Monday, February 28, 2011

A Roadside Northern Shrike

Northern Shrike - Durand, Wisconsin

While Northern Shrikes are "regular" winter visitors in Pepin County, Wisconsin, I am always surprised to see one.  This winter I've spotted shrikes several times in a half-dozen places - including at my bird feeders.  I spotted this one today around noon on State Road 85 across from the Tappe farm (fire sign W5332).

It was sitting on a wire along a busy road - not a great place to hunt small bird prey and rodents (the ground is covered with a crust of ice).

We pulled off the road and watched, hoping to see this bird make a move - get a meal, hover, or cast a pellet. 

It was not meant to be.  After only a few minutes, the bird took off and headed towards the subdivision to the east.   We did not follow.

While I "know" this bird is a Northern Shrike, I can't seem to remember the differences between the Northern and Loggerhead Shrikes.  I see so few of them that I always have to check my field guide.

Take a look at the two shrikes:

Loggerhead Shrike (l) and Northern Shrike (r)
Mockingbirds are also gray, black and white.  But shrikes are chunkier in both colors and size.  When in doubt, think "mockingbirds on steroids."

Northern Mockingbird © HvHughes

Sunday, February 27, 2011

Sharp-shinned Hawk Kills Again

1st Year Sharp-shinned Hawk plucks a Downy Woodpecker

How many songbirds does a Sharp-shinned Hawk eat in a day?

I watched this one catch and eat 3 at my birdfeeding station today:  a junco, goldfinch and this downy.

Saturday, February 26, 2011

Cooper's or Sharp-shinned Hawk Revisited

Sharp-shinned Hawk kills an American Goldfinch

It was another snowy day in the coulees today.  I was sitting at the kitchen table eating a late lunch when I heard the boom of birds bouncing off my kitchen windows.   

No birds were injured by the plate glass, but I spotted a male American Goldfinch dead on the ground, victim of the other predator in my yard.  An accipiter was staning over the body.

I knew it was an immature (brown plumage and yellow eye), but which one?  A Cooper's Hawk or a Sharp-shinned? 

Sharp-shinned Hawks have heavy streaking on the breast;  Cooper's have light streaking.  What's "light?"  What's "heavy?"

I see so few of them, I wasn't sure.  So I went to my bookshelf and pulled out the Photographic Guide to North American Raptors


The photo on page 34 showed a juvenile Sharp-shin with "streaking on underparts extends onto belly."  The Cooper's photo on page 37 showed "fine dark streaking ... sparse on the belly."

No question:  it's a Sharp-shinned Hawk.

I wonder how many birds that Sharp-shinned Hawk needs to eat on a snowy winter day...

Friday, February 18, 2011

Winter American Kestrels

In the decade I've lived in Wisconsin, I don't remember seeing these robin-sized raptors in February.  So I was surprised to spot an American Kestrel last week during the "thaw."   Today we spotted four more during our search for Golden Eagles in the coulees in west-central Wisconsin. 

Do kestrels winter here - or is this a sign that migration has started?

I found the answers in the Atlas of Breeding Birds of Wisconsin.

Kestrels are present in Wisconsin year-round.  During the winter, kestrels are uncommon in northern Wisconsin - and fairly common in the southern half of the state.  They begin their northern migration in March and head south in August.
American Kestrel - Christmas Bird Count                     

While these wintering birds feed on small birds and mammals, during the breeding season they also eat large insects (beetles and grasshoppers), reptiles and amphibians. 

They nest in tree cavities (abandoned woodpecker nests), on cliffs and in chimneys.  They also will use human-made nest boxes if the habitat is "right (edges along highways, agricultural fields and grasslands).

American Kestrel Map
American Kestrels - Wisconsin Breeding Bird Atlas

For a "guaranteed" look at American Kestrels - head over to Buena Vista Grasslands Wildlife Area in May.

Nestling American Kestrel at Buena Vista Grasslands

Monday, February 14, 2011

A Valentine's Day Caterpillar

Isabella Moth Caterpillar - Valentine's Day in Wisconsin

It's hard to believe the temperature was -35º F just last week.

We've had two near record-setting warm days in a row! 40-degrees F.   The snow piled up along the roadside is melting and the County Roads are wet and covered with wet sand.  The local meteorologists say it's a temporary tease.  Winter will return by the end of the week.

Today was the first day this year that I spotted insects outdoors:   a fly on my car windshield ...and a Woolly Bear caterpillar crossing Rustic Road 107.   (Yes, I brake for caterpillars).  I hopped out of the Prius, snapped a photo and gave the little insect an assisted road crossing. 

How does this caterpillar survive the cold?  Woolly Bears have a natural anti-freeze (glycerol) in their "blood."

What is it doing out and about in a February thaw?

It could have been disturbed by the snow plow that pushed the white stuff away from the shoulders.
It could have been out enjoying the sunny, warm weather.
It could have been hungry or thursty.

Whatever the reason - this was the earliest I've seen a Woolly Bear out and about.

Sunday, February 13, 2011

Pileated Woodpecker Eating Hackberries

Pileated Woodpecker in a Hackberry Tree

We took the Prius out this morning to see how the wildlife along the Lower Chippewa River would react to the February thaw (temperatures in the 40's).   We were heading east into the coulees on Kings Highway in Maxville, Wisconsin when I spotted a commotion at the top of one of the leafless deciduous trees on the north side of the road.  At first I thought it was a crow.  Then I saw the signature red knot of feathers on the back of its head:  a Pileated Woodpecker.

She was floundering and flapping.  My first thought was:  was she tangled-up in fish line?

We pulled out our binoculars and watched.   She seemed to lose her footing.  Then she flapped her wings to maintain her balance.   What was going on?

After a minute or so, we were relieved to see her find stability on the tiny branches.  She looked okay.  But then she lost her balance again and started flapping.

That's when I noticed the tiny fruits hanging from the top branches.  This huge woodpecker was picking Hackberry fruits!  I've seen robins and waxwings feed on Hackberry fruits, but never a Pileated.

When I got home, I checked the Birds of North America monograph to see what else, aside from carpenter ants and beetle larvae, these birds eat.

Their diets change seasonally, but they eat carpenter ants year round.  They focus on fruit in the fall, carpenter ants in the winter, wood-boring beetle larvae in the spring and a broad selection of insects in the summer.

Insect surprises:  cockroaches, paper wasps, beetles and termites.

And the fruits... greenbriar (smilax), hackberry, sassafras, blackberries (rubus), poison ivy (!), dogwood and black gum.

They eat nuts and tree sap too.


What other birds did we see in the Durand area?

A kestrel out on Marsh Road.

A dozen Horned Larks on Stai Coulee Road east of the potato shed.

Several Red-tailed Hawks, including a pair in their "regular" tree south of County V on State Road 25.

And several Bald Eagles flying, roosting and fishing.

At my feeders:  Tufted Titmouse, chickadees, 5 pairs of cardinals and dozens of juncos, tree sparrows and goldfinches.

Wednesday, February 9, 2011

How Do Birds Keep Their Feet From Freezing?

Wild Turkey in Arkansaw, Wisconsin
Today's high temperature was 9º F with an overnight low of -8.  The sun was out - so it didn't feel so cold - inside my Prius.  Outside was another story altogether.

The chickadees at my feeders were all puffed out.  Their little bodies were almost as wide as they were long.   The eagles were perched in their usual trees back in the coulees, soaking up the rays.  But there weren't many birds along the roadsides, even though the snow plows had been by to clear the shoulders of the road - exposing grit and weed seeds.

The windchill advisory warned of temps in the double digits below zero.

We headed out to Arkansaw, Wisconsin.  I wanted to see how liverworts deal with winter.  I'd staked out a roadside colony of these primitive plants last fall.  We found them and I was surprised to see that they stay alive - and green - over the winter.

Mosses & Liverworts (green) and Ferns (brown)

On the way back to town, a Wild Turkey trotted out of the woods in front of the Prius.   I stopped the car, rolled down my window (the blast of cold nearly took my breath away) and pointed my camera at the hen.

She trotted off into the snow - sinking up to her feathered tibiotarsus.  I expected her to fly, but she pulled herself out of the deep snow and walked up on the crust.  Brrr...

Even in my insulated boots, I have trouble keeping my feet warm.  So how do birds keep their naked feet from freezing?

It's all about controlling heat loss in their feet.

Avian feet are comprised primarily of tendons, ligaments and bone - and not much muscle, nerves and blood.  They don't need to keep their feet as warm as we do.  Just above freezing will do.

   -  Their feet are covered with scales which are less susceptible to freezing.

   -  The circulatory system in avian feet - the proximity of their veins and arteries - creates a biological "countercurrent" heat exchange.  Waterfowl have a more complex net of arteries and veins - a "rete mirabile" - that helps keep the temperature in their feet just above freezing.

    -  Birds can constrict the muscles in their legs to actually pump warmer arterial blood into their feet.

And when that's not enough, birds can stand on one foot.  That way they can heat up their cold feet in warm downy feathers - one foot at a time.

Saturday, February 5, 2011