  Nonadiabatic transitions are known to be major loss channels for atoms in
magnetic traps, but have thus far not been experimentally reported upon for
trapped molecules. We have observed and quantified losses due to nonadiabatic
transitions for three isotopologues of ammonia in electrostatic traps, by
comparing the trapping times in traps with a zero and a non-zero electric field
at the center. Nonadiabatic transitions are seen to dominate the overall loss
rate even for samples at relatively high temperatures of 10-50 mK.
