What is the ruling on keeping animals—such as birds—in bathrooms?

Concealing oneself from animals is not obligatory. Thus, one does not sin by bathing or relieving oneself naked in the presence of an animal. However, nudity is generally disliked without necessity, out of modesty before Allah, due to the Prophet's (peace be upon him) saying: "Guard your 'awrah except from your wife or what your right hand possesses." And his saying when asked about being in seclusion: "Allah is more deserving that one should feel shy before Him than people."