Hoofed nightlife provides behavioral insight

Photo: Linas T/Adobe Stock

Ungulates, characterized by their hoofed feet, form a diverse group of mammals including species like horses, deer, cattle, and giraffes. Adapted to specific habitats worldwide, from Africa to North America, these species are essential components of ecosystems.

To understand ungulates’ behaviors, especially those in captivity, a study published in Ecology and Evolution investigates the nocturnal behavior of 18 distinct ungulate species across 20 European zoos. Many of these species, including giraffes, African elephants, and others, are native to Africa, emphasizing the importance of understanding their natural behavior even when observed in zoos. Challenges in studying nocturnal behavior in the wild make zoos an accessible and feasible option for observations, providing valuable data that enhances our understanding of these species.

The study, based on the examination of 192 individual animals from various species, reveals insights into the nocturnal rhythms of these ungulates. The analysis goes beyond basic descriptions, delving into the lying-standing cycle and specifically, the time between 2 lying down events, termed as a lying cycle. The study identifies a high degree of rhythmicity in this cycle across species, with notable differences between Artiodactyla (even-toed ungulates) and Perissodactyla (odd-toed ungulates).

Initial findings highlight age as a significant factor influencing nocturnal behavior. Younger animals exhibit a higher proportion of extremely short lying cycles, indicating potential differences in sleep patterns compared to adults. Additionally, the lying fraction, representing the proportion of time spent lying in a lying cycle, is greater in younger individuals than in their adult counterparts.

Further analysis reveals differences in the median time spent in the REM sleep position based on age. Like humans, younger and subadult animals tend to spend more time in REM sleep during a typical lying phase than adult individuals. Although statistically nonsignificant at the 5% level, these trends are noteworthy, especially considering the potential implications for the well-being and sleep patterns of these ungulates. The average length of periods spent in the REM sleep position ranged from 2.2 minutes to 7.6 minutes, raising questions about potential external factors affecting REM sleep, including environmental conditions and predation risk.

Beyond contributing to behavioral ecology, the investigation emphasizes the relevance of such studies in animal management and husbandry. Knowledge of behavioral patterns can enhance husbandry conditions, ultimately improving animal welfare. While acknowledging variations between zoo and wild environments, the study underscores the valuable insights gained from observing zoo animals, providing a noninvasive and consistent platform for behavioral analysis.

This detailed exploration of nocturnal behavior in ungulates offers a nuanced understanding of their activities during the night, paving the way for enhanced animal welfare assessments and further comparative studies between zoo and wild environments.

Ava Landry is a 2026 PharmD candidate studying veterinary pharmacy at the University of Connecticut in Storrs.

Reference

Gübert J, Schneider G, Hahn‐Klimroth M, Dierkes PW. Nocturnal behavioral patterns of African ungulates in Zoos. Ecology and Evolution. 2023;13(12). doi:10.1002/ece3.10777