Hi varna!!
You'll find that bunnie ears will change temperature quite often. AsJen mentioned, that's one way for them to help cool themselves.
Here's what Pam put in the Cheat Sheet:
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"Here's info on keeping rabbits cool:
Air movement is required for proper cooling in very humid areas ormoisture cannot evaporate. While many say to never blow a fan directlyon the rabbit, I recommend it when it's extremely hot and humid. Placethe fan a distance from the rabbit and have it gently blowing over thehot bunn. A little water can be placed on the ears, which serves tocool as it evaporates.
Understanding how the rabbit cools itself helpsus to provide the most comfortable environment for our rabbits:
The rabbit is cooled by 3 primary factors: Respiration, Ears and Nasal Mucosa.
80% of heat dissipation in rabbits occurs through the evaporation ofmoisture during respiration (breathing). Fans help this cooling processby speeding evaporation.
Cooling also occurs through nasal mucosa (by air passing over mucous membranes).
The ears are also important for cooling as the blood moves to the farthest (coolest) points away from the body core.
The rabbit will also stretch its body out as far as possible to coolthrough radiation/convection. Rabbits do not have functional sweatglands, and only loose a small amount of moisture through the skin dueto perspiration. The rabbits fur further inhibits the process of therabbit being able to cool itself by evaporation of moisture from theskin.
Since the rabbit cools primarily through respiration, we want toprovide air movement throughout the cage to evaporate the moisture fromthe rabbit's breath. In a serious situation of heat stress, you willnotice moisture around the rabbits face (especially around the mouthand nose) because the moisture is not evaporating.
A frozen bottle may be of only limited help without the proper air movement and evaporation.
Pam Nock"