Sunday, July 31, 2011

Black Skimmers Take a Rest

I visited the Edwin B. Forsythe National Wildlife Refuge in Oceanville, New Jersey, this weekend.

Atlantic City looms across the bay. But cocktails and casinos seem a thousand miles away. The sounds of the Jersey shore on the refuge are the cries of gulls and hawks, the sudden clattering duets of clapper rails, and the rustling of marsh grass.

On this trip I saw something I have never seen before -- black skimmers lying flat on the beach like seals. Normally I see these flashy birds flying inches above the water surface "skimming" the water with their oversized lower mandibles while flying in tight formations. More often I see them sitting on the beach showing off their stunning profiles like in the picture below.

Black Skimmers and a few Forster's Terns on a marsh beach. 

Today many of the birds in the colony were lying prone and resting their big beaks in the sand, like in the next picture. It was about 100 degrees in the marsh. There is little shade. Birds of all kinds were cooling by gulular fluttering -- the avian version of panting. 

Perhaps the real surprise was that all of the skimmers weren't lying down; if there had been a wave-lapped sand beach on my side of the channel I would have considered it too. 

The skimmer on the left and the four in the center are prone on the damp sand. Click for a closer look. 

Sunday, July 24, 2011

European Visitors

New York City has seen record-breaking heat this week, but the crowds of summer tourists seem undaunted. Despite the 98-feels-like-102 degree temperature, there were European visitors on the Brooklyn Heights Promenade on Saturday morning -- both human and insect kind. One of them was Polistes dominula, the invasive European Paper Wasp.

The European Paper Wasp, Polistes dominula

This pretty black and yellow wasp with brown cellophane-like wings was first noticed around Boston about thirty years ago. It has since spread throughout the northeast and was recently seen in California. It likes urban settings, including New York City.

It seems to be shouldering out our native Northern Paper Wasp, Polistes fuscatus. And it preys on caterpillars, which is bad news for urban butterflies. As if that were not bad enough, it builds papery nests in crevices and hollows around human dwellings, like in unused pipes or inside birdhouses or porch lights; it's possible to intrude on a nest without noticing and get stung.

So the European Paper Wasp is an unfortunate import. I felt nevertheless sympathetic as the temperature pushed upward and I stood in the heat watching a wasp pause to drink from a small pool of water caught on a leaf.

Sunday, July 17, 2011

The Black-eyed Susan Universe

I followed a butterfly into a patch of black-eyed susans this morning. Then I spent the next hour finding interesting things there. Here are pictures of everything that sat still long enough to be photographed.

The painted lady butterfly, Vanessa cardui. 
A Eupithecia caterpillar that will soon become a small drab moth. 
Lygus lineolaris, the notorious Tarnished Plant Bug. This bug is so famous that it has a nickname -- TPB. It is one of the most serious pests of vegetable and fruit crops in North America. 
This pollen-covered bee is a female in a genus of "long-horned" bees, Mellisodes. Males in the genus are famous for their long antennae. (Which seem long only by bee standards.) 
A honeybee, Apis mellifera
A hoverfly -- easily mistaken for a bee. 
A hoverfly with a red mite attached to its leg. Oh no! 
A question mark butterfly, Polygonia interrogationis
The question mark butterfly gets its common name from a mark on its wing (click on the photo to enlarge it) -- a silver mark broken into an arc and a dot. Looks like a question mark, doesn't it?

Question marks are part of a larger group known as anglewing butterflies,  which all live in the northern hemisphere, have jagged looking wings, and spend the winter hibernating in shelters as adults. Their camouflaging colors help to conceal them when they settle in cracks and crevices for winter. Although they are not big nectar eaters (usually preferring overripe fruit, tree sap, animal feces, and carrion) they clearly sometime sip black-eyed susan nectar -- perhaps to clear the palate.

When you are checking the wings of brown butterflies for question marks, be prepared to find the question mark's close relative, the comma. Comma butterflies look similar except their silver wing mark is a one-piece comma-shaped arc.

Question marks and commas are called punctuation butterflies. There are just question marks and commas -- no apostrophes, which is probably good because they would likely be misused. But if there were periods, I would have put one right here at the end of the black-eyed susan story.

Sunday, July 10, 2011

Bird droppings...

Like humans, birds defecate the undigested remains of things they eat. Also like humans, they excrete the metabolic waste products that are left over after food is broken down for use by cells; that's mainly nitrogen. Humans excrete waste nitrogen as urea in urine -- it takes lots of water to make the dilute solution.

Birds can't be burdened with heavy water-filled bladders, and they need their metabolic water reserves for other things -- like long distance flights. They excrete nitrogen as a chemical called uric acid. It is excreted in a concentrated form with no dilution necessary. So birds stay light for flight. And uric acid excretion works fine inside eggs. The metabolic waste produced by a developing shell-bound bird fetus can be neatly stored within until hatching.

The white pasty part of bird droppings is uric acid. The dark part, sometimes brightly colored from the bird's diet, is feces. Birds simultaneously evacuate uric acid and feces from an opening just under the tail that is called the cloaca or vent. The cloacal sphincter muscle can provide ejaculatory force, as demonstrated by the defecating osprey in the photo below.

An osprey expels waste in a white stream with enough force to clear the nest. Click to enlarge!  

Some raptorial birds, like ospreys and owls, eat whole organisms. Ospreys eat fish and digest almost but not quite everything. They vomit the scales and other indigestible bits in compact "pellets." Owls regurgitate pellets of hair, bones, claws, and undigested parts of the small animals they eat. Both end up without much solid waste in their droppings, just a lot of white uric acid. The areas around their nests and eating perches get covered with droppings called "whitewash." Pellets can often be found on the ground below whitewash.

A royal tern in an indelicate moment. That's a little Forster's tern on the right, discretely averting its gaze.  

Sunday, July 3, 2011

Happy Independence Day!

A Black Swallowtail butterfly, Papilio polyxenes. It's the only red white and blue (and black) critter in my files.