Transcript
Outdoor video tracking setup to study bird orientation
Rachel Muheim1 and Mark Deutschlander2
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Department of Biology, Lund Vision Group and Center for Animal Movement Research, CAnMove, Lund University, 223 62 Lund, Sweden;
[email protected]
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Department of Biology, Hobart and William Smith Colleges, Geneva, New York 14456, USA;
[email protected]
Here we provide some practical tips for how to set up outdoor video-based orientation experiments that can be analyzed with BirdOriTrack. The pictures are all from our setup at Braddock Bay Bird Observatory, NY, USA, except for the last two that were taken at Falsterbo Bird Observatory, Sweden. All pictures were taken by Rachel Muheim.
For more detailed information, including a full description of the BirdOriTrack, please view Muheim et al (2014), J. Field Ornithol. 85(1), 91-105, and the manual for BirdOriTrack, available at http//:canmove.lu.se/birdoritrack. For reprints of the paper, please contact any of the authors.
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Setup of the video recording system In this easy to build setup, two cameras are attached on the top of net poles, recording the movement of six birds each. The orientation funnels are made of flower pots (see below for details). For BirdOriTrack to be able to track the movements of the birds, it is of utmost importance that the view of the cameras and the positions of the orientation funnels do not shift during the recording, thus both the camera(s) and the funnels need to be stable and withstand wind.
A digital video recorder (DVR) set with QUAD view makes it possible to record from four cameras simultaneously. The DVR provides power to the cameras. However, the movies can also be recorded directly onto a computer, onto DVDs or onto other type of video recording media.
The cameras can be attached to net poles or similar structures. Depending on the distance between the camera and the funnel(s), the intensity of the IR lights in the camera needs to be reduced. This can be done with inserting sheets of wax paper. Also, if the IR diodes are not aligned symmetrically around the camera lens, i.e., if there is a gap in the distribution of the diodes because of the light sensor, as in the example below, some of the diodes can be made invisible, for example by using heat shrink tubes.
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3M reflective light dots may glued on the birds’ head to improve tracking in darkness. 3M Reflective tape is available from 3M under the brand name: 3M™ Scotchlite™ Reflective Material - 8710 Silver Transfer Film).
Orientation funnels or cages It is important that the orientation funnels or cages are circular in shape and provide enough room for horizontal movement from the center towards the edge of the funnel or cage. The shape of the orientation cages or funnels should be chosen so that the birds are forced to return to the center after each activity bout. The slope has to be shallower than in the traditional funnels, so that the distance between the central part and the outer funnel edge allows the outward movements of the birds to be reliable distinguished from movements within the central part of the funnel. In the given example, the orientation funnel is made of a plastic flower pot, with plastic window screening glued on top (with hot glue). The inside of the funnel is sprayed white to obtain a better contrast. If 3M reflective tape is used, however, the background of the cage does not matter. An opening is cut in the bottom of the pot to easily place in and remove the birds. The bottom lid is attached to the funnel with Velcro tape.
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An alternative way to record migratory orientation is to use orientation cages with a central perch. The cage is made of a plastic tub, with four windows cut out and covered with plastic window screening. The top is covered with screening and a hole cut out of the bottom to place in and remove the birds. The lid is made of a plastic flower pot bottom, and the round sit perch of plastic tubing. The advantage of this type of cage is that the birds are more ready to return to the center to sit on the perch, compared to the funnel where they sometimes sit along the sloping wall of the funnel, instead of returning to the center.
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