Monday, April 27, 2015

One Kind of Mutualism

Left: An unbanded grackle ignores the photographer. Right: Horchata forages for trash
Pictures by Michelle Gertsvolf

A few class sessions ago, we were talking about the different relationships between different species. What caught my attention was the talk of symbiosis, or mutualism. In this +/+ relationship, both species benefit from the interaction. I began to wonder, can humans be included in this sort of relationship? While by no means neccasary to either species, the humans at the Santa Barbara Zoo do benefit a bit from the resident Great-Tailed Grackle population.

As part of my research under Dr. Corina Logan, I go to the Santa Barbara zoo every week to observe the resident Great-Tailed Grackle population. We had captured and banded eleven of these grackles over the past two quarters, and tested their intelligence with some basic tasks such as stone-dropping and object manipulation. Now after these grackles had been released, we observe them in the wild to see if the 'smarter' birds according to the tests end up with more nests and chicks (currently it's breeding season - a few of the grackles already have hatched eggs and it's adorable!)

I noticed something interesting though. The grackle's primary source of food is what they steal from human zoogoers. During lunchtime, the food court is a flurry of bird activity as grackles zoom from their nests to grab french fries and back. I wonder, is this a sort of mutualistic relationship? Humans get a cleaner zoo while grackles get food for their young. Perhaps it's not very significant, but it sure is interesting.



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