Manna Farmers of Australia

“You Must Construct Additional Pylons!”…

Well, no…  not really pylons…  this manna I am referring to is also not the same as heavenly mana, nor is it the same as the biblical manna.  In fact, the manna I am referring to is a sugary crystallized sap that oozes out of manna-gum trees in Australia.  As for the farmers that ‘farm’ them?  They are an endangered Tasmanian songbird known as the ‘forty spotted pardalote’, Pardalotus quadragintus!

Forty Spotted Pardalote  By JJ Harrison (jjharrison89@facebook.com)

What makes this bird so unique is that scientists have observed the most interesting behavior from these small peckers.  Amanda Edworthy and Samuel Case of the Australian National Univerisity in Canberra monitored these birds, whose population drastically fell 60% in 18 years, in the latter half of 2014.  When they observed this novel foraging behavior called “mining” or “farming” in these pardalotes, they were ecstatic with the hope that this trait can help them recover their numbers in the wild.  In nature, this foraging behavior of “mining” or “farming” sap from trees is very rare.  However still, the foraging behavior of these pardalotes is very similar to the North American Sapsuckers.  Just like sapsuckers, these pardalotes also return to a scar on the tree that they have left behind, to enlarge the hole and increase sap production (or in this case, inducing sap leakage).

Case and Edworthy discovered that these pardalotes preferably feed their nestling chicks manna, which accounts up to about 85% of their diet!  The crazy part about that is, manna in their natural environment only accounts for about 2% of the total available foods!  Fruits, insects, and other invertebrates are far more available in their immediate vicinity, yet they still choose to “farm” these sources of manna.  As to why this might be the case, the scientists propose that these birds might be “farming” manna because it is rich in carbohydrates along with easily metabolized nitrogen.  Case and Edworthy propose that this outstanding adaptation might have arose because parent birds wanted to feed their nestling chicks the most valuable food resource available to them!

Although “farming” or “mining” is definitely observed throughout the animal kingdom, they are still considered a rare aspect of nature.  Other species of birds and other mammals that also feed on these manna however do not “farm” the manna source directly from the tree.  This shows that these pardalotes may be contributing to their ecosystem as eco-engineers as they are providing a food source, not just for themselves, but for many other animals as well.  So in all essence, these pardalotes definitely deserve the title of being Manna Farmers of Australia.