Birds that buzz…

Two words that are usually said together:  bird song, or better yet songbirds, those usually small birds in your garden that produce the wonderful, lilting, sometimes piercing, often warbling, unique collection of notes that identifies each species.

But not all songbirds sing, or sing exclusively — some of them have adopted a buzz as part or all of their song. In fact, their soft buzzes or wheezes are remarkably similar and difficult to pinpoint when looking for that buzzing bird that you’re not really sure isn’t some sort of insect.  Why would male birds want to buzz instead of sing?

Take the Blue-winged Warbler for example; wouldn’t you assume from its name that its song would be a melodious warble, rather than a two-note “bee-buzz“?

blue-winged warbler-

A beautiful Blue-winged Warbler sitting out on the edge of the forest overlooking a prairie grassland, buzzing away.

blue-winged warbler-

A better look at the blue wing of the Blue-winged Warbler. He was little and mighty far away.

Just 20 feet away, a Clay-colored Sparrow is buzzing away, with a very similar, low frequency, raspy buzz call.

clay-colored sparrow-

Pale-colored, but with distinctive stripes on its head and face, the Clay-colored Sparrow blends in well to its usual background of dry grass.

clay-colored sparrow-

Its pink bill resembles that of a Field Sparrow, but its buzzing “song” makes it easy to identify.

Buzzing seems to be a common characteristic of “song” in grassland birds, like Grasshopper Sparrows and Savannah Sparrows.  So, one wonders if these birds are trying to avoid detection in prairie habitat by mimicking insects when they “sing”, or whether female birds just find buzzing particularly enticing?

It turns out that buzzing sound made with the bird equivalent of a larynx (called a syrinx), is actually quite physically challenging, and therefore could be an indicator to females of the quality of a potential mate.  German researchers* found that larger, more robust male Nightingales incorporated more buzzes in their song, and enjoyed greater attention from females than their less robust or younger competitors.

Another possible explanation for buzzing birds found in grassland habitats is that low frequency buzzing notes apparently carry long distances, and can be heard throughout and beyond the male’s territory.  Banded Wrens incorporated more buzzing notes in their early morning song that was directed toward other males in the nearby vicinity, at times before females were present.**

*Citation: Weiss M, Kiefer S, Kipper S (2012) Buzzwords in Females’ Ears? The Use of Buzz Songs in the Communication of Nightingales (Luscinia megarhynchos). PLoS ONE 7(9): e45057. https://doi.org/10.1371/journal.pone.0045057

**Citation: P.L. Trillo and S.L. Vehrenkamp. Anim Behav. Song types and their structural features are associated with specific contexts in the Banded Wren. 2005 Oct; 70(4): 921–935. https://dx.doi.org/10.1016/j.anbehav.2005.02.004

on the edge

Tromping around Weaver Dunes, south of Wabasha MN, for 8 hours trying to identify every bird we could find was exhausting but rewarding, and what an absolutely beautiful day to participate in The Nature Conservancy’s bird blitz on May 12.

Cape May Warbler-

First bird of the day — Cape May Warbler, high in a leafy tree (bane of photographers — the tree, not the bird)

The spring migration was running a little behind schedule, but we managed to find (and identify) 58 species (which admittedly doesn’t sound like a lot for 8 hours of work).  We explored a variety of habitats, but the best places to look were edges between shrub and forest, or prairie and forest.

Yellowrump Warbler-

Yellow-rumped Warblers outnumbered other warbler species, and thankfully posed at much lower elevations in the trees.

Rose-breasted Grosbeak-

We only saw one Rose-breasted Grosbeak, and he was quite shy about coming out in the open to show off his raspberry bib.

Lark Sparrow

Lark Sparrows were more common than the warblers, flashing their white outer tail feathers as they flew. True to their name, their song is much more of a warble than a buzz — i.e., lark-like.

Lark Sparrow

Lark Sparrows typically nest in shrubs and forage in grassy areas removed from the nest. They have the unusual habit of walking, instead of hopping.

Northern Waterthrush-

Down at the edge of a small pond, a Northern Waterthrush hunted for insects.

Northern Waterthrush-

A distinctive eyestripe and wagging tail made this large warbler easy to identify.

Brown Thrasher-

A Brown Thasher was very uncooperative about posing, and remained hidden in the dense foliage of trees in the grassy savannah.

Baltimore Oriole-

Orioles foraged high in leafy treetops, but were easy to find by listening for their characteristic song.

Gray-cheeked Thrush-

Another edge-lover found skulking among the low vegetation in the woods surrounding a pond was the Gray-cheeked Thrush, with its characteristic white eyering.

Our efforts were added to those of the birders walking other TNC properties throughout the tri-state region of MN, North Dakota, and South Dakota.  Together all observers on May 12 found over 200 different bird species, or approximately 50% of those known to reside or pass through MN on migration in May.  Not bad…it’s a nationwide competition, so we’ll see how MN bird numbers stack up with those elsewhere in the U.S.

Considering that our American birds have to navigate and survive stormy weather and drastic climate changes, glass windows and glass-covered buildings, marked habitat alterations, and depleted food supplies from all the pesticide and herbicide applications, it’s a wonder that we see the diversity that we do.

Fall-ish

Warm days, cool nights, sometimes rainy and blustery — that’s fall.  You never know what it’s going to be like because the weather changes day to day, or even from morning until evening.  But the combination of short daylength (less than 12 hrs of daylight) and very cool nights starts the color change in the vegetation that we love to see.  (For an explanation of how that color change happens — click here.)

fall-prairie-wm-obrien-park-

Not all plants are as sensitive to the daylength and temperature cues — making the fall season a long and colorful display.

fall-color-

Maples and aspens are some of the first to show their fall colors, and oaks are one of the last, making the forest a kaleidoscope of green, yellow, red, and orange.

new-england-aster-

A few remaining flowers like this New England Aster can still be found in the prairie, but there are few insects around.

milkweed-pod-

Milkweed pods open to disperse their airborne seeds.

yellow-rumped-warbler

Yellow-rumped Warblers are one of the more abundant migrant species, found and heard in almost every habitat — even the prairie.

nashville-warbler-

Waves of warblers (like this Nashville Warbler) move through with the weather fronts in the fall. But these are wary little birds, and even harder to photograph in the fall when they are feeding ravenously to replenish their migratory fat supply than they were back in the spring when they came through on their way north.

out on the prairie

We spent the weekend in central Minnesota taking photos of different stages of prairie restoration.  Prairie grasses are above knee high already, and there are quite a few perennial forbs flowering — injecting some highlights of color into that huge expanse of green.

prairie-flowers at Lake Johanna Esker

Tall stems of timothy grass stand behind the lower herbaceous perennials on the Lake Johanna Esker prairie.

Many thousands of years of growth of perennial prairie grasses in this area resulted in a several feet thick layer of black, organic-rich soil — perfect for farming.  But as a result, less than 2% of the original 19 million acres of native prairie remain.

prairie vs cropland in central Minnesota

Any prairie that could be plowed (not too dry or wet, not too steep or rocky) was converted to cropland over a hundred years ago. But here, pasture (on the right) is being returned to a prairie, while the hill in the background (too steep to plow) has been heavily grazed. In the absence of fire or heavy grazing pressure, prairies are easily invaded by trees.

Where there are large acreages of prairie or grassland landscape, we can usually find some of the native prairie animals and plants that live there.  What a treat to drive down one gravel road that dead-ended in a soybean field and find a family of Sandhill Cranes walking through the meadow grasses.

sandhill cranes-

This pair of Sandhill Cranes tried to distract us from finding their two chicks by walking up the hill away from where the chicks hid in the longer grass.

sandhill crane chick

One of the chicks was a little less than half the height of the adults — with no tail yet.

sandhill cranes-

I suppose they thought we might follow them up and over the hill, but as we backed away, they flew back toward the chicks.

Harvest time

It’s corn harvest time in parts of Minnesota.  Most the fields have either been cut down to stubble, or had the stubble plowed under, but a few fields were still being harvested when we drove through central Minnesota the other day.

corn harvest - central MN-

A harvester chewed its way down a row and prepared to turn around for another swipe churning up a lot of dust in the process. When it’s bin is full, it shoots the grain out the long arm into the bed of a waiting truck.

corn harvest in central MN

Corn stubble fields like this will attract numbers of migrating blackbirds, cranes, and waterfowl, but these harvesters are so efficient, they don’t leave much grain behind.

Rail cars full of corn dot the landscape, trucks hauling grain crowd the highways, and grain silos are bulging with feed left over from last winter’s storage plus the additional grain deposited this fall.  Sometimes there just isn’t anywhere to put all that corn, except on the ground waiting for the next available transport.

Mountain of corn at Sunburg, MN during fall harvest

A mountain of corn is building up on the ground next to two full storage silos in Sunburg, MN

corn harvest - central MN-

More trucks arrive in a steady stream, getting weighed first and then depositing their load in the growing mountain of corn.

mountain of corn-Sunburg, MN

At this point the mountain of excess corn is about 20 feet high and 150-200 feet long. How many tons would that be, I wonder? And what is the fate of this pile of corn left out to the elements for how many days?

old barn near Sundberg, MN

This old barn near Sunburg, MN has been falling down for several years, and this past year really took its toll on the structure.

Just the beginning

As nighttime temperatures dip toward freezing, the trees are starting to show a little color.  It’s just the beginning of the most colorful season of the year —

beginning fall color-

Warm days and cold nights signal plants to cease photosynthesis and begin breaking down the chorophyll pigment in their leaves to unmask other, colorful light-gathering pigments.

Fall weather and decreasing day length signal animals to begin making preparations for winter — either storing food (like the squirrels have been doing) or eating like crazy to get fat enough to migrate south.  Waves of warblers and other small songbirds have been moving through the Twin Cities recently, and some wind up in the backyard, looking for insects on late-blooming plants.

female or juvenile yellow-rumped warbler-

Large flocks of Yellow-rumped Warblers move quickly through the vegetation, but occasionally stop to pose for a photo.

showy goldenrod-

Only a few species of perennial plants are still flowering here, like this Showy Goldenrod that is buzzing with several species of insects.

showy goldenrod pollinators-

Pollinators looking for a late autumn meal of nectar and/or pollen crowd onto a Showy Goldenrod plant that stands out in a field of Little Bluestem grass.  In addition to the bumblebees, two species of hoverfly, a beetle, and a small wasp were foraging here.

sulfur butterfly on new england aster-

New England Aster was buzzing with Pink-edged Sulfur butterflies, bumblebees, and hoverflies.

Seed-eating migrants might find a banquet waiting for them too, as perennial plants put forth their seed crops.

canada goldenrod seed head

Canada Goldenrod seeds are buried in the wispy tendrils that help disperse the seed around the prairie.

indian grass-

Perennial grass seeds are ripe for the taking as well.

With all the rain late this summer, I hope this will be one of the most colorful fall seasons in recent years.  But that depends on the day-night temperature differences in the next few weeks.  So, stay tuned for more posts on fall color later.

A place to call home

Meet the star of our show for today — Henslow’s Sparrow.   It is a colorful bird with a lot of yellow on its head, and a rather thick beak and short neck, that inhabits tallgrass prairie in the spring and summer and then retreats to its winter home in the southeastern U.S.

henslow's sparrow, Frontenac State Park, MN

This is a rare bird in the Minnesota prairies, or in most midwestern prairies for that matter. Populations have declined precipitously as their preferred habitat has disappeared, and even when birds breed in tallgrass prairies one year, they may not be present the next.  Why? 

It seems that although Henslow’s Sparrow does prefer tallgrass prairie as a nesting site to raise the next crop of offspring, not just any prairie will do for this bird.  It must be a rather large acreage, and it must have lots of standing dead stems still poking up through the deep thatch of last year’s grass growth.  In fact, this bird is rather fussy about its home, and numbers of nests are directly correlated with how long ago that patch of prairie was burned.  They are so fussy about the exact structure of their tallgrass prairie home, they are willing to tolerate breeding in small colonies of closely spaced nests.  Some researchers feel the particular grass structure of their favored breeding sites protects them better from predation and the nest parasitism of Cowbirds.

henslow's sparrow, Frontenac State Park, MN

Yes, we like a lot of dead, tallgrass stems still standing, thanks. The better to suppress the current year of grass growth and make it easier for us to scuttle about, hidden from view on the prairie floor.”

It’s a precarious balance between burning the prairie often enough to suppress the growth of woody vegetation and keep it in prairie, and burning infrequently enough to satisfy the needs of birds like this one, which require a lot of standing dead biomass in their prairie homes. What’s a prairie manager to do?

Derr sandhills prairie - prescribed fire.  March 2012

Burn only part of the prairie at a time, leaving that standing biomass in other parts?  Derr sandhills prairie – prescribed fire. March 2012. From the Prairie Ecologist.

Whatever humans do to protect or conserve one species, inevitably, it seems to  come at the expense of others.  But one solution is to simply conserve more natural habitat — one parcel at a time, until there is a substantial enough acreage to manage for multiple species at one time.

Not your average chicken

Prairie Chickens might cackle a little like a farmyard chicken, but they are definitely not in the same class.  These native prairie inhabitants put on quite a show in the spring, with 20 or more males joining up to display their prowess to the local females in a central “booming” ground, called a lek.  Here’s a little of the show we saw early this morning while sitting in blinds provided by the Nature Conservancy at Bluestem Prairie near Moorhead, MN.

male prairie chicken display

The males arrived right at 5:20, as usual, and got right to work displaying to each other and to an occasional female wandering through their little area of the community lek on the booming ground.

Bright yellow colored skin on the neck is inflated with air as the chicken utters its low frequency,two syllable “woo-hoo” which can be heard from quite a distance away.  They lean forward, tilt the tail feathers upward and spread them, and then raise elongate black neck feathers like two horns behind their head.  It’s quite an intricate display between the sound effects and the posturing with raised feathers.  In between booms, males occasionally drum their feet by dancing a little in place or run toward another male to chase them off their booming area, as the video below shows.

prairie chicken display-

An elaborate series of postures and displays between males may escalate to flying at each other or to simply turning around and going the other direction.

prairie chicken display

Now this interaction might lead to something…

prairie chicken display

Instead of a fight, we have parallel displays, both presenting sideways, instead of threatening each other face to face.

prairie chicken display-

But every now and then, one bird just ticks the other one off, and the back and forth postures and displays erupt into a great flapping of wings and wild leaps in the air.

prairie chicken display-

No blood was spilled, and the two birds went right back to displaying, booming, and running around their little area of the lek.

Unfortunately, numbers of Greater Prairie Chickens have declined markedly due to loss of grassland habitat and hunting pressure in the early 1900s.  Where once hundreds of thousands of birds roamed throughout the Great Plains, now managed grassland areas hold just a few hundred birds, and populations fluctuate as the land around them is converted from idle cropland (e.g., land in the Conservation Reserve Program) back into full-scale agricultural production.  In addition, these small, isolated populations are prone to some inbreeding and loss of genetic diversity, which makes it even more difficult to them to meet the challenges of a changing environment and climate.

prairie chicken display

These energetic little males put on a 3-hr show for us, and then suddenly departed all together right at 8:30, just as they have every day in the past month.  One male insisted on displaying right in front of the blind, giving us a rare frontal view of the booming display.

LATE ADDITION: If you wander over to Paul Sundberg’s blog for this week, you’ll see a similar display in another lekking species, the Sharp-tailed Grouse.  Paul’s photos, taken in bright morning light (instead of the rainy overcast we had) really highlight the action and color of these otherwise very cryptically colored birds.

a day in the life of a Sandhill Crane

sunrise on the Platte River, NE

Sunrise on the Platte River near Grand Island, NE. Already, hundreds of Sandhill Cranes have launched themselves skyward to fly out to crop fields to forage.

Sandhill cranes at sunrise-

One large flock of cranes flew off before sunrise, but several more flocks still remain on the sandbars. You can just barely see one group in the lower third of the photo.

From sunrise to sunset, Sandhill Cranes make their presence known with their loud rattle call (click here to sample the sounds of a single bird or that of a large flock of cranes).

Sandhill cranes at sunrise-

All but a few of the Cranes in the foreground have taken off, but a huge flock in the background is still waiting for just the right time.

Sandhill cranes at sunrise-

What are they doing, besides preening, calling to each other, and occasionally stabbing a bill into the mud to find a snack there? Waiting…waiting, for just the right time to take off.

Sandhill Cranes flying to crop fields to feed

Often still vocalizing, it’s follow the leader to the first foraging site at some farmer’s corn field.  These birds are strong flyers, and move quickly across the landscape!

Sandhill crane flying and calling

Calling out….”follow me”

Sandhill Cranes flying

Large flocks accumulate in fields of corn stubble a few miles from the river, but often a small flock simply joins another larger flock if the foraging looks good there.  Here, this small flock is gliding in to land with another larger group.

Sandhill cranes flying

Put down the landing gear…

Sandhill Cranes flying and feeding

Gliding in for the landing…

Sandhill Cranes feeding

Heads down, the Cranes are intent on gobbling up every kernel they find. However, more efficient machinery for harvesting corn leaves far less waste on the ground these days than in previous decades. Cranes must search more intensively or stay longer on their stopover to gain adequate fat stores to complete their migration.

Sandhill Cranes feeding in corn stubble

The Cranes spread themselves out in a straight line across the remains of last year’s corn crop. You can see there is not much in the way of edible nutrients left on the ground.

Sandhill Cranes flying back to the river at sunset

After a long day of foraging in the corn stubble, Sandhill Cranes head back to the river in huge flocks of hundreds of birds — for another night on the river’s sandbars.

Three subspecies of Sandhill Cranes converge on the shallow sandbars of the Platte River from their wintering grounds in New Mexico, Texas, and northern Mexico in late February to early March.  They might stay several weeks, depending on how quickly they can refuel their fat deposits, before taking off for prairies in central and western Canada and Alaska.

Central Flyway_Map

Cranes and other waterfowl funnel through the narrow channel of habitat along the Platte River in the Central Flyway.

Sandhill Cranes are one of the oldest bird species, with fossils (found in Nebraska) indistinguishable from living cranes dating back 9 million years, long after the the rise of the Rocky Mountains and the development of prairie grasslands.  It’s amazing to think that these birds may have been repeating this same migratory journey for millions of years — and hopefully will continue for years to come.

Sandhill Cranes flying