A bettong in exhibit

Measuring the Impact of Light and Sound on Animal Welfare

A view, from above, of a bettong in exhibit

Purpose

Zoos and aquariums strive to create environments in which animals experience great welfare. Two environmental aspects that scientists in the Animal Welfare Science Program often consider are sound and light. By measuring how different intensities affect the behavior of different species, zoo scientists can help improve animal care at Lincoln Park Zoo and institutions across the country.

A Red-light Special for Brush-tailed Bettongs 

Brush-tailed bettongs are nocturnal marsupials native to a small part of Australia. The species has fascinating adaptations: they dig holes nightly in search of fungi, raise their young in kangaroo-like pouches, and bounce around with bundles of nesting materials wrapped in their tails.

At Lincoln Park Zoo, the brush-tailed bettongs live in a habitat with a “reverse light cycle” that is kept dark during the daytime and lit at night. Reverse light cycles allow Animal Care staff and visitors to observe the nocturnal animals during their active periods. However, in order to observe the animals, a little bit of light is still necessary. Healthy sleep is essential for great animal welfare, and healthy sleep can be difficult to obtain if lighting is not just right.

At Regenstein Small Mammal-Reptile House, scientists worked alongside Animal Care staff to create dark-period lighting that facilitated a healthy sleep-wake cycle without hindering visibility. This was accomplished by using light meters to measure brightness (lux levels) in the habitat and motion-activated cameras to monitor animal activity 24-hours a day. Zoo scientists continue to monitor the brush-tailed bettongs through the ZooMonitor volunteer program.

The bettongs, and many neighboring nocturnal animals at Regenstein Small Mammal-Reptile House, are currently housed under red light during their dark period, the wavelength that has proven least disruptive to the physiological regulation of sleep-wake cycles.

A graph showing the aggregate activity detected over several days. Activity is nearly absent during “daylight” (overnight), indicating a good sleep-wake cycle.

Asking the Animals What They Want: Sun or Shade? 

Many of the animals at Lincoln Park Zoo have access to outdoor habitats year–round. As the seasons change, so do the temperatures and the patterns of sun and shade in the habitats. Scientists in the Animal Welfare Science Program have developed methods to systematically map out where sun and shade are available in the outdoor habitats year–round. Scientists then integrate this information with patterns of animal space use collected by the ZooMonitor volunteer program. Considering this information together, scientists and Animal Care staff can make predictions about habitat modifications that could increase animal comfort and, therefore, animal welfare.

The shade map on the left shows the sun and shade available in a Sichuan takin habitat in July, and the ZooMonitor space-use plot on the right shows the areas the takins preferred during that same time. Considering these together, one can see that takins prefer being in the shaded spaces along the edges of their habitat in July, and that they may be even more comfortable with the addition of shaded edges elsewhere.

For example, integrating these two types of information (shade availability and space use) led to the addition of strategically placed shade structures in the Sichuan takin habitat. ZooMonitor volunteers continue to observe their space use to evaluate and potentially further enhance takin welfare with future changes.

Sound at the Zoo and Animal Welfare 

Scientists in the Animal Welfare Science Program work alongside Animal Care staff to ensure the auditory environment promotes great animal welfare. This is a rich area for research, as animal hearing can vary drastically from human hearing. Scientists measure the intensity of sounds from visitors, heating and cooling systems, construction, and other events using microphones, remote recording devices, and decibel meters. By connecting auditory measures to animal behavior and space-use observations, zoo scientists can make inferences about animal comfort and subsequent recommendations that promote great welfare. Projects to date have focused on Puerto Rican parrots, polar bears, Japanese macaques, gorillas, and more.

Staff

Katherine Cronin, Ph.D.
Senior Animal Welfare Scientist
Animal Welfare Science Program
Jason Wark, Ph.D.
Animal Welfare Scientist
Animal Welfare Science Program

Contributors

Natasha Wierzal