Transmitters

[marika.solo]

1) Why do black storks wear transmitters?
To learn how they migrate, where they stop, what habitats they need, and when a bird may be in trouble. This knowledge helps protect the species.

2) Does the transmitter harm the stork?
No. It is very light (1–3% of body weight) and attached either as a small “backpack” with a soft Teflon harness or as a leg-mounted device. For a human, it would be like carrying a 700 g–2 kg backpack.

3) How does the transmitter work?
It records the stork’s GPS location, speed, altitude, and temperature. When the stork enters an area with mobile coverage, the device sends the stored data to a server.

4) How does the data get to the online map?
The map is connected to the database that receives the transmitter’s data. When new positions arrive, the map updates automatically and draws the latest route.

5) Why do we sometimes see no data for days, weeks, or even months?
Because many migration and wintering areas have poor or no GSM signal. The transmitter continues recording and stores the data. When the bird later reaches a place with coverage, it uploads all stored points at once.

6) Why can winter gaps last several months?
This is normal. Some storks send their last autumn point in late September and the next one only in March during spring migration. The stork was moving normally — only the signal was missing.

7) What are SMS-only updates?
Sometimes the transmitter can send just an SMS with a basic status. This may confirm the bird is alive, but it cannot update the map because SMS contains only a tiny amount of information, not full GPS tracks.

8) When should we worry about a bird?
When, in normal weather, the data shows:
• almost no movement for many hours or days,
• identical coordinates again and again,
• no changes in altitude,
• unusually low temperature.
These can signal illness, injury, or predation.

9) Can the transmitter fail?
Yes, though rarely. Possible causes include battery issues (e.g., low solar charging), physical damage, or long-term lack of GSM coverage.

10) Why do some birds send data very often and others rarely?
Because each transmitter uses different settings (battery-saving mode, recording intervals) and birds migrate through areas with very different mobile coverage.

11) Does the transmitter store old data?
Yes. It keeps a large backlog safely until it can upload everything together. This is why many points may appear on the map suddenly after a long silence.

12) What happens if the bird dies?
The transmitter usually remains in one spot. The data pattern changes suddenly to no movement, no altitude change, and often a drop in temperature. Researchers then investigate if possible.

13) What do x, y, z acceleration values mean – and when are they concerning?
Transmitters measure movement in three dimensions (x, y, z). These values show how actively the stork is moving (flying, walking, preening, resting). Healthy birds produce constantly changing acceleration patterns.
Values become concerning when all three axes (x, y, z) stay very low or almost unchanged for a long period. This may mean the bird is not moving at all.
We worry when:
• x, y, z are close to zero for several hours,
• the values look almost flat (the same again and again),
• there is no difference between day and night,
• there is no morning “wake-up” activity,
• or when activity suddenly stops after normal movement.
These patterns can indicate injury, weakness, entanglement, or death. Researchers then analyse the data closely and, when possible, try to check the situation in the field.