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Archive for the 'Edge of Nature' Category

Edge of Nature: Big bat’s numbers decline in O.C.

February 23rd, 2010, 9:57 am by

The sound would come at night, from high in the sky — to our ears a chirping bird, but to experts, unmistakably a mammal.

The creature is the western mastiff bat, the largest U.S. bat with a wingspan of nearly 2 feet.

These high fliers are seldom seen as they cut the night sky with their piercing echolocation pulses, searching for moths and other insects. They typically fly hundreds of feet up, their sonar helping them zero in on otherwise elusive prey.

Bat researchers say this sound can be heard across the county, as well as throughout the rest of the Southwest and northern Mexico.

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Edge of Nature: Humble ‘water flea’ is surprisingly useful

February 16th, 2010, 2:23 pm by

At two millimeters long, the tiny “water flea” — really a crustacean — is unlikely to qualify as charismatic wildlife.

It might be worth a second look. The creature not only serves as prey for a variety of animals, but has proved useful to humans, both in the laboratory and the aquarium.

These often transparent organisms live in fresh water. Their odd lifecycle fascinates naturalists: as with fairy shrimp, their eggs can survive in dried-out form. When rains return the eggs come to life and hatch, populating storm-fed pools and ponds.

Female water fleas also give birth to clones of themselves without needing to mate, a trait known as parthenogenesis. They reproduce in this manner most of the year, but then, later in the year, give birth to males. The males mate with females to produce more offspring.

Water fleas, however, are extremely sensitive to pollution of almost any kind, which kills them quickly. That allows scientists to make judgments about water quality based on the presence, or absence, of water fleas.

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Edge of Nature: Small duck makes big impression

February 9th, 2010, 10:15 am by

Among the winter visitors paddling around in bays and reservoirs, the bufflehead is a standout: both this duck’s small size and its white head-patch earn it many a second look. edgeg0209

While the duck itself is among the smallest in North America, its head looks almost too large for its body. According to one source, the puffy nature of the head invited comparisons to buffalo, and gave this bird its common name.

These are diving ducks, becoming completely submerged as they hunt for underwater insects. Buffleheads are also known to favor snails in winter.

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Edge of Nature: A prickly start to flower season?

February 2nd, 2010, 10:31 am by

As the rains soak in and the sun shines, the early bloomers will begin to splash Orange County’s wild hillsides with color. One likely candidate is prickly phlox, a three-foot shrub that explodes with pinkish flowers. phloxeon

The phlox can bloom as early as February, one wildflower authority says, and can be found in open portions of the county’s chaparral habitat. It favors dry hillsides.

The word “prickly” suits this native plant. Its leaves are pointy and sharp, despite the inviting blossoms. It even has something of a prickly nature: the plants, which thrive in decomposed granite, often grow alone.

Look for rosy-pink flowers 1 to 11/2 inches across, with a white center and a long tube.

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Slimy intruder takes gardens by storm

January 26th, 2010, 7:56 am by

They were brought to California in hopes of inspiring a restaurant rage. Today, brown garden snails provoke rage among homeowners and landscapers. bgsnailgoc

Though slow-moving and delicate, they’ve invaded urban areas, and are surprisingly tough, able to survive the hot, dry months. When it’s cloudy or rainy, they can emerge from their hiding places in staggering numbers, making slimy trails in a beeline for garden plants.

The snails are said to have been a poor choice for escargot; introduced in California in the 1850s for eating, they proved to taste bad, and were soon replaced with choicer breeds.

By that time, of course, the snails had escaped.

These snails hide on sunny days under boards, down low on fences, under rocks, or among weeds at the bases of trees. In dry times, they seal themselves in their shells with a membrane described as “parchment like,” often glued to fences or walls.

They’re hermaphrodites, so all can lay eggs by the dozens. Their single, muscular foot leaves a trail of mucus that stays visible after they’ve passed.

And they devour a wide variety of plants, including leaves, flowers and fruits – helping them become established throughout the state wherever there are plants and irrigation.

Scientific name: Cornu aspersum
Sources: Orange County Entomologist Nick Nisson; “Snails and Slugs Management Guidelines,” University of California Integrated Pest Management Program Web site.
Next week: Prickly phlox
Illustration: Register files

Edge of Nature: This phoebe thrives in dry country

January 19th, 2010, 8:23 am by

The Say’s phoebe is most plentiful this time of year in Orange County, when winter visitors swell its ranks, often appearing in urban settings with open country nearby. saysphoebegoc

Unlike two other phoebe species that frequent the county, this tail-wagging, insect-snatching bird thrives in dry settings where trees and shrubs are sparse. Fields of grass, whether native or non-native, are the phoebe’s hunting grounds, and they’ll even take advantage of ballfields and urban parks.

This time of year, however, they can be seen in moist habitats as well as dry.

The phoebes might perch on weeds, rocks, fences or small bushes, waiting to snag insects on the wing, or hover over a patch of ground to drop down when they catch sight of prey.

The menu includes bees, wasps, beetles, moths, grasshoppers, crickets, even flying ants when they can get them.
Far fewer of the birds are seen in summer, but Orange County does have some breeders – more were found to be here than birders thought, in fact, during survey work done in the 1980s. They might nest under eaves of houses or in bridges or cliff faces close to dry creeks and grassy fields.

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