What is unclear to me is whether a special phone app is required or not. One of the web pages indicates that it piggybacks onto the infrastructure for airtags/android tags (not clear which). Certainly, if I was building these, that is what I would do as getting a custom app in enough phones would be extremely difficult.

Having said that, the claim is also that these tags report temperature as well — but there is a field (personalized name) that could be used to transport that information. In any case, it is an impressively small tracker!

Thank you - the tracker they use weighs in at 60 milligrams, incredibly light.

An app for tracking monarchs with these tags is here for iOS [1].

[1] https://apps.apple.com/us/app/project-monarch-science/id6460...

I've moved some of those links to the toptext. Thanks!