Sunday, August 29, 2010

Wow -- that's a great egret!

The great egret, Ardea alba.

This bird has lots of names. It’s called the common egret, large egret, American egret, and white egret. And it's no surprise that many people have noticed the elegant and beautiful bird; it is more than three feet tall and has a wingspan over four feet.

The great egret is white with a yellow beak and black legs and feet – a combination of colors that distinguishes it from other herons and egrets you may encounter. It flies with its neck folded back, flapping deeply and slowly. 

It is often seen wading in shallow water or in mud, stalking its prey – frogs, snails, fish, insects, crayfish, and similar small things. This one often hunts in New York City's Central Park at the narrow end of The Lake just north of the Bank Rock Bridge. 

The great egret is found throughout the southern states and in estuaries and wetlands on both coasts during some part of the year, breeding mainly in the east but with exceptions. Some pairs breed in isolated spots and others in colonies. They build big nesting platforms of sticks, usually in trees, but also on the ground or in shrubs. Typically they lay three pale blue-green eggs. Males and females look the same. In breeding season they develop long plumes on their backs, which they erect and spread like big lacy fans.

The beauty of their plumes caused big trouble for them in the 19th and early 20th century. They were very popular decorations for ladies' hats. Wild bird hunting was unregulated then. Millions of egrets and other birds were slaughtered for their plumes and feathers. Common egrets were hunted to the edge of extinction. 

Public outcry saved them just in time and led to legislation that protects wild birds to this day. The Audubon Society was formed around then -- they incorporated in 1905; they led the cause, and later adopted the great egret as their symbol.

The great egret population has recovered and is doing well; its range in the United States is expanding.

Our taste in hat decorations has improved too.

There is more information about urban birds in my book,  Field Guide to Urban Wildlife, which will be published by Stackpole Books in spring 2011. 

Sunday, August 22, 2010

Eastern Tiger Swallowtail

It is easy to mistake this tiny caterpillar for a dried up bit of bird droppings. Clever disguise! It helps the little guy get through the treacherous early stages of caterpillar life when many are snatched up and eaten by birds.

A closer look reveals the caterpillar behind the disguise. This one is feasting on a lilac leaf. Eventually it will grow into the beautiful eastern tiger swallowtail butterfly, Papilio glaucus.

This one is a female -- the males have a few small spots of blue where she has those extensive blue patches on her hind wings. Take a close look and you will see that her wing edges are damaged; she may have escaped a bird  attack, or been tossed by rough winds.  As butterflies age their wings get worn and tattered.

Eastern tiger swallowtail butterflies sip nectar from a variety of flowers, including wild cherry and lilac blossoms. They don't mind urbanization so we see them in city parks and yards, and sometimes flying incongruously through the concrete canyons. This one was visiting the Shakespeare Garden in Manhattan's Central Park.

Sunday, August 15, 2010

Fennel time!

Fennel, Foeniculum vulgare 

A handful of crushed fennel leaves smells deliciously of celery and licorice. 

There is a little patch of fennel among the flowers growing on the extension of Middagh Street that passes over the Brooklyn-Queens Expressway near my home. The plant is tall with pretty feather-like foliage. Its tiny yellow flowers are borne in little bouquets that are technically called compound umbels, like the flowers of parsley and carrots.  Fennel is one of the main flavors in the cordial Absinthe, and it is used in herbal medicine too. The seeds are used as a spice, and some of us eat fennel bulbs and leaves as a vegetable. 

But we are not the only ones who like fennel. Wasps love it! 

On a sunny day a seemingly endless parade of exotic looking insects visits fennel blossoms, each more elegant that the last: thread-waisted wasps, potter wasps, mud dauber wasps, a good compliment of honeybees and bumble bees, and lots of fancy flies come in for a tasty sip of fennel nectar. 

Here are photos of a few recent visitors.

Isodontia elegans -- a "grass-carrying" wasp. 

They got the common name "grass-carrying" because they incorporate grass into their nests. 

Another Isodontia species. 

Polistes dominula -- the reviled European Paper Wasp. 

The European paper wasp is a relative new comer to the United States, introduced from Europe and first recorded in the northeastern United States in the 1980s. It has already gained a bad reputation as a cranky wasp that becomes aggressive toward humans with very little provocation. 

Sceliphron ceamentarium -- a black and yellow mud dauber wasp. 

Eumenes fraternus -- a potter wasp.

Visit this link to see how the potter wasp uses that fancy tail end to build a pot-shaped nest out of mud: 

There is more information about urban insects in my book,  Field Guide to Urban Wildlife, which will be published by Stackpole Books in spring 2011. 

Sunday, August 8, 2010

The Ailanthus Webworm Moth

Ailanthus altissima, the tree-of-heaven.

You may have seen this weedy looking tree growing in a vacant lot, or an alley, or in the space between sidewalk slabs. It thrives in cities and seems able to grow almost anywhere, even out of the sides of abandoned buildings. It has a strong smell that stays on your hand when you crush a leaf.

It's a Chinese native that was  introduced to the United States in the 1700s. It became naturalized and can now be found growing wild all over the country. This is the famous tree that Betty Smith wrote about in "A Tree Grows in Brooklyn."

The ailanthus tree has its own moth, Atteva aurea, the ailanthus webworm moth. The moth holds its wings rolled and close around its body while resting, so it looks a little like a long beetle.

Atteva aurea, the ailanthus webworm moth.

Like many other insects, this one was named after the food it eats -- ailanthus leaves. The "webworm" part of the name refers to its lifestyle during the caterpillar stage. The "webworms" spin silk webs on ailanthus trees and live in groups while eating foliage, like more familiar tent caterpillars.

Ailanthus webworms at home in their silk web.

Like the ailanthus tree, the ailanthus webworm moth is an introduced species. Except for populations native to southern Florida, ailanthus webworm moths came from Central and South America, where they feed on a tree that is closely related to the tree-of-heaven.

The introduced ailanthus webworm moth switched its diet to the introduced ailanthus tree and they took off together across the country.

How convenient!

There is more information about urban insects in my book,  Field Guide to Urban Wildlife, which will be published by Stackpole Books in spring 2011. 


Sunday, August 1, 2010

The false head hypothesis

The gray hairstreak butterfly, Strymon melinus.

This butterfly often perches upside down. It has tiny tails on its hind wings; when the butterfly is perched it occasionally rubs those wings against each other causing the tails to move. The black spot in the orange area is called an eyespot.

Upside down orientation, eyespot, and moving tails create the illusion of a butterfly's head!

Take another look. If you were a bird intent on eating that butterfly you might take a bite of the false head and be left with a mouthful of tails, wondering what happened, as the butterfly flew off in a totally unexpected direction.

(But some scientists think that birds preferentially attack butterflies from behind and the purpose of the false head is to deflect attacks toward the real head where the butterfly can see them coming.)


There is more information about urban insects in my book, A Field Guide to Urban Wildlife of North America, which will be published by Stackpole Books in spring 2011.