An audio lure for owl banding can be constructed from a few inexpensive / commonly-available parts. For this lure, I am using a small MP3 player module with a built-in amplifier; this module can play files directly off of USB flash drives or micro-SD cards.
All it needs is connection of a power source and a speaker.

There are many variations of this kind of MP3 player module availalble. I chose this one due to the larger built-in amplifier and an actual knob for power/volume (most use buttons); the analog volume control is just a personal preference.

In the past I’ve used heavy SLA (sealed lead acid) batteries in this kind of lure. But recently I’ve switched to using off-the-shelf Lithium Ion power banks combined with USBC PD adapters that provide 12VDC. These power banks can be swapped out quickly and charged with standard USBC chargers.

The speaker is an outdoor waterproof deck horn. The whole assembly is mounted in an old waterproof Pelican case (which is no longer waterproof due to all of the holes I’ve drilled in it over the course of many audio lure variations).

A list of parts with product links is included at the end of this post; all of these parts are only examples.

The MP3 player module includes wire pigtails for connection of power and two speakers (stereo output). I’m only using one speaker here but this system could be expanded to drive two speakers.

Power is provided to the MP3 module by means of a 12VDC USB-C PD adapter cable.
This cable has a USBC connector on one end and a barrel plug on the other end.
To make the connection to the MP3 module’s power wires, a spring-terminal barrel jack is an easy solution. These barrel jacks are also available with screw or solder terminals.
Alternately, the barrel plug on the adapter cable could be cut off and the wires spliced with wire nuts, solder, WAGO connectors, etc.

The audio lure file (mp3) is saved on a MicroSD card and inserted into the ‘TF Card’ slot on the player:

Components used above:
Amazon links provided but all of these parts are available from many sources.

Component	Sources
MP3 player module	https://www.amazon.com/Bluetooth-Amplifier-Decoder-Microphone-Player/dp/B0DRX5VP5B
Deck horn speaker	https://www.amazon.com/Indoor-Outdoor-Horn-Speaker-Impedance/dp/B002UL0WH8
USBC-PD 12V power cable	https://www.amazon.com/HSZJsto-5-5mm-Charging-Charger-Output/dp/B0CBNQN7CR
Spring terminal barrel jack	https://www.amazon.com/JacobsParts-Barrel-Screw-Connector-Electronics/dp/B01NAYPUAY?th=1
USBC PD power bank	Many possibilities; this is the bank used above: https://www.amazon.com/Anker-PowerCore-Portable-Charger-Compatible/dp/B09VPHVT2Z

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.

 

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.

 

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.

Built a new audio lure for the Holiday Beach owl banders a few months ago, after promising them a new one for a couple of years.  It was time to retire the CDs and the portable CD player in favor of something MP3 based.

The new lure consists of cheap parts from eBay and some others salvaged from the junk drawers.  The main components:

• mp3 player board with remote
• stereo amplifier board
• 4x 16650 Lithium batteries
• Plastic enclosure
• Deck horn

A few photos of the finished lure:

The sticker on the deckhorn seemed appropriate for this use.