Some more info on frog tracking I have found these days online. A real tracking device for frogs exists and has been tested in a number of studies already. it is more of a belt rather than a backpack. I am not sure how much it affects the swim performance but it definitely looks much cooler than the pack!
Image from Holohil Systems Ltd., paper Evaluation of a radio-belt for ranid frogs by Galen B. Rathbun and Thomas G. Murphey
Image from UCBerkleyNews from a study in the Sierra Nevada to research the decline of the mountain yellow-legged frog.
There is more to this topic about amphibians and reptiles in our gardens tough. Apparently no one really knows what is happening at dawn, dusk or tough out the night at the back in the grass. An online article on BBC.co.uk describes with the title 'Stock-take' of garden creatures and calls out “Whether it is frogs in your ferns, or toads in your tulips, a coalition of wildlife charities is asking for volunteers to carry out a national "stock-take" of the reptiles and amphibians in the UK's gardens.” So if you are a proud user of a back garden, report the activity you observe.
Actually, the two frogs ‘Blurb’ and ‘Rosi’ are now out and about the garden again, but without the GPS devices. No need to worry about them they are fine and probably remember the first of April!