排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
2.
Valentina Gaggini N. Emilio Baldaccini Fernando Spina Dimitri Giunchi 《Behavioral ecology and sociobiology》2010,64(8):1333-1342
Hierarchical relationships among different compass systems in long-distance migrants are still a matter for discussion because
different studies have led to highly variable and apparently contradictory results. We carried out cue-conflict experiments
during spring migration on pied flycatchers Ficedula hypoleuca (Passeriformes, Muscicapidae). Birds were exposed to a conflict between celestial and magnetic information by altering the
polarized light pattern or magnetic field. The polarization pattern was shifted (±90°) with filters, whereas the magnetic
field was altered (+90°) through Helmholtz coils. Birds were tested in modified Emlen funnels both before and after the cue
conflict; during the tests, only the natural magnetic field was available. This protocol was designed to test whether the
experimental birds recalibrated their magnetic compass on the directional information derived from the light polarization
pattern when the region near the horizon was visible during the conflict. Contrary to this expectation, we did not record
any significant shift in magnetic orientation after one or repeated exposures to the cue conflict. Our results support earlier
studies, which suggest that the magnetic field is the primary compass cue during the migratory period. 相似文献
3.
In a previous paper, we reported that juvenile barn swallows (Hirundo rustica) trapped during the autumn migratory season and tested in modified Emlen funnels under overcast conditions can use magnetic
information for compass orientation, although they did not orient toward the expected migratory direction. To further investigate
this behaviour, in the present paper, we report the results of two series of displacement experiments performed on juvenile
barn swallows belonging to two different roost sites [Massaciuccoli Lake (ML) and Terzo Cavone (TC)] and tested using the
same protocol as that previously adopted. On the whole, the outcome of the ML and TC experiments was quite different with
respect to (a) the degree of bird activity within the funnel (substantially lower for TC) and (b) the effect of the experimental
displacement on the directional preferences of the tested subjects (not detectable in TC, while evident in ML swallows). Taken
together, these results suggest that migrating swallows could react differently to the experimental tests depending on the
roost site where they were caught. Indeed, TC swallows, trapped in southern Italy, close to the seacoast, and characterized
by fairly large amounts of fat stores, mainly broke off their migratory activity or reoriented their directional preferences
toward inland sites, possibly in search of more profitable habitats. On the other hand, ML swallows, trapped about 660 km
to the north and characterized by lower amounts of fat stores, apparently tried to compensate for the experimental displacement.
相似文献
N. Emilio BaldacciniEmail: |
1