Shortly after being fed, most songbird nestlings produce what is called a fecal sac – a mucous membrane (usually white with a dark end) that contains their excrement. This sac enables easy removal of the chicks’ waste by the parents. In an effort to keep its young healthy and to reduce the chances of predators finding the nest, the parent takes the fecal sac in its beak, flies away and discards it some distance from the nest.
Some nestlings, including those of Warbling Vireos, are extremely cooperative when it comes to assisting their parents in keeping the nest clean. Just prior to producing a fecal sac they position themselves with their rear ends up in the air (see photo), where their parents can easily procure the fecal sacs when they appear.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Some of the most prolific flowering shrubs in the Northeast are dogwoods. In the spring, their flowers attract attention and at this time of year their colorful fruit stands out. There are many species of dogwood, two of which are Red-osier Dogwood (Cornus sericea) and Silky Dogwood (Cornus amomum). These two shrubs can be hard to tell apart, as they both have white flowers, red stems and similar foliage. In the fall, however, the color of their fruit differs, as does their pith, or central stem tissue. The mature berries of Red-osier Dogwood are dull white and its pith is also white. Silky Dogwood’s blue berries have white blotches, and its stem and branches have a salmon-colored pith.
The fruit of these dogwoods and others is an extremely important source of food for many migrating songbirds, as well as resident birds. Wood ducks, Northern Cardinals, Eastern Bluebirds, Gray Catbirds, Purple Finches, Evening Grosbeaks, American Robins, Yellow-bellied Sapsuckers, Wood and Hermit Thrushes, Red-eyed and Warbling Vireos, Cedar Waxwings and Downy Woodpeckers all consume dogwood berries.
As a rule, male birds do not sing near their nest. When they approach their nest, whether to take their turn incubating eggs, brooding nestlings or delivering food, they are apt to be silent, or sing much more softly than usual, so as to avoid bringing attention to the nest. There are exceptions to this rule, however – male Chipping Sparrows, House Wrens, Common Yellowthroats, Hermit Thrushes, Black-billed Cuckoos, Scarlet Tanagers, Orchard Orioles and American Goldfinches have been heard singing not just near their nest, but while sitting on it! Warbling Vireos are by far the most persistent nest singers. When the male Warbling Vireo is incubating, he sings at all times of the day, as many as 20 bursts of song during one spell on the nest. Listening for the Warbling Vireo’s song and locating the songster can often lead you to its nest. One wonders what function the song has that makes it worth drawing this kind of attention to the nest.