Swift Call Attraction Kit
The kit consists of an amplifier which plays the calls on a loop from a recording on a SD memory card, a power adaptor and a small speaker which is fixed to the nest box. The amplifier can only be used indoors and so is connected to the speaker on the nest box via a thin cable which is routed through an openable window. The power adaptor can be plugged into a timer (not included) so that the calls are played at the optimum times. Click here to open an advice sheet on playing the calls. The system is best installed at the same time as the nest box.
Image courtesy of Action For Swifts http://actionforswifts.blogspot.com/p/attraction-call-systems-for-swifts.html