How do animals in the wild use their time? A Rice University researcher is part of a new study showing what motivates the daily migration of tropical populations.
The study, by an international team that includes Rice bioscientist Lydia Beaudrot and led by Andrea Vallejo-Vargas, a PhD student at the Norwegian University of Life Sciences and currently a visiting scientist at Rice, found that mammalian communities in the humid tropics divide days similarly, all generally focused on finding their next meal. (Or avoid being the next meal.)
Using millions of images from camera trap networks in 16 protected forests around the world, they studied the relationship between mammal activities, body size and dietary habits to find common traits across populations.
Your open access study in nature communication confirms that despite their diversity, similar patterns dominate wildlife days in Africa, Asia, and the Americas.
The study showed that the activity of herbivores and insectivores was strongly influenced by the temperature in the environment (in the study lingo, “thermoregulatory constraints”). For example, large African herbivores are seven times more likely to be nocturnal than smaller herbivores.
Interactions between predator and prey were mainly dominated by the time of day.
Within this regime, the researchers found “top-down” activities that dominate prey days, naturally focusing on avoiding being eaten. They avoid exposure when predators are most likely to be on the hunt. Size matters too: small carnivores, for example, change their activities to reduce encounters with large carnivores.
Conversely, “bottom-up” strategies affect how predators adjust their activities to maximize encounters with prey.
“When you think of a food chain, top-down refers to how higher tropic levels – that is, predators – affect their prey, while bottom-up refers to how lower trophic levels – food sources including plants and insects – affect the animals that they eat,” said Beaudrot, assistant professor of life sciences.
‘This paper is an excellent example of the importance of replicating standardized data collection across large spatial extents,’ she said. “By analyzing data collected in the same way in national parks in the tropics, we were able to identify similarities in behavioral activity that could not previously be quantified.”
Beaudrot provided feedback and advice to the team throughout the development of the research project and manuscript based on her experience working with the camera trap data.
She said all cameras are well located in the national parks and set up in the best possible way to assess tropical wildlife with the least human impact. “None of the protected areas are free from human impact, but they give us the best opportunity to measure similarities in wildlife between regions,” said Beaudrot.
She noted that although species in different regions have evolved in isolation from one another, the study provides solid evidence that similar environmental conditions in rainforests around the world result in consistent patterns of wildlife activity.
“This suggests that there has been a convergence in animal behavior in response to the rainforest environment,” Beaudrot said.
The work is co-authored by Rice visiting scholar Asunción Semper-Pascual; Douglas Sheil from the Norwegian University of Life Sciences, Wageningen University in the Netherlands and the Center for International Forestry Research Indonesia; Robert Bitariho from Mbarara University of Science and Technology, Uganda; Jorge Ahumada of the Moore Center for Science, Conservation International, Arlington, Virginia; Emmanuel Akampurira from Ghent University, Belgium, and Mbarara University; Santiago Espinosa from the Autonomous University of San Luis Potosí, Mexico, and the Pontifical Catholic University of Ecuador, Quito; Vittoria Estienne from the Wildlife Conservation Society, Republic of the Congo; Patrick Jansen from Wageningen and the Smithsonian Tropical Research Institute, Panama; Charles Kayijamahe from the International Gorilla Conservation Program, Kigali, Rwanda; Emanuel Martin from the College of African Wildlife Management, Tanzania; Marcela Guimarães Moreira Lima from the Federal University of Pará, Brazil; Badru Mugerwa from the Leibniz Institute for Zoo and Wildlife Research, Berlin, and the Technical University of Berlin; Francesco Rovero from the University of Florence and the Science Museum of Trento, Italy; Julia Salvador from the Wildlife Conservation Society of Ecuador; Fernanda Santos from the Museu Paraense Emílio Goeldi, Belém Pará, Brazil; Wilson Roberto Spironello from the National Institute of Amazonian Research, Brazil; Eustrate Uzabaho of the International Gorilla Conservation Program; and Richard Bischof from the Norwegian Institute for Life Sciences.
The Research Council of Norway (NFR301075) and the National Science Foundation (DEB-2213568) funded the research.
Materials provided by Rice University. Originally written by Mike Williams. Note: Content can be edited for style and length.