Kit fox comes to visit

I happened to glance out in the backyard after helping to move the refrigerator around in the kitchen this morning and spied a red fox and its kit exploring the area around the swing set. Just one kit, but a cute one, that ran circles around its parent, nose to the ground.

It was surprising to see them out in the middle of the morning on a bright, sunny day. The kit was very active, running all around the backyard. I wonder if this was the first time out — the snow only disappeared from the backyard two days ago.
The kit is just a fluffy ball of fur at this stage, with bluish eyes and a stubby little tail.
There was a little grooming and nose to nose communication, but the kit seemed free to explore without the mom hovering over it.
And off they went, up the hill, and into the neighbor’s backyard.
Now I know who the fox was that visited this time last week — a lactating mother. I wonder if the broken-eared fox is the father…

the long-term bond

Spring draws ever nearer, the days are longer, and the migrating and resident backyard birds are in courtship mode preparing for another breeding season. Some of these pairs might form for just one season (or less) — most often in the case of species where the female does the lion’s share of nest building, incubating, and feeding. Take Red-winged Blackbirds or House Wrens or Mallard Ducks for example.

But many bird species, especially long-lived ones, where both partners of the pair engage in incubating eggs and rearing of chicks each year, form pair bonds that last the lifetime of the individuals. In the case of the Laysan Albatross that can live more than 50 years in the wild, that is a really long-term bond! Note: the average length of a marriage in the U.S. is just over 8 years.

Here are some examples of species with long-term pair bonds from previous Backyard Biology blog posts over the past 10 years:

Average lifespan of Atlantic Puffins is 30+ years in the wild. Both parents incubate the eggs and both feed the chicks, trading off long distance trips out to sea to bring back a mouthful of fish.
Green-winged Macaws, like many parrot species, are very long-lived, at least 30 years in the wild and 50-60 years in captivity. The female incubates the eggs, and the male feeds her while she is incubating. Both parents feed the chicks.
The iconic Trumpeter Swan courtship ritual is beautiful to watch as the pair mimic each other’s actions, resolidifying their pair bond each spring. The duration of their pair bond would be less than their average lifespan (about 25 years) because they don’t start breeding until they are 4-7 years old. Males guard the female while she is incubating, and he is the chief protector of the offspring once they hatch.
Bald Eagles mate for life, beginning when they reach adulthood in 4-5 years. They may live 20 years in the wild (but more than 50 in captivity). Both parents incubate the eggs and both feed the chicks. I think the much larger female of the pair is on the right. An exceptional Photo by Michael Powell.
Osprey live 15-20 years in the wild, but take about 3 years to mature to breeding status. Like most raptors, both parents incubate the eggs, and both feed the chicks. This particular photo was part of a series that eventually led up to the act of copulation between the pair as the male (left) landed on the female’s back and proceeded to deposit a load of sperm. The birds might mate several times during the courtship and nest-building phase before she lays her eggs.
The European Shag (a relative of cormorants) live 15-30 years in the wild. The female does most of the incubation, but both parents protect and warm the chicks during their long nestling period, and both parents feed them regurgitated fish.
Canada Geese live 10-24 years in the wild, and like most waterfowl, the female incubates while the male protects her and the eggs when she is off the nest getting some food for herself. In this photo, the male was quite aggressive toward a Great Blue Heron that wandered too close to the nest placed on a little mud island in the lake.
Caspian Terns mate for life, which averages about 12 years in the wild. To cement the pair bond each year, the male usually brings gifts to the female (like a fish or two), thus providing her with an easy source of protein while she is forming her next batch of eggs. Both parents incubate the eggs and both feed the chicks during the nestling period until they are able to fly and feed themselves.
Lilac-breasted Rollers inhabit the woodlands and savannas of southern Africa. They live about 10 years in the wild and share the duties of raising the next generation by incubating eggs and feeding the chicks. Look-alike parents also engage in similar “rolling flight” behaviors in territorial displays and provide aggressive protection of the nest and chicks, so it’s hard to tell which sex is which. In this photo, the bird on the right is offering an insect to the other, so I would guess it is the male?
Gila Woodpeckers live less than 10 years in the southwestern deserts of the U.S., and they mate for life the year after they fledge. Both sexes help construct the nest in a saguaro cactus, and both incubate the eggs. The male does more territorial defense around the nest than the female, but both sexes feed the chicks until they fledge.
Mourning Dove pairs form a strong bond, but their lives are short (average two years in the wild), and so the bond cannot be a long-term one unless they survive more than two years. Billing and cooing (shown here) cements that bond before copulation, and then they share the incubation duties as well as feeding the chicks. In an unusual twist for birds, both sexes secrete what in humans is the milk production hormone, prolactin, and in doves and pigeons causes them to produce a milky secretion from their crop which they feed their very young chicks.

Side note: I don’t want to give the wrong impression that the pair bonds between the sexes in birds is an absolute in their monogamous relationship. It has often been shown, that even in these long-lived and long-term partners, extra-pair (sneaky) copulations do occur, and not all the chicks in the nest have the male partner’s DNA.

“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 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.

Uff-da, it’s cold

That’s what we say in the MN northland, when the temperatures drop below 0F. The other day when I ventured out in the early morning, it was -17F (-27C). When I got back in the early afternoon, it had made it all the way up to -3F (-19C), which is just barely tolerable if the sun is out and there is no wind.

And the wildlife aren’t enjoying the cold temperatures any more than I am. Little birds don’t show up at the feeders until mid-morning, and the squirrels (both gray and red) are usually found huddled next to the tree trunk with tails curled over their backs, or basking along the trunk to soak up warmth in the early morning hours.

Sitting against a background of evergreen trees, you would never know the outside temperature was sub-zero, except for this gray squirrel’s curled up posture and hyper-fluffed tail.
Fluffing out his fur and tail makes this little red squirrel look pretty chunky, but that is the way it can maximize its insulation in extreme cold. This little guy was actively shivering, as his forearm paws and tail vibrated with each breath.

For those animals (and humans) that can afford to do so, the best solution to surviving cold temperature extremes is to fire up the metabolic furnace.  No one enjoys standing out in the cold shivering intensely, but that and the physical exertion of exercise are the first line of defense in staying warm.  The trick is to preserve the heat inside the body by improving insulation with a nice layer of subdermal fat, a thick fur coat, and minimizing the surface area exposed to the air.

Another strategy for staying warm in mammals (but rarely in birds) is metabolizing brown fat, which is a special kind of adipose tissue located along the vertebral column, heart, and kidneys. Brown fat is highly vascularized and contains lots of heat producing mitochondrial organelles. The heat produced by a process of non-shivering thermogenesis in the central core of the body can then be circulated to other parts of the body.

Newborn and hibernating mammals utilize brown fat thermogenesis to warm up. Other small mammals use the heat produced by brown fat as a supplement to shivering thermogenesis. Diagram from McMillan Higher Ed publications.

So, bundle up and think warm thoughts — the days are getting longer and the sun is getting higher in the sky each day. Winter won’t last too much longer.

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! “


A fellow blogger reminded me that over the course of a year, or a decade, we write a lot of words about a lot of photos on our blogs. I have been writing this blog since July 2011, roughly a month after I retired. Somehow, I completely missed celebrating the 10th anniversary of “Backyard Biology” in July this year, and so after the end of 2021, I’m summarizing the highlights and milestones of the blog in this post.

This was the featured animal on the first ever Backyard Biology post — a Japanese beetle eating my raspberry plants.

Since that first entry, I have written 1689 posts, and the blog has had 415,000+ visitors (some just came once, some visited several to many times), with a total of more than 640,000 views during the past ten years. During that decade span I’ve written more than 307,000 words, which is about the equivalent of the word length of 4 novels, and I’m now finding that I am repeating myself, writing about the same topics in much the same way. And so the posts are more infrequent, and are now focused more on the natural history of the global backyard, rather than just my own backyard.

During the past 10 years, the post with by far the most views on one day (722) was on May 23, 2018, “Waterfall Extravaganza” in Hraufossar, Iceland, where there are 900 meters of continuous waterfalls streaming from a monster glacier and falling over impervious lava rock.

Every view in Iceland is spectacular, and I captured quite a few of them. But this post seemed to pique the most interest in readers. This is a very small section of a long ridge of waterfalls draining into the Hvita River in western Iceland.

The same three or four posts seem to generate the most interest every year, probably as a result of a Google search for an answer. The top three each year tend to be: “How many seeds in a sunflower seed head?”, “Gigantic black horse fly”, and “Scary-looking, big, black wasp alert”. The post on sunflower seed heads gets about 30,000 views a year. Inquiring minds want to know!

This 6.25 inch diameter sunflower seed head had 1080 seeds in it. The beautiful geometric pattern of spirals is the most efficient packing of seed material into the given space — where the numbers of seeds in a given clockwise and counter-clockwise spiral are consecutive Fibonacci numbers. This post is from September 30, 2012.

This year, the most viewed post (528 views on October 17) was “Reflections”, which included some photos of images reflected in rippling water, like this one of Bald Cypress in the Mobile-Tensaw river delta.

In fact, the posts from our Fall trip to Alabama, a unique environment I had never seen before, were the most viewed posts of the entire year. Lagging far behind in views (350) was the post I entitled “Apocalypse”, thinking that would really capture readers’ attention.

On August 17, winds drove the smoke from the Caldor fire in the foothills of the Sierra Nevada mountains into Desolation Valley where we were camped at 8100 feet.

And now it’s time to find some new material to showcase on Backyard Biology, with adventures near and far in 2022. Happy reading!

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.