Sunday, February 24, 2013

Duck Date

Last February I wrote about a pair of interesting puddle ducks I saw in Brooklyn Bridge Park. Click here for that blog. She was a mallard, Anas platyrhynchos. He was an American black duck, Anas rubripes. She would normally mate with a green-headed male mallard duck. But they appeared to be a couple. 

I think I saw the same pair in the same spot today.  

This is the female mallard duck. Both genders of mallard have conspicuous white borders on the blue patch of wing feathers called the speculum.
This is the male black duck. His plumage is subdued compared to the famous green-headed mallards.  His speculum does not have a white border. Click on this to see the male mallard in a previous blog. 
When I came upon the pair today, they were performing courtship displays. She had her neck extended and was lying low in the water. He was swimming around her, pumping his head up and down. 
Courtship postures. 
He stepped onto her back briefly, they mated in the water, and then he hopped off. He flapped his wings and raised his body in a splashy post-copulatory display. Then he paddled to the shore to nibble at plants and preen. The female dashed around the pond for about ten minutes of post-copulatory splashing. 

When the celebration is over, she may lay eggs, and hatch some hybrid chicks with a combination of mallard and black duck features.  

Monday, February 18, 2013

A Clone is Born

Purple-spotted lily aphids, Macrosiphum lilii. Click to enlarge.
This is a picture of the lower surface of a lily leaf, flipped over. I took it in the Shakespeare Garden in Central Park in June. Look what's going on underneath! The big aphid in the upper left of the group is giving live birth to a tiny red-eyed baby.

The nymph is exactly like its mom except for size. It's a clone! Throughout the summer, aphids in this genus reproduce without sex by a process called parthenogenesis. Offspring develop from unfertilized eggs that do not undergo meiosis.

This method of reproduction is one of the reasons that an infestation of aphids can grow so quickly -- no need to date and mate. If an infested plant gets too crowded, winged females may be born and fly to another host plant. Near the end of the year, after many parthenogenetic generations, males and sexually reproducing females are born. They mate and lay eggs. The eggs lie dormant over the winter to hatch in spring and start it all over again.

An odd thing about aphids that reproduce like this is the possibility of telescoping generations: a female may be carrying an unborn daughter that is parthenogenetically pregnant with its own daughter. Like those nested Russian dolls. Cool!

Sunday, February 10, 2013

Meet the Yellow-collared Scape Moth

The yellow-collared scape moth, Cisseps fulvicollis. Click to enlarge.
I found this moth near Atlantic City, New Jersey, in September, 2012. It is black with bright yellow trim, slender, and about half an inch long. It was nectaring on goldenrod at mid-day. Almost as if trying to pass itself off as a wasp.

It is Cisseps fulvicollis, a wasp-mimic member of the Tiger Moth family, Arctiidae. But it is all moth at heart. They fly at night, too, and are attracted to lights.

A scape is the lowest section of an insect's antenna; theirs must have really impressed the entomologists who named them.

Sunday, February 3, 2013

Along the East River

I took a cold walk by the East River today. Brant geese, Branta bernicla, were lunching on the lawn in Brooklyn Bridge Park. 

Brant are often mistaken for Canada geese, but they are different species. I've written about their differences; click here for that blog
The lawn the brant geese were trying to eat turned out to have too much human traffic for comfort. The flock flew away, silhouetted against lower Manhattan. 
There was a female red-breasted merganser, Mergus serrator, dozing among the pilings south of Pier 1. She had her head turned back and her beak tucked into her feathers. She didn't raise her head, but she was watching me. Expand to full screen, and click to enlarge the photo and you will see her dark eye. Also note the crazy hairdo, and the Dr. Seuss-like reflection of her head in the water. I have written about this duck before; click here to see a picture of the red-eyed male
Beautiful ring-billed gulls, Larus delawarensis, were riding the river swells, pecking tidbits from the water. 
Click on the photo to enlarge. 
Other ring-bills were dining on takeout. 
And the flag on the Brooklyn Bridge was at half mast for Ed Koch.