Fig. 1: The set-up for image acquisition.

a Illustration of the image acquisition system with a constant power supply. A wire connected to a lid was stretched out when the lid was lowered fully. Instead of a normal battery, a custom-made DC coupler was placed in a RICOH WG-40 camera using a flat cable. A UPS was installed as a temporal power source in case of a power cut. b Close-up of a DC coupler with wooden fixing panels (one for each side of the DC coupler), a flat cable, a connector, and a DC cable. A DC coupler was used instead of a normal battery. Wooden fixing panels and a DC coupler were inserted together in the camera battery slot to position the DC coupler stably. Details of the set-up are shown in Supplementary Fig. 1. c Support bars with DC cables fixed using cable ties and a movable scaffolding clamp with a black rubber sheet in between. d A wire (yellow oval) lifting the camera lid to avoid contact with the camera. e Overview of the image acquisition system. The polytunnel frames were covered with mesh, with the top mesh being removed during winter in Switzerland as seen in the photo.