Songbird nests on the ground as islands of diversity of ptyctimous mites (Acari: Oribatida) in the primeval Białowieża Forest (Poland)

Due to specific microclimatic conditions and accumulation of organic matter, bird nests are microhabitats that are often inhabited by various invertebrates, including mites (Acari). We tested whether nests of the ground-nesting passerine Phylloscopus sibilatrix (Bechstein) (Passeriformes: Phylloscopidae) [wood warbler] were associated with an increased local diversity of ptyctimous mites (Acari: Oribatida) on the forest floor in the Białowieża National Park, East Poland. In 2019–2020, we analysed 150 warbler nests shortly after they had been vacated by the birds, and additionally we sampled mites in leaf litter at 1 and 6 m distances from 21 of the collected nests. We found on average more mite species in nests sampled in 2020 than in nests sampled in 2019. Although the species composition largely overlapped between bird nests and the litter, bird nests contained a greater average number of mite species than litter samples, including species found only – Microtritia minima (Berlese) and Phthiracarus crenophilus Willmann – or mostly – Euphthiracarus cribrarius (Berlese) and Phthiracarus globosus (C.L. Koch) – in bird nests. The results suggest that the presence of bird nests may increase the local diversity of the invertebrate species assemblage

UAV Propulsion Analysis System with Reconfigurable Controller Feature

In this paper, a custom measuring system for propulsion units of multi-rotor UAV is presented. Designed solution provides measurements of thrust, rotational speed and power consumption of popular electric propulsion systems consisting of BLDC motor, electronic speed controller (ESC) and various propellers. The method is applicable to both single and twin (coaxial) configurations of rotors. Thanks to the use of a precision 6-axis force/torque sensor and sensorless method of speed measurement it is possible to record performance of propulsion with convenient PC software. The system is equipped with complete galvanic isolation between power and sensory circuits. A unique feature of presented solution is the possibility of remote reconfiguration of various controllers, governing speed or thrust of the propeller. Possible applications of the presented test rig are: estimating the performance of UAV design (flight time, power consumption, payload capabilities), mathematical modelling of electric propulsion and analysis of faulty states of rotor operation