urban wildlife

Back at one of my new favorite walks around Lake Temescal in Oakland, California, I was amazed to find the wildlife there so habituated to human traffic.  Apparently, people don’t try to bother or scare them, so the birds sit very still and just watch us walk by. We passed within six feet of this Black-crowned Night Heron, and the grandkids were not particularly quiet about seeing it either.

black-crowned night heron-

I’m liking my smart phone more and more as my go-to camera when out for a walk with the grandkids (instead of a regular photo hike).

At the other end of the lake from the Night Heron was a “gulp” of double-crested cormorants, or you could say, a “fllght, rookery, sunning, or swim” of them — such are the collective nouns for a group of Cormorants.

double-crested cormorants-

Three of the “gulp” found a raised platform in the lake on which to rest in between dives. Any surface projecting from the water will do as a sunning and drying-off place.  

Perhaps “sunning of cormorants” is a better descriptor of the group, since each time they get out of the water, they spread their wings and turn toward the sun to dry off.

Even the Wood Ducks are tame here, and quietly paddle around their small pond, not flying away the minute they spot you.  I wonder how long it takes wild animals to become as habituated to human presence as they have here — and why don’t the animals in my backyard let me approach this closely??

Snow day

A “snow day” in Minnesota usually means kids get out of school, businesses close early, and we are warned to stay indoors until snow plows have made the roads manageable.  Although none of that happened, high winds and rapidly falling snow made it seem like much more of an emergency than it really was.  But the effect on the landscape was truly beautiful, as only heavy snowfall can be.  I gazed out my porch windows wishing some little animal would stop by and get framed in the puffy snowflakes that were accumulating on every surface.

Not more than 5 minutes later, the deer herd wandered into the yard, nosing around for fallen bird seed or scraps of months-old dead plants.  And this was the scene…

deer herd in the snow-

The deer seemed surprised that there was so much white stuff covering up the food. White splotches on the deer are the snowflakes closest to me as I shot the view through the porch window with my cell phone camera.

deer herd in the snow-

There is usually something to eat in the wildflower garden in the spring and summer, but not now.

deer herd in the snow-

Then it’s off to the neighbors yard to see if there is anything good to eat over there.

And that will be the last of snowy scenes on this blog for a couple of weeks, while I’m traveling to warmer, greener, and more scenic spots in tropical climates.

Alone again…un-naturally

trumpeter swan-reflection-

A lone swan resting on the ice in the early morning in a vast landscape of white looks forlorn by itself.

trumpeter swan-reflection-

I was able to stand directly across the inlet from the swan, and the bird seemed unperturbed by my presence, resting on its one leg.

Trumpeter Swans most often pair for life, but not until they are about 5-7 years old. Perhaps this is a young bird, or perhaps its mate has died — in any case, this lonely swan has been hanging out at the inlet to Sucker Lake in the Vadnais Heights reservoir system for the past couple of weeks. Pairs of Trumpeters come and go there, but there is always one lonely bird, perhaps this same one.

trumpeter swan-

On another day, a lone swan swam in the inlet with a few Mallards for company.

trumpeter-swans-on-the-mississippi-1

Too bad Lonely Swan doesn’t know there is a party going on about 50 miles up the Mississippi River at Monticello, where the Trumpeter Swans feast on corn handed out to them daily. 

For those music lovers in the crowd, the reference in the title of the post is to a hit song from the 70s — Alone Again, Naturally (by Gilbert O’Sullivan).

Blending in… or not

In the winter, everything seems to take on shades of gray and brown, even the several day’s old crusty snow.  When I looked out in the backyard early one morning recently, I saw a few members of the local deer herd wandering down the hill toward the pond, but didn’t think there was much of photographic interest there.  So I just snapped a quick couple of images.  When I finally got around to looking at those photos, I found the deer match their gray-brown background so well, I didn’t even see the large buck having a morning rest in the snow.

white-tailed buck resting

It’s easy to miss even large-bodied animals, like the buck in the left background, when they aren’t moving around.  When the light is dim in the early morning, and the world is gray-brown, whte-tailed deer blend in nicely with their surroundings.

white-tailed buck resting

A little photo “massage” makes the buck stand out a little better.

Most of the gaudy male birds wear their less conspicuous plumage in the winter — to better blend in and avoid being someone’s lunch.  But there’s always an exception to that general rule:

male Northern cardinal - wnter-

Mr. Cardinal doesn’t stay in one place long, and he is obviously the brightest thing visible in this monochromatic (almost) background.  He visits the feeder right at dawn and again at dusk, and stays tucked into dense vegetation during the rest of the day.

female cardinal - wnter

Mrs. Cardinal is less colorful, but she too only visits the feeders at dawn and dusk, when there is barely enough light for me to see which birds are there.

Busy beaver

Judging by the change in the landscape around the creek that drains into Lake Vadnais, the beaver there have indeed been very busy this past fall and winter.  A maintenance crew came by in the fall to pull downed trees out of the creek, but the beaver have chewed through most of the remaining aspens that line the banks creating this scene.

beaver work

I assume they harvested the smaller branches of these aspen for their winter food storage.  Those amazingly sharp incisors cut through trees 12-16 inches in diameter.  I wonder how long it takes a beaver to fell one of these trees — can they do it in on night?

I noticed footprints of what might have been beaver in the path so I followed them back to their lodge.

beaver tracks-

Clear footprints of a path going to and from the lodge over a thin icy crust of snow on the frozen part of the marsh.  The front foot looks almost like a handprint, the rear foot has elongate toes with webbing between them.  (The toe of my boot for size comparison.)

beaver lodge-

Footprints led right up to the back door entrance (on the backside of this view) from the woods.  The lodge hasn’t changed shape much in the past two winters — no new material has been added to the top.

beaver lodge painting by Jennifer Garrett

An artist’s (Jennifer Garrett) view of what goes on in the beaver lodge during the winter (imagine that’s me up there on my skis). Photo from Jon Nelson’s blog post on “life under the ice“.

Entrance and exit tunnels from the lodge take beaver out to deeper water in the marsh, as well as exits onto land where they can continuing foraging (and felling trees, I guess). One adventuresome pair of skiers caught a beaver that had just emerged from one of those tunnels into the bright glaring snow scene.

beaver in snow-frametoframe.ca-

If food supplies run low in the lodge, the beaver can always run out and harvest a few branches to snack on. The problem is getting that bulky branch to follow them through the icy water and back through the tunnels into the lodge. Photo from Bob and Jean’s blog:  frame to frame

I don’t think there is any other animal (other than humans) that modify their environment to the same extent that beaver do.  By impounding water in larger pools, they create a safer environment for themselves, and change the habitat to become more suitable for many other wetland species as well.

Surviving the cold – part II

In yesterday’s blog post, I summarized the challenges of living in (and surviving) the harsh weather of northern latitude winters and described a few of the solutions to those challenges.  But there are more solutions available to animals — and humans.

4. Turn up the heat:  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 physical exertion are the first line of defense in staying warm.  The trick is to preserve the heat inside the body by improving insulation.

red-bellied-woodpecker

Flying around looking for food generates body heat for this Red-bellied Woodpecker, but the bird must fluff out those feathers when sitting still to retain the heat produced by activity.

gray-squirrel-

Mammals, like this Gray Squirrel, fight the cold by increasing both shivering and non-shivering heat production, using an extra source of heat production from their “brown fat”.  It doesn’t hurt to have a furry tail to keep your back warm either.

Brown fat (more vascularized than regular white fat) is more prevalent in mammals acclimated to cold (even humans!) and especially in young mammals and in hibernators that undergo dormant sleep for most of the winter.  Localized in the trunk and back, brown fat heat production preferentially warms the spinal cord and brain.

5. Don’t spend what you don’t have:  In cases where food is limited or costly to obtain (i.e., resulting in a net loss of energy), the opposite strategy from #4 above is to be more conservative in expending energy by turning down the metabolic furnace when resting, decreasing activity, sleeping more, etc.  A variety of mammals, some birds, and even some humans employ this strategy in the winter.  Hibernation, or winter sleep, is key to survival in many rodent species (except tree squirrels), because there is little energy wasted on heating up their body that is essentially the same temperature as their burrow.

hibernating chipmunk-sni.schlastic.com

Hibernating chipmunks store food in their underground burrow, and rouse every couple of weeks from their torpid sleep to snack a little before becoming dormant again.  Photo from sni.scholastic.com

human hiberanation

The British Medical Journal described a case of “human hibernation” in a group of Russian peasants, living in an impoverished area with inadequate food, who typically slept through the winter, rousing only once a day to eat a little bread, drink some water, and add fuel to their fireplace.

Just turning down the furnace and lowering body temperature a few degrees at night can make the difference between survival and succumbing to the cold.  Birds as small as Black-capped Chickadees and as large as Red-tailed Hawks save 30-40% of their overnight energy expenses by cooling off a few degrees.

Red-tailed Hawks sitting on phone poles

It’s not unusual to see Red-tailed Hawks perched on telephone or light poles along highways in the winter, where they can get a good view of potential prey moving around below them.  But if these hawks miss a few meals, they may not have enough energy reserves to make it through the night. Better to reduce night-time costs and save energy.  Photo by Allan Block

6.  Tolerating net energy loss:  This is kind of a last-ditch effort to survive winter, but may be a viable strategy in larger-bodied, well-fed animals.  For example, White-tailed Deer may not find enough forage to sustain themselves over an entire winter, so they put on weight by eating a lot in the Fall and coast through the winter, using up their reserves.

white-tailed-fawns-feeding

Winter cold must be especially tough on smaller-bodied fawns with less energy reserves than the adults.

Longer winters with more extreme temperatures may mean lower survival rates, and may even compromise an animal’s ability to recover in the spring.

white-tailed-deer-late winter

This White-tailed buck looks pretty emaciated after a long, cold winter.  He may not be able to rebuild his muscle mass over the summer in time for the Fall rut season.

A more atypical illustration of this strategy is that of hibernating bears.  They aren’t really hibernating in the true sense, since their body temperatures are only a few degrees lower than normal, but they purposely fatten up in the fall, and then metabolize that fat over the months of winter sleep, losing 25-40% of their body weight before they emerge from the den in the spring.  Females use an additional portion of energy reserve to nurse cubs born during the winter sleep.

black-bear-hibernating - bearlakereserve.com

Hibernating Black Bear and cub; photo from blackbearreserve.com

In summary, animals use a variety of strategies to offset the cost of surviving winter cold; it’s not really mysterious or magical, but is a product of selecting what works best in a particular situation.  Animals using the wrong strategy are quickly removed from the breeding pool, and thus solutions get better and better over time.

Surviving the cold — part I

Even though I’ve just read that 2015 was the hottest year in historical weather record-keeping (2 degrees F above average world annual temperature), the backyard here is buried in the deep freeze.  Several of my fellow bloggers have been posting queries about how animals survive conditions like this in the wild — or how humans who live and work outdoors all winter survive these extremes.  So, being somewhat of an expert on this topic once upon a time, I’m going to try to explain how they do it.

goldfinch-winter chill

Yikes — it’s chilly out there. for this young American Goldfinch

First — the challenges of winter at far northern latitudes:

  • low temperatures mean warm-blooded animals need to turn their heat producing furnaces to high to offset heat lost to the environment
  • wind, sleet, and any precipitation carry body heat away even faster than just being surrounded by cold air
slate-colored-junco

Who ordered this sleety, icy rain?  But Slate-colored Juncos are tough, and they outlast this kind of inclement weather.

  • the sun is low in the sky and it’s often cloudy and overcast, so radiant heat input is hard to come by
  • where’s the food?  Summer production is long past, food is buried under snow, other animals got to it first — so how does a warm-blooded animal get enough energy daily to fuel the heat-producing furnace?
white-tailed-deer-in-snow-

Really, there isn’t much here to fuel the needs of a large-bodied animal like these White-tailed Deer.

Solutions:

1. Prepare for it:  Those chilly fall mornings and waning daylength are signals that challenging days are ahead.  Animals prepare for the challenges of winter by hoarding or stashing food in places where they can find it later. Usually, there is a flurry of activity at bird feeders as birds and squirrels take seeds to their winter roosting sites.

chipmunk

Packing those cheek pouches full, a chipmunk carries his prize underground to eat later.

And — a new set of freshly molted feathers in the fall not only disguises once brightly colored birds, but provides a nice, new downy coat of insulation.  An under coat of dense fur beneath longer guard hairs helps keep mammals warm in the winter.

2. Eat like crazy — in order to put on a nice layer of fat reserves.  This strategy works better if you’re a fleet-footed mammal, because when birds put on too much fat, they can’t fly.  In addition to the insulative value of a layer of fat, it does provide an energy reserve for overnight energy expenses and the days when foraging for food was inadequate.

house-finches

Dining with friends (House Finches) is always a good idea, so that many eyes can spot the skulking predators.

common-redpolls-

Pine Siskins are so good at searching out and consuming high volumes of seed per day that they can maintain their body temperatures, even at very low extremes.  Like Common Redpolls, these little birds are champions at cranking up the metabolic furnace to generate heat.

And — since there aren’t many insects active in the winter, avian insectivores like chickadees switch their diet to take advantage of the high-energy content in seeds.

black-capped-chickadee

Do you wonder how a bird that weighs less than a McDonald’s ketchup packet stays warm in sub-zero cold weather?

3. Hide from the worst extremes:  Chickadees, nuthatches, and woodpeckers find a refuge from extreme temperature and wind in a roost hole.  Some sparrows and larger birds like Robins and Blue Jays huddle in the thickest part of evergreen vegetation which protects them from the effects of wind and precipitation.  Many mammals retreat to underground burrows, tree cavities, or leafy nests to hide from extremes.

bear-in-den-illustration (nps.gov)

Below ground, temperatures are above freezing, and mammals are protected from wind and precipitation. (Illustration from http://www.nps.gov/katm/blogs/Bear-Hibernation.htm)

To be continued tomorrow with more solutions….

white-tailed-buck-in-snow

Basking for warmth

It’s difficult to get any warmth out of a January sun at this latitude, especially on days when the high temperature for the day is in the negative digits.  The squirrels finally made an appearance in the backyard by late morning, but they favored clinging to vertical surfaces where they could maximize the amount of sun hitting them.

gray squirrel with amur maple seeds-

After collecting a few of the Amur Maple seeds still present on a nearby tree, this gray squirrel paused for several minutes to warm up, pressing its body tightly to the trunk of a walnut tree.  Oops, it looks like one seed escaped and has fallen out of the squirrel’s mouth (behind its ears).

gray squirrel eating amur maple seeds-

Assuming the Nuthatch posture (head down), the squirrel proceeded to eat (or husk) the seeds). I wonder if it was warmer in this position?

I’ve often seen squirrels performing this kind of behavioral thermoregulation on extremely cold days.  In fact, you often see humans do the same thing, while waiting at a bus stop in cold weather — turning their backs to the sun to soak up the heat. Increasing their surface area by pressing their bodies flat on the tree trunk probably helps the squirrels gain a few extra quanta of heat from that weak sun.

baby, it’s cold out there!

The thermometer read -13F (that’s -25C) in the backyard this morning — birds, squirrels, and deer were sleeping in until the sun rose high enough to hit the trunks of the trees and the bird feeders (around 10 a.m.).  And then the rush was on to grab peanuts, eat suet, and grab a few sunflower seeds before disappearing back into some warmer niche.

black-capped chickadee

Chickadee waiting patiently for a turn at the peanut feeder. 

These little birds look like balls of fluff, with their feather insulation expanded out for maximal warmth.  But a stiff wind today makes heat conservation pretty difficult with wind chill temps hovering around -35 F!

chickadee eating peanuts

Got one!  One small peanut weighs about 1 gram — providing about 0.5 grams of fat, 0.2 grams of protein, and 0.2 grams of carbohydrate.  Just the fuel needed for a cold chickadee.  The bird might come back to the peanut feeder several times, but will probably stash most of them for consumption later.  The chickadee itself only weighs 10-12 grams.

red-bellied woodpecker eating peanuts-

Red-bellied Woodpeckers are peanut specialists, and return many times for these high energy capsules.

white-breasted nuthatch eating peanuts-

White-breasted Nuthatches prefer peanuts over sunflower seeds on a day like this.

I really dislike going out in weather like this, but animals have no choice.  Foraging hours are shorter on extremely cold days, and the birds prefer the high caloric fuel to make energy ends meet overnight.  Of course, retreating to a nicely insulated nest hole helps too.

The other day when I was out walking in the far backyard (marshy swamp area) just before dusk, I stopped to look at a snag (dead stump) with a variety of different sized holes in it, when suddenly a Hairy Woodpecker flew out from one of the holes.  A moment later another woodpecker flew out from the same hole.  They might have been a breeding pair that decided to share their heat in an old nest hole — which is a great way to survive this frigid weather.

a brief reprieve

On days when the thermometer creeps up above 20 F, it’s time to get outdoors and check on how the local wildlife are faring.  There were no Trumpeter Swans visiting the creek that joins the two lakes in the St. Paul reservoir system on this “balmy day”, but the Mallards and Canada Geese were enjoying a morning nap on the trail along the creek.

mallards and canada geese-9893

I think they may have been waiting for locals to bring them a morning snack.

With out latest spate of sub-zero weather, there is very little going on in the backyard.   Even the treats in my bird feeders don’t seem to attract much in the way of feathered friends these days.