Wednesday, November 18, 2020

All About American Bitterns


Here is a recent post from the Union Bay Watch Blog published by Larry Hubbell, long-time local photographer and birder.

Masters of Camouflage

Last weekend was only the third time in nine years that I have seen an American Bittern on Union Bay. All three sightings have been along the shore and within a one hundred yard radius. Each of the bitterns walked in and out of the cattails while inspecting the shallow water along the shore for prey.

Curiously, I have been in my kayak each time I saw one of the Bitterns. Being close to their preferred habitat may have improved my odds of noticing them. On each occasion, I have watched them hunt. Sadly, during the two previous encounters, I did not see them catch anything. 

All three of the Bitterns were immature. Each bird lacked the black patch on the neck that would indicate maturity (Click Here to see an example). Since Bitterns are immature for only a small portion of their lives, I must have seen three different individuals. All three sightings were in the Fall. Most likely when they were each migrating towards Winter warmth.

This time, out of the corner of my eye, all I saw was a brief flash of movement. I had no clue what creature caused the motion. When I looked closer all I saw was the cattails slowly shaking to a stop.

According to the current range maps in "All About Birds" (and "Birds of the World") Bitterns apparently no longer nest west of the Cascades. In my previous Bittern post, I explained that 70 years ago Bitterns were known to nest on Union Bay. (Click Here to read the story.) They are currently shown as nesting in the northern half of the US and the southern half of Canada from the Cascades all the way east to the Atlantic Ocean. 

They are widespread. However, they only nest in and around wetlands - areas which we, humans, tend to drain and develop. Like many other birds, their numbers are declining. But they are so good at hiding it is hard to notice their shrinking population. 

The American Bitterns are so secretive that in Birds of the World, where they normally relate what a species natal down looks like, it simply says, "Undescribed." We still have a lot to learn about these incredibly specialized and secretive creatures.

This photo focuses on the vegetation in the foreground, instead of the bird. I believe this is what our eyes tend to see when we are searching the shore for birds. Because I was in the kayak and using a telephoto lens this photo might even feel a bit closer to the bird than if we were using binoculars from a more distant location.

Now, the focus has shifted from the foliage to the Bittern. Don't be discouraged if you still cannot see it. Even immature Bitterns are masters of camouflage and concealment.

Finally, here is the same photo cropped and enlarged.  Even though the Bittern nearly fills the screen, it is not exactly easy to see. I suspect that we have American Bitterns passing through Union Bay every Autumn, often without being noticed at all. I wonder if some might even spend their winters here?

Skipping ahead, here is another classic American Bittern camouflage pose. In this case, the stripes on the long thin neck line-up with the vertical vegetation and help to hide the bird. 

Notice how the Bittern holds its bill up out of the way and peers around its 'chin' or neck. 

Luckily, there were moments when the Bittern stood tall and backlit by the brilliant sunlight.

I am always amazed by how the neck can shrink. The Bittern is returning to the hunt.

With a somber and stately stride, it proceeded along the dark bank of the shore.

Momentarily, it raised its head. Once again it is peering around its 'chin'. Evidently, this odd position enlarges its field of vision - at least in the area where it is hunting

I waited. Patiently hoping, that I might see it catch something to eat.

After the venture along the shore, the Bittern turned back towards the area it had previously hunted.

With a sudden extension of its neck, it snagged a pollywog i.e. a young bullfrog destined to never reach maturity.

A little mashing and thrashing turned the tadpole into a mid-day meal.

An American Bittern's long neck makes swallowing its prey a bit of a challenge. The food had a long way to go. I am a bit surprised that the bird did not extend its neck up into the air to get a little extra help from gravity.

Unlike with humans, for a Bittern swallowing can be a multi-step process.

It took at least a half-a-dozen repeats of the swallowing effort to transport lunch from the upper end of the throat to its digestive destination.

Afterward, the Bittern turned and headed back towards its original location.

It stopped along the way. It was clearly enthralled with something. However, no matter how hard I tried, I could not see what it was looking at.

I suspect a small insect because of the way the Bittern slowly raised its head while maintaining its laser-like focus.

I never did spot the insect. However, watching the full extension of the Bittern's neck was a perfectly adequate reward for my efforts.

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