There are clever ways of determining whether a number is a power of 2. That's no longer an interesting problem, so let's determine whether a given integer is an integer power of -2. For example:
-2 => yes: (-2)¹ -1 => no 0 => no 1 => yes: (-2)⁰ 2 => no 3 => no 4 => yes: (-2)²
Your input is a single integer, and output must be a truthy value if the integer is an integer power of -2, and a falsy value otherwise. No other output (e.g. warning messages) is permitted.
The usual integer overflow rules apply: your solution must be able to work for arbitrarily large integers in a hypothetical (or perhaps real) version of your language in which all integers are unbounded by default, but if your program fails in practice due to the implementation not supporting integers that large, that doesn't invalidate the solution.
This is a code-golf contest: the answer which has the fewest bytes (in your chosen encoding) is the winner.