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Capturing the behavior of animals in their natural habitat with high detail? Researchers from the Konstanz-based Cluster of Excellence "Collective Behavior" developed a unique outdoor camera system to measure 3D movements and postures of wild birds. The system is mobile, robust to field conditions, and adaptable to a wide range of experiments and species.

To better understand the lives of animals—for example, their social systems, migratory behavior, or interactions with the environment—researchers need detailed data on how animals behave in their natural habitats. But how can this data be collected in the field, i.e. far away from the technical resources of a fully equipped behavioral laboratory?

For this purpose, researchers from the Cluster of Excellence "Collective Behavior" at the University of Konstanz (Germany) have developed the mobile camera system "3D-SOCS" (short for "3D Synchronized Outdoor Camera System") and used it for studying wild passerine birds.

The state-of-the-art behavioral data collection system has been published in the journal .

It enables precise, automated, markerless 3D tracking of the postures and movements of multiple birds simultaneously using two or more synchronized cameras.

"3D-SOCS is one of the first systems to demonstrate complete 3D posture tracking of multiple individuals in the wild, as current 3D tracking is almost exclusively done indoors and with captive animals," says Alex Hoi Hang Chan, who led the study along with Michael Chimento.

"3D-SOCS is a leap forward for the study of animal behavior in wild, free-living animals," says Chimento. "Our method opens new doors for studying cognition and social behavior under ecologically valid conditions."

A closer look at wild birds' attention use

To showcase 3D-SOCS' potential, the team deployed it in the woods near the Max Planck Institute of Animal Behavior in Möggingen (Germany), inhabited by populations of great tits and blue tits.

In a field experiment, the researchers presented the local birds with visual stimuli—from mealworms to a taxidermy bird—and used 3D-SOCS to determine how the birds oriented their heads in response to these objects.

With the data from the mobile camera system, they were able to infer each bird's visual field use and even lateralization (the preference for using one eye over the other), thereby uncovering subtle differences in the visual attention of individual birds.

Beyond measuring behavior, 3D-SOCS offers powerful tools for ecological monitoring. Using posture data provided by the system, the researchers estimated the birds' body volume as a proxy for weight and achieved a very high correlation with the values they measured using a scale.

The advantage of estimating such body parameters using the camera system is obvious: it is a non-invasive alternative to capture-and-weigh approaches.

The method thus paves the way for an automated tracking of wild animals' body or health conditions and even species classification in the field. What is more: 3D-SOCS is an open platform. In the spirit of open science, all hardware plans and software pipelines are , thus enabling easy adaptation to different study systems and species.

A step forward for behavioral research in the field

Overall, 3D-SOCS opens up a new avenue for synergies between laboratory and field research. By enabling fine-scale behavioral tracking in the wild with a level of detail previously restricted to lab environments, 3D-SOCS bridges the gap between controlled, high-resolution lab studies and ecologically valid but often less detailed field observations.

"This allows for an integrated approach where the strengths of both worlds can be combined, potentially establishing a new interdisciplinary field in behavioral and cognitive ecology," says Fumihiro Kano, the senior author of the study.

As the demand for high-resolution behavioral data grows in ecology and conservation science, 3D-SOCS offers an accessible solution. "This new window into the secret lives of animals is poised to transform the way we study behavior—from the forest floor to the treetops," says Kano.