Photos 98 & 99*: More important than a toy, a gnawing
stick, a mirror or television is a perch for caged macaques.
It no longer restricts the animals to a terrestrial life style
- to which they are biologically not adapted - but opens up the
vertical dimension thereby increasing the usable cage space and
promoting species-typical arboreal activities such as climbing,
leaping, balancing, bouncing, perching and looking-out (photo
98). Serving as a prop for exercise the perch has therapeutic
value for animals suffering from cage paralysis [authors' own
unpublished observation]. The perch also allows for species-typical
vertical flight responses in alarming situations [Lindburg, 1971;
Chopra et al., 1992] and for retreat to a dry place during the
daily cage cleaning (photo 99). Access to elevated, 'safe' sites
has survival value for macaques. This explains why caged animals
never lose interest in a perch.
In a study with 25 adult single-caged rhesus
males who were exposed to a perch for 12 months, individuals
sat on their perch on average 28% of the time [Reinhardt, 1989b].
Inexpensive perches can readily be made from branches of
dead deciduous trees (photo 98; Reinhardt et al., 1987c) - preferably
from read oaks to forestall clogging problems of sewer drains
[Reinhardt, 1992e] - or sections of polyvinyl chloride (PCV)
pipes (photo 99; Reinhardt & Smith, 1988).
The diameter of a perch must be large enough so that an animal
can comfortably sit on it over extended periods of time.
Rhesus monkeys are inquisitive animals who want to know
what's going on outside of their cage, and they show a strong
preference for sitting in the front rather in the middle or rear
of the cage [Reinhardt, 1989c; Woodbeck & Reinhardt, 1991].
Therefore, perches should always be installed in such a way that
they enable the occupant to sit right in front of the cage (photos
98 & 99); probably, this fosters a sense of security by giving
the animal visual control over the environment outside of the
cage [cf. van Wagenen, 1950; Niemeyer et al., 1998].
Swings are less suitable than perches to enhance cage space complexity.
When given the choice, rhesus monkeys clearly prefer perches
over swings, presumably because perches - unlike swings - are
fixed structures permitting relaxed posturing rather than unstable
balancing in a cage that is too small for accurate adjustments
of body movements [Kopecky & Reinhardt, 1991; cf. Dexter
& Bayne, 1994; Phillippi-Falkenstein, 1998].