Must a Sotapanna take rebirth in the human realm again?

[Blueturtle227]

Or can they be reborn as a deva and reach Nibbana from the realms higher than that of the human?

[Ontheway]

Both ways are also possible. But due to the enormous merits accumulated during human lifetime, the immediate rebirth in Sutta stories are usually end up in Heaven.

For example, King Bimbisara (a Sotapanna) died and reborn as Janavasabha Devaputta under the command of Vessavana Maharaja (as in Janavasabha Sutta).

But then, after Sakkapanha Sutta event, the King of Gods - Sakka Devaraja (now a Sotapanna) will reborn to human world after his passing away from Tavatimsa Heaven.

‘Deceasing from the gods I shall forsake
The life that’s not of men, and straight shall go
Unerring to that womb
I fain would choose.

‘I who have had my problems rendered clear
And live delighting in His Word, shall then
Live righteously, mindful and self-possessed.

‘And if into my life thus rightly led
Enlightenment should come, then shall I dwell
As one who Knows, and this shall be the end.

‘This, lord, is the fourth meaning implied in what I said.

‘Deceasing from the human sphere, I then
Forsake the life of men, and lo! Once more
A god I’ll be, best in the Deva-world.....

[santa100]

Or can they be reborn as a deva and reach Nibbana from the realms higher than that of the human?

It depends on which type of Sotapanna they belong to:

(7) “Again, some person fulfills virtuous behavior but cultivates concentration and wisdom only to a moderate extent. With the utter destruction of three fetters, this person is a oneseed attainer who, after being reborn once more as a human being, [381] makes an end of suffering. This is the seventh person, passing away with a residue remaining, who is freed from hell . . . the lower world.

(8) “Again, some person fulfills virtuous behavior but cultivates concentration and wisdom only to a moderate extent. With the utter destruction of three fetters, this person is a family-to-family attainer who, after roaming and wandering on among good families two or three times, makes an end of suffering. This is the eighth person, passing away with a residue remaining, who is freed from hell . . . the lower world.

(9) “Again, some person fulfills virtuous behavior but cultivates concentration and wisdom only to a moderate extent. With the utter destruction of three fetters, this person is a seventimes-at-most attainer who, after roaming and wandering on among devas and humans seven times at most, makes an end of suffering. This is the ninth person, passing away with a residue remaining, who is freed from hell, the animal realm, and the sphere of afflicted spirits; freed from the plane of misery, the bad destination, the lower world.