Over the years I’ve built and used a number of audio lure systems for Saw-whet banding.
At Holiday Beach, around 2001-2002, we used a cassette deck and a P.A. amplifier; we had power in the banding station, so we ran a long cable out to a speaker at the nets. We used endless-loop answering machine tapes in the cassette deck. We later replaced the tape machine with a CD player set to repeat a track.
My current setup in Homer, AK has to be battery-powered. The system has gone through a bunch of changes as I tried out various amplifiers and playback mechanisms; initially this consisted of a Pelican box with a 5AH sealed lead-acid battery, a small MP3 player, and an amplifier scavenged from a pair of computer speakers.
The system now still uses an SLA battery (7.5AH), but I’ve switched the amplifier and MP3 playback to a small self-contained unit found on eBay; this unit plays MP3 files off of an SD card (or USB flash drive) and includes a stereo amplifier. It drives a pair of marine deck horn speakers. A single switch turns the unit on or off; the SD card contains a single 1-hour-long MP3 file that alternates between NSWO and BOOW every 15 minutes. This file auto-plays and repeats as long as power is on.
This system goes quite a while on a charge. I typically charge it about once a week; use is several hours per night.
Audio Lure
Inside of the audio lure, showing SLA battery, amplifier/MP3 player, and charging jack
Amplifier / MP3 player, made by ‘Lepai’
Smaller, lighter lure
I’ve also built a couple of smaller, lighter audio lure boxes for others; Holiday Beach now has one of these. This version is made mostly from cheap eBay parts:
- mp3 player board with remote
- stereo amplifier board
- 4x 16650 Lithium batteries
- Plastic enclosure
- Deck horn speaker
This variant also plays a single MP3 file off of a micro-SD card and auto starts/repeats on power-up; a single switch on the outside of the box controls power. It also has a fairly useless remote that came with the MP3 player board; this could be useful for changing the volume or selecting among multiple tracks (if present), but for NSWO banding it’s probably not of much use.
Smaller MP3 lure with remote
Inside- batteries, amplifier, and MP3 player board
Lure with warning – the sticker seemed appropriate for this application
Mono amplifier board (L) and MP3 playback board (R)
This system weighs a LOT less than the larger SLA battery-powered system. An external 16550 charger is used to charge the batteries.
The next iteration of this thing will probably use an even simpler MP3 module I just bought; it includes an amplifier on-board. It remains to be seen whether or not this new board’s amplifier is sufficiently powerful.