This is not a question we can answer, this is a question only you can answer because it is asking for your personal belief on wether alien's exist outside of earth or not.
Decline in the global population of amphibians is due to multiple reasons which include:
A moist ecosystem is necessary for amphibians especially for the purpose of their reproduction. The drainage of the wetlands deprives them of their habitat.
Pollutants adversely affects the survival of the gametes, tadpoles or the adult amphibians by acting as toxic agents and inhibiting their normal metabolic function.
Infectious diseases often cause their death resulting their population to decline.
Global climate warming affects their normal metabolic growth and development and hence causes their population to decline.
