Nighthawks

We could call it a "kettle," if they were hawks--a pretty good description of a flock where the individuals seems to boil from the top to the bottom over and over again. In that sense, I watched a kettle of Common Nighthawks over the dog park on September 20. I estimated at least 60 in the flock, but it could easily have been twice that. The kettle gradually moved west, the birds whirling and flashing like flakes in a snow globe. The birds never dropped as low as the tree tops, while below, a flock of migrating Green Darner dragonflies roiled in their own version of a kettle, 6 to 15 feet above ground. The Crossley ID Guide (Richard Crossley, 2011) mentions that they are often found along wooded streams, and the dog park is within sight of the Meramec River.

Nighthawks are not even close to being hawks, but they hunt on the wing, that is, they "hawk" for insects, and are most active in twilight. My dad used to call them "bullbats." If you use the word "bull" to mean "large or strong," they certainly would be large, strong bats, if they were bats. He told me they liked to hang around the lights at the ballpark and sometimes along the street. I used to see them in those places too as a kid, but I see fewer and fewer of them now flying erratically over towns. The Sibley Guide to Bird Life and Behavior, by David Sibley (2001), notes that Common Nighthawk populations have declined throughout their breeding range (p. 352). The breeding range covers most of the Canada and the US (excluding south and central California, Alaska, and areas near or north of the arctic circle), and the western portion of Mexico (excluding Baja California). Factors contributing to the decline include the use of insecticides, and the loss of open areas that they need for hunting and mating displays (Sibley).

Nighthawks don't build nests, laying their eggs on the ground in open, rocky areas. They have adapted to using flat roofs covered with gravel, but as these become less common and roofs insulated with smooth PVC coatings become the norm, nighthawks have lost an important resource. In her book 101 Ways to Help Birds, Laura Erickson (2006) discusses ways to accommodate nighthawk nesting sites (p. 169) by providing pads with gravel in shaded areas of flat roofs.

Besides their beautiful, haphazard flight, male nighthawks have an intriguing display. I heard it "in the wild" only once. I was sitting on the front stoop of a shop, enjoying a traditional St. Louis treat, a "concrete," when I heard it. Nighthawks had been flying overheard, calling with nasal, off-key notes, "beans...beans..." when I heard a sound that shouldn't have come from a bird. Greg Budney, audio curator of the Macaulay Library at Cornell, describes it as similar to "a truck roaring by, that suddenly disappears." Somewhere along the city street, a male nighthawk dove between the buidlings, creating that roar as wind passed through the long flight feathers. Perhaps he planned his display to take advantage of the echoes in the urban "canyon."

At the end of the recording below, you hear this mechanical sound. If you have 2 minutes, check out the video from Cornell's Lab of Ornithology which I embedded below it. Thanks to Bill Bouton for his great photo of a Common Nighthawk above, taken in northern California, and to Don Jones who recorded the species in New Jersey, and the Cornell Lab, all of whom licensed their work with Creative Commons.



You might also like:

Crossley ID Guide   

Macaulay Library of Animal Sounds

Mysterious Sounds of the Night

Pa-RUM-pa-pum-pum

Through May and early June I occasionally heard a rapid, metallic drumming—almost a trill. "I'll bet a woodpecker is drumming on someone's aluminum siding," I thought, but I could never find the bird. On Memorial Day weekend however, I heard the sound again—very close, but where?

  

Caught in the act! See the little drummer bird, just beneath the metal cap on my chimney? It is believed that woodpeckers use drumming as a substitute for song. Woodpeckers don't have a song for claiming territory or attracting a mate like a robin or cardinal would employ. They don't need one. All a woodpecker has to do if find some resonant material—a hollow snag, or your aluminum gutter—and drill, baby, drill! David Sibley's website has a great article about drumming, complete with sonagrams and recordings of Downy and the similar-looking and similar-sounding Hairy Woodpecker.

Sibley notes some intriguing findings in the research: both male and female Downy Woodpeckers drum and at all times a year. We assume the male is trying to attract a mate with his drumming/song. Is the female doing the same? And if we hear drumming in January, is that drummer defending a territory even though it's not nesting season? My grainy photo doesn't show the red nape patch, but this was a male playing his drum for me, and the neighborhood. What is he trying to say with his 15 beats per second?

When I visited southeastern Arizona in the summer of 2000, I fascinated to see that birders decorated their yards with dried agave stalks. The stalks seemed to advertise to hummingbirds that dinner time had arrived. Fiesty little Rufous and Black-chinned hummers would perch on the stalk, survey the feeders, and dive in. I was dying to carry off one of these stalks for my own yard, but alas, it would not fit into my baggage. I cast around for a substitute, and saw the potential in a year-old Compass Plant stalk.

I wrote about Compass Plant (Silphium laciniatum) last August. It's one of my favorites. This spring I tied several Compass Plant stalks to my fence. Investigating the stalk this morning, I saw not a hummingbird, but a young female Downy Woodpecker. 

She drilled into the stems and pulled out something that was black. You can see tiny drill holes near the top of the right stalk. Even tinier ones are barely visible in the left stalk, just below the center of the photos. According to John Hilty's website, Illinois Wildflowers, inside the dried stem could have been the larva of the Tumbling Flower Beetle. What a great name! Check out MOBugs' post on this insect, with great photos.

In the Rooky Wood

Great Horned Owl vs. Crow, photo by Jerry DeBoer

It seems like everyone hate crows. Throughout much of the world, crows--ravens, carrion crows, jackdaws, rooks, choughs--fill the same niche as vultures. Garbage collectors are indispensable of course, but not celebrated. Associated with death and bad fortune in European folklore, crows have been an object of persecution. 
Then there's that voice. I once worked with a nun who had some very uncharitable things to say about crows. She complained that they perched at the top of the chapel's cross and screamed! And they did. 
After Macbeth murdered his king, he plans more killings with these lines (3.2.50-53):

Light thickens, and the crow

Makes wing to the rooky wood:

Good things of day begin to droop and drowse;

While night's black agents to their preys do rouse.

(Of course, crows and rooks are not nocturnal, but this is Shakespeare, not ornithology.)
Kevin McGowan has been studying crows for 20+ years, and his research shows that those groups we see as feathered juvenile delinquents are actually families. Just as we wouldn't tolerate a dangerous snake or spider in our home, crows vigorously defend their nesting area against predators. In winter, when crows gather at night in roosts, sometimes in the hundreds or thousands, what could be more terrifying than an owl swooping through the dark to take a one as prey? No wonder crows take every opportunity to drive owls away. Studies show that American Crows are at or near the top of the intelligence quotient of all birds, and those calls, which seem so offensive, have variety and meaning.

Birders know that a flock of screaming crows often means that an owl is nearby. Sometimes the owl will flee its tormentors, sometimes--as in the amazing photo above, by Jerry DeBoer--they stay put, stoic and grumpy.  Why doesn't the owl attack? Great Horned Owls are the top bird predator in our region, with a wing span up to 5 feet. For a bird, it's quite heavy: around 3 pounds--triple the weight of an American Crow. Beyond the fact that owls are most adept at maneuvering in the dark and crows have some advantage in daylight, the answer to that question remains a mystery. 

Mourning Warbler Meets Madison Avenue

Mourning Warbler, female (above), male (below)
by Louis Agassiz Fuertes Wikipedia

Although it was warm, it wasn’t the heat that made me so exhausted. I just couldn’t keep up with my 19-year-old boss. I earned $5 and hour that June surveying birds in scraps of habitat that remain in industrial Saint Louis, Missouri. He trotted through a mile of remnant prairie along the edge of Calvary Cemetery, never drawing a short breath, reaching our lunch spot well ahead of me. When I finally arrived at the thicket of walnut trees and sumacs, I had a horrible allergy attack—in fact, the only one I’ve ever had. In spite of my sneezes, I could hear the most amazing bird. Thankfully, he kept on singing while I wiped my eyes and wracked my brain trying to match the song to my bird tape. Peering through a spiny clump of Hercules Club (Aralia spinosa), I caught just a glimpse of a Mourning Warbler!

According to Birds of the St. Louis Area: Where and When to Find Them, the Mourning Warbler is a migrant only, “sparingly recorded” in most of May and September. The best shot at seeing one is mid-May, when the “seasonal occurrence bar graph” shows it as “easily missed”—a step up from rare. It isn't expected at all in June, and certainly not a singing male! It’s a beautiful and distinctive song—still, it’s hard to put a name to a song, especially if you haven’t watched the bird sing. Of course, it shouldn’t have been that hard to recognize the song of the Mourning Warbler.

Rare though the bird is in my area, the song is all too common. Every TV commercial or film director that aspires to add a little outdoor atmosphere throws the Mourning Warbler’s song into the sound track. As you read my list of TV ads and shows where I've heard it, keep in mind that Mourning Warbler prefers tangled, second-growth forests. Read more about this shy bird in Seabrooke Leckie's blog, The Marvelous in Nature.

Mourning Warbler in its favorite habitat
photo by Seabrooke Leckie

• In a SUV commercial as the car drives along a lakeshore.
• As detectives investigate a crime scene in a high elevation spruce and fir forest in Montana (about 300 miles west of its expected migration route).
• In the “allergy eyes” commercial, when the allergy sufferer applies the product. (This one might not be too far fetched.)
• In a manicured backyard, as Michael Jordan advertises hot dogs.
• In an ad for the St. Louis Zoo, as 2 llamas sing, “Waltzing Matilda.”
• Among the monuments and government buildings of Washington, D. C., in an antacid commercial.
• In a baseball stadium, in an ad for a sports show.
• In Manhattan, as a morning-news show host talks about pigeon control.
• And my favorite: in a carpet commercial, along with the songs of Hermit Thrush and open-field loving Savannah Sparrow.
• Listen for it, in a theatre near you!

They'd Rather Fight than Switch!

Hummingbird throwdown! Photo by Amyn Kassam

Here’s what we love about hummingbirds: They have that vertical posture, they make eye contact, they love sweets, and of course, they fight. They’re so human!

Watching hummingbirds is not like watching other wildlife. Hummers get up close and personal. Laura Erickson, in her 2006 book, 101 Ways to Help Birds, tells us about hummers that tap on her window when they want her attention. I watched a hummingbird pirouette around a friend wearing a coral-colored shirt, even though he was surrounded by a crowd partying on a small deck.  Hummers have come within inches of my face to catch the spray as I water my plants.

My neighbor recently told me about two hummers that clashed and then crashed, knocking each other to the ground right in front of his basset hound. Both recovered and flew off before the dog could get over her surprise and devour them. Last summer, a skirmishing hummer clobbered my brother-in-law in the head!

The level of aggression in hummingbirds is a mystery to me. Isn’t fighting over resources a waste of valuable foraging and feeding time? In her 2000 book, Attracting and Feeding Hummingbirds, Sheri Williamson points out that plants must be frugal with the nectar they produce. Nectar is of no use to the plant directly. It’s sole purpose is to pull in pollinators, so once a blossom has been pollinated, it ceases to produce nectar. Since plants are so stingy, hummers adopt a strategy of claiming a  territory and protecting their resource ferociously. According to Williamson, “Territories are smaller where flowers are abundant, larger where they are scarce (14).” I can see the evolutionary advantage of resource guarding, but I’m not sure why it seems so much stronger in hummers than—say—woodpeckers.

Like grizzly bears and bull elephants, hummingbirds use “mock charges” to panic their rival into flight, while minimizing the risk of injury to themselves. Adult males can flash their color throat feathers (the gorget) to intimidate from a distance. Females and juvenile bird display the white tips of the outer tail feathers for the same purpose, as you see in the photo above by my Flickr friend, Amyn Kassam. Hummingbirds can scold predators and interlopers with chirping sounds, and some can startle  with buzzing sounds produced by tail or wing feathers. There are times however when, like Taryton smokers, hummingbirds would rather fight than switch.

Some of my readers know that I worked at a youth camp in the Ozarks for many summers. Trumpet creepers (Campsis radicans) brought in birds by the dozen. Like Snoopy and the Red Baron, hummers battled around the camp office from sun up till sundown. Once, a staff member was actually injured in a hummingbird fight. As she crossed the parking lot, two hummers collided in front of her and a dislodged feather hit her in the eye!

Trumpet Creeper is a hummingbird magnet! Photo by AMcCormack

Trumpet creeper is a hummingbird magnet for a reason. In a 2003 article in LOS News, the newsletter of the Louisiana Ornithological Society, Dennis Demcheck wrote about the “Sugar Content of Hummingbird Plants in Louisiana Gardens.” Demcheck used a refractometer to measure the concentration of sugar in the nectar of blossoms in his garden—the same equipment used by wine makers. He found that, among wild/native plants, the trumpet creeper had the highest concentration of sugar at 34.3%, with each bloom producing a large volume of nectar. To reach that nectar, the bird must actually climb inside the 3-inch long bloom. It’s quite a risk for a bird to limit its vision like that, but obviously worth it.

If you’re thinking about adding trumpet creeper to your home garden, linger on this blog a little longer. Trumpet creeper is a big plant; every bit as aggressive as the hummers that love it. The main stem can be wider than your hand and all those branches in summer are heavy as they lie on the roof of your garage or branches of your prized specimen tree. Maybe you can persuade your neighbor to grow it.