Influence of external factors on the success of transmissing messages during the monitoring of wild reindeer movements using the “Argos” satellite system (<i>Rangifer tarandus</i>)

Currently, satellite telemetry is increasingly in use in environmental research. As a result, researchers obtain a large amount of data on the use of space by animals. However, despite the perfection of modern satellite navigation and data transmission systems, reports on the positions of animals are extremely uneven. We consider here the main technical and natural factors that may influence the success of spacecraft in the “Argos” satellite system receiving messages emitted by radio beacons installed on animals. Among the natural factors when an animal is under the forest canopy, the greatest influence has been established to be exerted by the closure of tree crowns, which can be offset by the abundance of snow in the crowns after heavy snowfalls. Dense clouds have a weaker effect. Of the technical factors associated with the characteristics of flights of satellites of the “Argos” system, the success of receiving messages is influenced, first of all, by the maximum angle of elevation of the satellite above the horizon and the intensity of flights of satellites with a maximum angle of elevation above the horizon of more than 10° per unit time. This is due to the high unevenness of message receipt. At night and in the afternoon, due to a reduction in the number of satellite flights and a decrease in the altitude of their trajectories, the success of reception may decrease to 3% of the number of transmitted messages.