Last year’s owl banding season was one of the slower seasons we’ve had here, with a total of 69 Northern Saw-whets banded. This was the first season in 17 years of operation that NO Boreal Owls were banded.
The start of the 2026 season is looking better so far.
Nets were set up a couple of weeks ago, and have been opened a couple of hours during several nights where weather permitted. We’ve already banded 20 Northern Saw-whets (1 adult, the rest hatch-year). Our regular banding season starts on Sep 1.
Much appreciation to the Kachemak Bay Birders for the group’s generous support that allowed purchase of a new set of nets!
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.
Portable low-cost owl audio lureInternal arrangement of componentsExploded view of lure components and connections
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.
MP3 player module connections
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.
Barrel jack and plugConnection to the deck horn speaker is made by splicing the wires together
The audio lure file (mp3) is saved on a MicroSD card and inserted into the ‘TF Card’ slot on the player:
Loading the Micro SD card into the player moduleTesting the audio lure after wiring everything up
Components used above: Amazon links provided but all of these parts are available from many sources.
This last week in September is usually the peak of the season here. Despite lots of rained-out nights, we’ve had a few good nights over the last week. 19 Northern Saw-whets banded tonight so far, and 4-8 owls banded most nights over the last week.
Two Boreal Owls have been banded so far, which is up from last year (only one banded), but far from years like 2011 (56 Boreals banded) or 2017 (48 Boreals banded). Boreals tend to come later in the season, so more might be on their way.
At the suggestion of a couple of friends, I finally scraped together enough parts from the junk drawer to put together a BirdNET-PI system. This is a Tensorflow-based machine learning system that listens to the audio stream from an outdoor microphone and can identify over 6000 species. A station can be set up inexpensively; all that is needed for a minimal system is a Raspberry Pi board and an outdoor microphone.
The results are pretty impressive so far, although I’ve seen a few false detections- the local squirrels are being detected as Belted Kingfishers.
The system is configured to ignore detections of Northern Saw-whet Owl, Boreal Owl, and Western Screech-owl for now since the owl banding operation uses audio lures of those species- no need to pollute the BirdNET results with our lure playback.
We’re approaching the end of the owl banding season and things are slowing down here. It’s been below freezing for the last several nights. I’m seeing at most 1-2 owls per night now.
