Birds by the bay

Arriving at the peak of low tide the other evening gave us some great looks at a diversity of shorebirds foraging along the shore of Eloise Roemer bird sanctuary on Alameda Island in San Francisco Bay.

Lots of Dunlin, Willets, Curlews, Great Egrets, Pelicans, Cormorants, Avocets, — wow, what a shorebird mecca this tidal area is!
A couple of Long-billed Curlews resting on one leg…
A trio of Willets…
Double-crested Cormorants, White Pelicans, and kayakers enjoy the quiet water of this sheltered bay.
Low Cormorant on the totem pole gets the small rock, I guess.
Stilts and Yellowlegs hunting in the shallows.
Greater (i think) Yellowlegs have beautifully edged wing and back feathers when you can see them up close.
Black-necked Stilts have such delicate toes at the end of those long, pink legs.
and on the grassy side of the beach, a beautiful little Western Bluebird hunting for insects in the waning light.

Down by the bay

A quick trip to the marshy shoreline of Alameda Island in San Francisco Bay yesterday evening gave us an impressive view of hundreds of busy shorebirds feasting on mud-dwelling critters.

And the skyline of San Francisco across the bay from the island…
And a lovely sunset with little shorebirds still foraging for last crumbs from the mud.

“smoked” turkey?

It is often said that “variety is the spice of life”, and we recognize that almost all individuals of a single animal species exhibit some variation from one another. But sometimes that variation is markedly and drastically different — and we wonder how that variation came about and what the consequences of it are. For example, we came across a large flock of wild turkey hens at Sax-Zim bog, foraging along the side of a field, almost all of them identical to one another, except….

Notice anything different in this flock?

The turkey hen on the far right is a “smoke” color morph, a bird that lacks the normal expression of the rich browns and reds we usually see in turkey feathers.

Hen turkey in early winter exhibiting the rich spectrum of blacks, browns, grays, and reds we associate with wild turkey plumage.
The smoke morph of the wild turkey plumage is largely white with dark black and brown accents. Its lighter coloration makes it stand out in the flock, but it actually blends in better with the predominantly black and white coloration of the northern winter landscape.

How did this happen? Coloration of feathers in birds is a complex process, and can be completely different in males and females (leading to the basis for why males are so much “prettier” than females). A given stretch of genetic code for feather color in birds can be “alternatively spliced” as the pigment is being expressed in newly developing feathers, leading to wildly different outcomes between the two sexes and at different times of year in male birds or between juvenile and adult birds. But that isn’t the entire explanation for “smoke” color morphs in wild turkeys.

Normal plumage coloration of wild turkey hens includes that “smoke” look in some of their wing feathers. It would seem that the smoke morph has that type of pigment expression all over its body, instead of just in the wings.

Coloration of bird feathers is largely dependent on eumelanin pigments that produce brown, black, and gray colors and pheomelanin pigments that produce yellowish and reddish coloration. Combining amounts of these pigments like an artist does with a paint palette is what results in the variety of rich color in the plumage.

The “smoke” morph plumage lacks the full expression of a lot of browns and blacks, and it has virtually no red and yellow highlights in its plumage. The morph is very infrequently seen in the wild population, occurring in only about 1 in 100 birds on average, and thus, it is a recessive mutation of melanin expression, especially pheomelanin. More interesting is the fact that the “smoke” morph seems to occur only in females, which probably means it is a sex-linked recessive trait.

There aren’t enough of these birds in the wild population to determine whether the “smoke” morph is at a distinct disadvantage in the winter, or whether they are more or less attractive to breeding males in the spring. But this color morph has been seen by turkey hunters from Oregon to Tennessee, so the mutation must occur in most wild populations.

A different sort of Chickadee

Watching Black-capped Chickadees flitting about in the vegetation in the winter, you have to marvel at how successful they are at finding food and staying warm in such a challenging environment. I wrote a lot more about this in an earlier blog post: “Baby, it’s cold out there”.

It doesn’t matter whether it’s snowing or blowing, or 20 below, perky little Black-capped Chickadees will always be around to greet the day.

But there is another cousin of the Black-capped species that winters even farther north, in even more intemperate (in the winter) habitat: the Boreal Chickadee – named for the fact that it is a permanent resident of the coniferous boreal forests of Canada and Alaska.

They are brown-headed and rusty sided, but Boreal Chickadees have the same black chin patch as their Black-capped relatives. In the winter they usually are found in small family groups, but at the Sax-Zim bog, where Boreal Chickadees show up infrequently, the birds are often single individuals, found foraging on suet.

Boreal Chickadees spend most of their time in the spruce and balsam fir forests, where they forage for insects and spiders in the middle of the trees, rather than out on the tips of branches like the Black-capped species. When food is plentiful in the summer, Boreal Chickadees will cache food items in cracks in the bark of the underside of tree limbs where it is protected from winter snowfall, and then they secure them in place with their saliva. It is thought that these storage sites are communal property of the flock, so the birds don’t have to remember exactly where they cached individual stores. This food reserve is critical to their winter survival, in addition to seeds and hibernating insects they might find. Most of their European relatives, the titmice, and Mountain Chickadees have also been observed to use food caches as a winter food reserve.

At the Sax-Zim bog feeders, Boreal Chickadees go after the chunks of animal fat instead of the seed-rich suet cakes. Fat isn’t very nutritious but it provides them with a source of calories to metabolize overnight and keep warm.
Boreal Chickadees are a little smaller than the Black-capped species, which makes staying warm in frigid weather even more difficult.

Not much is known about the behavior and physiology of this lesser-known relative of our popular Black-capped Chickadee, especially their strategy for surviving in the intemperate environment of the boreal forest in winter. I guess not many researchers are willing to brave the conditions where Boreal Chickadees live in the winter — I certainly wouldn’t!

the long-winged mouse hunter

In the Minnesota boreal forest around Sax-Zim bog, we finally found and photographed the hawk counterpart of the Great Gray Owl (from the last post). Rough-legged Hawks are also mouse specialists, but use a completely different strategy to hunt their prey compared to the owls. Where the owls use auditory cues to localize mice under the snow, these particular hawks use visual ones, even honing in on urine trails of voles, which reflect UV light the hawks can detect. Then they perch, sit and wait, and pounce when movements in the snow indicate mouse (in this case, vole) activity.

We weren’t quite sure what we were seeing early in the morning along the roadside as we drove into the bog area. From a distance in the dim light, the hawk first resembled a juvenile Bald Eagle, then the black and white facial pattern resembled an Osprey, which would have been well out of its range for this time of year. Finally, up close we saw the typical mottled plumage of the Rough-legged Hawk.

Rough-legged Hawks are the most northerly breeding Buteo (broad-winged) hawks in North America, setting up breeding territories in the far northern Canadian and Alaskan tundra areas to prey almost exclusively on lemmings there. But they leave the tundra and migrate south to boreal areas of southern Canada and the northern U.S. that have lots of marsh and prairie expanse where they can hunt for voles and other mice where there is less snow cover.

Their name might imply that they have rough scales on their legs, but it is quite the opposite. They are one of three raptors with entirely feathered legs, like owls have — insulation that is invaluable for birds hunting in extreme cold climates like northern Minnesota. This bird, from the carolinabirds.org website (photographed by Dick Daniels) is a captive, tethered with falconry jesses, but its raised wings allow you to see the heavily feathered legs.

Rough-legged Hawks have very long wings for their body size (up to 60 inches in a large, 3.5 pound female) and they are adept at soaring effortlessly over long distances to hunt for mouse activity. Winter birds on a foraging territory in Idaho had home ranges of up to 200 square miles that they traversed over the course of several days of hunting. Researchers estimated that the bird could sustain itself in the winter on a diet of about 5 mice per day. On days when hunting success was limited, the hawks did much more perching than flying, conserving energy for the next day’s hunting attempts.

Long wings give the Rough-legged Hawk a great advantage in soaring, and just cruising over the landscape looking down for potential prey. Although their diet in the summer is largely small rodents, they might prey on rabbits or grouse when they find them in the winter. (Illustration from the Crossley ID Guide to Raptors, on Wikimedia Commons)

I won’t forget this bird — we’ve made four trips to Sax-Zim bog to see it, and finally found one right next to the road, rather than sitting a 1/2 mile away or flying hundreds of feet over our heads. Its striking plumage, feathered feet, and black and white wing patterns should make it easy to ID in the future.

to catch a mouse

The best way to catch a mouse is to be a Great Gray Owl, with hearing out of this world to localize the mouse under a foot of snow, a dive bomb attack force that can break through a crust of snow hard enough to support the weight of a 180 pound man, sharp talons to grab the mouse scurrying along under all that snow, and a crushing beak that can separate the mouse brain from its spinal cord.

Behold! The mighty mouser! Notice those two parabolic reflectors of specially arranged feathers surrounding the eyes — that’s what captures the sounds of voles scurrying along their tunnels beneath the snow. Asymmetrically placed ears on the side of the owl’s skull receive sound at different times and help the owl localize exactly where the sound is coming from.

On a one-day trip to Sax-Zim bog, we were lucky to find a champion mouser Great Gray Owl hunting right next to the road along one of the boundaries of the bog. It caught and ate an amazing four mice in under an hour. In fact, it was 100% successful in its mousing attempts!

I’ve put together a series of images into a very short video, accompanied by special “hunting” music so you can enjoy what I was able to see and photograph. If you’re looking at this post in your email, you might need to go to the Backyard Biology website to view the video (click on the title of the post in your email to get to the site). The video is best viewed in full screen (rectangular icon in the lower right corner of the video as it plays), then hit ESC to return to the blog post.

In the video sequence you see the owl take off, from a perch, fly quickly to a site and dive to the snow feet first, dip its head down to the feet to grab the mouse in its beak, fluff its wings above the snow level to take off, fly to a perch, spend some time looking around (not shown in the video), take the vole’s head into its mouth and crush it, transfer the vole to its feet and squeeze it some, then back to the mouth where it is swallowed.

Great Gray Owls look around continuously as they try to localize sounds they hear coming from beneath the snow. In this image, the owl was perched about 10 feet above the snow and stared down intently for several moments before making a dive, and coming up with a mouse.

Our Great Gray caught four voles in a very short span of time. But on average they may catch and eat up to seven voles a day while hunting in the early morning and late dusk hours during the coldest winter days.

It’s National Bird Day

What is that, you ask? In 2002, the Animal Welfare Coalition created a National Bird Day on January 5, to raise awareness of the challenges our feathered friends face in this era of extreme environmental changes to their lives.

Birds are diverse, colorful, interesting to watch, beautiful to see and to listen to, easy to find (mostly), and can be predictors of environmental changes that affect us — literally, the canaries in the coal mine. The behavior of my backyard birds is often just as telling as the latest weather report.  For example, judging from the frenzy of activity going on at the bird feeders today, the thermometer must be headed for negative numbers again.

There are well over 10,000 species of birds in the world, but their numbers and their diversity are decreasing every year. Hundreds of species have become extinct already, and more than a thousand are threatened with extinction currently. The species diversity of birds in the tropics of Africa and of South America is astounding, but is diminishing as pressure from habitat loss/alteration and human encroachment increases in natural areas.

Four species of Bee Eaters and a Lilac-breasted Roller in Botswana, members of an order of birds related to Kingfishers, Motmots, and Todies.

Birds are our links to creatures that lived in the past. Their closest living relatives are the crocodiles, both groups of which descended from the dinosaurs that ruled the Mesozoic world. But they survived the massive extinction period at the end of the Mesozoic, and have diversified into thousands of niches that don’t overlap or compete with mammals. They are an amazing evolutionary success story.

From the ancient crane lineage of birds to the tiniest modern hummingbird species, all birds capable of flight have unique physiology that powers their high metabolic life-style.

Birds are high energy creatures with unique anatomy and physiology that set astounding records among vertebrate animals for things like:

  • fastest heart beat (>600 beats per min in a Ruby-throated Hummingbird),
  • highest altitude flight (>30,000 feet in Bar-headed Geese, Common Cranes in Europe, Ruppell’s Griffon Vulture where the air is only 6% oxygen instead of 21% at sea level),
  • fastest flight (>200 mph in Peregrine Falcons),
  • greatest g-force tolerance pulling up from a dive (>25g in Peregrine Falcons and Gyrfalcons — that’s 25 times the earth’s gravity!),
  • greatest speed plunging into water (>50 mph in Gannets)
  • greatest weight capable of sustained flight (44 pounds, Great Bustard)
  • longest time airborne (>10 months!, flying 14,000 miles, Common Swift)
  • longest migration (>55,000 miles in one year, Arctic Tern)

You can’t help but marvel at the accomplishments of the birds, and so on this special National Day of Birds, take time to get out and enjoy birds. And to quote fellow bird-watcher/photographer, Debbie (The Itinerant Birder):

“Watch a bird, feed a bird, learn about a bird, donate money for a bird! “

Looking back at 2021

Another year of Covid prohibitions on activities, but not such a bad year for seeing new places and new species. The highlights month by month look like this:

January: a trip to Sax-Zim bog in north central Minnesota, and an exciting afternoon shooting Great Gray Owls diving for mice in the snow.
Great Gray Owls blend in so well with the tree stumps they are sitting on, you might drive right by them on the forest roads in north central MN.
February: Yes, the most memorable highlight of February was winning the vaccine lottery and getting my first vaccine shot — after waiting in line for almost 2 hours with 1000 other anxious people.
March: hiking with adventurous grandkids at frozen (well, mostly frozen) Minnehaha Falls in downtown Minneapolis. Caves behind the falls are fun to explore when you’re steady on your feet.
Also in March — Great Horned Owlets are growing up fast and almost ready to leave their nest hole to perch on tree branches.
April: the great Road Trip of April and May netted us over 160 species (many new and never seen before), after visiting over 40 parks and driving over 6800 miles). Some of my favorites were the ever-amazing hummingbirds, like this composite of a Broad-billed Hummer coming into a feeder in southeastern Arizona.
We visited many beautiful places on our long April-May adventure, but we keep coming back to this place deep in the Chiricahua mountains of southeastern Arizona — Cave Creek ranch, where exotic birds and gorgeous scenery captivate.
May: On the way back to Minnesota in May, we stopped at Antelope Island in Salt Lake City, where grazing bison and antelope are abundant and the mountain landscapes behind the city are spectacular.
June: another Road Trip — this time with the grandkids camping across the western U.S. on our way to the mountain cabin near Lake Tahoe.
My favorite bird highlight from June was this Western Tanager male in all his bright breeding finery — the jewel of the Sierra.
July: with almost all the grandkids and missing one son-in-law (who had to work), the rest of us gathered for the 4th of July at the cabin near Lake Tahoe.
August: surreal landscapes in the back country of Desolation Valley in the CA Sierras on our backpacking trip, as the Caldor Fire literally burst upon us one morning.
September: fall migration began with the arrival of a dozen or more warbler species, along with assorted vireos, flycatchers, finches, blackbirds, etc. Mr. Magnolia Warbler was not quite as beautiful as he was in the Spring, but nevertheless, is a handsome bird.
October: a trip to Alabama to see the birds of Mobile Bay and Dauphin Island and its pristine white quartz sand.
Fall color was unusually bright and long-lasting in October this year. A pleasant surprise after a somewhat hot, dry summer.
November: foxes and turkeys passed through the backyard frequently, but there was little snowfall this month. Very unusual.
December: at last it looks like winter, but a warm-ish spell right before Christmas melted all this lovely stuff.

Reflections

It is snowing this morning, and the yucky weather here in southern Minnesota means the wildlife has deserted the backyard (temporarily, I hope). Even the chickadees are absent from the feeders this morning!

So, it’s a good time to reflect back on the adventures of the summer — to warmer times and prettier views. I found a lot of photos from Don Edwards National Wildlife Refuge north of San Jose CA that I had never posted. That’s a good excuse to go back a couple of months to October and revisit the marshy pools in southern San Francisco bay

Shorebirds are abundant here in spring, fall, and winter. Even late summer is a good time to catch migrants moving through these shallow pools, which apparently provide enough sustenance to attract a great diversity and abundance of birds.
The reflections of these Dowitchers (type to be determined in later images) were mirrored perfectly in the still water.

Dowitchers are medium-sized chunky shorebirds that use their very long bills to probe deep into the mud of shallow pools to find insect and crustacean larvae and small molluscs, as well as seeds and even vegetation that is buried there. Extremely sensitive tactile receptors in the tips of those long bills help them discriminate what is animal, vegetable, and mineral. Their continuous up-and-down motion as they probe the mud has been likened to the action of a sewing machine needle moving through cloth.

Long-billed and Short-billed Dowitchers are common (often seen) to abundant (very numerous) in these pools during spring, fall, and winter. But how to tell which species this is? I am always confused by these birds and wanted to find some characteristic I could use to more easily identify them.

Unfortunately, despite their names, bill length is not a definitive characteristic! Long-billed Dowitchers are mostly found in fresh water, and the Short-billed species is mostly found in salt water, but the pools here are full of a mix of salt and fresh water depending on the tides in the bay. And in their drab, non-breeding plumage, all their distinctive coloration is missing, so one must rely on their different calls to determine the species. However, I have no memory of what they sounded like, so what else can I use to tell them apart?

Fortunately, “how to tell long-billed from short-billed dowitchers” is a frequently asked question on Google. And one website clued me in to differences in the black and white barring pattern in the tail feathers, which can be seen on the bird on the left. Long-billed Dowitchers have more black than white in their tail barring — that’s the answer. These are Long-billed Dowitchers.

Not all of the shorebirds are so difficult to identify. Two species of long-legged wading shorebirds stand out: avocets and stilts.

Avocets are easily recognized by their long, up-turned bills. It wasn’t particularly cool on this morning, but the birds seem to be conserving heat by standing on one long leg at a time. The long bill of this bird is used as a sieve rather than a deep probe. The birds swish their bill side-to-side in shallow water to filter out small prey suspended in the water.
Black-necked Stilts really are on stilts. They have the second longest legs in proportion to their body size — Flamingos having the longest stilts. As they wade through the muck, with water levels sometimes reaching up to their breast, they peck at and seize small crustaceans, amphibian larvae, snails, or even tiny fish swimming in the shallow water.
Such attractive birds with their stark black and white plumage, long pink legs, red eyes, and rounded forehead.

Still hanging on…

Not only are the leaves stubbornly clinging to the trees, but the lovely Fall weather just hasn’t given into Winter cold yet. And we are grateful because the last of the colorful, balmy (?) days are perfect for exploring outdoors.

The color in Reservoir Woods was somewhat dulled in past peak days, but was still spectacular to walk around in.
A big buck went dashing through these aspen right before I managed to get out my phone to take a photo.
The last of the maple leaves have almost all dropped off the trees now.

The progression of activity in the backyard in the Fall is somewhat predictable. This is the time of year the turkeys and deer visit the backyard more often, looking for the best edibles.

Does with and without fawns make themselves comfortable on the lawn while digesting the morning feast.
Hen turkeys gather in flocks in the Fall along with their offspring and parade through the neighborhood completely at ease with the car and people traffic on the roads.