Clever -- in the Southern Ocean, scientists are using elephant seals like Argo buoys, attaching tags to the seals that record temperature, salinity and pressure, that they send via satellite when the seal surfaces. Here's a paper where they used these data to improve understanding of the deep ocean circulation in the Southern Ocean.
They say the tag is put on their head with a harmless glue that comes off when the animal moults.
Here are some tags on their back flippers. I think I'd prefer that, but am not totally sure.
The Internet of things now includes elephant seals. Squirrels can't be far behind.