With the sub tropical deciduous forests of Mexico left well behind, the forests of California appear with increased frequency this morning. The Pacific Slope Flycatcher is moving north through the night when the familiar crescent shape of the Monterey Bay interrupts the California coastline at daybreak. Halfway up the shore of the bay a body of water extends east to comingle with the oak woodlands and grasslands of the surrounding hills.
There, near a redwood lodge known to innumerable generations is its ancestral home. The large mature coast live oak west of the lodge escaped the woodcutters of the 1800’s and now dwarfs most other trees in the forest. This tree will mark the centerpiece of its life for the next four months.Gliding down towards this landmark tree, the flycatcher is one of the first of a rich parade of birds that migrate north every Spring. Ending its journey, the bird alights on the big oak’s hanging branches, a light and seasonally familiar presence taking its place on the Elkhorn Stage. Soon the distinctive squeaky “pseeet” call of the Pacific Slope Flycatcher joins the cacophony of birdsong that fills the air.
The canopy of the forest is alive with flying insects. The oak moth adults are in wing, flittering in light clouds. They are easy pickings for the Flycatcher, famished from its long journey to the Central Coast. It has been an especially good year for oak moths and they are everywhere and in various life stages.
Caterpillars are feeding on the oak leaves, nearly denuding some trees. The large oak is spared but nearby, some teenage live oaks have turned a dirty brown color as their leaves are consumed by the larvae. Caterpillars are crawling on the ground, easy prey for terrestrial predators. Small holes in the yard are testament to the feeding behavior of striped skunks who seek out the balling masses of caterpillars just under the surface of the soil. The worms move up fence posts, buildings and trees. Our mature oak is hosting a macabre parade of these animals as they settle in various parts of the tree to transition to the pupa stage.
In our area, there are often two generations of oak moths per year, and these spring pupae soon hatch out into adult moths to repeat the cycle in midsummer. By then, the Flycatcher has returned to its wintering ground in Central Mexico, probably intersecting with another insect bloom at its peak.
As the late summer and autumn oak moths continue their life cycles, the oak is once again peppered with pupa, nestled in the topography of its trunk, branches and stumps.
Many years ago, a malformed branch of the oak broke off in a high wind. Soon, fungi and other microorganisms softened the wound, creating a cavity that received small amounts of moisture condensed from the summer fog. In this moist tree cavity two meters above the ground, the arboreal salamander eggs are fully developed. Young fully formed salamanders are breaking through their translucent shells. Mother is nearby, protecting her young as they hatch. Within a few days as the fall rains moisten the air, they disperse from the cavity to the main trunk to ground level.
They were made to be climbers, equipped with prehensile tails and toe pads on their long digits. Although they are more tolerant of dry conditions than many other salamanders, they are lungless salamanders and need to stay moist in order to breathe through their skin. They quickly conceal themselves under the deep layer of oak leaves that have carpeted the forest floor. These inch long juveniles will spend most of their lives under this cover, coming to the surface on rainy nights to disperse further and feed on invertebrate prey brought to the surface. They relish the rainy season and feed in earnest to store resources as this season subsides.
As winter turns to spring, the salamanders go deeper under cover or up into the big oak as ring-necked snakes patrol the forest floor in increasing numbers searching for their prey. This common Central Coast species frequently feeds on small salamanders.
As this drama plays out within the drip line of the great oak, the Spring air is once again punctuated by the call of the newly arrived Pacific Slope Flycatcher, home again after its long travels.