Vision in echolocating bats - Fladdermus.net

to fly slower and closer to the ground than non-treated bats (Mueller
1968), indicating that they change their orientation behaviour when they
no longer are able to see. Bats also seem to rely heavily on their spatial
memory, as they often follow the same paths night after night (Höller
1995).
When commuting between roost- and feeding sites during
dusk and dawn periods, bats often follow outlines in the landscape, such
as river banks, forest edges, hedgerows and hillsides (Racey & Swift
1985; Limpens & Kapteyn 1991; Verboom & Huitema 1997). The reason
may be to minimise predation risk (Swift 1998), or to use outlines as
acoustic landmarks, which perhaps facilitate navigation by sonar
(Verboom et al. 1999). More likely, however, landscape outlines and
silhouettes provide the bats with visual cues, contrasting against the
twilight sky, and such cues are probably essential for orientation and
navigation along travelling routes (Davis 1966; Layne 1967; Griffin
1970; Manske & Schmidt 1979; Höller and Schmidt 1996).
Balantiopteryx plicata
(Emballonuridae) relies on
visual cues when presented
with conflicting information
from vision and sonar, for
example in front of a
window (Paper V).
The frequent observation that bats have a tendency to crash into windows
of buildings when released indoors (Fenton 1975), during migration
(Timm 1988), or commuting (Test 1967), suggests that they
predominantly rely on vision rather than on echolocation in situations
when both acoustic and visual cues are available. The performance is
greatly improved, i.e. there are fewer collisions, when the bats are blinded
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