Ice and Bluebirds--a Special Matter

Eastern Bluebirds are one of the most popular and enjoyable birds to have around your home. They don't mind being near people and their activities, and, like many other birds, they recognize you when you're providing food. Bluebirds that are familiar with you will even fly toward you when you are filling their mealworm feeder.

Our nesting Eastern Bluebirds in Tennessee are non-migratory and remain here year-around. They are joined by birds from neighboring states and young bluebirds from neighboring territories to form small wintering flocks that aid winter survival. These flock members help each other find food, spot predators and provide warmth when they roost together in a sheltered cavity, such as a nest box, when the temperature drops below 20 F degrees.

Bluebirds are not your typical feeder birds, however. Their natural winter diet consists of spiders, berries and fruits. If these foods are available they can maintain fat reserves that sustain them during the extreme cold. T. David Pitts, in his book, Studying Eastern Bluebirds, A Biologist's Report and Reflections,  also says the following:  "As a result of their high rate of metabolism, bluebirds can quickly use the fat they store.  If extremely cold temperatures linger for several days, many bluebirds may die since they normally store only enough fat to protect themelves for a day or so, and they may not be able to find enough food to replace the fat that has been used."

A male Eastern Bluebird feeding on the berries of the burning bush.

Pitts also conducted extensive studies in northwest Tennessee that revealed that bluebirds do not digest the seeds that are in the fruits they eat.   These seeds pass through their system undigested and provide no nutritional benefit.  Herein lies the challenge.  A non-seed eating bird that primarily recognizes insects, spiders and berries as food.  How do you feed them when winter gets rough?

And even more challenging, how do your feed them when larger, territorial birds are chasing them away from the berry sources?

Female Eastern Bluebird, above and below.

I had this challenge over the past week, when freezing rain and sleet coated everything with ice and temperatures plummeted to single digits with windchills below zero.  Suet crumbs froze, mealworms froze and larger birds, such as American Robins and Mockingbirds became aggressive, chasing smaller birds, like bluebirds and Hermit Thrushes away from the berry bushes. In fact, one robin was so territorial he chased bluebirds away from both the holly and the neighboring burning bush.

One male bluebird was familiar with the mealworm feeder guard and could navigate through it and eat suet and mealworms offered there, protected from larger birds.  The other bluebirds that came with him did not know how to navigate the guard.  With feathers fluffed against the cold and mealworms frozen motionless, there was little hope they would learn about the guard in sub-freezing conditions.

After consulting friends, Billie Cantwell and Liz Cutrone at Knoxville's Wildbirds Unlimited, I adjusted a Dinner Bell feeder to exclude larger birds by lowering the dome cover to a few inches above the tray, filled the tray with smooth "butter bark" suet pellets, small home-made suet crumbs and freeze-dried mealworms and hung it near the bluebird feeder.  When the male bluebird came to the feeder, his companions soon discovered the added food source and were also able to eat from it. In their absence, I noticed the Hermit Thrush landing on the dinner bell also to eat suet.

Additional good advice-- spread your suet feeders out so if a larger bird claims one feeder, there is an alternate area for the smaller birds to visit.
In the spring you can also consider planting Sumac near the borders of your yard.  In Pitts' studies in northwest Tennessee, two native species, smooth sumac and winged sumac, were the most favored fruit of bluebirds, composing 50-90% of their winter diet even when a variety of other fruits were available.

Pitts advises to plant more than one sumac spaced apart in different areas of the yard to prevent mockingbird dominance.  If a group of robins or cedar waxwings flies in and takes over the holly berry supply, a protective mockingbird will likely take over the sumac next.  Planting shrubs spaced far apart in different areas will give the bluebirds an alternative choice for feeding.

Northern Mockingbird in holly

More on wintering bluebirds
Previous post--Robin eating holly berries
More on feeding bluebirds
Bluebirds family videos

Winter Birds and Tennessee's Ice

Ice presents stressful winter conditions, not only for people, but for wildlife.  Though beautiful to witness from warmth and safety, a wintery mix of precipitation that coats food sources presents challenges for bird survival.

In Tennessee we have birds that live here year-around and remain for the winter because of the generally moderate winter conditions and abundance of food.  If enough food is available, many bird species can survive temporary plummets in temperature.  Extended periods of sub-freezing temperatures, however, such as the single digits that we recently experienced, and a quarter inch coating of ice over everything increases survival challenges considerably.  

The American Robin is one of the species that we call resident birds because they remain during the winter.  Many northern robins join our local ones to take advantage of the food sources, so we may see large flocks of robins descending on our yards and visiting fruit producing trees and shrubs. Asian holly is one of the berry producing shrubs that attracts many species of birds, though if you are planting holly, the native American Holly is a better choice.

In these images, you see a Robin picking berries from the holly.  He not only was feeding on berries, he soon claimed the holly for himself, driving away other robins and also driving away the area bluebirds that came to visit.  He ignored sparrows, the Hermit Thrush and did not bother the Mockingbird, the bird we all expect to be territorial with a holly.

The ice and the several days of below 20 F temperatures, presented conditions so stressful, that many birds we normally don't expect to be aggressive were chasing others away from their food source. Above, you see the robin in the act of grabbing another berry.  Notice what happens to the berry in the next image.

An ice coated berry is hard to hold on to!  People feeding birds during the ice storm and deep freeze temperatures in east Tennessee noticed many territorial birds and an influx of species that weren't commonly seen visiting their winter feeders.

I'll show you some of those species in the next few posts.

Next:  Bluebirds and ice--a special matter

More on wintering birds in this blog

A good article on Winter time feeding and water--Cornell

That Baby Bird Stuff Going on Out There!

There is a lot of baby bird activity going on this time of year. Not only are baby hummingbirds out of the nest and visiting feeders, more than doubling the number of nectar visitors, other young birds are foraging around the yard.  It just takes a minute of being still to find them.

I stepped outside because I heard tapping, a sign of a woodpecker near by.  I wondered if a Pileated Woodpecker was around, but found the next best thing--a female Red-bellied Woodpecker foraging in the pines.  I will show you images of her in my next post, but in this one, I wanted to show you some of the baby stuff going on under that same tree!

There were several American Robins running around on the ground and I quickly identified them as juveniles with rusty breasts still speckled with dark spots and white down, and their back and wing feathers also speckled with white.

They already have very robin-like posture and movements.  Alert stance, listening to everything above and below, lightening quick feet.  They learn quickly to watch for food and watch for danger at the same time.

 A good strategy--don't linger in one place for too long!

Right after the young robin scurried away, a Carolina Chickadee landed in front of me. I would not have thought much of it had I not snapped some images just because the camera was in my hand.

Parent and juvenile chickadees look the same. I glanced at these images and concluded, this must be a juvenile! He has picked up a yummy rock for all his foraging efforts!

 He seems to be wondering what to do with his prize.

Thankfully, Carolina Chickadee juveniles follow their parents around for several weeks while they learn to find food and feed themselves!

Next:  Red-bellied Woodpeckers foraging

Carolina Chickadee
American Robin

Eastern Bluebirds--Peace in the Neighborhood

Chronologically, this post happened earlier than my previous post about the bluebirds and their phoebe neighbors.  In particular, in this post, I wanted you to see how unflinching and determined a male bluebird can be when it comes to his nesting territory.    
Phoebe fledgling.

On this occasion, May 11th, sharp notes being issued by the phoebe parents alerted me to a change.  The phoebe nestlings had fledged and were perched all around the yard, mostly on oak limbs in the center of the yard.  This, of course, excited me. In three nesting seasons of two broods each season, I had never had the joy of seeing a phoebe fledgling until that moment.  Witnessing this event is a chance occurrence, especially when the nest is high over your head, and out of observation range.

Above, the youngest fledgling by appearance.

I searched for the nestlings by watching for movement and the parent's behavior.  Now that I knew the young had fledged, I couldn't be fooled into thinking that all phoebe shapes were the adults.  I found the youngsters, three, at least, possibly four.  They appeared to have different levels of maturity and flight experience, so I guessed that at least one, maybe two had fledged the day before.    

Enter, the male bluebird, who had been out hunting beyond the yard, and flew over the fledglings, landing on his favorite perch.  This was not okay with the male phoebe.  Two of his youngsters were on a limb on the other side of the oak trunk on the same level and about fifteen feet away from the perched bluebird.

Phoebe male.

This was one time I truly wished for a digiscope.  The distance was out of range for my lens, but the images will at least give you an idea of the events that transpired.  The male phoebe, erecting every feather possible to look menacing, issued loud, sharp warning chirps. The bluebird gave him his full attention, but did not budge from his perch.  This prompted the phoebe's aggression and he commenced diving.      

This male bluebird is clearly tough, determined, has nerves of steel. The male phoebe was defending fledged young, alarmed/angered by the closeness of the bluebird. I say angered because these two birds know each other. They share the same perching area and they've disagreed before. The male bluebird, obviously just as determined as the phoebe, held an unyielding posture on his perch.  

Below, you see the bluebird, far left, and the phoebe, far right, as they face each other before the phoebe begins another series of dives.  (Click the image to enlarge).  Sharp chirps are coming from the phoebe.  The bluebird is silent, stoic, alert.   

The bluebird wheeled around to face his opponent in whatever direction he approached.  But budge he did not.  He was firmly planted on that perch and its adjacent limbs.  Not only would he not be driven off, he sometimes rose up to meet the challenge, or leaped forward, perching closer to the phoebe rather than backing off.

At one point, right in the middle of a series of phoebe dives, a curious robin landed on a limb behind the bluebird at eye-level and began 'heckling' with the familiar thrush-y cackling noises that American Robins frequently make.  The male bluebird did not seem to appreciate this and wheeled around giving the robin the threatening stare shown in the image below.  The robin left shortly thereafter.

The end result of all this activity, to my relief, appeared to be a truce.  The bluebird apparently felt he had established his stand, and left voluntarily to help his mate with feeding nestlings.  Two of the phoebe fledglings began moving about, and the male phoebe also seemed ready to attend his young.    

I thought the moment above was interesting.  Even though several more dives occurred after this point, and moving closer can be considered intimidation, I wondered if ignoring each other or indicating disinterest is a mutual signal that its time to end the conflict.

The phoebe's aggression in this incident was understandable, given the presence of newly fledged young.  Even so, it came as a surprise to me, since these birds are around each other daily and share the same perching area.  But what surprised me even more, the unyielding determination of the bluebird male as he defended his right to stay on the perch that he and his mate use routinely.  He showed no avoidance, no moving away, no flinching as he faced the dives and only rose to meet a close encounter.

In hindsight, given that these families will likely continue to be neighbors, I can see how standing his ground was an important defense of his nesting territory.  

A phoebe fledgling landed close to me as the conflict ended.  A pleasant surprise.  And as you may know, I'm a fan of happy endings!

This is the sixth post in a series on this bluebird family.  To see all of the posts visit the link, bluebird family.   In Wishing Upon a Bluebird, an initial encounter between nest building phoebes and bluebirds is described at Vickie's Sketchbook.  I will be sharing more about this relationship between neighbors soon.

For articles leading up to the story on this post, visit my Wild Birds Unlimited articles:  Smitten with Bluebirds and April Celebrations.  And to see last season's chickadee family, visit the Secretive Chickadee Family and A Happy Fledging Time of Year.

Upcoming:  Bluebirds Love Water, and wing-waving in bluebird communication.

A Spring Head-dress and a Heart-stopping Thrush

This female northern cardinal visiting the bird bath for a drink gave me my first belly laugh of the day.     

Her plumes on her crest stood up like flames in the wind.  Despite the winter-y blast of heavy snow in the mid-western states, we're having mild temperatures and blustery pre-March winds in Tennessee.  And if that weren't enough to hint of spring, birds are showing signs of spring molting.  Just twelve days ago, I snapped the image below, of a female cardinal in the snow.  She was fluffed and warm in her thick winter plumage.   But in the days since, we've had more moderate weather with some days reaching as high as the 70's F.

My Atlas of the Breeding Bird of Tennessee says, "In late February and March, cardinals form stable, monogamous pair bonds. Both the male and female defend the territory with song, displays, and mild combat."   Females pick the nest site usually in April but as early as mid-March, meaning that the tolerance of communal winter foraging is about to end, replaced by freshened spring plumage and territorial attitudes.

Along with the tattered and comical appearance of her crest, feathers have molted around this cardinal's face. New feather sheaths will emerge quickly where old feathers have been shed and fresh ones will rapidly grow to replace the lost ones.  This female's colors are beautiful, nonetheless, even though she wears a wind-blown look.  I couldn't be sure if she was on the alert or if the wind was standing her remaining crest feathers up so tall.

The watering hole is definitely a fun place to hang out, a good place to watch the tall pines, oak and maples waving in the gusting wind, as well as, to see birds that may otherwise go unseen as they come for a drink.  Several times I've seen a yellow-rumped warbler both drink and forage near the feeders but, so far, not when I'm outside with the camera.

Today I enjoyed a better look at the beautiful streaking and contrast in an American robin's plumage as she braved the birdbath for a drink.  When she flew, my heart picked up a beat, as a hermit thrush popped in to replace her, its 7-inch stature seeming exceptionally petite next to that of a robin, ranging from 9 to 11 inches.

It was special to get lingering looks at this shy bird, standing tall on tiny legs.  More often I notice her hanging out in the shadows of the hemlock, impossible conditions for a good photo, and visits to the birdbath are usually glimpsed through the window.  This made today's surprise visit exceptionally appreciated and I fell in love with the wind-blown look below!

Hermit thrushes are best known in Tennessee as a migrant and wintering resident, generally arriving in October and departing by early April.  Breeding seasons have only been sparsely recorded in Tennessee in the higher elevations of Roan Mountain and the Great Smoky Mountains (Atlas of the Breeding Birds of TN, ed. Charles P Nicholson.)

When this thrush turned, giving me nice looks at her body proportions and rust tail, I thought she was leaving.      

But she lingered a few minutes longer and reached from the side to take several more drinks.  Sigh.  One of many special moments enjoyed in the backyard.  

Links and Resources:

Atlas of the Breeding Birds of Tennessee, edited by Charles P. Nicholson.  This book is out of print and pricey on the secondary market, but with patience, you may find lowered pricing on Amazon with time.  

More thrushes on this blog:  Bird Gratitude, Townsend's Solitaire, Eastern Bluebird, American Robin

And more about cardinals and molting in A Day-making Family of Cardinals

If you have not already signed the petition requesting a new management plan for the Eastern Population of Sandhill cranes, visit the petition site right now and voice your opinion on this important conservation issue.  Kentucky is battling a sandhill crane hunting proposal similar to the one deferred in Tennessee.  We have a lot of work left to do to protect this population that has only recently recovered from near extirpation.  To read more visit A New Plan for Eastern Sandhills.    

Linked to Bird Photography Weekly #130 at Birdfreak.com to promote the conservation of our world's birds.