The electronic mice repellers on the market are designed to specifically target rodents – this includes all members of the rodent family, such as rats, hamsters, guinea pigs, ferrets, rabbits, squirrels – and yes, gerbils. All reputable products come with clear warnings not to place the repeller in the same room as any pet rodents – so if these instructions had been read and followed, the gerbil would not have suffered stress and death. In any case, a pet rodent showing signs of distress should have immediately been taken to the vet for examination.
Electronic rodent repellers act by producing high frequency ultrasonic sound waves which are above the hearing range of humans and common pets (cats, dogs, birds, fish). The human ear can only detect sound waves up to 20kHz, and cats and dogs can only hear sound waves up to 27kHz. However, rodents can hear above these frequencies and therefore, will be affected by the high intensity ultrasonic sound waves emitted by repellers. This creates a hostile environment for them in the area around the repeller (similar to some humans avoiding loud heavy metal concerts!)and encourages them to avoid the area. The electronic repeller works as a humane form of pest control as it simply repels rodents without poisoning, harming or killing them. However, obviously a pet rodent which cannot independently move away from the repeller will be subjected to severe auditory stress which may lead to death.
Certain species of frogs (e.g.. the Chinese concave-eared torrent frog ‘Amolops tormotus’) have been discovered to communicate using ultrasound so it is possible, in theory, that the ultrasonic waves emitted by an electronic repeller may affect a frog, although it is unclear what the effect may be and also unclear if the particular species of pet frog in question would be affected at all. Ultrasound cannot pass through walls, floors and ceilings so if in doubt, it would be best to keep the frog’s terrarium in a different room to the one hosting the electronic repeller. Alternatively, contact the manufacturers of the product and query them specifically about its effects on pet amphibians.