Dig, Wait, Listen: A Desert Toad's Tale

The desert Southwest
is full of sounds.

Skitter, skitter, scratch.
A scorpion is crawling.
Pop, pop, pop.
kangaroo rat is hopping.
Tsk, tsk, tsk.
A rattlesnake is
shaking its tail.

But the spadefoot toad
is quiet in her
underground burrow,
listening for one sound
in particular...
What is that sound?
And what will the
spadefoot toad do
when she hears it?