Field Note: A Great Blue Heron on Thin Ice! … and Its Neighbors – a Drama in Three Acts

It often happens that shortly after I publish a blog about a particular park, something interesting pops up there that I wish I could have included.

Text by Cam Mannino

So to solve that issue, Dr. Ben VanderWeide, Oakland Township’s Stewardship Manager and I decided that it might be fun to slip in a short piece, a “field note,” now and then about these intriguing and/or surprising discoveries. And wouldn’t you know, one cropped up last week!

A Young Blue Heron Discovers a New Challenge: Ice!

Readers may remember that in the recent Bear Creek Nature Park blog, my photographer friend Paul Birtwhistle introduced us to a voracious juvenile Great Blue Heron (Ardea herodias) who for weeks spent its mornings snapping up green frogs and fish from the drought-depleted Center Pond at Bear Creek.

Photographer Paul Birtwhistle and Stanley the Wonderdog

Well, after one frigid night last week, the pond froze with a thin sheet of ice. And of course, the Heron returned in the morning to continue its feast. But to its apparent dismay, the water had changed drastically since the day before. The heron stepped out cautiously on this oddly slick surface and looked about. In the short video below, you’ll hear that Paul was amazed at what he was filming. And the young Heron was just as surprised at finding the pond surface inaccessible after weeks of dipping into it to find a rich trove of food. [Note: Vimeo, which formats our videos, attributes everything on Ben’s Vimeo account to Ben. But this week, all of the photos and videos were generously shared with us by Paul Birtwhistle.]

“What’s this? Tap, tap, tap. The water is hard?!!! What’s this? Video by Paul Birtwhistle

This youngster didn’t give up easily! It stared at the surface repeatedly. Paul guessed that he was seeing movement under the thin ice.

I see something down there, but why is my vision so fuzzy? And how do I deal with the slick, hard barrier between me and breakfast? Photo by Paul Birtwhistle

I wonder if perhaps the juvenile thought something was wrong with its eyesight, as it tried to bend down and get closer to the ice. Or perhaps it still thought it could snag its prey if it crouched down a bit…

Hmmm…maybe I just need to get a little bit closer. That usually works. No? Drat! Photo by Paul Birtwhistle

The heron tread verrrry cautiously on the thin, icy surface but – Yikes! Suddenly its feet slipped from under it and up went those dramatic wings to help it find its balance.

Whoops! Wings up! What’s the deal with this weird pond? Photo by Paul Birtwhistle

Trying to keep its hopes up, the bird spent about a half hour stepping carefully on the slippery surface and peering down at the ice-blurred surface of the pond. The youngster appears to warm one foot by bringing it to its feathers – or maybe it’s simply scratching an itch. In any case, this young bird looks pretty frustrated at this puzzling new experience.

I just don’t get it! How annoying! Photo by Paul Birtwhistle

After more than a half hour of exploration, the young heron took flight. Let’s hope it found its way to deeper water and the society of older herons who would show this young ‘un how to fish from the icy edge of open water.

OK! I’m outta here! There must be normal water around here somewhere! Photo by Paul Birtwhistle

Paul was surprised and delighted to see a heron on ice! And so was I when I received his photos! We thought Great Blue Herons would already have migrated. But when I contacted experienced naturalist and bird bander, Allen Chartier, he explained that, in his experience, though many migrate further, some herons just keep moving south to find open water. He sees them where warm water thaws the ice near power plants, for example. He believes most of them depart by January when even large bodies of water freeze over. Cornell University’s subscription website, Birds of the World, indicates that those mighty wings carry many of them as far south as the Caribbean. So bon voyage to our young puzzled friend. Hope you found a belly-full of food before nightfall!

Meanwhile, Nearby, More Experienced Neighbors Also Coped with the Icy Pond

Muskrats (Ondatra zibethicus) have created a “push-up” or lodge on the Center Pond this year, probably because Bear Creek marsh, where they more often spend the winter, has less open water than usual. Muskrats spend the winter mostly under water. Their metabolism drops and they efficiently utilize oxygen stored in their muscles. They slowly swim about, foraging for aquatic plants, though their diet can also include frogs, snails, small fish, occasionally even small turtles – if any remained after our hungry young heron departed! Since muskrats are mammals, however, they need to come up for air. Their push-ups have a platform inside where they can enter from underwater and then eat and rest comfortably in the air. Nice arrangement, eh?

The first time Paul noticed a muskrat, it was near the heron, gnawing its way through the thin ice to keep its channels open. In the photo below, note the ice being pushed up onto the muskrat’s muzzle as it acts like an icebreaker. Its long fur helps keep it warm and it can close its ears when under water. But as you’ll hear Paul say in the video, “It looks ever so cold!”

A muskrat acting as ice-breaker. Photo by Paul Birtwhistle

The next morning two muskrats fed at the pond. The first one in the short video below seems to be eating frozen plant material pulled up from the shallow water. Watch ’til the end of the video to see the second muskrat emerge from the push-up, gnaw on some ice and then decide to make a beeline underwater toward the first one – probably its mate.

Two muskrats on an icy morning at Bear Creek’s Center Pond. Video by Paul Birtwhistle

It turns out that this affectionate pair is sharing its home with 3-4 other muskrats that Paul saw a few days later. They may be a family, though muskrats are known to hole up with unrelated muskrats in the winter. I suppose that more muskrats inside means more warmth. But the shallow water and the depleted amount of prey may turn out to be a challenge to these animals this winter. Drought like we’ve had lately can be a hazard to semi-aquatic animals. It’s much easier for predators like foxes and coyotes to reach the muskrats if the shallow water freezes solid.

Amazingly enough, a savvy potential predator did indeed show up on Paul’s next visit – an American mink (Neogale vison)! I’ve been hiking Bear Creek Nature Park for many years and never seen one there. But late one morning, this powerful, beautiful animal appeared on the north bank of the pond right behind the muskrats’ push up. Hmmm…. Various sources report that though minks eat several different small mammals, their favorite food is, you guessed it, muskrat! Well, winter’s a challenging time and the mink may have a mate to feed as well since minks breed during the winter. Everyone has to eat, right? Look at the magnificent specimen Paul saw! Its size, white chin patch and small white chest spot are good field marks for this impressive creature.

An American Mink looks with great interest at the push-up of a group of muskrats, a possible tasty treat for the mink! Photo by Paul Birtwhistle

What a drama played out at the Center Pond this November! Will the young heron learn quickly how to find food on an icy morning? Will the muskrats find enough prey in the shallow water after the heron’s weeks of feeding? Will they successfully fend off the hungry mink or will this elegant, potentially lethal predator find a meal for itself at the pond? We’ll probably never know the conclusion to this series of events. But thanks to Paul, you and I had front row seats for this adventure in three acts, each featuring a creature coping with the vicissitudes of the season.

Lost Lake Nature Park: Fishers of all Kinds, a Tree’s Generous Afterlife and a Lively Meadow

Fragrant Water Lilies (Nymphaea odorata) in Lost Lake

Lost Lake Nature Park, a small 58 acre park probably best known for its sledding hills, hums with life in every season. Right now, fishers of all sorts – birds, animals and humans – are testing their skills against the fish in its 8-acre kettle lake. In the meadow that slopes upward along the sledding hill, dragonflies bask on dried flower heads in early fall sun while a crane fly dances over the soil, laying her eggs among tall native grasses and bright wildflowers. And deep in the woods that cover the slopes, an old tree stump sustains a vivid collection of life. On every short trip this month, Lost Lake sent me home with a little something special.

Around the Lake: Fishers, Flowers and Frogs

On each of my visits, Green Herons (Butorides virescens) foraged and flew at Lost Lake. On my first visit, a young Green Heron stood at the corner of the dock, surveying the eastern pond in the late afternoon sun. The telltale field marks are the streaked side of its head and breast, its greenish yellow legs and its smaller size. Two adult Green Herons flew overhead, giving their distinctive alarm flight call (at this Cornell link under “advertising call”) and later I saw them more  closely in a wetland down the road. The adults are a bit more glamorous than their young, I’d say.

A young Green Heron peruses the far side of the pond from the dock.

A mature Green Heron flew to a marsh nearby

On my second visit, the herons were only visible through binoculars on the far side of the lake. But the third time, I was rewarded. A very young green heron, about half the size of an adult, landed in the pond, flew to a mud flat fairly near the dock and began to fish. I watched this skillful youngster successfully snag a meal twice, and then watched as it struggled to swallow its trophies, as you’ll see in the slideshow below. (Use pause button to read longer captions.)

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On my last visit, a small green heron again appeared, perhaps the same one, this time flying above the head of a fishing  Great Egret (Ardea alba).

A small Green Heron flies behind a fishing Great Egret

The egret was also a successful fisher, though swallowing took no apparent effort for this elegant bird with a long graceful neck. (Click to enlarge; hover cursor for captions.)

As I was leaving the deck one afternoon, I saw movement out of the corner of my eye. As I turned, an American Mink (Neovison vison) paused at the end of the dock before slipping away into the tall grass. I’d never been that close to a mink before. Quite exciting! Mink always live near water and do lots of fishing, eating crayfish, frogs, and fish as well as rodents and occasionally birds or their eggs. A mink coat, with its dark sheen of guard hairs, looks best on this little creature, I think. Since the mink moved too quickly for a photo, I’ve borrowed one from a gifted and generous photographer at iNaturalist who uses the name DigiBirdTrek.

An American Mink, photo by DigiBirdTrek (CC-BY-NC-SA) found at iNaturalist.org

On two afternoons over Labor Day weekend, human fishers showed up at Lost Lake as well – a threesome one day and a young couple another.  Not sure if they were as successful as the green heron!

Human fishers enjoy Lost Lake as well.

With all those fishers, it’s not surprising that this tiny green frog squeaked and leapt into the pond as I walked off the dock one afternoon. It may have been a young Bull Frog (Lithobates catesbeianus), since it has a fold around the tympanum rather than a ridge running back from the eye, which would indicate a Green Frog (Lithobates clamitans). Small bullfrogs are also more prone to squeaking when alarmed; I’ve never heard a squeak from a small green frog.  I’m open to correction, though, since we can see so little of this small frog.

Admittedly, the pond is not at its best right now in terms of flowers. Many of the water lilies closest to the shore have withered into a brown mass and the brown leaves of some Pickerel Weed (Pontederia cordata) stalks protrude from the water near the shore. But in the distance, the water lilies float on a bed of green (see above) and in some places, the lovely lavender plumes of the pickerel weed still stand tall with their huge, graceful leaves. Along the shore, the sunny ball-shaped heads of Sneezeweed (Helenium autumnale) nod in the breeze near the delicate purple chevrons of Great Blue Lobelia (Lobelia siphilitica).

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Down the road, at the same wetland where I saw the mature Green Heron, an elusive family of Wood Ducks (Aix sponsa) caught my eye. On each trip, I’d notice a threesome of young ducks being shepherded by the male parent.  This dad wanted nothing to do with me and quickly herded his family around a bend, or behind greenery at the edge of the water. But one day I was able to catch two fairly good shots of dad and his three offspring.

Into the Woods: A Blackened Stump with Vivid Life and Some Clever Seeds

The path into the woods at Lost Lake in dappled afternoon light

The path into the woods starts at the end of the driveway that runs in front of the caretaker’s home, and you’re welcome to use it.  It’s a short, uphill path that is quite steep at the end and then runs quickly downward as you descend the sledding hill. The forest floor is deep green and beautifully dappled by sunlight.

On the dry, wooded hillsides,  some native grasses and wildflowers are beginning to create and disperse seed. The long graceful pods of Sicklepod (Boechera canadensis), a native member of the mustard family, crack open when dry, releasing a long line of seeds to the wind. Jumpseed (Persicaria virginiana), another native, is appropriately named; according to the Minnesota wildflower site, its seed “jumps off the stem at the slightest touch,” sometimes as much as 10-13 feet. Cluster-leaved Tick-trefoil (Hylodesmum glutinosum) makes cool fruits called loments that have little pods with one seed each that travel by sticking to anything that comes close. And an old fave, Bottlebrush Grass (Elymus hystrix), sends its seeds flying on arrow-shaped “awns” that can actually stick upright in the earth when they land. Plant evolution has produced some very creative ways to spread seed!

At the bottom of the hill, in the deeper shade of a wetland, I discovered an old black stump that hosted a variety of brightly colored life. According to Peter Wohlleben, author of The Hidden Life of Trees, the insect and fungal life of felled stumps and logs help the forest by breaking down the nutrients held in the trees’ wood for hundreds of years. The process of decomposition can take as long as the life of the tree – in the case of oaks, up to 300 years! And eventually those released nutrients feed the tree’s offspring and other trees and plants. Well, this old tree stump, a White Pine (Pinus strobus), was busy doing just that. Its surface presented all kinds of colorful life that was busy working to break down its nutrients or using it for shelter.

A tree stump hosting lots of life in the forest at Lost Lake – harvestmen, ants, moss and mushrooms.

What originally caught my eye was a group of tiny, deep orange/red mushrooms.  I couldn’t determine the species of these mushrooms, though they could be an early stage of the Jack-o’Lantern mushrooms (Omphalotus olearius) featured recently at Bear Creek. A few minutes later a second spot of red caught my eye. A group of Harvesters (order Opiliones, suborder Eupnoi), which are arachnids, but not spiders, scrambled around the inside of the stump. The one below came festooned with tiny bright red mites! And then I spotted a ruby red ant, whose species I was unable to discern.  And a lovely patch of green and orange moss with its sporophytes tipped with the capsules that contain its spores graced the flat top surface like a miniature forest. Quite a colorful bunch of creatures, bryophytes (mosses), and fungi working and living on this old stump!

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Down the Hill to the Meadow – Basking Dragonflies, A Dancing Crane Fly, Wildflowers and Native Grasses

A soft lavender bank of Bee Balm (Monard didyma) still blooming near the caretakers’ lawn before you enter the woods

Wildflowers are still blooming in glorious color on the steep sledding hill, the small meadow below it and a short distance from the pond. A few Yellow Coneflowers (Ratibida pinnata) hang on nearby, their drooping petals still golden in early autumn light, along with some Smooth Asters with their dark red or yellow centers (Symphyotrichum laeve). Showy Goldenrod (Solidago speciosa) and Grass-leaved Goldenrod (Euthamia graminifolia), both late summer/autumn wildflowers, are being visited by native bumblebees. Pale/Thin-leaved Sunflowers (Helianthus strumosus), that love the forest edge,  shine bright under the trees as you approach the wood. An Evening Primrose (Oenothera biennis), with its four-parted stigma forming the characteristic x-shape, stands alone at the edge of the parking lot. Near the entrance to the woods, the slender pods of Poke Milkweed (Asclepias exaltata), a milkweed of shady savannas, will eventually dry and break open to release their seeds to the wind. Among the flowers, native grasses sway, like Big Bluestem (Andropogon gerardii) which is now flowering and Indian Grass (Sorghastrum nutans) which has started to form its seeds.

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Among these grasses, a group of Autumn Dragonflies (Sympetrum vicinum) rested on dried flower heads, needing a bit more sun on cool days. This species has a little cloud of yellow near the base of the hindwing. They hatch out in August and September, providing more late summer color. Mature males are the easiest to spot with their red abdomen. Juvenile males (in closeup below) have a yellow thorax and a yellowish brown abdomen, according to Wikipedia. And the females (second and fourth from the left  in the photo at the far right below) have a brown thorax and a brownish/red abdomen. I find it hard to distinguish between females and juvenile males in Autumn dragonflies,  so feel free to correct me!

One of the oddest sights at Lost Lake occurred on my last visit. I saw something with very long legs dancing vertically, up and down, above small holes in the earth between the grass stems. Eventually, after developing and cropping a lot of photos and doing online research, it became clear that I’d been seeing a Tiger Crane Fly (Tipula dorsalis) laying her eggs in the soil. Taking photos of a crane fly rapidly jumping up and down is a bit challenging, but if you look closely, I hope you can see her curving, vertical body as she pokes the needle-sharp ovipositor at the end of her abdomen into the soil. Her narrow wings and very long legs were splayed in every direction as she danced from one hole to another, laying potentially hundreds of eggs. Click this link  from bugguide.net for a much better photo than mine!

A Tiger Crane fly holds herself vertically as she jumps into and out of a hole in the earth, laying her eggs.

By the way, crane flies are gangly, harmless creatures who can’t bite or sting humans or animals as the unrelated mosquitoes do. Crane flies live only 10-15 days and drink nectar, if they eat all (some don’t!). The only damage they do is in their larval form, when the caterpillars, called “leatherjackets,” do eat some turf grasses and agricultural plants.

The Persistence of Life

Despite the ravages of early September – hurricanes one after another, wildfires, earthquakes – here in the protected natural areas of Oakland Township, life persists. The young green heron successfully fishes its food from among the water lilies. In forest shade, the flowers and grasses produce seed, relying on another spring to foster the next generation. A crane fly dances above the earth, seeing to it that their offspring still float over the grass stalks when summer comes again. And what about us?  Well, of course, we’re members too in that community of life on earth. I like the thought that as you and I foster and nourish that community, we’re doing our part to see that life persists on this little blue planet.

Footnote: My sources for information, besides Oakland Township's Stewardship Manager Ben VanderWeide, are as follows: The Hidden Life of Trees by Peter Wohlleben;butterfliesathome.com;Pollinators of Native Plants by Heather Holm; Stokes Nature Guides: A Guide to Bird Behavior Volumes 1-3; 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.