"otter spraints and tern's eggs and coypu skulls"
by cm
Coypu
Creative Commons Attribution Share AlikeCoypu - Credit: Philippe Amelant

 Spraints are (very specifically) the faeces of otters, counted by researchers as a proxy for otter numbers.

 Terns are seabirds, similar to gulls.

 Coypus are semiaquatic rodents, similar to beavers.

 

Coypu Skull
Creative Commons Attribution Share AlikeCoypu Skull - Credit: B0rmann, Wikimedia