EPOW - Ecology Picture of the Week

Cuckoo With A Lesson

Little Bronze-Cuckoo (Chrysococcyx minutillus), Family Cuculidae
Northern Territory, Australia

Explanation:  While exploring deep in the gray mangrove forests of coastal "Top End," northernmost reaches of Northern Territory, in northern Australia (ha, lots of "northerns" here for such a "southern" continent), I happened upon this Little Bronze-Cuckoo on perch overhead.  

Ranging in southeast Asia, New Guinea, and northern and eastern Australia, Little Bronze-Cuckoos hold the record for being the world's smallest member of their cuckoo family.  It is one of seven species of cuckoo that breed in Australia.  

But what struck me about this underside view was the ecological lesson of countershading, or how so many species of diverse groups -- insects, fish, birds, reptiles, and mammals! -- have evolved lighter coloration below (on the ventrum) and darker coloration above (on the dorsum).  The function is to better blend into the light sky when viewed from below, and into the darker ground when viewed from above.  And the advantage of that is to be more cryptic, to help avoid predators!  

This is such a common phenomena in nature, that it earned its own title as Thayer's Law.

And that's a cuckoo with a lesson!