Three winters of searching the southeast U.S. by a team from the Cornell Lab of Ornithology has apparently yielded a lot of bird data but no ivory-billed woodpeckers.

“The lab will continue to be a hub for information, reports and scholarship about the ivory-billed woodpecker,” said Ron Rohrbaugh, director of the lab’s Ivory-billed Woodpecker Research Project—“including through an online database where members of the public can report sightings.”

“But unless new evidence surfaces, it’s probably safe to say that we’re not going to put forward any more comprehensive, systematic searches like we’ve been doing for the last five years in Arkansas and with the mobile team,” Rohrbaugh said.

Birdwatchers contributed $36 billion to the U.S. economy in 2006, the most recent year for which data is available, according to the U.S. Fish and Wildlife Service. Read the announcement here.

Here’s an experiment for the kids during summer vacation: Use a clean jar and a coffee filter to find out what kind of particles the rain washes out of the atmosphere. Find instructions here, courtesy of the state Department of Environmental Conservation.

I spotted an indigo bunting in my backyard this morning. The bird was hopping around in some ferns and scrubby brush behind the house.

Indigo buntings, if you’ve never seen one, are just so, so blue – bluer than blue jays, bluer than bluebirds. They’re very eye-catching.

But that color in birds — we’re talking blue — is an optical illusion. The feathers of blue jays, bluebirds and indigo buntings don’t contain a drop of blue pigment. The appearance of blue is a function of the feather’s structure.

In a blue jay feather, a transparent layer of clear cells containing tiny particles and air spaces lies on top of a layer of dark cells containing melanin pigments. Upon striking a blue jay feather, light first passes through the clear, upper layer where molecules of gas or tiny particles scatter the shorter wavelengths of blue and violet light back to our eyes. When the light enters the underlying, heavily pigmented layer, most of the wavelengths longer than blue – including red and orange – are absorbed by the melanin pigment. So we see a blue bird.

Indigo Buntings have no blue pigment; they are actually black, but the diffraction of light through the structure of the feathers makes them appear blue.

Photo of eastern bluebirds by TJN photographer Frank Becerra.

And speaking of dying and/or dead fish, check out my colleague Laura Incalcaterra’s story about dead carp found in the Hackensack River in West Nyack. The state Department of Environmental Conservation is checking out the matter.

Researchers will be trying to figure out what apparently killed a 20-foot-long basking shark that washed ashore today a few miles east of Jones Beach.

Thought to weigh about a ton, the shark was spotted this morning by surfers in the waves breaking on a town beach. It’s thought to have suffered from some illness.

Basking sharks aren’t considered dangerous because they eat plankton. More on the species here.

And, of course, here’s the headline reference.

Also missed last week during my absence was the return of El Nino, which, the National Weather Service describes as “a climate phenomenon with a significant influence on global weather, ocean conditions and marine fisheries.”

What does that mean for you?

El Niño’s impacts depend on a variety of factors, such as intensity and extent of ocean warming, and the time of year. Contrary to popular belief, not all effects are negative. On the positive side, El Niño can help to suppress Atlantic hurricane activity. In the United States, it typically brings beneficial winter precipitation to the arid Southwest, less wintry weather across the North, and a reduced risk of Florida wildfires.

When we last left the bobolinks in North Salem, there were 23 male birds, according to the Bedford Audubon Society.

Well, the birds were busy this year in the unmowed fields in Westchester County’s northeastern corner. Jim Nordgren, the society’s executive director, and Tait E. Johansson, Bedford Audubon’s naturalist, visited the fields again last week where they first found bobolinks this spring. They had tried to convince some landowners and managers not to mow their fields until the bobolinks raised their families because the birds nest on the ground.

Nordgren then supplied this update:

. . . we counted a total of 116 bobolinks, a combo of adult males and females and fledglings—a huge number.

Our initial take on this is that there were the original 23 adult males, an equal number of adult females, for about 50, the rest, 60 or so, must be fledglings, which is stunning.

But it makes sense, 23 or so active nests producing 3 young for about 75 fledglings, 50 surviving.

These 50 fledgling would be a total of zero fledgling if mowing had taken place in June.

Among the items I missed during my vacation last week was this: “A runway at John F. Kennedy International Airport was shut down briefly Wednesday morning after at least 78 turtles emerged from a nearby bay and crawled onto the tarmac.”

The herd(?) of turtles on July 8 was said to consist of females looking for a place to lay their eggs.

A group of 78 diamondback terrapin turtles, each weighing two to three pounds and measuring about nine inches long, spent about 35 minutes on the runway before they were removed via pickup truck. The turtles appear to be a group of females who are getting ready to lay eggs, and were looking for a place to nest en masse.

Want to check in on some of your favorite critters this holiday weekend? The state Department of Environmental Conservation, along with some partner organizations, has put together a Web site dedicated to the state’s Watchable Wildlife.

New York State has long been one of the nation’s premier, year-round destinations for wildlife viewing because of its range of habitats, migration corridors, public lands and public facilities. A national survey estimated that there are nearly four million people that participate in wildlife watching in New York annually, and while participants are increasing their appreciation of nature, they often also contribute to local economies. Watchable Wildlife . . . provides a user-friendly way to look up the best locales and settings to view wildlife – and helps promote eco-tourism opportunities in the state.