Bufflehead

Migration Miracles: How Migrating Birds Find Their Way to Us … and Survive the Journey

/ Cam Mannino / 5 Comments
Sandhill Crane in flight over Stony Creek Ravine Nature Park.

They’re coming our way. And others are bidding us farewell. The spring bird migration is under way and will really gain steam in early May. Are you curious about how many birds flew through the night over Oakland County yesterday? Here’s a great tool from Cornell University’s Ornithology Lab that can give you a data-based estimate! (Thanks to birding friend Vinnie Morganti for the link!)

The Dark-eyed Juncos (Junco hyemalis) and Tree Sparrows (Spizelloides arborea), who nest in colder climates, are beginning to depart from the hedgerows and from under our feeders as they wing their way to their northern breeding grounds. Bufflehead dabbling ducks (Bucephala albeola) showed up on Cranberry Lake in mid-March as they made their way through Michigan to their nesting grounds that extend from Ontario to Canada’s Northwest Territories. And of course, the hoarse, ancient cries of the Sandhill Cranes (Antigone canadensis) now draw our eyes skyward. (Click on photos below to enlarge.)

Dark-eyed Juncos breed near Hudson’s Bay in Canada.
A Tree Sparrow can nest directly on the tundra!
A Bufflehead on its way north settled on Cranberry Lake.
Text and photos by Cam Mannino & friends

I’m always impressed by the ability of birds to survive the ordeal of migration, successfully navigating their way twice each year across the country and sometimes far beyond. This spring a lot of questions bubbled up in my winter-weary mind.

How does the tiny hummingbird beat its wings thousands of times on its way to Central America without expiring from exhaustion? How do fledglings find their way when they travel without adults, which happens more often than not? How do birds flying nonstop over oceans eat and sleep? And what’s up with birds using the earth’s magnetic field to navigate? I sure can’t perceive the earth’s magnetic field!

Recently, while doing some spring cleaning, I came across an article that I’d saved which gave me some possible explanations and some resources to go further. (See references below.) So I wanted to share with you the astounding and somewhat bizarre adaptations that allow our avian neighbors to successfully make such arduous journeys.

First, a big Thank-You! My photographer friends, Paul Birtwhistle and Bob and Joan Bonin have again generously shared some of their wonderful photos for this blog. My heartfelt thanks to all three!

So How Did This Whole Migration Pattern Get Started, Anyway?

Doesn’t semi-annual migration seem a bit extreme? I mean, why don’t birds just stay in warm regions all year ’round happily eating and breeding? (I’m glad they don’t, though!) The Cornell Lab of Ornithology describes two theories: the Northern Home theory that northern bird ancestors moved south little by little as ice ages advanced, or the Southern Home theory that southern bird ancestors followed the ice north as it retreated. According to a recent University of Michigan study of the evolutionary lineage of 800 species of North American song birds, the Northern Home theory seems more likely. (Very cool detail about this subject at this link! Click on the words “Evolution of Bird Migration” at the top left.)

Birds have continued to migrate for eons because of the basics: food and breeding opportunities. Temperate zones like Michigan are very buggy places. Our inland wetlands and shorelines produce a glorious abundance of insects and their caterpillars each spring and summer. Just look at the meal this Song Sparrow (Melospiza melodia) found in one of our parks! Quite a haul!

A Song Sparrow with a beakful of caterpillars, soft food with plenty of nutrition for its nestlings. Photo by Paul Birtwhistle.

So when daylight lingers in spring or shrinks in autumn, birds notice the change and start feeling restless. Even captive birds in scientific studies evidence migration restlessness, which is known among researchers by the German name zugunruhe. As the season approaches, they eat more and later into the evening. Their sleep decreases by as much as two-thirds in some species. (Sounds familiar somehow. Maybe human “snow birds” are experiencing zugunruhe?)

The other big draw is mating, of course. Favorite stopovers bring together migrating birds of the same species, which means a more diverse choice of mates. Let’s hear it for diversifying the gene pool!

And then there’s the “housing market”; early birds enjoy a greater selection of the preferred, sometimes scarce, nest sites.

A year ’round resident, the Red-bellied Woodpecker (Melanerpes carolinus), claims one of the high-demand cavity nesting sites in a branch of the Big Oak near the Center Pond at Bear Creek Nature Park. Photo by Paul Birtwhistle.

OK, So How Do Birds Prepare for Migration?

It’s tough to generalize about bird migration. Consider that some travel long distances, like the Ruby-throated Hummingbird (Archilochus colubris) who flaps its tiny wings to reach Central America, or the Magnolia Warbler (Setophaga magnolia) who sets off for the Caribbean. Others travel short distances, like Eastern Bluebirds (Sialia sialis) and American Robins (Turdus migratorius) who simply move just far enough in winter to find open water and more food.

The Hummingbird can double its weight quickly before migration. Photo by Paul Birtwhistle.
A male Magnolia Warbler in Cranberry Lake Park. Note his black necklace!
Five bluebirds socialize before moving south. A House Finch joins them (behind the trunk.)
An American Robin plumped on a cold winter morning.

Many songbirds, like the Rose-breasted Grosbeak (Pheucticus ludovicianus), make their way at night to avoid migrating predators like the Cooper’s Hawk (Accipiter cooperii), which migrates in daylight. Also, according to the Audubon Society, “Free of daytime thermals [rising warm air], the atmosphere [at night] is more stable, making it easier to maintain a steady course, especially for smaller birds such as warblers that might fly as slowly as 15 miles per hour.”

The Rose-breasted Grosbeak migrates at night riding tail winds as much as possible . The darkness hides them from many predators.
Cooper’s Hawks like this one year old travel by day so they can see and snag their prey, but their prey can see them better, too!

Some migrators fly in single species flocks, like the Snow Buntings (Plectrophenax nivalis) that arrive in the fall from the Arctic to spend winters in Michigan. Their plumage is whiter in the snowy north to camouflage them while breeding. During their winter visit here, their plumage includes more brown, making them less visible in fallow farm fields and open prairie. Others, like the Greater (Tringa melanoleuca) and Lesser Yellowlegs (Tringa flavipes) make their way north in mixed flocks during spring migration.

Snow Buntings travel here together from their Arctic breeding grounds in the fall. Photo by Joan Z. Bonin.
Many shore and water birds travel in mixed flocks, like these Greater and Lesser Yellowlegs at Stony Creek Ravine Nature Park. The loss and fragmentation of wetlands around the world are causing a severe drop in the numbers of shorebirds. Photo by Joan Z. Bonin.

According to Scott Weidensaul, author of A World on Wings: the Global Odyssey of Migratory Birds, even if huge numbers of birds are aloft together, a migrating songbird flying at night, “does not fly in cohesive, coordinated flocks; each is migrating on it own.” House Wrens (Troglodytes aedon) and Red-eyed Vireos (Vireo olivaceus), for example are lone nighttime migrators.

A House Wren negotiates its migration from Florida on its own.
The Red-eyed Vireo travels finds it own way to its wintering grounds in South America! Photo by Bob Bonin.

Given all that that diversity, here’s what I’ve gleaned so far about how birds prepare.

They Fatten Up Big Time!

A large flock of Canada Geese (Branta canadensis) here in Oakland Township building up their fat stores for migration.

Birds really lard up for migration. Experienced naturalist and local bird bander, Allen Chartier, checks the weight of each bird he bands and gently blows the breast feathers aside to actually see the fat layer. He told me in a helpful email that our Ruby-Throated Hummingbirds, which normally weigh about 3 grams during breeding season can weigh more than 5 grams as they leave Michigan. They need to keep bulking up along the way and amazingly can double their normal weight in about a week just before heading across the Gulf of Mexico in the autumn or the Yucatan in the spring.

Blackpoll Warblers (Setophaga striata) transit across our state twice a year and Allen says they, “… undergo a long water crossing, sometimes from the mid-Atlantic coast down to Venezuela, non-stop. Normally they weigh 10-11 grams, but can put on enough fat to more than double their weight for these multi-day flights.” He reports that “in the Great Lakes, I have had Blackpoll Warblers that weigh more than 20 grams.” Fat is clearly the essential fuel for bird migration!

The Blackpoll Warbler can fly over the Atlantic for 3 days nonstop on its way to its wintering grounds.

As author Scott Weidensaul points out, “By any typical measure, a migratory bird ready for travel ought to head to the ER, not the skies.” But he says, unlike seriously overweight humans, fattened-up migrators are not plagued by increased risk of hypertension, heart disease, diabetes or stroke. Weidensaul says that “Researchers hope that insights from avian physiology may help may help unlock new treatments and preventive approaches in people.” I hope so too!

They “Grow or Jettison their Internal Organs on an As-needed Basis!”

The quote above from Scott Weidensaul’s book just blew me away. The internal organs of birds actually shrink and expand for migration? Yes! “Internal flexibility is actually common among migrants … a thrush or catbird, feeding on the dogwood berries in a corner of the backyard, has undergone a late summer expansion of its intestines to squeeze every calorie from lipid-rich fruit.”

This digestive tract of this Gray Catbird (Dumetella carolinensis) feeding in September 2019 at Bear Creek Nature Park would have extended as the the fall began in order to get as much polyunsaturated fat as possible from the pulp or seeds within the berries it’s eating!

Migrating birds, which need to travel non-stop over oceans or deserts for long distances, shrink their digestive organs since they’re expendable when they can’t stop to feed. But their hearts, lungs and pectoral muscles grow larger, and do so without exercise! On arrival, the digestive organs make a comeback that allows them to start feeding again. Imagine! Transforming organs!

The little Chestnut-sided Warbler (Setophaga pensylvanica) below, photographed by Paul Birtwhistle in Costa Rica, may not have needed such drastic transformation for its nonstop trip across the Gulf of Mexico. I couldn’t find a definitive answer to that but it definitely burned a lot of fat! According to Cornell Lab of Ornithology’s subscription website, Birds of the World, a Chestnut-sided Warbler in non-breeding plumage could have weighed 10 -12 grams when it left the U.S. coast. But these birds are recorded as weighing only about 8 grams when they reach Central America, having lost most or all of their stored fat on their nonstop flights across the Gulf of Mexico.

This Chestnut-sided Warbler in Costa Rica probably lost a lot of weight flying over the Gulf of Mexico to Costa Rica. I’d say a soothing bath was called for! It will probably take a more leisurely trip around the edge of the Gulf on its way to us this spring. Photo by Paul Birtwhistle.

Weidensaul also reports that both male and female birds shrink their sexual organs for fall migration. Anything to make flying lighter and easier, I guess! Allen Chartier wrote, “Ever since humans began preparing “study skins” for museums, more than 200 years ago, it was discovered that during the non-breeding season the gonads of birds shrink in size, to maybe 10% of the size that they are in the breeding season. It was figured, eventually, that this was to reduce weight for migration, and allow for more body fat to be laid on for migratory flights.” Their gonads are ballooning right now, which is why we are beginning to hear that robust morning chorus in the spring!

Once They Start Moving, How in the World Do They Navigate?

A flock of migrating Tundra Swans (Cygnus columbianus) called to each other as they flew over Cranberry Lake Park. Photo by Bob Bonin.

In her lively and well-researched New Yorker article, “Where the Wild Things Go: How Animals Navigate the World,” (April 5, 2021), Kathryn Schulz wrote: “A bird that migrates over long distances must maintain its trajectory by day and by night, in every kind of weather, often with no landmarks in sight. If its travels take more than a few days, it must compensate for the fact that virtually everything it could use to stay oriented will change, from the elevation of the sun to the length of the day and the constellations overhead at night. Most bewildering of all, it must know where it is going — even the first time, when it has never been there before – and it must know where that destination lies compared with its current position.” Wow.

Like humans with our much more limited ability to orient and navigate, birds use a variety of basic navigation strategies, and different species may use a combination of them. Kathryn Schulz lists as strategies: sight, sound or even scent cues, landmarks (mountain ridges, coastlines), compass orientation or vector navigation (stringing together multiple orientations (e.g. south and then southwest for a precise distance) or dead reckoning (calculating based on bearing, speed and time elapsed from a previous location). But she points out, “… to have a sense of direction, a given species might also need to have other faculties, something like a compass, something like a map, a decent memory, the ability to keep track of time, and an information-rich awareness of its environment.” And Weidensaul adds to the list: the patterns of stars around Polaris (the North Star) and the movement of “bands of polarized light that are invisible to us but easily seen by birds.” Wow, again! All that in one small skull!

According to Weidensaul, “Migratory birds grow fresh neurons before autumn migration” and scientists have correlated longer migrations with more neuron growth, presumably as an aid to navigation. The neurons also increase according to whether birds travel individually or in flocks. Warblers which generally fly alone show increases in the hippocampus which processes spatial information and memory. Birds in large migrating flocks see most of the increase in regions of the brain that may be more important for noticing and understanding the actions of other birds.

Researchers believe that a bird’s general destination may be defined by instinct, especially in young birds, many of whom make their first trip alone or with other juveniles. But learning clearly occurs during their first flight with or without adults and plays its part in perfecting the best route from then on.

But what I wanted to know was, how do some migrating birds create and use a mental map of the earth’s magnetic field? I kept finding references to their ability to do so, but no one told me how! Well, Weidensaul had an answer which he says “most experts accept.”

This little Wilson’s Warbler could have navigated from Central America to Tawas City, Michigan using a starlight map of the earth’s magnetic field in its retina! What a feat!

Imagine the little Wilson’s Warbler (Cardellina pusilla) in the photo above glancing upward at the stars as it flies through the night from Central America to where I saw it in Tawas City, Michigan. As I understand it, photons of the stars’ blue light hit specialized cells in the bird’s retina containing molecules of a protein called cryptochrome. (Love the Superman sound of that!) Those molecules react by thrusting one of their electrons into a neighboring molecule and the two become connected (“entangled” in scientific jargon) and magnetic. (That’s the quantum mechanics part which is a bit beyond me.) As light continues to stream in, multiples of these paired molecules build a map of the magnetic field within the bird’s eye. Scientists think the map may appear as a “dim shape or smudge — visible as the bird moves its head, but not opaque enough to interfere with normal vision — that shifts with the bird’s position relative to the ground and to the inclination of the magnetic field lines arcing out of the planet” (Weidensaul). Evidently, birds can orient themselves within that map to help find their way to their destination. Many of us humans have a tough time reading a road map!

If my brief summary leaves you with more questions than answers, you’re in good company. Even scientists don’t completely understand how cryptochrome works its magic and some disagree with the whole theory. But at least that little map in the eye created by starlight and quantum mechanics satisfies my curiosity for now. If you’d like a somewhat what more detailed description, I recommend Chapter Two of Weidensaul’s book, A World on the Wing.

Eating and Sleeping,: How Do They Survive Along the Way?

Eating Strategies

Eating on migrations varies according to what and how a bird eats. Most migrating birds depend on trusted stopover sites for food and rest. Allen Chartier wrote that “Migrating warblers, sparrows, and thrushes migrate at night, and put on fat to fly 200+ miles each night…” to their next stop. Eastern Kingbirds (Tyrannus tyrannus) and Barn Swallows (Hirundo rustica) migrate to Michigan from deep in South America during daylight hours, in order to gobble up flying insects while on the wing as well as at known rest stops.

The Eastern Kingbird gulps down insects in flight on its way to us from the Amazon.
A flock of Barn Swallows gathered at Stony Creek Ravine Nature Park in 2022. They were preparing to fly to Argentina while feeding in flight.

Amazingly, some birds in other regions of the world fly nonstop for multiple days and nights without eating at all! Weidensaul describes the Bar-tailed Godwit’s “7,200-mile nonstop flight each autumn from western Alaska to New Zealand, a journey that takes them eight or nine days of uninterrupted flight — the longest nonstop migration known.” They are an impressive example of “jettisoning” organs and living on fat. I’m really glad I’m not a godwit – but I am impressed by them!

The amazing Bar-tailed Godwit who jettisons its digestive organs and lives on stored fat for its 7200 mile migration. Photo taken in Australia by an iNaturalist.org photographer who uses the name fubberpish (CC BY-NC)

Drinking in Flight

Birds don’t sweat but they do lose moisture through breathing and excreting. That may account for so many birds migrating at night when the air is cooler and more humid, according to Weidensaul. Of course they look for freshwater wetlands as a basic source of drinking water. But on long ocean or other nonstop flights, for instance, research shows that they can still maintain a healthy amount of moisture by extracting water from their beefed-up muscles and organs while in flight.

Sleeping on the Wing

Most migrating birds do their journeys in stages, resting during the day or night depending on when they travel. Weidensaul reports that “For migratory songbirds, like White-throated Sparrows and Hermit Thrushes (Catharus guttatus,) the onset of migration seasons … decreases the amount of time they sleep by two-thirds, even in captivity, and well before they start migration. They may compensate by taking micronaps during the day.”

White-throated Sparrows ((Zonotrichia albicollis) breed from northern Michigan all the way to Hudson’s Bay but they winter from here to Florida, slipping in naps at stopovers on the way.
A Hermit Thrush (Catharus guttatus) during fall migration at Cranberry Lake Park stopped before dawn to rest and eat before traveling on to the southern North America.

Mallards (Anas platyrhynchos) have evolved to use unihemispheric sleep, a condition in which only half the brain sleeps at a time and one eye stays open. Neils Rattenborg directs sleep research at Germany’s Max Planck Institute and his team’s work centers around birds. According to an article from the Max Planck Society, Rattenborg documented that “in a group of sleeping ducks, those [Mallards] sitting at the edge kept their outwardly directed eye open and the corresponding brain hemisphere remained awake. The birds can thereby rest a part of their brain while keeping an eye out for potential predators.” I’m on the lookout for that phenomenon!

Paul Birtwhistle caught this lovely male Mallard feeding. But researchers have learned that while in flocks, Mallards can have unihemispheric sleeping, with one eye open and one half of the brain awake while the other half sleeps!

By outfitting birds Great Frigatebirds (Fregata minor) near the Galapagos Islands with tiny transmitters, Rattenborg also discovered something even more important about sleep. It seems these large birds take repeated unihemispheric naps averaging about 12 seconds long while foraging at sea for six days or more. Sometimes these birds’ entire brains slept while slowly gliding up or down in thermals! Talk about power napping, eh?

A Great Frigatebird hunting off the Galapagos islands naps while in flight! Photo by spinomaly (CC BY-NC) at iNaturalist.org.

What Can We Humans Do to Make Life Easier for Migrating Birds?

Clearly, we’ve created big challenges for migrating birds, despite their amazing adaptations over the eons. So here are just a few of those difficulties and how we might help our beautiful migrating neighbors.

  1. Light Pollution: Birds need a clear view of the night sky even more than we do. (Don’t you miss seeing a sky filled with stars?) So we can turn off outside lights (at home and in workplaces), make the light bulbs yellow or red instead of white, or install shades on outdoor lights that direct the light downward. Inside, we can close curtains or shades where a light is near a window in the evening during migration season. It all helps.
  2. Reflective glass like picture windows: Birds that crash into windows may fly off but they often do so with concussions. Check out this link for options for preventing bird strikes.
  3. Cats: Keep our beloved felines indoors. To quote Cornell Lab of Ornithology on this subject, “These are non-native predators that, even using conservative estimates, kill 1.3–4 billion birds and 6.3–22.3 billion mammals each year in the U.S. alone. Exhausted migratory birds and fledglings are particularly at risk.
  4. Habitat Loss: Restore natural areas and plant native plants at home. Birds count on finding the adult insects, caterpillars, and seeds that make up their diet when they arrive at a stopover or their final destination. If that land is covered by concrete or invaded by non-native plants that don’t provide the nutrition or cover they need, birds suffer along with the rest of the creatures in that habitat.
  5. Climate Change: Actively, drastically and quickly reduce our use of fossil fuels. Climate disruption effects migratory birds in so many ways. But here are at least two important ones. It causes more severe weather events which vulnerable migrators must negotiate over long distances. Also, insects and plants initiate hatching or blooming by ground temperature; as the ground warms earlier, overwintering insects hatch earlier, plants mature more quickly. Birds, however, initiate migration by the position of the sun and the length of daylight. As a result, tired migrators may arrive in the spring unable to find the insects, nectar or pollen on which they depend. Want evidence? Look here!

Birds Do It, Bees Do It, Even Whales in the Seas Do It … Let’s Do It. Let’s Start to Adapt…

A sky full of Broadwinged Hawks (Buteo platypterus) at the Hawkfest in 2018 at Holiday Beach near Windsor, Ontario.

Obviously, we humans need to adapt just like the migrators have – but a lot faster! We don’t have thousands of years for evolution to re-engineer our bodies and nature itself to cope with the new climate we’re creating with fossil fuels. No miracles of transforming digestive systems, cryptochrome maps in our eyes or unihemispheric sleep are on our immediate horizon. Nature already gave us our adaptive tools – our brains and our will. We already know much of what is needed; the trick is, do we find the collective will as a species to do it in time? The changes we need to make are significant, but not insurmountable. Nature is already warning us with tornadoes, floods, droughts, melting glaciers. It’s insisting “You can do this! Use the adaptation tools between your ears that you were blessed with and save us all!” I certainly hope more humans heed that desperate call – and soon!

Main Sources:

  • A World on the Wing: The Global Odyssey of Migratory Birds by Scott Weidensaul, W.W. Norton and Company, New York 2021
  • “Where the Wild Things Go: How Animals Navigate the World,” by Kathryn Schulz, published April 5, 2021 in the New Yorker magazine
  • Birds of the World, a subscription-only website from Cornel Lab of Ornithology, Cornell University in collaboration with the American Ornithological Society.
  • “The Evolution of Bird Migration, “Adapted from the Handbook of Bird Biology, Third Edition, on Cornell University’s website “All About Birds”‘
  • “Snoozing between the skies and earth” a posting on the website of the Max Planck Society.

Letting Nature Breathe Again: Restoration at Cranberry Lake Park

/ Cam Mannino / 1 Comment
North meadow at Cranberry Lake Park after forestry mowing

Ah, at last! The native trees and plants can breathe again! Many of the invasive shrubs that had crept across open areas at Cranberry Lake Park are gone. Now the sun washes across the landscape, rain sluices into the ground, nourishing the roots of native trees, grasses and wildflowers waiting for spring. As the carpet of mowed stems and branches decompose, the nutrition previously taken up by autumn olive, privet, glossy buckthorn and other non-native shrubs can gradually re-nourish the soil. The diverse wildlife that evolved with our native plants will once again benefit from the food and shelter that they’ve depended on for thousands of years. With the help of careful stewardship – treatment of non-native re-sprouts and the spreading of native seed – a habitat will be reborn.

So come have a a look at the new vistas in the park. I can’t show it all, but maybe I can give you taste of it. Along the way, we’ll see a few creatures that shared my walks during the mostly gray days of November and early December.

Miraculous Transformation Along the Hickory Lane

To appreciate the dramatic changes made by forestry mowing, here to the left is a typical view of most paths at Cranberry Lake Park before the restoration work began – and it’s not too scenic, I must say. A tangle of invasive shrubs and vines created very little nutrition for wildlife, left only a narrow edge along the path for native wildflowers and had spread thickly into the fields beyond the trails. The almost impenetrable density of the shrubs blocked views of wetlands and the open vistas of large trees that had existed before the invasive plants took over. The invasives also took up nutrients and shaded out native plants all over the park.

As I headed north from the parking lot at West Predmore Road and stepped into the Hickory Lane, I first noticed that I could see into a wetland that I’d struggled to reach from the opposite side last summer when a group of volunteers and staff monitored a vernal pool there. How nice to see it so clearly from this direction! Perhaps you can see the density of shrubs on the far side, which is what used to exist along the Hickory Lane.

A wetland along the Hickory Lane, now visible after the removal of invasive shrubs

The mature trees along the Hickory Lane, of course, were not touched and only a scrim of shrubs remain between them. Look at the contrast between the un-mowed left side and the open area in the distance on the right! I was immediately tempted out into that cleared meadow.

The Hickory Lane with recently mowed meadow on the right and dense shrubbery remaining on the left

I found a place to slip between the trees and look at the landscape that had appeared. I’d never seen this sight before!

Once dense with shrubs, this beautiful meadow with mature trees opened up before me.

I was elated! The large trees, once shrouded with thickets of invasive shrubs, now stood clear in the November light. I wandered across the shredded trunks and branches of the former thicket, looking down for any signs of native plants which had survived beneath that carpet of invasives. And even though it was early November then, I found two. The tiny evergreen plant popping out in the photo on the left below is named Haircap Moss (a Polytrichum species). These plants thrive in moist, partial shade so they may eventually disappear in this location and be replaced by more sun-friendly species. And on the right below is native Wild Strawberry (Fragaria virginiana) which does well in the sun. Its flowers provide sustenance for butterflies and moths in spring and its tiny berries do the same for wildlife in the summer.

Haircap moss likes the shade so next summer a sunnier plant may replace it.
Wild strawberry is a native that feeds wildlife in spring and summer.

This sprawling meadow is divided by a tree line and in the northern section, a huge Shagbark Hickory (Carya ovata) stood tall in the sunlight, freed at last from the tangle of invasives. It still had one intruder, though. One of the least welcome invasives, Oriental Bittersweet (Celastrus orbiculatus), hung in its branches. Though the mower had chopped it off near the ground, it will try to make a comeback since its seeds will drop to the ground or be carried all over the park by birds.

A huge Shagbark Hickory in the newly mowed field with a few strands of Oriental Bittersweet clinging to its branches.
The yellow berries of Oriental Bittersweet are eaten by birds but provide very little nutrition for them.
These berries will start new vines and can be widely distributed in bird droppings.

This invasive vine spirals up tree trunks, choking them while climbing to the sunlight. It shades out growth below and since it accumulates in the canopy can make trees vulnerable to being toppled in high winds. I saw a smaller tree felled in just this way farther east in the park. (See below left.)The hickory will survive, but a nearby tree in the restored meadow (below right) was heavily infested with Bittersweet. Look at the number of berries that can be spread from one vine!

A small tree on the eastern side of the part felled by the weight of Oriental Bittersweet.
A tree in the newly cleared field heavily infested with Oriental Bittersweet, an invasive non-native vine.

Now that the field has been forestry mowed, our township stewardship manager, Dr. Ben VanderWeide and his crew will take on the extensive follow-up processes to prevent re-sprouting by carefully applying herbicides to invasive shrubs like Bittersweet, or by girdling the trunks of non-native trees. Once that’s completed, native plant seeding can begin. We can do our part by not using Oriental Bittersweet for fall decorating and by cutting and treating any stems that appear near our homes.

The clearing of this wonderful meadow also brought the beauty of the Long Pond into view – a series of linked ponds that runs north and south on the eastern side of the restored meadow. What a treat to get close like this! I look forward to seeing the water glinting through the trees next summer and seeing the water fowl that drop in to forage or rest during migration.

The Long Pond from the eastern edge of the restored meadow beyond the Hickory Lane – a vista not seen until the forestry mowing was completed.

Blue sky days were rare in November. Most of the time, the sun struggled to get through heavy cloud cover.

The sun was dimmed by dark clouds on three of my four trips to Cranberry Lake Park.

On one of those cold, dark days, when most birds were silent, I heard a gruff squeak repeated incessantly by a Red-bellied Woodpecker (Melanerpes carolinus) who fled from one tree near the Hickory Lane to another. (Click here and choose the December call recorded in New York near the bottom of the list for a sample.) I thought it might be issuing a warning but I couldn’t see a threat. Later however, I spotted a Red-tailed Hawk (Buteo jamaicensis) eyeing me from high in a distant tree and wondered if it prompted the Red-belly’s call.

A Red-bellied Woodpecker called repeatedly near the Hickory Lane, perhaps a warning about a nearby hawk.
A Red-tailed Hawk eyed me from afar, perhaps the one that worried the Red-belly?

On one of the snowy, quiet days on the Hickory Lane, it cheered me to see the tracks of little animals who’d visited the lane just after the snow fell the previous night or early that morning. I wasn’t alone! I followed the tracks of an Eastern Cottontail (Sylvilagus floridanus) for quite a distance, a squirrel, probably the tiny Red Squirrel (Tamiasciurus hudsonicus), had bounded across the lane and a White-footed Deer Mouse (Peromyscus leucopus) had left its stitching tracks as it scurried diagonally across the spot where two paths met.

I walked along the lane following the tracks of a rabbit who’d visited after the snow fell.
The outside prints are the five-toed back feet of a Red Squirrel. It pushes off with the four toed front feet.
Mouse tracks skittering across the trail.

Opening Up the Path to Cranberry Lake

Like the Hickory Lane, the path to the lake had been crowded with non-native invasives. Once the forestry mower got to work, though, the lake could actually be glimpsed from far up the trail.

Invasive shrubs crowded the edges of the path to the lake, obscuring the view of the lake.
With the invasives removed, the lake now appears in the distance.

Along the trail in November and early December, birds were more heard than seen on dark cold days. Of course, Canada Geese (Branta canadensis) still trumpeted overhead. I love it when they get close enough to hear the snap of their wings!

A squadron of Canada Geese honking their way to warmer climes.

Along with the usual year ’round inhabitants, I did get to see two more unusual birds , migrators that I’d missed earlier in the autumn. Early in November, the birding group spotted a small flock of Rusty Blackbirds (Euphagus carolinus) high up in trees near the lake. The numbers of these pale-eyed blackbirds have “plunged an estimated 85-99 percent over the past forty years,” according to Cornell University’s website allaboutbirds.org. The ones near Cranberry Lake were too high for my lens to reach that day, but luckily I’d gotten a closer look back in 2017 at Bear Creek.

Rusty blackbird female at Bear Creek Nature Park in 2017. Note the pale eyes on these close relatives of the Grackle.

On one late November visit, a speckled Hermit Thrush (Catharus guttatus) surprised me by stopping by so late in the season. Since they are known to like open areas in woods, maybe this one found Cranberry Lake Park a good stopover after a late start at migration.

A late-migrating Hermit Thrush

When the birding group reached Cranberry Lake early in the month, a bobbing flotilla of ducks floated in the distance.

Hundreds of ducks floated, fluttered and cruised along Cranberry Lake in early November

The ducks stayed out of the reach of even our binoculars. But some of the more expert birders were able to discern three species by the patterns and colors on their wings or heads: Buffleheads, Lesser Scaup and Ring-necked Ducks. Later in the week, I was able to get a bit closer to the Buffleheads (Bucephala albeola) when a friend let me cross his lawn on the far side of Cranberry Lake. (Thanks, George!)

Bufflehead ducks spend the winter with us wherever they can find open water.

My photographer friend, Paul Birtwhistle, shared his photos of a variety of ducks on open water at Stony Creek Metropark one January. Here are Ring-necked Ducks (Aythya collaris) hanging out with a larger group of Redheads (Aythya americana) and Mallards (Anas platyrhynchos) on a cold winter day. For Ring-necked ducks the white swoop on the flanks and the stripe at the base of the bill are good field marks for this black-and-white diving duck. Some Redheads spend the winter here, but most migrate to the Gulf coast.

Ring-necked ducks (the black-and-white ones) hanging out at Stony Creek Metropark with Redheads and Mallards.

Paul also shared some fine photos of Hooded Mergansers (Lophodytes cucullatus) who frequent Cranberry Lake as well as the lake in Stony Creek Metropark during the winter. Here’s a male and female Hooded Merganser and one of a lucky male who snagged a crayfish!

Hooded Mergansers scooting between a Canada Goose and some Mallards . Photo by Paul Birtwhistle
A male Hooded Merganser who’s no doubt pleased with his crayfish catch! Photo by Paul Birtwhistle

I found a photo of the Lesser Scaup (Aythya affinis) by a generous photographer at iNaturalist.org. These ducks may have been migrating through when the birding group saw them in early November. They tend to spend the winter along the Gulf Coast. The ruffled “cap” on the back of its head is what separates it from the very similar Greater Scaup.

That fuzzy little ridge at the top of the head makes this a Lesser Scaup instead of a Greater one! Photo by Robert Pyle (CC BY-NC)

Mute Swans (Cygnus olor) with their bulbous orange and black bills fed actively on the far side of Cranberry Lake. The Cornell All About Birds website describes the difficulties presented by these beautiful, but non-native birds. “Their aggressive behavior and voracious appetites often disturb local ecosystems, displace native species, and even pose a hazard to humans.” Our native Trumpeter Swans (Cygnus buccinator) were once endangered, and though Cornell Ornithology says they are “recovering,” they still have a hard time competing with Mute Swans. Trumpeters, which have solid black bills, breed in our area, but winter farther south.

Non-native Mute Swans feeding near the dock on the eastern side of Cranberry Lake
Our native Trumpeter Swans migrate south. Photo by Jason Miller (CC BY NC SA)

A Quiet Walk Back Wakes Me to the Small Details of a Winter Walk

The last of autumn on Cranberry Lake Park’s eastern meadow in late November

On these four quiet days in the park, I didn’t see much wildlife on my way back through the park’s eastern section. When that happened, I looked more carefully downward and as usual I was rewarded by paying attention. Below a wooden walkway over a small wetland on the trail, leaves made a mosaic under a skim of ice. That’s the kind of detail I can miss when looking up.

A mosaic of leaves beneath a scrim of ice in a wet area by the trail.

The dry Showy Goldenrod plumes (Solidago speciosa) drew my attention to bands of late autumn color at the edge of the Eastern Meadow. Along the paths, fertile fronds of Sensitive Fern (Onoclea sensibilis), clad in their bead-like sori, contain the spores for next year’s crop.

Dry plumes of Showy Goldenrod pointed toward bands of late autumn color.
The Sensitive Fern produces its spores on stems separate from the leafy green ones that photosynthesize in the summer.

Dry Wild Cucumber Vines (Echinocystis lobata) were draped like garlands across bushes here and there in the park. In summer, the vines look delicate and airy. In autumn, they produce the prickly seed capsules that give this plant its name. Each capsule opens in the fall, dropping four seeds from within its two chambers.

The spring flowers and green prickly fruit of Wild Cucumber vine
Dry Wild Cucumber vine draped across a tangle of other vines.
The dry fruit will break open at the bottom when winter ends just in time to deposit its seeds into spring soil.

Tall Thimbleweed (Anemone Cylindrica) is a favorite of mine in early winter. I often miss its modest flowers in the spring. I begin to notice it when its small green center begins to extend into a cylinder as it forms its thimble-like fruit. I appreciate it most when colder weather prompts its seed head to burst forth in a cottony tuft filled with tiny black seeds.

Thimbleweed blossom with green cone at the center and five petal-like sepals
The central “thimble” beginning to expand into a cylinder as summer moves on.
The cottony tufts of thimbleweed seeding in early winter.

So Exactly What is Being Restored at Cranberry Lake?

A thicket of native Gray Dogwood on the path back to the parking lot

At times, I’ve thought of restoration projects as similar to the restoration of an historic home. The work that Dr. Ben VanderWeide and our stewardship crew perform restores natural vistas that thrived here for thousands of years before European colonization. At Cranberry Lake Park we’re removing invasive shrubs and vines so that native trees, shrubs, and wildflowers can reestablish a mosaic of forest and meadows. That’s historic preservation, for sure!

But what’s essential to understand about the work being done in our parks is that it’s about much more.

One presenter at a Michigan Wildflower Conference compared nature’s intricate systems to the thousands of lines of code in your cellphone, each one of which depends on the performance of thousands of others to make the system work. Imagine, the presenter said, randomly removing just one line of code from your cellphone. You wouldn’t do it! The system might crash!

Nature spent eons perfecting its “coding,” creating a delicate balance that fed and sheltered a huge variety of life forms. Sometimes unwittingly, sometimes knowingly, humans have removed one “line of code” after another from nature’s finely-tuned system. It’s happened everywhere on our small, blue planet, even right here in our yards and parks. Non-native plants introduced into our parks, fields, and gardens can act like an aggressive computer virus, spreading quickly, damaging nature’s finely balanced systems with destructive force.

So as we begin a new year, let’s celebrate that in our little spot on the globe, we’ve chosen to support stewardship and restoration in our natural areas. As the native wildflowers, trees and grasses that nature fostered for eons return to their rightful places, they provide a healthy foundation for the rebirth of our meadows, forests and wetlands. We can justifiably hope that with time and effort, some small part of nature’s intricate and carefully balanced “lines of code” can be restored to our ecosystem. If so, the myriad of complex relationships that once thrived here will again sustain the rich variety of life that nature planned for us.

Cranberry Lake Park: Have Hope! Sure but Subtle Signs of Spring!

/ Cam Mannino / 2 Comments

The solstice has passed; the days and nights get equal time. But when I’m shivering, my fingers and ears go numb in a stiff  wind, I struggle to hold on to the idea that we’re heading into spring. Until, that is, I head into the parks.

Blog by Cam Mannino

In mid-March,  water birds began splashing down in Cranberry Lake, finding any narrow stretch of open water within the ice sheet. They floated and fed – until one glorious morning, the whole lake turned liquid and bright blue! Migrating flocks honked, chattered and wheeled overhead. Some stopped to rest and feed before heading further north; others explored nesting sites. Our year ’round residents tuned up their spring songs. Territories must be established! Potential mates must be impressed! Best of all, the tiny frogs thawed after their frozen winter state – and now they are  singing! Can genuine spring, with its fulsome birdsong and burgeoning buds be far behind? I think not!

Water Birds Arrive Early, Despite the Ice – and the Muskrats Emerge, too!

It always impresses me that some of the first migrators to arrive in early spring are the water birds! They float, seemingly content, in the icy cracks that form as the sun begins to work on the frozen lake surface. Their cold water strategies involve body fat, oiled feathers, down insulation, and a circulation system which allows cool blood coming up from their feet to pass close to  warm blood traveling down, warming it as it returns to the heart. Below a group of Common Mergansers – black-headed males and brown-headed females –  glided along a thin channel of water on the far side of Cranberry Lake’s iced-over surface.

Common Mergansers – black-headed males, brown-headed females – find a small slit of open water at Cranberry Lake early in March.

Off in the distance, the Wednesday birders spotted the hunched silhouette of a Muskrat (Ondatra zibethicus) perched on the edge of the ice as a goose floated nearby. It slipped in and out of the water, hungry no doubt for food but also for a meager scrap of sunlight after living under the ice all winter!

Two sunny but cold days later, the ice had disappeared and the lake was bright blue and busy with migrating ducks and geese. Two Bufflehead (Bucephala albeola) and a group of Ring-necked Ducks (Aythya collaris) – black-and-white males and brown females –   dove and surfaced as they foraged near a Canada Goose (Branta canadensis).

A group of Ring-necked Ducks and two Bufflehead dove and rose next to a Canada Goose as they rested and foraged in the lake.

I got a bit closer to a Bufflehead by checking from the opposite side of the lake. This lone male rocked along on the surface, bobbing under to feed every few minutes. Cornell Lab of Ornithology says Bufflehead accomplish this dive  by compressing their feathers to drive out the air and then pitching forward. A few seconds later, they pop to the surface like a cork and float on.

The Bufflehead dives underwater by pitching forward with its feathers compressed to squeeze out the air, making it less buoyant and able to submerge.

And that same cold morning, what I think was a large muskrat came steaming across the pond toward the eastern side. At the time, I thought this bustling swimmer was a Beaver (Castor canadensis), since there is a large beaver lodge on the western side of the lake. But I’m just not sure of that, so I’m sticking with it being a large muskrat. In the water, its tail looked wide enough to be a beaver, but as it approached the shore, it just didn’t seem to be big enough to be a beaver, unless it was a yearling. And beavers tend to swim with only their heads out of the water. In any case, nice to see this furry fellow plying the pond in the sunshine. What do you think? Big muskrat or young beaver?

The width of this swimmer’s tail made me think this was a beaver, but I think now it was a large muskrat.

From this nearing shore photo, it appears I’ve seen a large muskrat, rather than a small beaver.

Hearing the ancient bugle of the Sandhill Crane (Antigone canadensis), I quickly looked up to see two in the distance, flying into the far end of the lake.  Aren’t we lucky that they breed in our wetlands?

A pair of Sandhill Cranes fly in to check out the edge of Cranberry Lake as a possible breeding ground.

 Spring Songs Signal the Beginning of the Mating Season

As I approached the park one icy afternoon, bright spring music reached my ear – Western Chorus Frogs. These tiny frogs (Pseudacris triseriata – about 1.5 inches long!) are daytime relatives of the nocturnal Spring Peepers (Pseudacris crucifer). They spent the winter frozen solid, no heartbeat, no brain activity, but protected by an anti-freeze of sorts that keeps their tissues from breaking down. Pretty amazing! They thaw out and start singing as the days lengthen. The first afternoon I scanned a wetland trying to see these tiny creatures that seemed to be singing right at my feet, but I could not spot one! So on a second try a few days later, I found a log to sit on near the wetland in the trees just east of the parking lot. After about 20 minutes with my binoculars, I finally spotted two (of the hundreds that were probably there!), the sacks beneath their chins bulging, as they tried to impress a female with their piercing calls. Have a look and a listen!

Two tiny Chorus Frogs with bulging necks sing to attract a mate in the shallow water of a wetland.

A male Northern Cardinal (Cardinalis cardinalis) sang from the tree tops in the eastern meadow, turning every few minutes to send his territory call in a new direction. He’s a bit faint on the recording below, so you might need to turn your volume up! I got a bit closer to another male in a bush near the parking lot later on. He was doing “call and response” with another cardinal hidden in the trees nearby.

A male cardinal turns periodically to send his call in all directions.
A male cardinal sang near the parking lot. Another answered from the woods nearby.

And of course, the American Robins (Turdus migratorius) that went south to Ohio and Kentucky returned as well, joining the hardy ones that spent the winter here.

One of many Robins that have returned from Ohio and Kentucky to breed here in the summer.

His spring call is also a bit soft.  And he makes a longish pause before his second “tit whoo” call.

Woodpeckers, of course, use drumming to establish territories, rather than singing.  Both male and female Downy Woodpeckers (Picoides pubescens) attract mates and protect territories with drumming. You can hear their typical drum roll in this Cornell Lab recording which was put to use by the little female Downy below.

I get a huge kick out of hearing flocks of American Goldfinches (Spinus tristis) chirp in the shrubs and small trees. To my ear, they are the only bird that actually says “tweet, tweet, tweet!”  Have a listen at this link and see if you agree! The males are currently molting into their bright yellow summer outfits.

Groups of American Goldfinches are singing their “tweet, tweet” calls in Cranberry Lake Park right now.

On a bird walk one Wednesday, we heard the far distant, insistent drumming of a Pileated Woodpecker (Dryocopus pileatus). Mark, one of the great spotters in the bird group, finally located it with binoculars on a very distant tree, and suddenly its mate (we assumed) dove across the trail far ahead of us before slipping up and away between the trees. No chance for a photo.  But here’s an incredible closeup by talented photographer Monica Krancevic at iNaturalist.org.

Pileated Woodpecker by Monica Krancevic (CC BY-NC) at iNaturalist.org

The First Blooms and Some Sturdy Ferns Wait Patiently

The lovely red blossoms of the Silver Maple (Acer saccharinum) brighten gray days in early spring. They emerge on bare branches before the leaves and are pollinated by the wind before butterflies or other insects emerge and start to pollinate. Those big clusters of scarlet florets are a great food source for hungry squirrels in the spring, when food is scarce, since nuts and seeds are either already eaten or beginning to crack open and sprout.  Last week, I found these male (staminate) clusters fallen from the treetops onto the exposed roots of a large silver maple. I love how the red at the edge of the root echoes the red of the flowers.

The scarlet blossoms of a silver maple are echoed in the root of the tree itself.

Take a closer look at this cluster of florets, some still closed, others waving stamens that have already shed their pollen to wind.  Once pollinated, the female florets will produce winged fruits, called samaras.

A closeup of a cluster of male florets, some closed, some with their stamens already emptied of pollen.

Nearby on the trail to the lake, some sturdy ferns survived the winter with fertile fronds intact.  The brown beads below are the sporangia on the fertile fronds of the Sensitive Fern (Onoclea sensibilis) that carry the spores for this year’s crop of new plants. On the right, are the vegetative fronds that provide sugars through photosynthesis in the summer months.

The fertile frond of Sensitive Fern waits for warm weather to release its spores.
Sensitive Fern vegetative fronds in summer do the work of photosynthesis.

And the feathery ones below left are the fertile fronds of Ostrich Fern (Matteuccia struthiopteris) whose spores will be released and carried by the wind in the spring. Their vegetative fronds on the right stood tall and bright green, taking advantage of the moist soil and spotty sunshine in the forest.

The fertile fronds of Ostrich Fern wait for spring to release their spores.
Fronds of Ostrich Fern glowing in the sunlight

Spring Just Peeks Out…Here and There

A pair of Canada Geese rest in the quiet refuge of a shaded wetland

Behind a scrim of small trees on the way to the lake, I spotted these two Canada Geese floating serenely in a secluded wetland, away from the noisy flocks gathering on the lake. They reminded me that, at this time of year, spring has to be sought out. It appears and disappears. One day the lake is iced over, a few days later it’s rippling and blue and then the snow falls again. On some days, spring isn’t easily seen – just a few red blossom clusters floating in a vernal pool  or scattered on the lifeless grass. Sometimes spring can only be heard and not seen. Frogs as tiny as your thumb sing unseen one day and the next, perch on a bit of floating grass, their throats bulging with amorous sound. Flocks twitter or honk high in a cold blue sky or male birds rehearse the first tentative versions of their mating songs. Woodpeckers tap out a seductive rhythm on the bark of trees.

The Eastern Meadow at Cranberry Lake doesn’t look very spring-like yet – but the clues are there.

Early spring isn’t flamboyant and colorful, like it will be in a few weeks. It’s hesitant, waiting to be found and enjoyed if we can only slow down enough. If we watch, we’ll see it peeking through the alternating rain or snowfall, cracking and opening in thawing ponds or hear it whistling, chirping, trilling from inside the brush or high in the treetops. So I hope you have time to delight in these  subtle hints of early spring as they unfold. It won’t be long now…

Footnote: My sources for information, besides Oakland Township's Stewardship Manager Ben VanderWeide, are as follows: Caterpillars of Eastern North America by David L. Wagner; inaturalist.org;Allaboutbirds.org, the website of the Cornell Ornithology Lab at Cornell University; Wikipedia; Herbarium of the University of Michigan at michiganflora.net; various Michigan Field Guides by Stan Tekiela;Butterflies of Michigan Field Guide by Jaret C. Daniels,  and others as cited in the text.