Floor-covering research benefits primates (2001)

Chamove, A. S.

Abstract

Many zoos, labs, and people keep animals on concrete or in wire cages. It is believed to be hygienic, efficient, and adequate for the needs of the animals. ... We tested a variety of floor-coverings-wood-chips, wood-wool, peat, straw, hay, sawdust, and shredded paper from the cigarette industry. The sawdust did not dry out easily; the paper, wood-wool, hay, and straw did not absorb urine very well; the peat appeared messy with black dust everywhere. Peat was the preferred substrate for those gardeners who worked in the primate unit, and is now enriching some of the flower beds around Stirling Castle. For more practical reasons, we did most of our remaining studies using wood-chips. ... The basic study involved scattering the smallest food items we could find either onto the bare floor or into some substrate... Aggression was reduced. .. Food intake was more evenly distributed. When the floor was bare, the dominant monkey showed about 30 hand to mouth contacts per minute versus 5 in subordinates; however when the floor was covered, there were only 3 in dominant versus 2 in subordinate monkeys. ...The university was worried about the smell. Naive human smellers rated the small daily from 1 to 4 -- none, slight, strong, very strong. A bare pen cleaned daily rated just over 1 (slight) on average but received 5 strong and 5 moderate ratings. A pen with chips after 4-8 weeks of no cleaning rated under 0.6 (none-slight), and only a single moderate rating. ...Monkeys preferred to sit on a substrate-covered floor to a bare one. The walls and viewing windows remained cleaner with a floor-covering in place. Monkeys used the floor ten times as much as when it was bare. ... Mature litter is more inhibitory to may disease organisms as well as to yeasts and moulds than fresh litter. ...We found NO bad effects ... The monkeys were foraging 14% of the time through the wood-chips looking for and eating grain even though that same grain was available from hoppers full of the stuff nearby.I shall conclude by saying that these are all non-social techniques of environmental enrichment. The very best form of enrichment for most primates is the presence of other primates.