Developing an Environment 

Enhancement Plan

Gwendalyn M. Maginnis, DVM

Nonhuman Primate Specialist

Center for Animal Welfare

Regulatory Challenge of 3.81

• Performance Standard

– Outcome: psychological well-being

• Currently Accepted Professional 

Standards

– Professional standards evolve and change 

over time
The Science and Art of 

Psychological Wellbeing

Our primates don’t read 

the scientific papers on 

how they are supposed 

to behave
General Comments in the 

Regulations

• Must “develop, document, and follow” a plan

– A written plan

– Facility is doing what is in the plan

• “in accordance with the currently accepted 

professional standards”

– Needs to be up to date 

• “and as directed by the attending 

veterinarian”

– Documentation, veterinary sign-off
Environment Enhancement Plan

Special 

Considerations

Environmental 

Enrichment

Social 

Grouping

Exempt.

Restraint
Social Grouping

• “plan must include specific provisions to 

address the social needs of nonhuman 

primates of species known to exist in 

social groups in nature”
Social Housing with Conspecifics
Social Housing with Other Primate 

Species

• “Nonhuman primates may not be housed 

with other species of primates or animals 

unless they are compatible, do not prevent 

access to food, water, or shelter by 

individual animals and are not known to be 

hazardous to the health and well-being of 

each other.”
Social Housing with Other Animals

• Nonhuman primates can also experience 

companionship with many different nonprimate species

– Some facilities are successfully cohousing 

primates and rabbits

• BE AWARE: Regs prohibit their housing with other 

species unless it is for scientific purposes

• A variance can be requested
Positive Human Interaction

• Should aspects of their occupation be 

considered environment enhancement?
Be Prepared

• What is your plan if a social group becomes 

unstable?

– Socially housed primates must be compatible

– Should separately house if

• “vicious”●“debilitated”

• “overly aggressive”● “suspected of having a 

contagious disease”

• What is your plan if a member of a stable pair 

dies?

• Individually housed animals must be able to see 

and hear other primates*
Environmental 

Enrichment

• “The physical environment in the primary 

enclosures must be enriched by providing 

means of expressing noninjurious speciestypical activities.” 

• Examples 

– Perches

– Swings

– Other increased cage complexities
Species Specific 

Movement
NC3Rs
Understanding Animal Research

Oregon Primate Rescue
Species Specific Resting 

Behavior
Scent Marking
Environmental enrichment

• “The physical environment in the primary 

enclosures must be enriched by providing 

means of expressing noninjurious speciestypical activities.” 

• Examples 

– providing objects to manipulate

– varied food items

– using foraging or task-oriented feeding 

methods
Photo Credit: Mehgan

Murphy, National Zoo
Michael Blatherwick
Resources
The Specifics

• Enrichment offered

– Not specific enough: Various enrichment is 

provided to support species specific behaviors

– Very specific: An exhaustive list of every single 

enrichment item ever created or offered

– Balanced approach: Categories of enrichment 

based on function, with examples

• Frequency

– Not specific enough: Occasionally

– Very specific: Tuesdays and Thursdays

– Balanced approach: Twice weekly
Noninjurious Also Means Safe

• Condition of enrichment

– Sharp edges

– Holes/entrapment

– Ability to clean

• Toxicity

– Poisonous plants

– Pesticides

– Treated wood
Special Considerations

“Certain nonhuman primates must be 

provided special attention regarding 

enhancement of their environment, based 

on the needs of the individual species and 

in accordance with the instructions of the 

attending veterinarian.” 
Who Needs Special Attention

• “Infants and young juveniles”

• “Those that show signs of being in 

psychological distress through behavior or 

appearance”

• “Those used in research for which the 

Committee-approved protocol requires 

restricted activity”

• “Individually housed nonhuman primates that 

are unable to see and hear nonhuman 

primates of their own or compatible species”

• “Great apes weighing over 110 lbs.”
Infants and Young Juveniles

• The psychological well-being of nonhuman 

primate infants depends on appropriate 

infant development

– psychological and social development 

• Optimally maintained with care giving 

parent(s) of their own species until an age 

that approximates the age of infant 

independence in nature
Hand Rearing

• Criteria for removal from parent(s) if 

necessary

• Specific details of any hand-raising or 

fostering practices

– Nutritional support

– Stimulation similar to what would be received 

under normal circumstances

• Sensory

• Motor

• Psychological

• Social
Hand Rearing

• Program to develop and maintain speciestypical social competence 

– peers and/or adults 

– same or compatible species.
Psychological Distress

• Be prepared

– Caretakers should be able to recognize

– Who is to be contacted

– Strategy for assessment

• Attending Veterinarian

• Intervention and assessment of response

• RECORDS
Research Related Exemption

• Based on IACUC review and 

approval

– Justification- especially for 

individual housing

• Alternative enrichment 

offered
Individual Housing

• Specifically, animals without the ability to 

see and hear other primates

• Section on Social Grouping states that 

provisions must be made for social needs
Great apes

• “additional opportunities to express 

species specific behavior”

• 3.80 Primary Enclosures (b)(ii)

– “additional volume of space in excess of that 

required for Group 6 animals”

• Policy 7

– chimpanzees, bonobo, and young gorillas and 

orangutans are also brachiators
Restraint

• Not typically included in the environment 

enhancement plan

• If you use methods of restraint, policies 

and procedures should be documented

– Most have a separate policy, SOP, or other 

documentation
Exemptions

• Attending Veterinarian

– “health or condition, or in consideration of its well-being”

– “must be recorded by the attending veterinarian for each 

exempted nonhuman primate”

– “Unless the basis for the exemption is a permanent 

condition, the exemption must be reviewed at least every 

30 days by the attending veterinarian”

• IACUC

– “for scientific reasons set forth in the research proposal”

– “documented in the approved proposal” 

– reviewed at least annually
Acknowledgments

This presentation was 

adapted by the 

USDA Center for Animal 

Welfare. 

Kansas City, Missouri

centerforanimalwelfare

@aphis.usda.gov