Physiological and behavioural assessments of stress levels in owls housed at owl cafes

Owl cafes, where customers view and interact with owls, have become popular in Japan. There are multiple aspects of the environment which may be stressful to nocturnal owls, including lighting, tethering and frequent interactions with humans but, to date, welfare has not been investigated. This preliminary study examines the effects of owl cafes and customers on the physiological stress (faecal corticosterone levels [FCL]) and behaviour of the owls. Seven eagle owls (Bubo bubo ) and two African scops owls (Ptilopsis leucotis), in two cafes, were studied over an eight-day period. Cafe A (n = 5) was closed for one day per week, whilst cafe B (n = 4) was open every day. In cafe A there was higher FCL in owls during open days than closed days suggesting that the conditions on open days increase stress in owls. Eight of nine owls showed evidence of some aversion or avoidance of humans, whilst no affiliative behaviours were observed. The number of visitor interactions was not associated with the level of physiological stress; and when comparing owls, there was a tendency for individual owls with a higher percentage of aversive responses to customers to also have higher FCL. Close human interactions of a negative nature, that result in aversion, may be a significant stressor, but further research is required.

The ideal porous structure of EDLC carbon electrodes with extremely high capacitance

We propose an ideal porous structure of carbon electrodes for electric double-layer capacitors (EDLCs). The porous carbon successfully improved the gravimetric capacitance above ∼200 F g^-1 even in an organic electrolyte by utilizing the carbon nanopore surface more effectively. High-resolution transmission electron microscopy images and X-ray diffraction patterns classified 15 different porous carbon electrodes into slit-shape and worm-like-shape, and the pore size distributions of the carbons were carefully determined applying the grand canonical Monte Carlo method to N₂ adsorption isotherms at 77 K. The ratio of pores where solvated ions and/or desolvated ions can penetrate also has a significant effect on the EDL capacitance as well as the pore shape. The detailed study on the effect of porous morphologies on the EDLC performance indicates that a hierarchical porous structure with a worm-like shaped surface and a pore size ranging from a solvated ion to a solvent molecule is an ideal electrode structure.