually conspicuous objects, such as leaves and twigs, which they then use as landmarks during exploration, moving the markers when the area has been explored.[38]
Path integration
Since Darwin's On the Origins of Certain Instincts[2] (quoted above) in 1873, path integration has been shown to be important to navigation in animals including ants, rodents and birds.[40][41] When vision (and hence the use of remembered landmarks) is not available, such as when animals are navigating on a cloudy night, in the open ocean, or in relatively featureless areas such as sandy deserts, path integration must rely on idiothetic cues from within the body.[42][43]
Studies by Wehner in the
Path integration in mammals makes use of the
David Redish states that "The carefully controlled experiments of Mittelstaedt and Mittelstaedt (1980) and Etienne (1987) have demonstrated conclusively that [path integration in mammals] is a consequence of integrating internal cues from vestibular signals and motor efferent copy".[47]
Effects of human activity
Neonicotinoid pesticides may impair the ability of bees to navigate. Bees exposed to low levels of thiamethoxam were less likely to return to their colony, to an extent sufficient to compromise a colony's survival.[48]
Light pollution attracts and disorients photophilic animals, those that follow light. For example, hatchling sea turtles follow bright light, particularly bluish light, altering their navigation. Disrupted navigation in moths can easily be observed around bright lamps on summer nights. Insects gather around these lamps at high densities instead of navigating naturally.[49]
See also
Notes
- ^ The book was A Journey on the Northern Coast of Siberia and the Icy Sea (2 vols.), London, 1841. Wrangel is variously spelt Vrangel or Wrangell.
- ^ JJ Murphy (d 1894), of County Antrim, was treasurer and then president of the Belfast Literary Society. He attempted to harmonise evolution and religion, publishing a book The Scientific Bases of Faith in 1872.
- ^ A diagram of the experimental apparatus is available from JEB.[21]
References
- S2CID 196608896.
- ^ doi:10.1038/007417a0.
- S2CID 22346811.
- ^ a b c von Frisch 1953, pp. 93–96.
- ^ Keeton, William (1974) The orientational and navigational basis of homing in birds. pages 47–132 in Advances in the Study of Behavior, Vol. 5. Academic Press.
- ^ a b Yoon, Carol Kaesuk. Donald R. Griffin, 88, Dies; Argued Animals Can Think, The New York Times, 14 November 2003.
- ^ Lockley 1942.
- ^ a b Lockley 1967, pp. 114–117.
- ^ Lockley 1967, p. 9.
- S2CID 205441391.
- S2CID 15142890.
- ^ Tinbergen 1984, pp. 58–79.
- S2CID 17881211.
- ISBN 978-0-87893-149-1.
- ^ ISBN 978-0-87893-225-2.
- ^ Lockley 1967, p. 74.
- ^ Lockley 1967, p. 136.
- S2CID 52859195.
- JSTOR 3981988.
- ^ Roach, John (2003). "Dung Beetles Navigate by the Moon, Study Says", National Geographic News. Retrieved on 2007-08-02.
- S2CID 40840205.
- PMID 23352694.
- ^ Wits University (24 January 2013). "Dung Beetles Follow the Milky Way: Insects Found to Use Stars for Orientation". ScienceDaily. Retrieved 25 January 2013.
- PMID 18331980.
- ^ a b Kimchi, Tali; Etienne, Ariane S.; Terkel, Joseph (2004). A subterranean mammal uses the magnetic compass for path integration. PNAS, 27 January, vol. 101, no. 4, 1105–1109.
- ^ M. Lindauer and H. Martin, in S.R. Galler et al. Animal Orientation and Navigation 559/1, 1972.
- PMID 9317262.
- PMID 5276278.
- S2CID 26072452.
- ^ Wallraff, H.G. (1974). Das Navigationssystem der Vögel. Ein theoretischer Beitrag zur Analyse ungeklärter Orientierungsleistungen. Schriftenreihe 'Kybernetik'. München, Wien: R. Oldenbourg Verlag.
- PMID 9317275.
- ^ Lockley 1967, p. 180.
- ^ Lohmann, K. J.; Lohmann, C. M. F.; Endres, C. S. (2008). The sensory ecology of ocean navigation J Exp Biol, 211: 1719–1728.
- PMID 24194860.
- PMID 25392461.
- PMID 17297138.
- .
- PMID 12697070.
- ^ Breed, Michael D (2001). "Path Integration". Animal Behavior Online. Retrieved 10 December 2012.
- ^ Gallistel. The Organization of Learning. 1990.
- S2CID 7897256.
- ^ Mittelstaedt, H.; Mittelstaedt, M.-L. (1973). "Mechanismen der orientierung ohne richtende aussenreize". Forschr. Zool. 21: 46–58.
- S2CID 37845357.
- S2CID 4571290.
- ^ Gibson, J.J. (1950). The Perception of the Visual World. Houghton Mifflin.
- S2CID 16928213.
- ^ Redish 1999, p. 67.
- ^ Black, Richard (29 March 2012). "BBC News: Science & Environment". Pesticides hit queen bee numbers. BBC. Retrieved 30 March 2012.
- ^ Witherington, Blair E. (1997). Clemmons, Janine Rhea; Buchholz, Richard (eds.). Behavioral Approaches to Conservation in the Wild. Cambridge University Press. pp. 301–328.
Sources
- Lockley, Ronald M. (1967). Animal Navigation. Pan Books.
- Lockley, Ronald M. (1942). Shearwaters. J. M. Dent.
- Redish, A. David (1999). Beyond the Cognitive Map (PDF). MIT Press.
- Tinbergen, Nico(1984). Curious Naturalists (Revised ed.). University of Massachusetts Press.
- von Frisch, Karl (1953). The Dancing Bees. Harcourt, Brace & World.
Further reading
- Gauthreaux, Sidney A. (1980). Animal Migration, Orientation, and Navigation. Academic Press.
- Keeton, William (1972) Effects of magnets on pigeon homing. pages 579–594 in Animal Orientation and Navigation. NASA SP-262.
- Keeton, William (1977) Magnetic Reception (biology). In Encyclopedia of Science and Technology, 2nd Ed. McGraw-Hill.
- Keeton, William (1979) Pigeon Navigation. pages 5–20 in Neural Mechanisms of Behavior in the Pigeon. (A. M. Granda and J. H. Maxwell, Eds.) Plenum Publishing.
External links
- How Stuff Works: Animal Navigation
- Oldenburg University: Animal Navigation
- National Geographic: Animal Navigation (resources for teachers)