Sound recorder (song meter) Photo B Wykes
The tools of the trade for investigating Masked Owls, apart from patience, warm clothing and insect repellent, are high quality head-lamps and hand-held torches with red as well as white light, red light not being visible to night animals; binoculars; cameras and sound recorders; and a GPS location recorder.
A call play-back unit with amplifier is used to initially survey and locate Masked Owls. Playback is only used judiciously for research purposes. Technically call-playback can constitute ‘disturb’ under the legal definition, and hence require authority to disturb (under the BC Regs either 25 or 31).
With approval of land holders, song meters are attached to trees and programed to record sound from dusk to dawn.
Recordings, analysed when translated to sonographs, identify presence of Masked Owls and other night life; dusk and dawn calling that indicates roosts; intimate courtship calling of chuckles, bill clatters and purring; the continual, monotonous begging of nestlings and fledglings and the chaotic begging when adults eventually arrive with captured prey. Very little adult behaviour is directly observed in order to avoid disturbance.
Sonagram of a pair of Masked Owls exchanging contact screeches
Sonagram of a begging duet by two fledgling Masked Owls
Sound recordings of local birds are ‘played back’ at prospective localities to identify new areas of Masked Owl activity; primarily in autumn when pairs are vocal and responsive as they prepare for mid-winter nesting. Photographs are taken of responding birds for ID purposes, ideally with one person steadying the camera while the other holds a torch. To avoid undue disturbance, wildlife specialist red-light torches are used to observe behaviour, with white light only used judiciously, particularly to obtain ID and developmental stage photographs. We do not use flash light as the sudden burst of bright light may be an issue for the bird.
Here are some of the Masked Owl calls that we have recorded and are linking to behaviour: screeches to communicate over a distance, various intimate chuckles and chitters, and begging by chicks and fledglings that becomes frenetic when parents arrive with dinner.
Brush-tail Possum ‘biffo’ can sound a lot like a soft Masked Owl screech