Consolidated analysis of responses to a similar question on
Tortoise Forum and Hermann Tortoise:
For a question such as this, you should supply your habitat.
- measured temperature
- measured humidity
- The tortoise could be allergic to your substrate
- changing to kitchen towels or newspapers can single out this issue.
- The substrate could be too dry and might require additional humidity.
- loose substrate could have become lodged in the tortoise's nasal cavity
Wheezing and clicking can occur with Redfoot tortoises when they lack proper humidity or are kept too dry.
- ensure he doesn't feel light or have dry, flaky skin; this can indicate dryness.
- if the eyes of the tortoise are slightly watery; this can indicate dryness.
- increase the humidity; try for 80%. You can use a digital hygrometer.
- provide access to a warm, fresh, water bath at least once daily
If you are concerned about shell rot due to increasing humidity, ensure the enclosure is kept clean and periodically clean your tortoise lightly with a soft toothbrush.
- ensure the water content of foods is sufficient
- ensure water is available
Illness / Disease
- whistling when breathing may indicate a respiratory infection or pneumonia.
- Metabolic Bone Disease (MBD) causes shell deformity, which could create breathing irregularities.
- if you suspect either of these, consult a professional veterinarian, as medications may be needed
Some red-footed tortoises just whistle regardless of humidity and health.
In your particular case, I suspect this is due to humidity, but we would need more data and an implementation of a humidity plan to conclude this.