EPOW - Ecology Picture of the Week

Tool-Users of the Islands

left:  Large Cactus Finch (Geospiza conirostris)
right:  Warbler Finch (Certhidia olivacea)
Gardner Bay, Espanola Island, Galapagos Islands, Ecuador

Explanation:  The Galapagos Islands -- off the coast of Ecuador in the Pacific Ocean, famous for inspiring Charles Darwin's concepts of evolution and adaptation -- still hold some amazing secrets. 

It is well documented that the Woodpecker Finch (Camarhynchus pallidus) -- one of 14 species of "Darwin's finches" -- uses sticks and cactus thorns as tools by which to extract insect prey from crevices.  In doing so, it deftly manipulates the stick or thorn in its bill. 

But unreported – as far as I can tell – are my observations of two other finch species that also seemed to have at least initial behaviors of manipulating sticks in their bills as they fed upon leaves and debris on the ground. 

These were the Large Cactus Finch (Geospiza conirostris) and the Warbler Finch (Certhidia olivacea). 

I speculate that perhaps these behaviors may be the initial stages of eventual tool use by these species, perhaps as may have initially evolved with the Woodpecker Finch.
  

Large Cactus Finch on the beach of Gardner Bay, 
Espanola Island, manipulating small sticks with its bill.
Is this the inception of the evolution of tool-using behavior?

This week's images were frame-grabs taken from videos I shot of these birds scavenging among the debris on this beach.  The birds were turning over leaves and branches in search of food.  Occasionally each bird would grab a stick, not just tossing it aside or digging under it, but truly grasping the stick and turning it around, manipulating it in its bill.

It would be most interesting to return to this island in years to come, to see if this behavior has developed further, perhaps into true tool use.

 

Information:
    Greenhood, W., and R. L. Norton.  1999.  Novel feeding technique of the woodpecker finch.  Journal of Field Ornithology 70(1):104-106.
    Tebbich, S., and R. Bshary.  2004.  Cognitive abilities related to tool use in the woodpecker finch, Cactospiza pallida.  Animal Behavior 67:689-697.
    Tebbich, S., M. Taborsky, B. Fessl, and D. Blomqvist.  2001.  Do woodpecker finches acquire tool-use by social learning?  Proceedings of the Royal Society of London B 268:2189-2193.