Fear and Trembling

The old nature-versus-nurture discussion was always a crude simplification of a complex situation. With the study of epigenetics, we are beginning to dive deeper into the details of information transfer between generations. Websters defines epigenetics as "The study of heritable changes in gene function that do not involve changes in DNA sequence." 

The classic example is a study with mice. The study, by Dias and Ressler from Emory University, shows that a parent's fear and knowledge can be passed on to their young, even when their offspring are unborn at the time of the initiating experience. You can read a more detailed report on the study by Clicking Here.

This week an encounter with three juvenile cooper's hawks made me wonder about the relationship between instinct and epigenetics. Websters defines instinct as, "Something you know without learning it or thinking about it."

The two young hawks in this photo are apparently siblings who have no problem being in close proximity. One of the ways we can tell they are young is the white spots visible on the back of the upper bird. (Thank you to Penny Lewis for pointing this out.)

Another clue is the whistling cry they make. The sound is their method of requesting food from their parents. This descending whistling sound only lasts for a few weeks. Once the birds are totally on their own they quit begging for food and the baby talk stops.

While watching the first two birds, another one popped out of the bushes with breakfast in hand. As the third juvenile flew away, I could see the prey was a smaller bird, most likely a dark-eyed junco or a black-capped chickadee. 

What was most interesting about the experience was the behavior of my daughter's dog, Ginger. Ginger is a 29 pound Labradoodle, with oddly straightened hair, compared to her curly-haired litter mates. 

A winter photo of Ginger from a few years back.

Ginger gets her daily walk by accompanying me while I photograph birds. Over the years she has learned to be quiet and patient when I stop for photos. I have never noticed Ginger being fearful of any bird. However on Thursday, with the young hawks crying all around us, Ginger came and sat down between my feet for the first time ever. Paying closer attention I noticed her tail was down and occasionally she was trembling. We headed for home, when petting and gentle talk did not help her calm down.

Ginger outweighs even the largest cooper's hawk by at least 28 pounds. We originally brought Ginger home when she was only a few weeks old so I am positive she has never had any negative interactions with any bird of prey. She has watched me photograph cooper's hawks many times without any sign of fear. The only things different about this situation were the number of birds surrounding us and the whistling, food-begging cries they were making.

Friday morning I took Ginger back to the same area. All was quiet and Ginger was perfectly happy. However, when I heard the young hawks in the distance and started walking towards them, Ginger whined and began pulling in the opposite direction. I took her home and she returned to being her happy, good-natured self. 

I was photographing the cooper's later in the morning, without Ginger, when one of my readers stopped by with her dog. The hawks were calling out nearby and when we looked her dog's tail was down in a fearful position. All of this makes me think that dogs may have an instinctual fear of the cries of juvenile cooper's hawks. 

Remembering about the study with mice, it made me wonder what is the difference between an instinctual fear and an epigenetic fear? I think of instinct as being species-wide and epigenetic knowledge as applying to direct progeny only. By definition it sounds like epigenetics qualifies as a type of instinct, but instinct may or may not be epigenetic in nature. Is it possible that species-wide instinct could simply be epigenetic knowledge that originated with the first common ancestor? 

I don't know the answer, but it will certainly be interesting once scientists can fully explain how nonverbal information is transferred between generations. The answers may even help us understand why we sometimes have irrational fears.

Of course not all fears are irrational. Later Friday, the three young hawks gathered in the branches above this squirrel. The squirrel had every reason to be afraid. It tried hiding behind this tree trunk before giving in to its trembling fear and running from tree to tree with the hawks in swift pursuit.

The most amazing thing about cooper's hawks is their ability to navigate through dense vegetation. Sometimes they fly, sometimes they hop and sometimes they walk among the branches.

It is nearly impossible to get good photos of their in-foliage maneuvers, but it is most amazing to watch. Luckily for the squirrel, the young hawks were not able to execute a coordinated attack. What they were doing was closer to competitive stalking. The squirrel's fear provided a heightened level of motivation, which no doubt helped it escape. I wonder if the squirrel knew the cooper's hawks were young and inexperienced.

Just for fun let's see if you can pick out the young and inexperienced hawk in the following photos. To increase your learning opportunity, associate each of the following descriptions with the correct photo. 

A) A juvenile cooper's hawk - roughly 2 months old

B) A young adult cooper's hawk - roughly 14 months old

C) A mature adult cooper's hawk - roughly 22 months old 

(Thank you to Martin Muller for banding this bird so we could determine its age.)

Number 1:

Number 2:

Number 3:

There are two clues in the photos that are critical to determining which description belongs with which bird. Below my name are both the clues and the answers.

Have a great day on Union Bay...where nature lives in the city!

Larry

Clues: 

The most obvious clue is the difference in colors on the chest. After roughly 18 months the birds have their mature plumage. They loose the vertical, brown, tear-drop stripes and instead gain horizontal orange bars on their chests. From this we can determine that bird #2 is the mature adult cooper's hawk.

The more subtle clue is in the iris color of each bird. As the birds mature, the iris goes from being very light in color to a pale orange and later a darker, reddish-orange color. These three photos give a clear view of the progression in color. From this we know that bird #1 is the young adult cooper's. By the way she is the same bird seen in last week's post.  Finally, bird #3 is a juvenile hawk.

Survival of the Fittest

Early Wednesday morning, a Cooper's hawk seemed to drop out of the canopy of a big-leaf maple as the sun burned through the morning mist. Fifty feet above the ground, it perched on a bare branch and calmly surveyed its domain.

Not seeing any immediate opportunities for breakfast, it focused on grooming. 

It made me wonder if this was a morning ritual, similar to washing your face and combing your hair.

The second year bird ignored the falling feather as it focused on a potential breakfast. Turning to follow its gaze, I spotted a pair of Stellar's jays as they silently worked their way through the witch-hazel. Jay's can be extremely noisy, but as a friend mentioned, whenever they are quiet there is usually a nest nearby. One jay picked a leaf off the witch-hazel bush and headed back the way it came. The other moved further away.

A moment later the second jay popped up out of the underbrush with an acorn. It perched proudly on a dead branch of a pacific madrone, no doubt enjoying the warm morning sun. I felt like the jay was teasing me, and the hawk apparently felt the same way.

One of my photographic goals is to get a beautiful photo of a bird perched in a madrone tree, but not on a dead gray branch. I would enjoy photographing a bird next to the gnarly bark at the base of one of the trees.

Even better would be a photo of a bird preening next to the smooth orange bark of one of the upper branches, especially where it peels back to reveal flashes of the lime green cambium. The icing on the photographic cake would be to have the outer edges of the photo surrounded by a rich green bokeh, in the color of the madrone leaves. Did you know that the pacific madrone is the only tree in the Pacific Northwest with evergreen leaves, instead of needles.

Obviously my personal desires meant nothing to the jay or the hawk, they were both much more appropriately interested in food and survival. As I focused on the jay, I heard a swoosh of displaced air coming from the direction of the big-leaf maple. The jay noticed the same sound and gave a loud two-part squawk as it disappeared into the undergrowth.

The hawk landed just below the jay's perch, also on the madrone, before following the jay into the bushes. A moment later the hawk flew out empty-handed and circled back the way it came. The jay survived its close encounter and the hawk went away hungry.

However, the hawk does eat. Five days earlier at the same spot I watched a hawk, which I believe is the same bird, rise up out of the underbrush with lunch.

Some of the later bites were dainty and nice...

...but an earlier photo shows a more graphic depiction of survival of the fittest.

Once it finished eating, the hawk flew to a dead branch on another madrone tree and began cleaning up. I think the birds prefer the dead branches because there are no leaves and very few twigs to obstruct their flight or their vision. It may take me awhile to get my perfect pacific madrone-bird photo.

Even though somewhat satiated... 

...the hawk remained always alert for additional opportunities.

**********************

Death may seem somewhat cruel to our civilized sensibilities, but it is nature's way of keeping a balance and evolving faster, smarter and stronger creatures. In nature, individuals die but only occasionally in unique situations do scores of complete species disappear. 

It seems ironic that our civilized society is causing the rapid extinction of multiple species. It is hard to even look at all the photos and drawings of the animal species that have been lost in the last century. If you are up for the challenge, Click Here. 

Even though the United States has been trying to address these issues for at least a hundred years, the U.S. Fish and Wildlife Service currently lists 484 animals and 725 plants that are endangered in the United States. The following piece from the British Broadcasting Company beautifully explains both the value and the wonder of saving as many species as possible. 

Saving Endangered Species

Saving the species around us may turn out to be critical for humanities future. It does make me wonder what will be the ultimate meaning of the term, Survival of the Fittest.

Have a great day on Union Bay...were nature lives in the city!

Larry

Too Close For Comfort

These young eagles have been constant companions since the second egg hatched, just over two months ago. Rain or shine, hungry or full, tired or rested they are always near each other. It must feel like the nest is shrinking, as they grow. To see how they have changed from two months ago, Click Here.

When one bird lands too close to the other you can hear their calls and almost read their thoughts, "Hey, watch it with those wings Buddy, I'm right here! Didn't you see me?"


During this growth phase, their greatest danger may actually have been from one another. Even if not intentional, an accidental wing stroke could easily send one of them over the side of the nest. Their constant awareness of each other may well be rooted in self-preservation. 

The second sibling seems to reply, "I barely brushed you. What's your problem?"

Then like a flash their anger seems to pass.

Still their youth, hormones and nature are driving them to spread their wings. They are often bouncing from branch to branch. As a matter of fact, this behavior is commonly called "Branching". 

When one bird takes to the air, the other ducks its head and spreads its wings, just in case.

For a moment, it looks like they will ignore each other...

…as the active eagle returns to its starting location. 

Then the whole process begins again. This time the eagle on the left feels the need for closer companionship.

As it approaches, the eagle on the right watches apprehensively.

The first bird on the branch seems to say, "Careful now! This branch may not hold us both."

Just like siblings, the whole world over, they are constantly on each other's mind and in each other's face. 

On Thursday, I watched as one of the young eagles landed on a branch, which broke. The branch was not above the nest. As the fledgling took to the air with the greatest of ease, my fears were relieved. It was the first time I had seen one leave the tree. It simply circled around and returned to opposite side of the nest. 

It was airborne for three or four seconds at most. When it landed, its sibling was all over it. It seemed to say, " Hey! You flew! And then you returned to the nest, just like the parents. They usually bring food. Did you bring me anything? Huh? Huh? Did you?"

As a parent it is easy to see the similarities between the young eagles and our own children when they were young. Lately, I have been reading how scientists are learning that all life on earth has shared genetic code. When you see the common behaviors of our young the shared DNA seems obvious.

At this point the fledglings are not quite ready to leave the tree, voluntarily. Any day now they will take to the air and leave their confinement behind. After which, they will never again have to be too close for comfort.

****************

This week I was saddened to learn that some of our leaders in Washington, D.C. think we should no longer enforce the protections offered by the Migratory Bird Treaty Act. The amendment to remove funding for the MBTA is through the House and on the way to the Senate. Audubon states, "If this amendment had been in effect when the 2010 Deepwater Horizon blowout occurred, BP would not have been subject to prosecution for the killing of millions of birds."

To learn more, and use Audubon's easy semi-automated process to oppose the change:

Click Here!

Thank you and have a great day of Union Bay…where young eagles grow up together!

Larry

PS: Just in case you need a little extra motivation, to oppose the MBTA amendment, here is a sample of stories about just a few of the migratory birds that visit Union Bay each year.

• Sapsuckers
• Osprey
• Western Tanagers

It Takes A Village

Bushtits are smaller than pine cones and lay eggs about the size of acorns. If your knowledge of bird nests was limited to robins and hummingbirds, you might reasonably assume that bushtits build a cup-shaped nest, two or three inches in diameter, but this is not the case.

Bushtits are not satisfied with the most common nest design or an average construction process. Plus, once the nest is complete it is not used by just one parent at a time. The whole family may sleep in the nest while the eggs are being incubated, per All About Birds.

The male, with solid dark eyes, weaves dried grass, twigs and other plant matter into the initial framework of the nest.

The female, with yellow irises, watches. Spider's silk provides additional strength and flexibility. A completed the nest will be three or four times longer than what we see here.

Unlike most birds, it is not just the male, or even just the mated pair that build the nest. At least three different bushtits were involved in this Foster Island nest building operation. A third bird is visible, though out of focus, in the lower right.

Sadly, when I returned to check on the progress of this particular nest, it was gone. I suspect one of the supporting branches fell and the construction crew relocated to a more stable job site.

Luckily, one month later, I happened upon a completed nest while taking a class at the University of Washington. Along with dried grass, spider's silk and twigs, a large quantity of moss was also incorporated into the nest. 

While I watched, an adult bird flew to an overhead branch and seized a mouthful of moss. Pull as it might the moss would not come loose. Finally, using all of its weight and beating the air with both wings the little bird pulled the moss free, and carried it back to the nest.

The completed nest was essentially a woven bag with an entry port near the top. Relative to the size of the birds the nest is huge. Bushtits are only about 3 inches in length, while the nest was nearly a foot long, and towards the bottom, nearly five inches in diameter. The extra space helps accommodate the family and friends who participate with the nesting process.

Both male…

...and female birds were seen coming and going from the nest. Birds of North America Online provides information from Sarah A. Sloane* which says, "Flocks of 10-40 individuals can have many simultaneous nests, each attended by 2-6 individuals." The ability of bushtits to work in groups to build nests, incubate the young and to live peacefully is truly impressive. 

It is interesting to compare the bushtit reproductive process with an Anna's hummingbird. Both types of birds weigh about the same, but their approach to nesting and incubation is totally different. The female hummingbird builds the nest, incubates the eggs and then feeds the young virtually alone, while the female bushtit may be one of a half dozen birds carrying out the same activities. 

We can see the result of the different approaches in their average clutch sizes. Anna's hummingbirds generally have only two eggs in a clutch, while All About Birds says that bushtits have from four to ten eggs in a clutch, which implies an average of seven. Evidently, many beaks makes the work light.

With bushtits, it take a village to raise their young, plus a crew of engineers to build their nests.

Have a great day on Union Bay…were bushtits nest in the city!

Larry

PS: You can see more about the socially advanced bushtits in the Feb. post, Sex in The City. 

* Sloane, Sarah A. 2001. Bushtit (Psaltriparus minimus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:http://bna.birds.cornell.edu/bna/species/598

doi:10.2173/bna.598