I've entered up into my attic recently to pull out an old shoe box of cassette tapes.

What's the box I think?

Oh yeah, a bit dusty.

There from 1994 I was studying red squirrels in England for my master's degree in ecology

and I recorded the whole experience on my Walkman.

Red squirrels 1994.

Here's a bit of the tape.

I'm walking through this forest and I've got 30 or so traps laid out.

So I've set our traps, caught the squirrel, fitted a radio collar to the squirrel that you want to follow.

And now it's a case of actually following the bleeps of the collar remits.

So let's give it a go.

Now you can perhaps hear a faint bleeping.

Talk about a trip down memory lane.

The UK has just one native squirrel species.

They'd almost disappeared all over England and I was studying their home range and activity patterns

just like I'd do later with slightly larger grizzly bears.

This is the second trap that I've set.

So I'll just bring the trap down from the tree.

This is one that I've been tracking.

This is a female and she's not lactating.

Otherwise her nipples will be showing through from her white chest hair.

She's still got the tough ton of hair.

...