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Sap Wells

Yellow-bellied Sapsuckers Drilling Wells & Lapping Sap

4-26-16 yellow-bellied sapsucker 191

Yellow-bellied Sapsuckers have returned and in between sending their Morse code messages, are drilling into over 1,000 species of woody plants to obtain sap.  At this time of year, sap wells are drilled into xylem tissues (transport water and nutrients from roots to branches) to feed on sap that is moving upward; after deciduous species leaf out, sap wells tap phloem tissues (transport sugars and other nutrients made in the leaves to other parts of the tree).  Unlike sap drawn from the xylem which contains from 2-3% sugar, phloem sap may contain 20-30% sugar.

Sapsucker tongues have a fringe of hair-like projections along the edges which enable the sapsucker to lap up the sap that accumulates in a well (“saplapper” would be a more accurate name for these woodpeckers).  Recently a female sapsucker landed on the trunk of a nearby Sugar Maple and tapped eight wells.  She then spent the better part of the afternoon inserting her brush-like tongue into the wells and drinking the sap that collected.  The entire time she was drinking sap, she was constantly (8 times per hour) evacuating a stream of clear liquid (as opposed to the typical uric acid excreted by birds).  Apparently much of what goes in must come out.

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