A keeper who sees a giraffe repeatedly roll its tongue has observed a behaviour. To interpret it, several other questions follow. Is this a rare moment or a large part of the animal's day? Has it always happened? Do other giraffes show the same pattern under different conditions?
Jason D. Wark and Katherine A. Cronin approached the comparison problem by bringing observations from 18 US zoos into one study. Their 2024 paper describes the behaviour of 66 giraffes, using a common recording system and shared definitions. It offers a wider reference than any single enclosure could provide.
Its most revealing result involves stereotypies: repetitive patterns such as tongue rolling, repeated licking or pacing along a fixed route. Every giraffe showed at least one during the study. Yet the frequency differed so greatly that describing the behaviour as present would tell a keeper very little about an individual's experience.
Making observations comparable
Participating zoos recorded behaviour during ten-minute sessions, usually following one focal animal and recording its activity at one-minute intervals. Observers also noted every occurrence of a stereotypic behaviour, including events between the scheduled recording moments.
Those two methods answer different questions. Interval records estimate the share of visible observation time occupied by a behaviour. Recording every occurrence is better suited to detecting short or infrequent events that can slip between those moments. An animal could therefore have no stereotypy recorded at the scheduled instants and still have a confirmed occurrence elsewhere in the session.
The observers worked from the same definitions. Tongue play meant repetitive twisting or rolling, whereas licking involved repeated tongue contact with a non-food object. Pacing required repeated travel along a fixed path without an apparent goal. Ordinary walking did not become pacing merely because it involved locomotion.
Training mattered across so many organizations. Observers identified behaviours from video, completed reliability exercises and then undertook in-person checks. The minimum video agreement was 85%; people who did not pass could not collect study data. A shared app coordinated recording, but comparability depended on these definitions and checks rather than the software alone.
The resulting dataset contained 9,204 daytime sessions, mainly collected over about a year per zoo. Coverage varied among individuals, and observations were concentrated in the middle of the day. These were samples of visible daytime behaviour, not uninterrupted recordings of whole lives or complete day-and-night budgets.
The same label covered very different patterns
Feeding and foraging occupied the largest average portion of observed time. Individual means nevertheless ranged from about 14% to 69%. The study distinguished browsing leaves or bark, extracting food from an object, and other feeding; it kept rumination—bringing up and chewing previously swallowed food—in a separate category.
That separation is necessary when comparing figures. A feeding percentage that excludes rumination cannot be treated as directly equivalent to a broader measure that includes it. Nor does a longer feeding duration automatically establish greater food intake: the observations recorded behaviour, not the mass of leaves consumed.
The contrast in repetitive behaviour was larger still. Three giraffes had only one recorded occurrence during the entire study. At the other end, one had 715. Because observation effort differed, the authors also calculated rates and individual average time budgets rather than interpreting those raw counts alone.
Figure 4 arranges giraffes by their observed rates. Its declining series of bars makes the heterogeneity obvious: a small group of frequent performers gives way to animals with barely visible bars. Oral behaviours dominated overall, but different individuals could show different mixtures of oral, motor and locomotor patterns.
The average stereotypy time was about 10%, while the median was about 5.5%. The median describes the middle individual; the higher mean reflects the influence of animals spending much more time in these behaviours. Neither number alone describes the full group.
Common does not establish a desirable target
Before systematic recording, staff reports had identified stereotypies in only some of the study giraffes. Later observations detected them in all. This does not imply that keepers suddenly missed an obvious problem. Rare events are inherently less likely to be remembered or noticed, and a survey of prior impressions answers a different question from prolonged structured sampling.
At the same time, the authors did not present widespread stereotypy as a reason to accept it as a welfare target. A behaviour can be typical of a managed population while raising concern about current conditions or previous experience. The present study mapped its expression; it did not determine the cause for each giraffe or establish that two animals with the same rate had the same welfare.
A smaller study by Sarah E. Koopman, Lindsay Brinda and Louis DiVincenti illustrates why that context remains necessary. In their observations around a giraffe feeding programme, repetitive behaviour differed among individual giraffes, while the overall comparison among programme phases did not show a clear change. Observations away from the actual feeding sessions also limited what the study could say about immediate responses. A population reference and a local event study provide different pieces of the assessment.
The 18-zoo project later supported a companion analysis of factors associated with behaviour. That analysis used the same study population, so it is an extension rather than independent confirmation of this baseline. The baseline's distinct contribution remains the range itself: it helps a keeper recognize when an individual's pattern warrants closer investigation, without turning an average animal into the standard every giraffe must meet.
Sources
- Wark, Jason D.; and Cronin, Katherine A. (2024). “The behavior patterns of giraffes (Giraffa camelopardalis) housed across 18 US zoos.” PeerJ, 12, e18164. Full paper.
- Koopman, Sarah E.; Brinda, Lindsay; and DiVincenti, Louis (2023). “Behavioural effects of a giraffe public feeding programme on Masai giraffe Giraffa tippelskirchi and plains zebra Equus quagga in a mixed-species exhibit.” Journal of Zoo and Aquarium Research, 11(1), 249–258. Related study.
- Wark, Jason D.; and Cronin, Katherine A. (2025). “Factors shaping giraffe behavior in U.S. zoos: A multi-institutional study to inform management.” PLOS ONE, 20, e0324248. Companion analysis of the same population.
