The stress of capture for scientific purposes affects both the smallest herbivores and huge predators. An international research team analyzed the activity of 42 species after wearing GPS collars. Interestingly, animals that encountered human traces on a daily basis coped particularly well with stress.
Tagging and tracking wild animals using GPS transmitters allows us to collect information about many aspects of their lives. However, this method is not without its drawbacks – the process of capturing and marking itself can be quite stressful for animals and affect their activity and behavior. In such a situation, the collected data may turn out to be false. The journal “Nature Communications” published an analysis of how various animals react to capture by humans and how this affects research.
Different responses to stress
The research team analyzed data on 1,585 individuals from 42 species that were fitted with GPS collars. The researchers observed each animal for 20 days after release, paying particular attention to their activity and the distances they traveled. Researchers also noted whether they were herbivores, omnivores or carnivores.
The researchers noted that 30 of the 42 species studied significantly changed their behavior in the first few days after release, although there were noticeable differences between species. Immediately after marking, predators covered shorter distances, while most herbivores tended to cover longer distances. Omnivores and carnivores were less active during the first few days, while herbivores showed both increased and decreased activity.
Moreover, the animals returned to “normality” at different rates. Omnivorous and carnivorous species resumed normal activity and movement within five to six days of capture. Although herbivores returned to normal in terms of distance covered more quickly (taking four to five days), their activity stabilized only six to eight days after capture. Larger species forgot about stress faster than smaller animals.
Accustomed to the presence of people
“Our assessment clearly shows that tracking periods for wild animals should be longer than a week,” said Jonas Stiegler from the University of Potsdam, lead author of the analysis. – Thanks to this, we will be sure that our results are true and that we are examining their natural behavior.
The researchers noticed another interesting regularity: animals living in habitats heavily transformed by humans turned out to be less susceptible to stress related to marking than those from wilder environments. This pattern was most clearly visible among species that encounter humans or traces of human presence on a daily basis. Scientists suggested that these animals may have simply become accustomed to the various disturbances.
Main photo source: Caroline Scholz