Primates: Present food in puzzle feeders

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • Two before-and-after studies in the USA and the UK found that the use of puzzle feeders decreased food sharing, increased foraging behaviour, and the use of tools but also aggression.
  • One replicated, before-and-after study in the USA found that the use of puzzle feeders increased time spent feeding and less time inactive.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A before-and-after study in 1992 in the UK (Gilloux 1992) found that presenting food in puzzle feeders increased foraging behaviour and the use of tools in chimpanzees Pan troglodytes, gorillas Gorilla gorilla gorilla, and orangutans Pongo pygmaeus pygmaeus compared to food being placed in the enclosures. The percentage feed orientated behaviour, including tool use, increased from 2% when food was placed in the enclosure to 30% when a puzzle feeder was introduced to orangutans, 2% to 20% for gorillas and 3% to 30% for chimpanzees. An open-ended 3 m length of 15 cm diameter plastic drain pipe, attached horizontally to the outside of the enclosure weldmesh, was used with each group of apes (four gorillas, seven chimpanzees and two orangutans) studied for 12 two-hour trials with food placed into the enclosure and 12 two-hour trials with food in the feeder.    (CJ)

    Study and other actions tested
  2. A replicated, before-and-after study in 1996 in the USA (Schapiro et al. 1996) found that when artificial turf foraging mats and acrylic puzzle feeders were provided separately to rhesus macaques Macaca mulatta more time was spent feeding and less time inactive than when pellets were fed. Using the artificial turf mats the time spent feeding increased from 14 minutes/hour when pellets were fed to 20 minutes/hour when artificial turf mats were provided. Inactivity was lower with artificial turf mats (two minutes/hour) than when just pellets were provided (five minutes/hour). When given the acrylic puzzle feeder’s time spent feeding increased from 14 minutes/hour when pellets were fed to 18 minutes/hour when acrylic puzzle feeders were provided. Inactivity was lower with acrylic puzzle feeders (two minutes/hour) than when just pellets were provided (five minutes/hour). The individually housed monkeys (n=63) were presented with mats and puzzle feeders loaded with 20g of seeds or grain every 1.5 hours, during which 15 minutes of animal observations were conducted on all monkeys. Artificial turf mats and the acrylic puzzle feeders were presented to each monkey every weekday for six months, with control observations when just pellets were provided, conducted for six months between times when enrichment devices were given.    (CJ)

    Study and other actions tested
  3. A before-and-after study in 1998 in the USA (Rapaport 1998) found that the increased difficulty level of finding food distributed in puzzle feeders (but not the amount of food given) decreased food sharing and increased aggression in golden lion tamarins Leontopithecus rosalia. The mean frequency per minute of food sharing went from 0.25/minute with the simple task to 0.15/minute with the complex task. The mean frequency of aggressive behaviour went from 0.05/minute in the simple task to 0.15/minute in the complex task. A 15 hole puzzle box containing grapes behind sliding doors was installed for 40 days. Four, eight or twelve grapes were given and two difficulty levels established: the animal either had to reach into a tube to retrieve the grapes (simple) or rummage and rip away a barrier to retrieve the food (complex). Two observers recorded the monkeys (n=4) food transfer behaviours and aggression until all grapes were consumed.    (CJ)

    Study and other actions tested
Please cite as:

Jonas, C.S., Timbrell, L.L., Young, F., Petrovan, S.O., Bowkett, A.E. & Smith, R.K. (2020) Management of Captive Animals. Pages 527-553 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.


Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Management of Captive Animals

This Action forms part of the Action Synopsis:

Management of Captive Animals
Management of Captive Animals

Management of Captive Animals - Published 2018

Captive Animal Synopsis

What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust