Branching out

Just two days ago I was stopped short by the incessant squawking of a young black phoebe bird (Sayornis nigricans) being fed an insect by its parent. This offspring was fully fledged and able to fly, yet it was still dependent on others for food. I saw the parent hop to an elderberry tree and take one of the berries into its mouth. The youth also watched but did not partake in the elderberry treat; rather, it remained on the branch as the parent flew to a different nearby tree.

At once I was struck by the monumental task that the youngster must be facing. Here on the verge of being pushed from the home, it still had to learn the fundamentals of survival. Already it had mastered the concept of gravity and learned to fly without injury. Food training was to begin.

First it was fed a juicy insect. Okay, insects are food. But then, with both of us watching, plants were also placed on the menu for this young phoebe. Looking around, I was staggered at the multitude of epicurean possibilities.

I began to wonder, how would this phoebe learn to discern what was food and what was not? All of a sudden I had a new appreciation of what it means to branch out and break the rut of safe comfortable routines.

Tyrant flycatchers

Phoebes seem designed for a lifestyle which, one hopes, makes branching out a little easier. Being part of the family Tyrannidae, phoebes belong to a group known as the tyrant flycatchers. They have acquired this name because of their ability to fly from the perch and catch insects on the wing.

There are about 400 species in the Western Hemisphere, 37 in North America. While there are at least 10 tyrant flycatchers found in the Santa Monica Mountains, only two are phoebes in the genus Sayornis.

The black phoebe is most common in wet riparian areas but is also seen in the chaparral and oak woodlands. Growing to a length of 7 inches with a wingspan of 11 inches, it is easily identified by its black head, breast, back, wings and tail. Contrasting sharply is the white belly. Head plumage gives it an appearance of having a sort of pointy crown. Another identifying feature is the tail-wagging behavior. The black phoebe will wag its tail in an up-and-down circular motion when perched.

The other phoebe found in the Santa Monica Mountains is the Say's phoebe (Sayornis saya). Unlike the woody wetlands that are home to the black phoebe, the Say's phoebe prefers wide open habitat such as farm fields and open meadows. I have often marveled at this bird's balance as it perches on a thin plant stalk to attain a better view of the field and the insects within.

Outwardly, this bird varies dramatically from the black phoebe. The head and upper parts are a light gray while the tail is black. The breast is a more pale gray, and the belly is buff orange. This bird is slightly larger than the black phoebe and will also wag its tail but in a figure eight pattern.

Food on the wing

Although differing in habitat and appearance, both phoebes rely on hawking or sallying for survival. Hawking is a sit-and-wait maneuver. The phoebe will sit on a perch and wait until it sights an insect. It will then fly out and catch the bug in midair. While all tyrant flycatchers use this behavior, phoebes have an additional strategy to aid in feeding. Rather than always catching on the wing, they will fly down from a perch and take insects and spiders moving on the ground. This is a behavior known as ground sallying.

Several adaptations aid the phoebe in its aerial acrobatics. The primary adaptation is the bill, which is large, broad and flat. The size and shape of the bill maximize the bird's chance of seizing an insect in midflight. It is interesting that unrelated families of birds that also rely on sallying for food have evolved similar bill shapes and sizes.

In addition, flycatchers have welldeveloped rictal bristles around the base of the bill. These bristles are more prominent on flycatchers that hawk and less so on those that glean insects off of branches. It is believed that these bristles help the bird to determine the position or movement of the prey when in the bill.

Beyond facial adaptations, phoebes have shorter, rounded wings designed to generate lift for takeoff and low-speed flight. This enhances their hawking ability, although it hinders their migrating potential.

Luckily, though, the phoebes in our mountains do little migrating. Rather, they remain here, learning new skills and branching out to enjoy the abundance of their home.