Summary
Displaced juvenile alligators,Alligator mississipiensis, were released on land in a 9 m diameter dodecagonal arena to test their ability to orient in the absence of terrestrial landmarks. Navigational ability seemed to improve with age. When displaced along a fairly direct route yearlings (age 7–14 months) compensated for their displacement, moving in the direction from the arena to their home sites. When displaced by a circuitous route, yearlings failed to compensate for their displacement, exhibiting instead simple compass orientation in a direction that would have returned them to water had they been released on land near the site where they were captured. The older juveniles were oriented in a homeward direction under all displacement and test conditions.
The latter animals may have been using geomagnetic map information to select their homeward directions as the errors in their homeward bearings correlated with small deviations in the geomagnetic field's dip angle at the time of the test (1980r s=−0.6047,P=0.0131, all testsr s= −0.4652,P=0.0084). This effect appeared to depend on a very short-term assessment of geomagnetic conditions, as values measured 20 min before or 30 min after the tests began did not correlate with the directions the animals moved. The older juveniles appeared to use magnetically quiet hours on the night of their capture as the baseline from which to measure the geomagnetic deviations that occurred at the time of the arena test. The magnitude of the magnetic effect in the older animals suggests that the geomagnetic information may have been used to perform a ‘map’ step, as small fluctuations in dip angle correlated with much larger deviations in homeward bearings. In addition, the compass-oriented yearlings and the seemingly route-based behavior of the homeward-oriented yearlings did not appear to be influenced by geomagnetic conditions. These findings have many parallels in results obtained from bird orientation studies, providing evidence that navigation may share a common basis in different vertebrate groups.
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References
Able KP (1980) Mechanisms of orientation, navigation and homing. In: Gauthreaux SA jr (ed) Animal migration, orientation and homing. Academic Press, New York, pp 282–383
Baker RR (1978) The evolutionary ecology of animal migration. Hodder and Stoughton, London
Batschelet E (1965) Statistical methods for the analysis of problems in animal orientation and certain biological rhythms. Am Inst Biol Sci, Washington
Batschelet E (1972) Recent statistical methods for orientation data. In: Galler SR, Schmidt-Koenig K, Jacobs GJ, Belleville RE (eds) Animal orientation and navigation. National Aeronautics and Space Administration (publ. 262), Washington, pp 61–91
Branover GG, Vasil'yer AS, Gleizer SI, Tsinober AB (1971) A study of the behavior of eels in natural and artificial magnetic fields and an analysis of its reception mechanism. J Ichthyol 11:608–614
Chabreck RH (1966) The movement of alligators in Louisiana. Proc Southeast Assoc Game Fish Comm 19th Annu Conf 1965:102–110
Deitz DC (1979) Behavioral ecology of young American alligators. PhD Dissert Gainesville, University of Florida
DeRosa CT, Taylor DH (1980) Homeward orientation mechanism in three species of turtles (Trionyx spinifer, Chrysemys picta, andTerrapene carolina). Behav Ecol Sociobiol 17:15–23
Ferguson DE, Landreth HF (1966) Celestial orientation of Fowler's toadBufo fowleri. Behaviour 26:105–123
Ferguson DE, Landreth HF, Turnipseed MR (1965) Astronomical orientation of the southern cricket frogAcris gryllus. Copeia 1965:58–66
Gould JL (1980) The case for magnetic sensitivity in birds and bees (such as it is). Am Sci 68:256–267
Gould JL (1982) The map sense of pigeons. Nature 296:205–211
Griffin DR (1952) Bird navigation. Biol Rev 27:359–400
Hasler AD, Wisby WJ (1951) Discrimination of stream odors by fishes and relation to parent stream behavior. Am Nat 85:223–238
Hasler AD, Scholz AT, Horrall RM (1978) Olfactory imprinting and homing in salmon. Am Sci 66:347–355
Keeton WT (1974) The orientational and navigational basis of homing in birds. Adv Study Behav 5:47–132
Keeton WT, Larkin TS, Windsor DM (1974) Normal fluctuations in the earth's magnetic field influence pigeon orientation. J Comp Physiol 95:95–103
Koch AL, Carr A, Ehrenfeld DW (1969) The problem of opensea navigation: the migration of the green turtle to Ascension Island. J Theor Biol 22:163–179
Kramer G (1953) Die Sonnenorientierung der Vögel. Verh Dtsch Zool Ges Freiburg 1952:72–84
Landreth HF, Ferguson DE (1967) Newts: sun-compass orientation. Science 158:1459–1461
Merkel FW, Fromme HG (1958) Untersuchungen über das Orientierungsvermögen nächtlich ziehender Rotkehlchen (Erithacus rubecula). Naturwissenschaften 45:499–500
Moore FR (1977) Geomagnetic disturbance and the orientation of nocturnally migrating birds. Science 196:682–684
Moore BR (1980) Is the homing pigeon's map geomagnetic? Nature 285:69–70
Murphy PA (1981) Celestial compass orientation in juvenile American alligators (Alligator mississippiensis). Copeia 1981:638–645
Newcomer RT, Taylor DH, Guttman SI (1974) Celestial orientation in two species of water snakes (Natrix sipedon andRegina septemvittata). Herpetologica 30:194–200
Papi F, Fiore L, Fiaschi V, Benvenuti S (1972) Olfaction and homing in pigeons. Monit Zool Ital [NS] 6:85–95
Perdeck AC (1958) Two types of orientation in migrating starlingsSturnus vulgaris L., and chaffinches,Fringilla coelebs L., as revealed by displacement experiments. Ardea 46:1–37
Phillips JB (1977) Use of the earth's magnetic field by orienting cave salamanders (Eurycea lucifuga). J Comp Physiol 121:273–288
Rodda GH (1984) Homeward paths of displaced juvenile alligators as determined by radiotelemetry. Behav Ecol Sociobiol 14:241–246
Twitty VC (1966) Course and timing of the homing migration in the newt,Taricha rivularis. Proc Natl Acad Sci USA 56:864–871
Walcott C (1980) Magnetic orientation in homing pigeons. IEEE Trans Magnetics Mag 16:1008–1013
Wilson DW, Findley JS (1972) Randomness in bat homing. Am Nat 106:418–424
Wiltschko R, Wiltschko W, Keeton WT (1978) Effect of outward journey in an altered magnetic field on the orientation of young homing pigeons. In: Schmidt-Koenig K, Keeton WT (eds) Animal migration, navigation and homing. Springer, Berlin Heidelberg New York, pp 152–161
Wiltschko W, Wiltschko R (1972) Magnetic compass of European robins. Science 176:62–64
Yeagley HL (1947) A preliminary study of a physical basis of bird navigation. J Appl Phys 18:1035–1063
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Rodda, G.H. The orientation and navigation of juvenile alligators: evidence of magnetic sensitivity. J. Comp. Physiol. 154, 649–658 (1984). https://doi.org/10.1007/BF01350218
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DOI: https://doi.org/10.1007/BF01350218