“Do phoebes raise more than one brood a season? asks Flo Vannoni of Redding.
“A pair of phoebes nested over our sliding door and succeeded in fledging three babies,” she writes. “The babies left the nest about one week ago and since then, we had not seen parents or babies. Today one of the parents returned to where the nest had been – I had removed it. Is it possible they would start another nest?”
Many species have more than one brood in a season, as Mary Walsh of Ridgefield – who sent the accompanying shot of a second-brood bluebird chick – can attest.
“The baby bluebirds fledged last week from a nesting box on my property,” Mary wrote July 14. “It is the second brood this summer.
“I found one baby hiding out on the running board of my Sequoia. As I tiptoed within a few feet, the baby bluebird hopped away. It appeared to be struggling to fly… Mom and Dad were in the trees chirping away. I had to leave and he was gone when I returned home. I hope he took flight.”
Flo wondered whether her phoebes would start another nest. They probably would, and perhaps in the same location since they would likely have used the old nest a second time.
Eastern Phoebes are very loyal to nesting location. They not only use the same nest for their two broods in a season, but also tend to re-use it for several years. That is relatively unusual among songbirds, most of whom build new nests every year. Phoebes simply make repairs and spruce up the previous year’s nest – “waste not, want not” is apparently the motto of this avian recycler.
For many songbirds, whose offspring hatch relatively quickly and don’t take long to fledge, having two broods in a season in this part of the country is normal. There is plenty of time to raise two families, and then fatten up for the migration south or, for many year-round species, to stock up on food for the winter.
Studies have found that northern birds of a given species tend to have fewer broods than southern birds, yet all produce around the same number of young per season.
In the North, for instance, Eastern Bluebirds typically have two broods. In the South, because the warm, insect-filled season is longer, bluebirds often have three broods.
Nevertheless, both northern and southern bluebirds produce about the same number of offspring per season because bluebirds in the North lay more eggs per brood than bluebirds in the South. A pair of Connecticut bluebirds might have two nestings, each with five babies, while a North Carolina bluebird couple might have three nestings with three eggs each. The result is about the same.
Did the southern birds work harder? They had more nestings, but fewer mouths to feed at each. Moreover, they probably did not migrate as far, if at all, to set up home.
(Photo of bluebird parent arriving with food for babies is by Kevin M. Doyle.)
Friday, July 31, 2009
“Do phoebes raise more than one brood a season? asks Flo Vannoni of Redding.
Saturday, July 18, 2009
A male cardinal is the most common, North American “animal” of size that is virtually all red, a color used by few wildlife species hereabouts. We have a few small red beetles and salamanders plus several birds, like tanagers, that mix bright red with other others, but what else is almost all-red?
Ornithologists say male cardinals have probably evolved their bright, distinctive color to attract female cardinals. However, how do they survive so well in the wild with such a rare, flashy outfit that, even among the fully leaved trees of summer, seems to stand out like a sore thumb?
Hawks see red. Why, then, don’t they decimate the population of male cardinals, which seem to do little to hide themselves, especially in winter when the deciduous trees have no leaves for cover.
The answer probably lies in our own perception of color vs. a bird’s perception.
“Birds see very differently from the way that we do,” notes Chris Elphick, assistant professor of ecology and evolutionary biology at the University of Connecticut.
“They see into the ultraviolet ranges and have different types of receptor cells in their eyes, so a bird that seems the brightest to us is not necessarily the brightest to another bird -- such as a hawk.
“How a hawk sees a cardinal -- or anything else -- is thus hard for us to conceive,” he adds.
An evolutionary biologist named John Endler found that how a color looks can depend on surrounding colors because of the wavelengths of light that are absorbed by the environment. Thus, in the forest full of green, red light tends to be absorbed, so red objects would not stand out the way they would against, for instance, a snowy background. “This phenomenon helps explain why scarlet tanagers -- or any number of warblers -- can be so hard to pick out even when there are not leaves obscuring them,” Professor Elphick observes.
He adds: “It’s important to remember that evolution always involves a balance between benefits and costs. Being conspicuous has potential costs -- e.g., increased predation risk -- but if those risks are balanced by greater benefits -- e.g., more/better reproductive opportunities -- then maybe that’s OK, evolutionarily speaking.
“Also, hawks are rare relative to cardinals, so even though a cardinal may be vulnerable when it encounters a hawk, there may be enough cardinals that do not have such encounters that the selection pressure to be less conspicuous is not as great as it might seem. And, of course, just because a cardinal is seen by a hawk doesn’t mean it will get caught.”
Laura Erickson, science editor at the Cornell Lab of Ornithology, notes that hawks can definitely see red. “But they can see a whole spectrum of colors, and much of their favored prey is more muted in color, so there is no good reason for hawks to focus on cardinals.
“Cardinals, like Scarlet Tanagers, spend much of their time hidden in foliage, and it’s very difficult for even accipiters [bird hawks] to grasp prey from the branches that cardinals favor.
“Goldfinch or Prothonotary Warbler yellow, Blue Jay blue, and oriole orange are almost certainly at least as vivid to a hawk’s eyes.
“The brilliant colors of many birds, especially when found on males only, tend to be territorial and sex signals. Of course, birds do tend to be safer when not noticeable to anything, so many of the most brilliant birds do molt out of those bright colors during the non-breeding season. New feathers on male Northern Cardinals are edged with brown, and the tips wear away to reveal the brightest red at the end of winter/early spring. But Baltimore Orioles and Blue Jays stay in their bright feathers year round.”
Laura adds, no doubt with a smile, “You know what color is even rarer than red in the bird world? Pink. Apparently, birds shun Mary Kay cosmetics, too.”
Monday, July 13, 2009
You can find them in hanging flower baskets, an old boot, a garage shelf, or under a bridge -- birds build nests in the strangest places, note the folks at Cornell Lab of Ornithology. As part of their Celebrate Urban Birds project, the Lab is sponsoring “Funky Nests in Funky Places!” competition.
Celebrate Urban Birds is a free, year-round citizen-science project, focused on birds in neighborhood settings. While we are much more “suburban” than “urban,” Cornell points out, “We will gladly accept data from all locations, including suburbs, small towns, small cities, as well as large cities. It is exciting for us to receive data from a large variety of ‘Green Spaces.’”
For the Funky Nests in Funky Places challenge, the lab wants you to take photos, do a painting, write a story, or shoot a video showing a bird’s nest built in some out-of-the-way or out-of-this-world place. “When observing nests please be sure to avoid touching them or disturbing the birds,” Cornell adds.
There are prizes for the best shots, including a Leica C-Lux 3 compact camera, bird feeders, shrubs for planting, and more.
To enter, email your entry to firstname.lastname@example.org. Links are acceptable for videos. Write “Funky Nests” in the subject line. Include your name and mailing address. Explain why you submitted your entry -- what's the story behind it?
Deadline for entries is July 31.
Visit the Celebrate Urban Birds website, birds.cornell.edu/celebration/ for more information.
Thursday, May 28, 2009
Readers over the years have reported sudden changes in the numbers of the usually common birds they’ve had at their feeders or in their yards, including Black-capped Chickadees, American Goldfinches, Blue Jays, Purple Finches, and even crows.
Among the factors that can change what shows up in your yard are:
- The neighborhood food supply. Feeders are only a fraction of the food source for birds. A change in the natural food supply can make a lot of difference in their local bird populations. For instance, last season’s acorn crop was apparently not a large one hereabouts. The mast, the annual production of tree nuts in a region, can vary from year to year, and a low mast year can drastically affect populations of Blue Jays as well as mammals, such as squirrels and chipmunks. Blue Jays are major consumers of acorns (and may plant more oak trees than do squirrels, which get all the credit). Wild Turkeys are also big acorn-eaters; wonder how they are doing.
- Neighborhood habitat. Changes in the places where birds nest, roost and feed can vary the population. For example, some birds like evergreens for roosting and nesting. If someone cut down, or disease killed, a noticeable number of evergreens in the area, certain species might become less common.
- Predator changes. A hawk or perhaps even an owl deciding to nest in the middle of an area popular with song birds would discourage the songbirds from hanging around. Even something as seemingly innocuous as a family cat – and worse, feral cats – can affect the bird population in a small area. (The number of birds killed by pet cats each year would astound most people.)
- Man-made environmental changes. Obviously, major sources of noise, light, or air pollution can affect local bird populations. Set up a rock crusher next to a stand of trees that have sheltered birds for years, and you will undoubtedly chase them all away. But less obvious changes can occur. For example, spraying trees for caterpillars may kill many of the insects the birds feed on, forcing them to look elsewhere.
- Disease. Of course, disease can affect local and regional populations of birds. We saw just recently many reports of Pine Siskins dying, probably from Salmonellosis. West Nile virus, to which corvids seem more susceptible to than many other species, may be lowering the jay population.
Tuesday, April 21, 2009
When an enemy approaches, many birds react with a technique called “mobbing.” Crows are famous and vociferous mobbers, ganging up and screaming at hawks or owls.
For years, scientists considered this mostly a method of chasing away predators.
But Eberhard Curio, a German scientist, wondered. He set up a special cage with two blackbirds, a stuffed owl, and a soda bottle. Only Blackbird A could see the owl while Blackbird B could see Blackbird A and the soda bottle. Blackbird A angrily yelled at the owl, while Blackbird B saw only the yelling bird and the bottle, and figured Blackbird A was yelling at the bottle. Blackbird B later taught Blackbird C to fear the bottle, and Blackbird C then taught Blackbird D, and so on.
The curious Curio concluded that mobbing blackbirds were acting as tutors, teaching birds to “know thine enemy.” So the next time you see a dozen crows mobbing a hawk, you may actually be witnessing a big outdoor seminar.
Friday, April 17, 2009
Each spring, many people take down their feeders for the season. There is plenty of natural food around, they figure, so why spend money on seeds?
Actually, plenty of food is almost always. Except in the direst conditions, such as a blizzard with deep snow and subzero temperatures, year-round birds can find enough food to survive our winters; otherwise, they wouldn’t be here in cold season.
For the birds, our feeders are added conveniences, be it summer, fall, winter or spring. For us, they are entertainment, as well as a source of knowledge about the wildlife around us.
The truth is, we feed the birds because it’s fun, not because they need our food.
However, there are arguments for not feeding in the early spring through late autumn. One arrived last week in the form of a warning from the Connecticut Department of Environmental Protection: it’s Black Bear season.
Bears have emerged from their winter dens and are wandering the countryside, looking for food and mates. Bird seed at feeders (along with garbage cans and outdoor grills) attract them.
“Homeowners can often prevent bear problems by making unavailable or simply removing food attractants that draw bears,” DEP said.
Most inland towns in Fairfield County, Connecticut, and Westchester County, New York, have annual bear sightings nowadays – Ridgefield had 11 last year, Wilton, 7, Redding, 3, Weston, 1, and New Canaan, 1, DEP records say. A Ridgefielder had two feeders torn down last fall by what was probably a bear (see photo).
Black Bears are shy and rarely get involved with humans. Some people would consider a bear in the yard exciting, but others would rather see these critters, weighing hundreds of pounds, only in a zoo. If that’s you, take down your feeder now.
Another problem with year-round feeding is disease. Warm weather can exacerbate the transmission of diseases, especially those involving bacteria like salmonella. Disease can come from seeds on the ground that develop molds and/or that have been tainted with feces.
Safe, warm-weather feeding requires maintenance: regular cleaning of the feeders as well as of the ground beneath them, especially if you use seeds with shells.
Some people don’t put out feed in the summer and fall because they think it will delay the departure of migratory songbirds, which may then perish in cold weather. However, scientists believe the changing length of the day – more light in spring, less in fall – triggers migration, no matter how much food is available locally.
Yard aficionados who like their lawns to look like putting greens eschew warm weather feeding, especially with sunflower seeds, because of the mess it can make. The husks of whole sunflower seeds, for instance, contain a poison that kills grass.
On the plus side, attracting birds to the yard in summer helps control many kinds of pest insects.
Bird-feeding in warm weather pretty much boils down to whether you want to do it, can afford to do it, and are willing to do it safely. If you are neat, clean and aren’t afraid of bears, feed on!
Thursday, April 09, 2009
We've gotten many reports of Pine Siskins this winter and early spring. The incredible irruption of these northern birds into southern territories is like none in recent years, and siskins are still here as of April 7.
But this big crowd of birds has brought with it a problem – aside from breaking our birdseed budgets with their gluttonous consumption. Siskins may be prone to disease.
Kathy Cory of South Salem, N.Y. tells us, “I noticed a lethargic siskin in the yard this morning, which perished soon after. That's the second dead one in the yard this week, and I remembered seeing another sickly one a few weeks ago.
“I have learned that they are very susceptible to salmonella, possibly from dirty bird feeders. Since all of us have had very busy bird feeders this winter, perhaps we need to be more diligent than usual about cleaning them. Could it be the feeders or is there another force at work out there?”
On the Connecticut bird hotline, sick siskins have been a hot topic.
Julie Keefer of Lyme said there were “a lot of reports of siskins dying in North Carolina this winter and I think it was pretty much a mystery as to why.” She wonders whether the ones succumbing here caught their fatal disease in the South – the ones we are seeing now may be migrating north and are not necessarily the same birds that were at our feeders in winter.
Paul Carrier, a Harwinton naturalist and wildlife artist who found dead siskins in his yard recently, said, “As we feed the birds from the same feeders continually in one spot all winter, it is not natural. The accumulation of husks and spillage under the feeders will eventually become a breeding ground for molds and disease, especially as it gets warmer. We all must clean up under the feeders as much as we can now that it’s warmer out.”
Paul added, “thistle is a very fast decomposing seed (husks), especially when wet. These I believe are the culprit to the sickness in these siskins, especially when they eat them from the ground. When it is cold, the seeds don't grow molds and such. But when wet and warm, they become instant breeding grounds for disaster!”
Cornell Lab of Ornithology’s Project Feeder Watch has been getting many similar reports. “As often happens in birds that feed and roost in tight flocks, there have been outbreaks of salmonella reported in some Pine Siskin flocks,” Cornell said. “Salmonellosis is caused by a bacteria... It is a common cause of mortality in feeder birds, but the symptoms are not always obvious. Sick birds may appear thin, fluffed up, and may have swollen eyelids. They are often lethargic and easy to approach. Some infected birds may show no outward symptoms but are carriers of the disease and can spread the infection to other birds.”
Salmonellosis is mainly transmitted by fecal contamination of food and water by sick birds, though it can also be transmitted by bird-to-bird contact, Cornell says. Occasionally, outbreaks cause “significant mortality.”
Cornell says, “Clean your feeders about once every two weeks, more often during times of heavy use. For best results wash your feeder thoroughly in soapy water, then soak or rinse it in a solution of one part bleach to nine parts water. Dry the feeder thoroughly before refilling.”
It adds, “Remember to rake the ground below your feeder to prevent accumulation of waste. Moldy or spoiled food is unhealthy, not only for birds but for your outside pets. Bird food scattered on the ground also can attract rodents. Consider moving your feeders periodically to limit the accumulation of waste.”
One hotline participant said sunflower chips, which siskins love, have the advantage of not having hulls to get moldy and diseased on the ground.
Friday, April 03, 2009
Nearly a third of the nation's 800 bird species are endangered, threatened or in significant decline due to habitat loss, invasive species, and other threats, says a new report on bird populations.
"Just as they were when Rachel Carson published Silent Spring nearly 50 years ago, birds today are a bellwether of the health of land, water and ecosystems," said U.S. Secretary of the Interior Ken Salazar in releasing The U.S. State of the Birds, the most comprehensive study of its kind.
"From shorebirds in New England to warblers in Michigan to songbirds in Hawaii, we are seeing disturbing downward population trends that should set off environmental alarm bells. We must work together now to ensure we never hear the deafening silence in our forests, fields and backyards that Rachel Carson warned us about."
The report also said habitat restoration and conservation have reversed previous declines in many species of waterfowl, such as pelicans, herons, egrets, osprey (pictured above), and ducks.
"These results emphasize that investment in wetlands conservation has paid huge dividends," said Kenneth Rosenberg, director of conservation science at the Cornell Lab of Ornithology.
"Now we need to invest similarly in other neglected habitats where birds are undergoing the steepest declines."
The report combines data from three long-running bird censuses conducted by thousands of citizen scientists and professional biologists. It indicates a 40% decline in grassland birds over the past 40 years, a 30% decline in birds of aridlands, and high concern for many coastal shorebirds. Also, 39% species dependent on U.S. oceans have declined.
Dr. David Pashley, American Bird Conservancy's vice president for conservation programs, said, "In addition to habitat loss, birds also face many other man-made threats such as pesticides, predation by cats, and collisions with windows, towers and buildings. By solving these challenges we can preserve a growing economic engine – the popular pastime of bird watching that involves millions of Americans – and improve our quality of life."
Surveys conducted by the U.S. Fish and Wildlife Service and U.S. Geological Survey, including the annual Breeding Bird Survey, combined with data gathered through volunteer citizen science program such as the National Audubon Society's Christmas Bird Count, show once abundant birds like the Northern Bobwhite and Marbled Murrelet are declining significantly, and may become extinct.
"Citizen science plays a critical role in monitoring and understanding the threats to these birds and their habitats, and only citizen involvement can help address them," said National Audubon Society's Bird Conservation Director, Greg Butcher. "Conservation action can only make a real difference when concerned people support the kind of vital habitat restoration and protection measures this report explores."
The report is available at www.stateofthebirds.org.
Posted by =jack at 5:38 PM
Saturday, March 21, 2009
Bird watching can be a lot more than just identifying what shows up in the yard. A good bird watcher also notices what the birds are doing.
Nine-year-old Blythe Filaski of Ridgefield is a good bird watcher. “Recently, I spotted two nuthatches on my pear tree,” Blythe writes. “The nuthatches must have been mates, because their bills were together, almost as if they were kissing. I think they were sharing seed.”
Blythe was lucky enough to observe an interesting courtship behavior of the White-breasted Nuthatch. Here is how Arthur C. Bent described a pair of nuthatches 60 years ago:
“All through the winter the pair has lived not far apart, feeding within hearing of each other, but the male has paid little attention to his mate; in fact, on the food shelf, he has shown dominance over her; but now in the lengthening, warmer days of spring, he becomes actively engaged over her comfort.
“A real courtship begins: He carries food to her and places it in her bill, he stores bits of nut in crevices of bark for her convenience, and he often addresses his singing directly to her. Standing back to her, he bows slowly downward as he sings, then in the interval before another song he straightens up, then bows as he sings again. The songs come with perfect regularity over and over again and can thus be recognized even in the distance as the courtship song.”
Ornithologists have been fascinated by this behavior in many species, including cardinals and hawks. Of course, on the simplest level, it can be taken as a way of wooing a mate by making her happy – just as men often take women out to dinner on dates.
However, scientists see more in the behavior. The food exchange not only develops pair bonding, but may also help convince the female that her mate will be a good provider during the forthcoming nesting period.
“Increasing evidence suggests that females who receive more food from their mates lay larger clutches” of eggs, wrote David W. Winkler, in Handbook of Bird Biology (Cornell Lab of Ornithology, 2004). “Mate feeding probably makes it possible for a female to raise more young, by keeping her in good condition and allowing her to put more energy into feeding the young.”
In other words, a nice dinner now may mean more and healthier kids later.
So, for the nuthatch and many other species, “the way to a woman’s heart is through her stomach.”