they’re on the move…

Thousands of birds are flying overhead right now, migrating south from their breeding areas in Canada.  Some might stop over along wooded streams for a few days to replenish their fuel resources, as dozens of small warblers, vireos, and sparrows did last week at our local reservoir.  But an even more impressive migration is taking place along the ridge that runs along the western shore of Lake Superior above the city of Duluth MN.

The forested ridge above the city of Duluth generates rising warm air currents in the fall that migrating raptors (like this Bald Eagle) use to gain the altitude they need to effortlessly soar south for hundreds of miles.

Migrating raptors by the thousands (and some in tens of thousands) are reluctant to cross the expanse of Lake Superior, but they funnel along the ridge line of its western shore, to be counted by volunteer observers of the Hawk Ridge Bird Observatory and photographed by the dozens of bird lovers and photographers who visit daily.

There’s always something to look at when the hawks, falcons, eagles, osprey, etc. are migrating through this area in the fall.

Information about the migration and the peak times of migration of particular raptor species is posted on E. Skyline Drive in northern Duluth, at the crest of the ridge where spectators gather.  Some species like Broad-winged Hawks and Peregrine Falcons have very short migration times, and we happened to be there on a day when 2000+ Broad-winged Hawks flew over.

Overcast skies bring the birds down low, closer to observers, which is ideal for photography, but we happened to be there on a sunny afternoon, and the birds were thousands of feet in the air above us.

Thousands of feet above us, Bald Eagles (large bird center left) circle in the thermals along with dozens of Broad-winged Hawks.  Photo by Debbie Reynolds.

Broad-winged Hawks are smallish, compact raptors common throughout southern Canada and the eastern U.S. during the summer, but they leave North America during a short span of time in September, largely because they are dependent on the thermals generated by warm air currents rising off the land in the fall.  If they wait too long to migrate, warm fall days become unpredictable and so do the thermals they use to gain altitude for migration.

Broad-winged Hawks exhibit unique formations in migration, when they form “kettles” of hundreds of birds circling in the thermals to gain the altitude they need to soar.  The term “kettle” describes the formation of these birds as they “bubble up” from low altitude to higher altitude circling in the thermal, until they reach several thousand feet when they peel away from the kettle to soar downwind toward the next thermal.  Photo from Brandywine Conservancy, Sept 2018.

Soaring, instead of flapping flight, is relatively inexpensive for raptors, and by using the thermals to gain altitude to then soar over long distances to the next thermal, they can travel hundreds of miles before running out of fuel stores.  For Broad-winged Hawks, the journey from southern Canada to northern South America might be 3-4,000 miles and take them about a month.  In optimal conditions, they can travel 300 miles in 6 hours.

Daily count totals were posted at 4:30 at the Hawk Ridge Bird Observatory site. Peak migration times are generally the warmest times of the day, 10 am-2 pm.  According to the chart, the 10-year average count of Broad-winged Hawks at this site is 37,000 birds, but in 2003, observers counted 101,698 in a single day!  That must have been an amazing sight, with birds literally filling the skies.

We weren’t fortunate enough to get close-ups, but we did see a lot of hawks during our short time at Hawk Ridge.

 

Out on a limb

A typical pose for a Merlin, scoping out the landscape below its bare branch for little birdies flying below.

We had a rare opportunity to photograph this little falcon while it scanned for small birds from its perch in a dead tree.  Merlins are known for chasing their prey in rapid flight, so you don’t often get a chance for a decent photo of them.

Those spear-shaped wings and their powerful pectoral muscle are what give this bird the ability to chase and capture small birds. (Photo by Debbie Reynolds)

Smaller than a Peregrine, but as swift and agile, Merlins prey on sparrow-sized birds, small mammals, reptiles, amphibians, and even insects in a variety of habitats from beach shrub-grassy area to coniferous forests throughout the Northern Hemisphere of the Americas, Europe, and Asia.  They are about the same size as the American Kestrel (Sparrow Hawk), but are much stockier, with large pectoral muscles.

Merlins were a preferred falconry bird because of their size and relatively gentle disposition, especially favored by noble ladies in Medieval Europe.  Even today, they are used to hunt small game birds like quail and doves, because of their ability to climb faster than the prey and then dive (stoop) down on them to knock them to the ground.

Harrier of the marsh

On another trip out to the central Minnesota prairie the other day, we were treated to a fly-by from the bird that used to be called a Marsh Hawk for its habit of hunting vast tracts of wetlands and wet grasslands.  However, because it is closely related genetically to the Harriers of Europe and Asia, it was renamed the Northern Harrier.

A Northern Harrier female in mid-wing flap, flies close to the ground, head facing downward, searching for its next meal.

Harriers are a subfamily of the hawk family (Accipitridae) that includes hawks, eagles, kites, and eurasian vultures, but not ospreys.  As a group they are different from others in the hawk family in being sexually dimorphic (male and female look different), with males distinctively gray and white and females a rich brown and white.

Brown-backed female Northern Harriers are slightly larger (typical of raptors) than the gray and white males.  Both birds exhibit a white rump patch in flight.  Photo by Becky Rosencrans

It’s easy to tell a Northern Harrier from any of the other hawks that hunt in open country by the distinctive white rump patch.

They also differ from their hawk relatives in having distinctive owl-shaped faces, with a specialized disk of feathers on either side of their eyes (like owls) that trap and direct low frequency sounds, like that of a mouse rustling through grass, to their ears.  It is thought that Harriers may use auditory cues to find prey more than visual ones.

A juvenile Northern Harrier photographed by staff at the Missouri Department of Conservation shows the distinctive facial disk of harriers.  Chocolate brown eyes indicate this is a young female, but the color will gradually change to a lemon yellow in the adult.

Because Harriers fly very low over the ground, they are constantly looking down, which is another characteristic that separates them from other hawks that spot their prey from high above the ground and dive down on them.

Typical search posture of a Northern Harrier: wings in a V for efficient gliding and head down picking up sounds or visual sightings of prey.  Photo by Debbie Reynolds.

With its feet extended, this female Northern Harrier may be about to pounce on some unsuspecting rodent moving along in the short grass.  Photo by staff of the Missouri Department of Conservation.

Lastly, Northern Harriers differ from many of their hawk relatives in their reproductive biology.  Where most hawk, eagle kite, vulture, etc. species form a strong male-female pair bond that may last several years, Northern Harrier males will try to court, attract, and feed multiple females on their territories (polygyny).  This behavior maximizes the number of offspring a particular male produces, especially if he maintains a territory rich in available prey (small mammals, birds, amphibians, snakes, even insects), but it also promotes better protection of chicks in vulnerable ground nests because there are multiple individuals present in an area to drive away aerial predators like owls and eagles, as well as fox, coyote, mink, racoon, etc.

Predation pressure is probably the reason that Harriers often roost together on the ground, sometimes even teaming up with their competitors, the Short-eared Owls that also inhabit the same wide-open prairies.  Lots of eyes to watch their backs…

another little bird at the slough

I went back to the same place in the Grass Lake slough where I found the Solitary Sandpiper the other day, and found a juvenile Green Heron fishing for its lunch in the duck weed scum.

A bumper crop of Green Herons were produced in the backwaters of the Grass Lake slough this year. This is one of 8 individuals I saw on this particular day (all in different places in the slough, so no repeats).

After a few minutes of watching the heron change locations, look around, and waiting for it to catch something…

Out of the corner of my eye, a little brown and white bird trotted out in front of the heron, and proceeded to walk toward me, quite unafraid.

Killdeer are distinctive brown and white birds with a broad black neck band and red lining around the eye. But even more distinctive is the trilled “kill-deer” made over and over as a warning or an announcement of their presence that you frequently hear on gravel paths or large expanses of short grass where they forage.

But eventually the bird walked too close to me and realized I wasn’t an inanimate object.

Too close for comfort, and then the inevitable, quick take-off…

Faster than you could move the camera, the bird was out of the frame and off to better foraging spots, calling “kill-deer” over and over as it flew.

what are you eating, little bird?

While I was photographing the beautiful wildflowers, bees, and butterflies at the Grass Lake slough last week, a Solitary Sandpiper (a type of shorebird) almost walked across my toes as it pecked in the sludge at the edge of the slough.

Solitary Sandpipers are, in fact, solitary, rarely seen in the company of other shorebirds. They forage along the shore of fresh water sources throughout most of northern North America (Canada and Alaska in the breeding season), and despite having a long bill that could probe deeply into the mud, they forage on the surface of the water for bugs, worms, crustaceans, spiders, tadpoles, etc.

The bird picked up what looked like juicy prey items, dropped them, picked them up again, squeezed it a little with the tip of its bill, dropped it again, picked it up again, threw it off to one side, went and found it and picked it up again, etc. In all of the hundreds of photos I took of the bird catching prey, I never saw it actually ingest anything.

But I was curious what potentially edible items the bird was finding in the muck, so I sent some photos off to my aquatic biology (and pickleball) friend to help me identify the victims of this bird’s torture.

This worm-like prey item being squished between the bird’s mandibles is possibly the larva of a Crane Fly. The bird squished this one several times until it became a flattened ribbon.

Plucking this item from the same vicinity as the last one, the bird threw what might be a Crane Fly pupa around into the muck and then plucked out again. It didn’t wiggle like the larva did, so maybe the bird thought it was a stick.

The bird picked this giant water bug up a few times, always by the front end. These bugs have a strong proboscis with which they can inflict a painful pinch. Thus, their common name — toe biters.  In Asia, people are fond of eating the 4-inch variety of this critter.

It took the bird just a few seconds to find a new prey item, which it deftly sorted from algae and other vegetation.  What sharp eyes this little bird has.  Given a pair of tweezers, I doubt a human could pick out these invertebrates from the algal muck — I certainly couldn’t.

Hovering specialists in the backyard

A wide variety of animals can fly (more than just birds, butterflies, bees, or bats), and among those flyers, a select few can perform aerial acrobatics, like hovering — suspended in space, defying gravity in the process.

A few of those hovering specialists passed through the backyard this summer, and I attempted to capture their effort one wingbeat at a time.  And this is by no means easy when the subject a) darts from one hovering location to another in a millisecond (the hummingbird and the dragonfly) and b) is so small it’s difficult to focus on it (the dragonfly and the hoverfly).  The video clips below illustrate the difficulty.

A Ruby-throated Hummingbird in a sea of red Cardinal flower, delicately moving from blossom to blossom while beating its wings 80 times a sec.  I could stop the wing motion of this bird with the camera shutter speed at 1/2000 of a second.

Hummers move their wings in a figure-eight pattern, rather like the sculling motion of the hands of water ballet performers make to keep them static in a column of water. Forward and backward movement of the wings cancel horizontal movement, and the lift provided by the figure-eight motion keeps them suspended vertically.

A stocky bee mimic, the drone fly (Eristalis tenax) took up territorial residence outside my backdoor, hovering near the peonies in May.  One of the most widely distributed species in the world, drone flies maintain small territories near flower beds to attract females, occasionally darting out to chase off intruders.

Freezing the drone fly wing beat in time required the fastest shutter speed on my camera dial (1/8000 of a sec).  Two tiny wings propel the fly forward, backward, or keep it motionless in space, moving faster than the eye can see them — sort of like a helicopter rotor.

Dragonflies hover with two sets of wings, i.e., four moving blades swooping independently through the air.  Normally, dragonflies dart along the shores of ponds and streams, moving quickly from spot to spot, but occasionally they pause in their patrol efforts to hover over particular spots they are defending or to advertise their presence to females.

The 4-spotted Skimmer hovered almost motionless in space in front of me as I tried to focus on its abdomen.  Although the wings look synchronized in this view, front and back pairs move independently, as illustrated in the video below.  The wingbeats flutter in a blur to the human eye, but they beat at a much slower rate than those of hummingbirds or drone flies, and I was able to capture static shots at 1/1000 of a second.

It’s a most impressive feat of flying that is demonstrated by these animals, and one that has been copied by human engineers seeking to copy vertical take-offs and hovering efficiency in aircraft.

Sunset at the slough

Sunset on the slough — a delightful time of night, when things happen that you would have never predicted…

The golden light gives the slough a special character at this time of day.  All was calm and quiet for a while, and then…

There was a flurry of action when a pair of Bald Eagles terrorized some of the Great Egrets that had just settled down to roost in trees across the slough from me.

Six of them had just settled in the top of a tree when the eagles showed up.

No birds — instant evacuation as the eagles descended. No time to get a photo of their flight.  It looks like there might be one or two egrets still sitting there (the white blobs near the tree tops).

The Egrets wasted no time taking off before the eagles got close.  One eagle eventually landed in a tree near the Egret roost, spent a few minutes looking down at the water, and eventually decided it wasn’t worth sticking around in this hot, sticky swamp.

Unfortunately, the eagle was too far away to get a decent photo. The bird was panting as it sat there, and I was sweating so much I could hardly see through my camera viewfinder.

With no warning I could discern, the eagle took off, just when I had relaxed my vigil and put the camera aside to wipe off the sweat.

Within a minute, all of the Egrets returned — en masse.  I counted 31 birds at the roost before I left after sunset.

Some of them flew around in circles, making sure the eagles had left I guess. Others immediately settled into the trees, close to where the eagle had been.

A few birds flew over my edge of the slough, but most were too far away for good flight shots.  Interesting that white birds turn a golden pink color at sunset.

Demonstrating appropriate social distancing at the roost —

Great Egrets seem kind of fussy about who they roost next to, and some individuals are just not tolerated, as seen in the short-lived skirmish below. I wonder if this was an adult vs. juvenile interaction.

Successfully chased off.

Across the street from the slough, the light was changing dramatically…

As the golden hour slowly turned into the blue hour, it was time for Great Blue Herons and humans to give up fishing for the day.

a wetland restoration

One of our local county parks has been the recipient of a make-over, with beautiful results. The place was overgrown with buckthorn, thistle, and other noxious weeds.  But now, wildflowers abound along the shore of the Grass Lake slough in Shoreview, MN amid a mixture of photogenic stumps and wetland plants.  And apparently the ducks, herons, egrets, and muskrats have found this make-over very satisfactory for breeding and foraging this summer because the place is teeming with wildlife.

What a pleasant surprise to find this oasis on a sunny, summer day — popular with walkers as well as bird life.

I don’t know how this Green Heron could see any fish or invertebrates swimming around under the duckweed, but the bird certainly gave it a try.

Great Blue Herons and Wood Ducks (in winter, eclipse plumage) were foraging in the mucky part of the slough, which is completely overgrown with duckweed.

Does fluffing feathers get the duckweed off?

Great Egrets have always loved this slough, although they were quite difficult to see because of all the tall weeds, cattails, dead trees and branches between us.  Now, the shoreline has been cleared, replanted, and the birds have become somewhat accustomed to humans gawking at them as they walk along.

I spotted this Great Egret fishing along the opposite shore, and walked over to that side and right up to it, without disturbing its fishing efforts.

The bird caught three fish while I was standing there watching.

A dead tree on the shore of Grass Lake beyond the slough has served several photographers as a subject for fanciful photo compositing. So, yes, this image is a fake — the tree, the sky, and the background are real, but the eagle and the flowers in the foreground were added.  Fellow Shoreview photographer and Grass Lake enthusiast Jim Radford has composed some dramatic scenes of this tree — with sunset and evening backgrounds.  https://www.radfordpictures.com/Favorites/i-fcdQ6BT

Mornings in the backyard

I’ve spent the last few (early) mornings sitting in a blind or a chair watching Ruby-throated Hummingbirds feed on the flowers in the backyard garden. Occasionally a male visits, but he is wary, hiding behind flowers where he is obscured from view. Two other female or juvenile hummers are bolder and will hover in full view on flowers about 20 feet away. Here are a few of my attempts to capture the action:

Oops, right search image, but wrong flower — a gladiola not open yet.

The reluctant male that couldn’t seem to face toward me to show off his gorgeous magenta bib.

I always thought Cardinal flower was the favorite target of hummers, but it turns out they like Salvia better.

Manuevering between closely spaced flowers gives you an appreciation of their aerodynamic capabilities.

Even by just entering part way into the flower, a hummingbird can tell whether there is a nectar reward there or not using taste receptors at the tip of their long tongue. This visit lasted less than a second.

To be effective at pollinating a flower, the hummingbird must insert its beak all the way in so that the flower’s reproductive parts, particularly the pollen on the anthers, will rub off on its head, as seen below.

Hummer is getting dusted with pollen on the top of its head; that pollen will rub off on the protruding female stigma of an adjacent flower the bird visits.

Ruby-throated Hummers have glittering green feathers on their back, which blends in well with the vegetation. So, at rest, they can be hard to spot.

Below is some HD video I took of one hummer.  You might not be able to see the video if you are reading the blog from your email, so go the blog post itself by clicking on the title of the blog in the email.  In the bottom right corner of the video are three icons. Click on HD to enable that view (recommended), or on the icon that looks like a speedometer to slow the action to 0.5 real time (also recommended). Click on the right-most icon to view in full screen mode (best view). It’s difficult to appreciate the incredible control these hummers have over their position in space until you slow it down. Click on the X in the top left corner after the video finishes to return to the blog post.

To learn more about the coevolution of cardinal flower and hummingbird pollinators, click here: https://bybio.wordpress.com/2013/08/17/a-perfect-fit/

Life on a restored prairie

The restored prairie at Tamarack Park in White Bear Lake is teeming with mid-summer activity.  Part of the restoration has included planting a very large 20 acre field with Big Bluestem grasses and other native forbs, and the grass “as high as an elephant’s eye” right now.  It’s amazing how much you can see in just an hour’s walk in such a place.

The Big Bluestem is already about 2 feet over my head. The park has cut paths through the prairie in places so you can see what being in the middle of a tall grass prairie is really like.

Most of Minnesota is part of the prairie-forest ecotone (the area where the two biomes intersect), and this photo is typical of that sort of vegetation.  Regular prairie fires, started by lightning or by native Americans, maintained the grasses and kept the woody vegetation from invading.  Trees competed better in wetter areas near lakes where prairie fires typically stopped burning.

Dozens of wildflower species are at or just past their peak, and add color to all the green.

Tall spikes of purple Blazing Star and yellow Tickseed and Black-eyed Susans stood out in the sea of green.

Several Goldenrod-Soldier Beetles were happily pollinating some of the Rudbeckia species plants.

Hundreds of dragonflies were flitting over and through the tall prairie grasses, hunting insects or perhaps a mate.

Halloween Pennant dragonflies (named for their orange and dark brown color) perched on the tallest vegetation in the prairie (on Mullein plant here) while they waited for something tempting to fly by.

Several male Widow Skimmer dragonflies were flitting around in the low grass near the edge of the path. These are mosquito specialists, so I like to see lots of them around.

Young fledgling birds were trying out their newly acquired hunting strategies to feed themselves.

A couple of young Bluebirds were eating fruit and looking for caterpillars. One was successful and immediately flew off with it — I guess to protect it from being stolen.

Two young Phoebes (with squeaky voices) were hunting by a small pond — competing with the dragonflies for flying insects.

Chipmunks, squirrels, and 13-lined Ground Squirrels scurried around, already storing up food for the long winter to come.

You don’t often see these 13-lined ground squirrels out in the open — and this one made a made dash for cover when he spotted me photographing him.

Life is busy on this prairie, and the only slow movements are those of the humans strolling along admiring all this beauty.

I could hear (but not see) frogs calling in the pond, and dragonflies were busy hunting along its edge. I love the clouds reflected in the clear water of a prairie pond.