Journal: PeerJ
Article Title: Multimodal system for recording individual-level behaviors in songbird groups
doi: 10.7717/peerj.20203
Figure Lengend Snippet: (A) Inside a soundproof chamber, we built a recording arena (red dotted line) for up to eight birds. We record the animals’ behaviors with three cameras mounted through the ceiling. These provide a direct top view and indirect side and back views via two mirrors (delimited by green and purple dotted lines). To record the sounds in the chamber, we installed five microphones (blue dotted lines) among all four sides of the cage (one attached to the front door is not visible) and the ceiling, and two small microphones in the nest boxes. The radio signals from the transmitter devices are received with four radio antennas (orange dashed lines) mounted on three side walls and the ceiling. One nest box is indicated with yellow arrows and a water bottle with blue arrows. (B) A composite still image of all camera views shows two monochrome nest box views (top left) and three views of the arena (top, side, back) with eight birds among which one is flying (red arrows). Yellow and blue arrows as in A. (C) Schematic of the recording system for gapless and synchronized recording of sound (microphones), acceleration (transmitter devices), and video (cameras). The radio receiver is implemented on a USRP with a large FPGA that runs at the main clock frequency of 200 MHz. Clock dividers on the FPGA provide the sample trigger for audio recordings and the frame trigger for the cameras. The data streams are collected on a host computer that runs two custom programs, one (BirdRadio) for streaming audio and sensor signals to disk and one (BirdVideo) for encoding video data. MXI, Multisystem Extension Interface; USB3, Universal Serial Bus 3.0; PCIe, Peripheral Component Interconnect Express; TDMS, Technical Data Management Streaming; MP4, MPEG-4 Part 14; UDP, User Datagram Protocol. (D) Zoom-in on an airborne bird, illustrating the spatial and temporal resolution of the camera.
Article Snippet: Into the three circular holes of the chamber, we placed industrial 3-Megapixel cameras (Basler acA2040-120uc) with zoom lenses (opening angles: top view: 45° × 26°, back view: 55° × 26°, side view: 26° × 35°) and exposure times of 3 ms. To visualize nests in the dimly lit nest boxes, we used monochrome infrared cameras (2 MP, Basler daA1600-60um) and fisheye lenses (143° × 112°).
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