Vidéo surveillance
At night, the traps light up and film in infrared. The (human) eye does not see it: what about the animals we observe?
For our year-round badgers, night is that moment of darkness, in the open air, punctuated by minutes of infrared. As to whether this wavelength gives them sunburn, well, that’s a mystery!
Badgers are known to have poor visual acuity. There is no record of them seeing the cameras. We have sometimes set a trap at nose height and yes, they can be seen sniffing around and then scurrying away as soon as our alien scent hits them. Conversely, the attitude of the foxes (and cats) suggests that they could see the infrared light of the traps.
A mix of movement and temperature change triggers the recording. We lift the traps once a week, to empty the memory cards and recharge the batteries. A quiet survey, collecting a time that is not ours on a territory that we share (more or less).
One night in April, a badger left alone started to cry. The poor microphone of the trap testifies to this. It’s time to get out more clever equipment.
Monochrome but sound
It is with the animal documentarian Yannick Cherel, also from Trégor, that we attempt a sound recording in binaural. An infrared-sensitive camera on the ground, two infrared projectors and a binaural head monitor one of the main mouths of the burrow network throughout the night.
As with the swallows, the cycle is interesting. The sun went down at 21:18, the recording starts at 22:24. Quite quickly, we have some small movements in the leaves, a little solidian (sound transmission by the ground), an owl, barking at several hundred meters, the acoustics of the corner and the rumour of road of the axis Guingamp-Tréguier because the wind blows nicely of the west. The ground is dry. The sound pick-up system is fixed to a tree by a rigid link: the whole tree is a transmitter of the low frequencies that propagate in the ground.
At 1.00 am, the badgers are out, for half an hour of their mini-puggles, as brief as they are intense: these little things growl quite severely. One last tinker for ten minutes and the whole team is underground.
At 5.46 am, the first day bird is heard, the sun rises at 6.59 am. Nice episode of owls around 5:30, with already the recrudescence of the distant car traffic.
