Ardenwood Farm and The Monarch Butterflies.

Just across the Dumbarton Bridge in the East Bay, lies Ardenwood Farm. This farm, now a park, was established by George Patterson around the time of the gold rush. He bought land with the money he earned working for farmers near Mission San Jose and became one of the wealthiest and most respected men in the area. His original house and land now form this park which still functions as a farm the way it did a century ago.

Purely by chance, it also enjoys occasional fame when the Monarch butterflies come there to spend the winter. For the last few years their population seemed to be dwindling, but in December 2011 they appeared to come back in full strength.

They are an unusual butterfly in that they are known to migrate over huge distances - they may be encountered anywhere from Western Canada down the western states all the way to Texas and Mexico. But these migrations last longer than the lifespan of a butterfly - it takes multiple generations to fly south and back again, so that a given population cluster may be three or more generations removed from the original cluster that migrated away from a given area.

Salmon will return from the ocean to the stream where they were born. Monarch butterflies will return from thousands of miles away to the grove where their great-grandparents were born - how they know to navigate and find the exact clump of trees is unknown.

There are only a handfull of places where the Monarch butterfly collects in large numbers - clustering in large clumps hanging from tree branches likes grapes on a vine. One of these places is Ardenwood Farm.


After entering the park at the main gate next to the car park, a few minutes stroll takes us past the old farmhouse. Because of the Christmas season, it has some traditional decorations - thankfully not too gaudy...


At the side of the house is a verandah looking out over an extensive lawn toward a classical Victorian gazebo. Adjoining the rear of the house is an "add on" to house extended family.


At the front gate we had asked where the butterlies were, and were told to walk past the main house until we came to a railway line passing thrpugh a grove of Eucalyptus trees, and that's where (we were assured) the butterflies would be.

Another five minutes walk past the main house brought us to the promised grove.


On the walk there we had encountered one or two solo butterflies flitting around some flowers, but the expected clusters of butterflies eluded us, until we met this gentleman in amongst the Euclyptus trees.

The badge hung round his neck identified him as a volunteer naturalist and docent - he looked the part with a many-pocketed jacket and binoculars to hand.

He pointed into the branches above us.


Looking more carefully in the direction he pointed, we saw them. A casual passer-by would have missed them as they were in the shade and didn't really jump out at the observer.

But once you knew what to look for, and wandered around to where the occasional shaft of sunlight penetrated the tree canopy to light up a cluster, then it became obvious.


A little bit of sunlight, and the clusters start to stand out.


Where a sunbeam actually breaks through, the real colors become apparent.


Some butterflies show the expected deep orange, others are much lighter in overall color. At first I thought this was a question of seeing the upper versus the lower surface of the wings, but that doesn't appear to be the case.


The colors are much more even in this group, but still there are a few very light-colored examples.


Here the colors run the gamut from light yellow to medium orange to a very bright darker red.


Clustered on the end of a Eucalyptus branch


Yea verily, Solomon in all his glory was not arrayed as one of these.


I assumed that the damage to the Eucalyptus leaves was inflicted by feeding butterflies, but they are unconnected.

The damage to the leaves is caused by an unrelated beetle, the butterflies feed on milkweed - which contains a toxin that makes them unattractive as food for predators.


The Monarch


I just happen to have flown over Ardenwood a few years ago and took this picture. This is the main house (seen earlier above) and the butterflies are in a Eucalyptus grove just off the bottom left corner of this picture.