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January 27, 2022

Public Barriers at Dangerous Animal Exhibits – A Study

Response to Recommendation 1 from OIG Audit Report 33601-0001-23

Introduction

During 2020, the USDA’s Office of Inspector General (OIG) conducted an audit of APHIS’ controls over 

the licensing of exhibitors of dangerous animals, with the stated objective of evaluating the agency’s 

efforts to safeguard both the animals and members of the public who visit these facilities.1

 OIG’s 

original intent had been to conduct site visits of 19 facilities that historically had dangerous animals on 

exhibit; however, the COVID-19 pandemic precluded them doing so. The final report contained 4 

recommendations. Recommendation 1 called for APHIS to “conduct a study to determine if there 

continues to be an issue with public barriers at licensed exhibitors with potentially dangerous animals. If 

the results indicate an issue, determine and implement the necessary corrective actions (i.e., new 

regulations, training, and/or guidance)”. We have since carried out such a study, and this report 

documents those findings, along with our conclusions and recommendations going forward.

Methodology

Complete details of the methodology can be found in Appendix A. Twenty licensed exhibitors with 

dangerous animals in their inventories were included in the study. The list of facilities included the 19 

facilities OIG had intended to visit as part of their audit. For purposes of the study, “dangerous animals” 

were defined as: large felines (lions, tigers, cougars, leopards, jaguars, cheetahs and hybrids), bears, 

great apes, hippos, rhinos and wolves.2,3,4

 Facilities ranged from large public zoos and those accredited 

by various professional standards organizations, to private zoos and those with no certifications or 

affiliations. 

Site visits were carried out by teams of 2 APHIS employees – an Animal Care Inspector (ACI) or 

Veterinary Medical Officer (VMO) and a Supervisory Animal Care Specialist (SACS) (or in a few instances, 

an Animal Welfare Operations Assistant Director). Facilities were contacted in advance and informed 

these would be courtesy visits. APHIS personnel were provided training that included a webinar and 

several guidance documents describing how to carryout measurements and photograph different types 

of public barriers. A group of internal subject matter experts (SMEs) from various units in APHIS-Animal 

Care (the “Barrier Study Team”) reviewed the data and photographs from each dangerous animal exhibit 

at every facility and made determinations on the adequacy of all public barriers. 

In addition, APHIS secured the services of an external SME as a consultant to independently review the 

data and photographs and provide a formal report. This individual is a Diplomate of the American 

College of Zoological Medicine and an AZA member, who works as a professional consultant to the zoo 

1 Audit Report 33601-0001-23, Follow-up to Animal and Plant Health Inspection Service’s Controls Over Licensing 

of Animal Exhibitors, USDA-OIG, March 2021. 2 9 CFR, § 2.131 (d)(3) Handling of animals. 

3 9 CFR, § 3.127 (d) Facilities, outdoor.

4 Animal Welfare Inspection Guide, Appendix B, December 2021.
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community. To ensure objectivity and to protect the privacy of the licensees, the consultant was 

blinded to their identity (facilities were identified only by a number, and photographs were modified to 

remove any potentially identifiable information, if applicable).

The findings and opinions of the internal and external subject matter experts were taken together in this 

report to generate our results and inform our conclusions.

Results

Site visits and data collection were carried out during October and November 2021. The list of 20 

facilities included in the study can be found in Appendix B. Twenty was chosen as a round number, 

which included the 19 facilities on OIG’s original list. A few substitutions were made for facilities that no 

longer have dangerous animals in their inventories. Additional substitutions were made due to 

declinations by a few facilities to participate voluntarily in the study (3 total). APHIS selected a variety of 

replacement facilities to ensure broad representation of dangerous species and type of licensees (e.g.,

public or private, accredited or non-accredited, geographic location).

In total, the 20 facilities had 170 exhibits (primary enclosures), with 212 associated public barriers 

protecting visitors from 720 dangerous animals.

Species Distribution

Large felines accounted for just over half of all dangerous animals in the study population, followed by 

great apes and bears. (See Figure 1 for a complete breakdown.)

 Figure 1: Distribution of dangerous animal species in the study – totals and (%).

Large Felines, 110 

(52%)

Bears, 27

(13%)

Hippos, 4

(2%)

Rhinos, 12

(5%)

Elephants, 13

(6%)

Wolves, 12

(6%)

Great Apes, 34

(16%)

Dangerous Species Distribution

Big Cats Bears Hippos Rhinos Elephants Wolves Great Apes
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Barrier Construction

Public barriers at dangerous animal exhibits were fashioned from of a wide variety of materials and 

constructs. The most frequently used materials were welded metal wire (89 instances), wood (88 

instances), vegetation (73 instances) and metal mesh/chain link (62 instances). Most barriers were 

comprised of a combination of different materials. Public barriers were noted as absent or “none” at 

several exhibits in which the primary enclosure was constructed of solid walls of a transparent material 

(e.g., Plexiglas). (See Figure 2 for a complete breakdown.)

Figure 2: Distribution of materials utilized in public barrier construction at dangerous animal exhibits 

in the study (numbers represent total instances each material was used). Other includes metal beams, 

stainless steel mesh, high-tensile steel, gunite, bricks, piano wire, hot wire, and nylon mesh. Clear 

Solid refers to glass, Plexiglas, or Lexan. None indicates that a separate public barrier was not present. 

This was only the case for selected exhibits where primary closures had walls of solid, clear material 

(as above).

None, 19

Rope/Chain/Cable, 55

Wood, 88

Metal Railings, 36

Mesh/Chain Link, 62

Metal Welded Wire, 89

Dry Moat, 19

Wet Moat, 7

Concrete, 40

Rocks/Boulders, 16

Vegetation, 73

Clear Solid, 46

Other, 24

Barrier Materials Distribution

None Rope/Chain/Cable Wood Metal Railings

Mesh/Chain Link Metal Welded Wire Dry Moat Wet Moat

Concrete Rocks/Boulders Vegetation Clear Solid

Other
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Barrier Measurements

Barrier heights and the distances between barriers and the primary enclosures were wide-ranging (see 

Table 1). 

Barrier Measurement Range Mean Median

Height 18"-264" (1.5'-22') 63" (5.3') 50" (4.2’)

Distance to Primary Enclosure 24"-1200" (2'-100') 105" (8.7') 79" (6.6')

Table 1: Cumulative ranges, means and median values for heights and distances to enclosure of 

public barriers in the study.

Documented Incidents Involving Barriers

Inspectors were queried and inspection reports were reviewed for documentation of any incidents 

involving the public intentionally or unintentionally breaching barriers at dangerous animal exhibits in all 

facilities in the study dating back to 2015. Four such occurrences met the criteria and are summarized in 

Table 2.

Date Species Incident Outcome Corrective Measures

July 2021 Leopard Adult patron climbed over 

wooden barrier fence. 

Fence height just under 4 

feet. Put arm through 

netting of primary 

enclosure.

Leopard clawed the 

patron's arm 

causing multiple 

lacerations.

1. Supplemental wire added above 

fence posts to increase height. 

2. Designated attendant assigned 

at all times. 

3. Monitoring camera installed 

with live feed.

July 2021 Elephant Adult patron climbed over 

barrier and jumped down 8-

10 feet onto the floor of the 

elephant barn. All 

attendants were at lunch.

Patron left without 

injury. Animals 

unharmed.

1. Laser/light beam system 

installed to detect unauthorized 

entry and sound alarm. 

2. Lunch shifts for attendants were 

staggered. 

3. Video surveillance added.

May 2016 Gorilla Child crawled through gaps 

in barrier fence, passed 

through vegetation and fell 

into moat of gorilla exhibit. 

Barrier height was 32 

inches.

Gorilla was shot 

and killed. Child 

was rescued 

without serious 

injury.

1. Barrier was reconstructed. 

Height now 42 inches. Wire mesh 

added to eliminate the gaps. 

2. Vegetation was increased and 

distance from barrier to edge of 

moat increased from 40 inches to 

61-70 inches.

April 2015 Cheetah Child was held over a solid 

wood barrier fence on a 

viewing deck by parent and 

fell into the cheetah 

enclosure.

Child incurred a 

broken leg. 

Parents jumped 

into the enclosure 

and rescued the 

child. Animals 

unharmed.

1. Plexiglass was installed above 

the existing wall of the barrier to 

prevent such mishaps.

Table 2: Summary of incidents involving breaches of barriers by the public at dangerous animal 

exhibits dating back to 2015.
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Subject Matter Expert Assessment of Barrier Adequacy

All data and photographs were objectively and subjectively evaluated by APHIS’ internal SMEs and the 

external SME (consultant) in determining the adequacy/effectiveness of all barriers to protect the public 

from harm and, conversely, protecting the animals from potential harm from the public.

Criteria utilized by internal SMEs in making such determination were multi-factorial, and included 

parameters as outlined in the Animal Welfare Regulations,

5,6,7,8 the Animal Welfare Inspection Guide9

and as described in the study protocol (Appendix A).

Internal SMEs concluded that only 1 dangerous animal exhibit in the study had a public barrier 

deficiency that represented a risk of injury to the viewing public. This was a lion exhibit with the night 

house for the lions and a reptile house situated adjacent to the exhibit. An unprotected 21.5” space 

exists between the buildings that allows direct access to the wall of the primary enclosure (Figure 3).

Figure 3: Lion exhibit with an unprotected gap between the lion house and a reptile house 

allowing direct access to the primary enclosure. Arrow indicates the wall of the primary 

enclosure.

The external consultant created a scoring system to aid in their assessment of the barriers based on 

three criteria – barrier material, barrier distance (to primary enclosure) and barrier height/gaps. Each of 

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9 CFR, § 2.131 (c)(1) Handling of animals. 6 9 CFR, § 3.77 (g) Sheltered housing facilities. 7 9 CFR, § 3.78 (c) Outdoor housing facilities. 8 9 CFR, § 3.101 (a)(2) Facilities, general. 9 Chapter 4.14.7. Public Barriers, Animal Welfare Inspection Guide, December 2021.
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the three parameters was scored as “0” (inadequate or substandard) or “1” (adequate), for a maximum 

possible score of “3” for each barrier (Figure 4). The consultant also reviewed all photographs in 

conjunction with the objective data on each barrier before making a final determination on adequacy.

Figure 4: Summary of the public barrier scoring system and parameters for each of the criteria used by 

the external consultant.

In total, the external consultant identified three exhibits with public barriers that scored less than 3/3 (3 

out of 3). All three exhibits contained wolves and all 3 were located at different facilities. A maned wolf 

exhibit had a barrier that was 35” high and positioned 37” from the primary enclosure and was scored 

1/3. A grey wolf exhibit had a barrier that was positioned 36” from the primary enclosure and was 

scored 2/3. And another grey wolf exhibit was scored 2/3 due to gaps through which an unattended 

child could easily pass (Figure 5).

In their report, the external consultant provided this summary conclusion on the adequacy of these 3 

barriers: “Due to these three barriers providing VISUAL cues for a “reasonable adult” to not pass under, 

over or through the barriers, and due to the natural behavior of wolves to be shy and retreating, the 

barriers subjectively are considered passable (with minor improvements). It is in the interest of creating 

an objective and unified approach to evaluating barriers in front of dangerous animals (see DEFINED 

PARAMETERS [Figure 4]), that these three enclosures were identified.”

1. Material (Score 1 point) Must be sturdy. Acceptable/suggested materials:

a. Metal, plastic, ropes, chains, wires, railings, concrete, the use of 

plantings/landscaping

b. Hot wire inside enclosure to keep the animal from interacting with the wall 

of the animal’s enclosure or escaping

c. Moat (wet or dry)

d. Barriers are not considered necessary when enclosure wall is constructed of 

appropriate solid unbreakable material such as glass or plexiglass variants

2. Distance (Score 1 point) Minimum distance chosen to be 42 inches for dangerous 

animals.

3. Height/Deficits (Score 1 point) The public should not be able to pass fully under, 

over, or between elements of the barrier, increasing the possibility of contact with 

the animal within the enclosure. 

a. Minimum height should be 42 inches. 

b. Any gaps must be less than 4 inches wide. 
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Figure 5: Public barrier at a grey wolf exhibit scoring 2 out 3. Gaps (arrow) between rails of this 

post and rail fence could allow an unattended child easy access to the primary enclosure.

Conclusion/Discussion

Modern zoological institutions have placed significant emphasis on modeling animal enclosures on the 

natural environments of the species they contain. This is important for the welfare of the animals, and 

for the enjoyment of the millions of visitors that attend U.S. zoos annually. Therein lies one of the 

challenges – the balancing of safety with style. Public safety and the safety of the animals is paramount, 

and therefore, irrespective of design, appropriate barriers must be established around animal 

enclosures to assure safety for all. The results of this study indicate that, with a few exceptions, the 

public barriers present around enclosures containing dangerous animals at exhibitors licensed under 

Animal Welfare Regulations are generally adequate and effective. Based on stated criteria, only 4 

barriers (1.9%) were deemed substandard, and only 1 of these 4 involved a complete absence of any 

barrier (in a narrow gap between buildings away from the primary viewing area). 

Yet, the documented incidents of barrier breaches at these facilities are a reminder that room for 

improvement exists. A guiding principle we employed in our evaluation of the barriers in this study was 

that an effective barrier should prevent a child from passing over, under, through or around it, and 

should prevent a reasonable adult from breaching it unintentionally or require considerable effort to 

breach it intentionally (i.e., more than simply stepping over or around it). The external consultant stated 

this concept about barriers in their report: “Barriers in front of dangerous animals should mitigate the 

risk of an unintentional aberrant behavioral action taken by either a member of the public (including 

children) or the animal housed in the enclosure resulting in unlikely but possible contact.” We feel it 

important to emphasize that barriers cannot be expected to counteract or offset all instances of poor 

judgment, misbehavior, or willful intent on the part of the public to enter a prohibited area. 

APHIS took this assignment very seriously, and we made a good faith effort to carry it out objectively; 

including enlisting the participation of an external consultant to review the data and provide an 
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independent assessment. Discrepancies between the assessments and conclusions of APHIS’ internal 

SMEs and the external SME are likely multifactorial in origin. APHIS SMEs first reviewed the data 

independently, and then held group discussions to go over any concerns they had about their

interpretations of the images or measurements. In addition, APHIS SMEs had direct access to the study 

teams that collected the data and could ask follow-up questions for clarifications. The external 

consultant did not have those opportunities. This may explain, for instance, why the deficiency depicted 

in Figure 3 was not identified by the consultant. Further, experts in any field will always have slightly 

different interpretations of, and opinions on, certain information or situations. The fact that out of 212 

public barriers under review, the internal and external SMEs differed only on 4 speaks to the integrity of 

this study and our conclusions.

We were pleased to find the mean and median values for barrier heights and distances from primary 

enclosures in this study exceeded the minimum standards of 42” for each, as proposed by the external 

consultant. In developing these criteria, the consultant relied on various resources, including building 

code standards, and human anatomical measurements – particularly as it applies to the distance 

someone can reach. Readers reviewing the measurements reported in Table 1 will no doubt be 

confused or concerned by the reported ranges reflecting heights and distances of some barriers being 

less than 42”. We have chosen to report the data for all barriers, rather than break it out by type of 

construct, type of primary enclosure and other variables such as the presence or absence of attendants. 

Unforeseen variability in the way some study teams collected and recorded the measurements lead us 

to believe that trying to parse the data further would not be of value. From review of the raw data, we 

can state that barrier heights and distances from primary enclosures were on the lower end for primary 

enclosures with solid walls (e.g., glass or Plexiglas) and where attendants were continually present.

Future Directions

Concurrent with this study, APHIS-Animal Care put together a working group in 2021 to review our 

current regulations and standards for licensed exhibitors that pertain to the handling of dangerous 

animals, training requirements for the personnel that handle these animals, and environmental 

enrichment for all Subpart F species. This work culminated in a white paper outlining the topics of 

importance, our goals for strengthening these regulations and standards, and the rationale behind it. 

We have been given Administrator approval to pursue this endeavor, with the first step likely to be

publication of an Advanced Notice of Proposed Rulemaking. The results of the study reported here, 

along with the report we received from our external consultant, are expected to be invaluable resources

as we move forward. 
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Appendix A: Study Protocol

Public Barrier Study – Dangerous Animal Exhibits

Purpose: The OIG Exhibitor Audit from 2020 made a recommendation to evaluate barriers at 

certain facilities that have dangerous animals during inspection

Goal of Study: Evaluate the public barriers at dangerous animal exhibits to determine if the barriers 

areadequate to prevent the public from coming into direct contact with the animals.

1 (See definition 

of, and parameters for, an adequate public barrier below.) If substantive deficiencies exist, the 

results of the study will be utilized to formulate a plan for corrective actions where needed.

For purposes of the study, dangerous animals include:

• Big cats – lions, tigers, hybrids (ligers etc.), cougars, leopards, jaguars, cheetahs

• Bears 

• Great apes

• Elephants

• Hippo

• Rhinos

• Wolves 

Facilities to be included: See Excel spreadsheet of facilities that were to be visited by OIG in 2020

AWO Inspectors Mission: During a scheduled, announced courtesy visit, evaluate each dangerous

animal exhibit public barrier utilizing parameters provided to all inspectors to ensure uniformity in 

datacollection. There may be multiple such exhibits in one facility. 

• Obtain spreadsheet from species specialist for facility. 

• Note species and number of animals that are contained in each dangerous animal enclosure. 

• Photograph each public barrier. Note photo number(s) on spreadsheet for each barrier.

o Take a minimum of 2 views (see attached photo examples).

 One perpendicular to the barrier looking straight across the barrier to 

theprimary enclosure with sufficient distance to see both the barrier 

and theprimary enclosure fencing.

 One parallel to the barrier (looking lengthwise along the barrier) that depicts 

thespace between the barrier and the enclosure.

o Additional photographs of any gaps, defects or deficiencies should be included 

(see below). 

• Describe the type of each barrier and the nature of the materials (e.g. solid concrete wall, 

thickvegetation, chain link fence, combination, etc.).

• Describe the primary enclosure fencing type (e.g. piano wire, woven wire, plexiglass, etc.).

• Measure the height of each barrier and, if gaps or defects are present, note the number 

anddimensions of the gaps or defects (i.e. the width of the gap)

• Measure the distance from the external surface of the barrier to the primary enclosure.

• Specifically note if there are any areas where the public – using common sense and 

reasonablecaution – isn’t prevented from intentionally or unintentionally breaching the 

barrier and entering the enclosure, and document with photographs and description.
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• Does the facility rely on attendants to replace the need for a barrier to prevent public

contact with animals? What is ratio of attendants to the public in these cases?

• Submit findings to species specialists (Maginnis and Gage) and cc: SACS on 

SharePoint/One Drive. 

Species Specialists: 

• Compile information from each facility and enter on spreadsheet.

• Provide internal assessment and summarize findings in a report (independent of consultant).

• National Policy Staff (NPS) collaborates on the report.

• Submit spreadsheet information and photos to outside consultant for an independent 

review and assessment.

Outside Consultant:

• Reviews the data for each public barrier for each facility.

• Determines if the barriers meet professionally accepted standards for public safety.

• If any are deemed inadequate, makes recommendations for corrections and improvements.

• Creates a report on findings and recommendations.

• Submits report to NPS.

• NPS integrates internal and external assessment and submits to Drs. Goldentyer, 

Sifford,Gibbens and Theodorson.

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Public Barrier – Definition and Parameters for Purposes of this Study

During public exhibition, any animal must be handled so there is minimal risk of harm to the animal 

and to the public, with sufficient distance and/or barriers between the animal and the general 

viewing publicso as to assure the safety of animals and the public.

Sufficient Distance and/or Barriers

In order to ensure the safety of animals and the public, an average adult must not be able to touch 

theprimary enclosure or have unsanctioned contact with the animal. Means to effectively accomplish 

this would be one of the following: 

• Use of an adequate public barrierThere must be an appropriate distance between the enclosure containing the animals and 

the public barrier. A barrier should be located no less the average adult arm length away 

from the animal enclosure. Factors such as enclosure fencing materials that allow animals to 

reach outside of the enclosure, the presence of hot wire inside an enclosure to keep animals 

away from the fencing, or a moat will have an impact on what constitutes an appropriate 

distance forsafety.

The barrier must also be constructed in such a way that a child cannot pass under, over, or

between any of the elements making up the barrier. An adult should not be able to step 

over the barrier without making an extraordinary effort.
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• Solid sided primary enclosureUse of solid primary enclosure materials such as tempered glass or plexiglass would be 

sufficientto prevent contact without the use of a public barrier.

• Use of an attendantAttendants may be used to ensure that members of the general viewing public do not 

haveunsanctioned contact with dangerous animals.

There must be a sufficient number present to control the crowds and ensure the safety of 

publicand animals.
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Appendix B: Facility List

Facility Certificate State

BLANK PARK ZOO 42 C 0168 IA

CHEYENNE MOUNTAIN ZOOLOGICAL SOCIETY 84 C 0001 CO

CINCINNATI ZOO 31 C 0044 OH

CITY OF DODGE CITY/Wright Park Zoo 48 C 0140 KS

CLEVELAND METROPARKS ZOO 31-C-0003 OH

COUNTY OF MILWAUKEE/Milwaukee Zoo 35 C 0020 WI

FOREST PARK ZOOLOGICAL SOCIETY 14 C 0003 MA

GLOBAL RESOURCES FOR ENV. EDU. / Tiger Sanctuary 43 C 0221 MO

JACKSONVILLE ZOOLOGICAL SOCIETY 58 C 0002 FL

JUNGLE ADVENTURES INC 58 C 1048 FL

LEE CRUTCHFIELD/Aloha Training Center 55 C 0242 NC

OMAHA ZOOLOGICAL SOCIETY 47 C 0003 NE

PUEBLO ZOOLOGICAL SOCIETY 84 C 0153 CO

SAVE THE CHIMPS 58-C-0706 FL

SIERRA NEVADA ZOOLOGICAL SOCIETY 88 C 0204 NV

SKUNKIE ACRES INC 58 C 1238 FL

THE CARE FOUNDATION 58 C 1007 FL

THE WILD ANIMAL SANCTUARY 84 C 0019 CO

WILD ANIMALS, INC. 43 C 0301 MO

ZOOTASTIC OF LAKE NORMAN INC 55 C 0272 NC