Bat
Microbats make use of magnetoreception, in that they have a high sensitivity to the Earth's magnetic field, as birds do. Microbats use a polarity-based compass, meaning that they differentiate north from south, unlike birds, which use the strength of the magnetic field to differentiate latitudes, which may be used in long-distance travel. The mechanism is unknown but may involve magnetite particles.
Bird vocalization
The songs of different species of birds vary and are generally typical of the species. Species vary greatly in the complexity of their songs and in the number of distinct kinds of song they sing (up to 3000 in the brown thrasher); individuals within some species vary in the same way. In a few species, such as lyrebirds and mockingbirds, songs imbed arbitrary elements learned in the individual's lifetime, a form of mimicry (though maybe better called "appropriation" [Ehrlich et al.], as the bird does not pass for another species). As early as 1773, it was established that birds learned calls, and cross-fostering experiments succeeded in making linnet "Acanthis cannabina" learn the song of a skylark, "Alauda arvensis". In many species, it appears that although the basic song is the same for all members of the species, young birds learn some details of their songs from their fathers, and these variations build up over generations to form dialects.