Sunday, September 15, 2019

Acorn Woodpeckers: Sap Connoisseurs!

Immature male Acorn Woodpecker consuming sap (identified by his dark irises and lack of a black band between the white and red on his forehead). This young male was the most avid sap-eater.

The local Acorn Woodpeckers started creating small holes in one of our re-grown live oaks last year. Some sap began to flow and they partook of it happily, although only intermittently and on a small scale. This is not particularly unusual behavior and has been documented for the species, but I had never personally observed it (let alone photographed it).

This year, in the first couple weeks of August, the sap holes were re-opened and the sap flowed freely! We had such a wet winter and spring that presumably the sap was more plentiful, and for a couple weeks, the sap flows on this tree were visible from quite a distance, they were so substantial. The woodpeckers were the primary exploiters of the sap, and had clearly been the creators of the flows in the first place, but other local residents tried to sneak some sap too. Most notably, a White-breasted Nuthatch would try valiantly to get a little sap when it could before being chased off by an irate woodpecker.

After several days of intense sapping, the tree was taken over by honey bees. Then the bird visitors, including the "rightful owners", the Acorn Woodpeckers, dropped off dramatically, seemingly not wanting to tangle with the buzzing hordes.

Eventually the sap dried up, and the woodpeckers have not reopened the holes to any great extent, which is probably better for the health of the tree anyway.

Below are photos of the tree, the sap flows and the avian visitors (before the bees took over).

The sap tree with the most holes, in our landscape. A couple nearby trees had fewer holes. These small live oaks had regrown from ground level following the Cedar Fire in 2003.

An example of how vigorous the sap flows were around their peak.

An adult female Acorn Woodpecker eyeing a sap hole. Note her pale iris and black band on the forehead.

In the act. She is using her tail as a stabilizer here.

The young male woodpecker with his bill in a hole. He was a devoted sap-fan. He (or a close look-alike) also likes visiting the hummingbird feeder.

I sat out in the open on a small stool to take these photos and the birds were quite comfortable with my presence. 

On the day that I did the most photography, this little White-breasted Nuthatch was able to move in on a sap hole after the woodpeckers shown above departed.

Finally some sap! The woodpeckers had little tolerance for moochers like this little one.

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