Why does np.bitwise_and() returns a boolean series , when two unalligned int64 series are passed to it as argument

Question

The two unaligned series below are:

sa = pd.Series([1, 0, 1], index=list("ABC"))

sb = pd.Series([0, 0, 1], index=list("ACB"))

Now when np.bitwise_and(sa, sb) is executed it returns a boolean series as given below:

A    False
B    False
C    False

dtype: bool

The answer should be series of integers ? why this operation is returning boolean series?

How ever if the labels of both series are aligned then the answer is also an integer series

sa = pd.Series([1, 0, 1], index=list("ABC"))
sb = pd.Series([0, 0, 1], index=list("ABC"))

np.bitwise_and(sa, sb) results in :

A    0
B    0
C    1

dtype: int64

Please make it clear