When autumn days grow short and temperatures cool, many birds that spend all summer at Hilton Pond Center return to their "winter" homes in the Neotropics. And it's a good thing, since many of our summer breeders are primarily insect-eaters that would find slim pickings after the first frost hits. Perhaps the only reason these birds come north in spring is to take advantage of North America's abundant topography, where there's plenty of room to raise a family or two. If so, there's no reason to stay here in winter when eggs would freeze and hungry nestlings would die for lack of food.

Considering all this, you might think it strange that we found an active bird nest colony at Hilton Pond Center the first week in October . . .

. . . until we explain that our discovery was actually a cluster of Bird's-nest Fungi. This little fungus is aptly named, for it does indeed look much like a structure built by birds, and the resemblance is greatly enhanced by a cluster of "eggs" that lies within.

Several species of Bird's-nest Fungi occur in North America, but among the most common--and the one we found at Hilton Pond Center--is Striate Bird's-nest, Cyathus striatus, so-called because of vertical lines or striations inside the cup.

Distantly related to the more familiar gilled mushrooms (Hymenomycetes), the Bird's-nest Fungi are grouped in the Class Gasteromycetes, an assemblage of oddly shaped fungi such as puffballs, earthstars, and stinkhorns. Despite their diverse external appearances, all these share a common characteristic--the basidiocarp--a structure that encloses the developing spores until it ruptures and releases them. In a Bird's-nest Fungus, the "nest" is the basidiocarp and the "egg" is a "peridiole."

Bird's-nest Fungi are true saprophytes that live off dead matter such as sticks, bark, old wood, or other plant debris; our colony at Hilton Pond Center erupted on wood chips we had spread to stop erosion along a trail. When conditions are right--i.e., moist ground and warm temperatures from July through October--Striate Bird's-nest appears as a tiny brownish-tan button that elongates into a shaggy, vase-like structure about a half-inch tall (above right). As the vase develops, the "nest" opening is covered by a thin, white membrane (below left) that eventually ruptures to reveal the dark gray "eggs" within.

Each spore-filled "egg" is tethered to the nest by a tiny coiled filament. When a large raindrop hits the inside slope of the cup, it propels the "egg" up the other slope and out of its nest, snapping the filament. Ideally, the filament wraps around an old twig and holds on tightly until the "egg" finally opens and releases the spores. (This process by which the "egg" is expelled provides Striate Bird's-nest with an alternate common name of "Splash Cup.") As it germinates, the fungal spore produces a root-like mycelium that grows into the twig and begins digesting the woody cellulose.

Although Bird's-nest Fungi occur naturally in open woodlands in much of the U.S., perhaps the best place to look for them is beneath the shrubs in your own front yard--right where you scattered that layer of wood mulch to keep down the weeds. A Bird's-nest Fungus may not be as showy as your spring azaleas, but it's at least as interesting to look at, and it plays a valuable role by decomposing organic matter and returning valuable nutrients to the soil. At Hilton Pond Center we're more than a little grateful for decomposers such as Bird's-nest Fungi, without which our trails would soon be knee-deep in unrotted twigs, leaves, and tree limbs.

The following species were banded this week (1-7 October):

Chestnut-sided Warbler--1
Magnolia Warbler--2
Hooded Warbler--1
Palm Warbler--2
House Wren--1
American Goldfinch--4
Carolina Chickadee--1
Eastern Phoebe--3
Common Yellowthroat--1
Black-throated Blue Warbler--1
Ovenbird--3
Gray Catbird--1
Northern Cardinal--3
Swainson's Thrush--8
House Finch--1
Scarlet Tanager--4
Gray-cheeked Thrush--1
Downy Woodpecker--1
Eastern Towhee--2

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WEEKLY BANDING TOTAL
(1-7 October 2001)
19 species
38 individuals

BANDING GRAND TOTAL
(since 28 June 1982)
122 species
39,438 individuals

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