waiting for detection
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Ronny Hullegie — nature lover in Nijverdal. Here I share what I build and what I hear.
more about me § 01 · Welcome
Ecological Monitoring System Nijverdal.
What do you hear in a village garden if you keep listening twenty-four hours a day? What do you see in the sky if a camera takes a photo every ten minutes? This is the personal field journal of one such spot in Nijverdal, with home-built equipment.
Status Live
Listening stations 3 fixed · 1 mobile
Bat sensor 200 kHz
Weather station Davis VP2
Sky camera 140° fisheye
Migration data KNMI FlySafe
Location
Village garden · Nijverdal
52.37°N, 6.47°E · Overijssel, NL
Motto
“You protect
what you know.”
The reason EMSN exists. Biodiversity disappears unnoticed. This system makes it visible.
★ Just in Live, refreshes when something new comes in
quiet during the day
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§ VV · Find of the day2 June 2026
§ 01a · Stories One paragraph a day
The journal.
Every evening around six a short note appears about the day in the garden. What the microphones caught, what the weather did, who sang and who stayed silent. Written in Dutch.
Read the journal § 02 · The project What is measured here
Microphones
in the garden.
52.37°N · 6.47°E
Nijverdal · Overijssel · NL
In my garden in Nijverdal there's a handful of home-built measuring kit. A microphone under the gutter on the south side of the house, one under the gutter on the north side, and two microphones under the gutter in the garden right by the shrubs. On top of that a bat sensor, a weather station on the roof, a camera that watches the sky. They note down what passes by: birds, bats, rain, the odd aeroplane. It all runs to a NAS in the shed.
Started in 2025, out of curiosity. I wanted to know what passes by here twenty-four hours a day in such an ordinary place. No nature reserve, just a garden with trees and shrubs in the middle of a village. It's more than you'd expect, if you keep listening.
There are now three fixed listening stations, a separate sensor for bats, and a mobile station that comes along when I go out elsewhere. The Sallandse Heuvelrug, a river floodplain, a night-time walk on the heath. All the data comes together on the NAS and is visible in a handful of Grafana dashboards.
It's a hobby project. The data is open, under CC BY-NC 4.0. Whoever has a use for it is welcome to it. The source code is also open on my GitHub repository, free to read and to reuse.
§ 03 · Listening Acoustics 24/7
What sounds
in the garden?
Three fixed stations and one mobile station listen along. Birds, bats, rustling undergrowth: what the microphones pick up ends up here.
- Acoustics · north/southBladerdakTwo microphones under the gutter, listening to birds 24/7.
- Acoustics · lowStruikgewasWhat rustles in the bushes: birds and small mammals.
- Ultrasonic · 200 kHzBatsA Dodotronic Ultramic picks up bat calls at dusk.
- Expeditions · Sallandse HeuvelrugMobielThe station that comes along into the field. Not live, with a delay.
§ 04 · Environment Weather, sky and large-scale migration
The context of
a sound.
The weather shapes a lot of what the microphones pick up. On a wet morning you hear little; on a clear spring day the garden is full of sound. Migrating birds that call as they pass overhead end up in the recordings too. These pages give the context for what we hear.
- Davis Vantage Pro 2WeatherTemperature, rainfall, wind and pressure, logged every minute.
- Analysis · correlationsWeather × DetectionsDoes a finch prefer rain or sun? How does activity shift with temperature?
- KNMI FlySafe · seasonMigration & phenologyRadar data on migration above the Netherlands, plus when I first hear each species each year.
§ 05 · Watching Imagery 24/7
And what do
the cameras see?
Three nest boxes with a camera inside, a sky camera that looks up every ten minutes, and an archive of photos from years past. What an image captures fills in what the ear misses.
- Camera · AI speciesNest boxesThree boxes with cameras that automatically recognise who is nesting.
- Sky camera · 140°AtmosBirdA photo of the sky every ten minutes. ISS, moon, meteors.
- Imagery · fieldPhotosBirds, butterflies, insects, plants and landscapes — from the garden, the field and on the road.
§ 05a · Year wheel The rhythm in one glance
The year
as a circle.
Twelve months in a round, each ring a species. Who sings year-round, who passes through only in summer, who slips away in autumn. A needle points to today.
View the year wheel § 06 · Technology Under the hood
And if you want
to know how.
The code, the databases, the Raspberry Pis in the attic and in the shed, the microphones under the gutters. For anyone curious about how it actually fits together.
★ Stay in the loop
Don’t want to miss anything?
Two easy ways to keep up with what passes through here. It’s a hobby project, so no daily newsletter. Only when something happens that’s worth a note.