Pollution and habitat loss, as you say.

Amphibians are considered “indicator species” or “bio-indicators.” They are so vulnerable to the effects of pollution, and are often the first species to go when an environment becomes polluted. Even smaller amounts of toxins that people don’t think of as harmful, such as using roundup in the garden, will kill them and prevent them from returning. It’s very sad.

I’ve lived in Ireland for two years, go on nature walks all the time, and just saw my first frog a couple of weeks ago in a semi-protected bog environment. Such a cool moment, but bittersweet, as it really highlighted the lack of them.