The Northern mockingbird boundary dance

In between searching the web and bird guides for plant and other IDs for my (long-time coming, I know!) next Costa Rica blogs, I’ve taken time for nature walks so that I can continue to see lovely wildlife and plants here in my home area. A recent discovery came up unexpectedly when I was with a couple friends looking for migrating warblers at a local lake.

Previously, I’ve written about how Northern mockingbirds (Mimus polyglottos) engage in wing-flashing behavior, which scientists continue to study in an effort to pinpoint its various functions. I’ve seen the wing-flashing every year since I began watching the mockingbirds, but a few days ago I saw a pair of mockers exhibiting a different type of behavior that was very interesting to watch. (If you click on a photo, you can see it larger.)

The two birds landed on a section of parking lot and proceeded to face off against one another.

They slowly drew closer.

Then they stretched to stand very erect.

 

They confronted each other face to face.

 A little hop by one or the other followed. A shifting from side to side ensued.

Occasionally, they flew up with flapping wings to confront one another in the air (I tried to video this but obviously don’t know yet how to take proper videos with my new camera). According to research, they might actually have an airborne physical tussle but that didn’t really happen with this pair.

So why do the mockingbirds do this? These displays are called boundary dances, where male birds go to the edge of the territory they claim to ensure that another male does not encroach on their domain.

After several confrontations, this pair eventually decided that they had made their point. It has been reported that they stop when one dominates but these males seemed evenly matched. Or perhaps they were not feeling very aggressive. Each one flew off and presumably they settled in to patrol the areas that they had claimed as their own. It was nice that there was a peaceful end to the show of masculine bravado!

Going out in nature is such a delight – you never know when you will discover something new (at least to yourself!)

The gorgeous grebes when aggrieved and grumpy!

During my great-crested grebe (Podiceps cristatus) observations at the Gouwzee in July 2018, it became apparent that they don’t mind swimming about amid groups of Eurasian coots (Fulica atra).

It turned out, however, that the grebes can also be quite aggressive and one morning these birds treated me to a stunning display as they had six years earlier. This time it was not a peaceful event like their mating dance, however, but apparently a territorial dispute. Two pairs were each tending a young one near reeds in a cove on the Gouwzee side of a dike. It appeared that one adult had ventured into space that the other pair considered their own. An epic battle ensued – I wish I’d had the presence of mind to change my camera settings to get better photos, but it was so sudden and exciting that I was just glad to be able to get some shots. The whole dispute only lasted about three minutes but seemed to last much longer!

References I found in the literature online appear to indicate that researchers believe territorial aggression mostly takes place when the grebes are building nests and tending eggs. They mention that it stops once the young are born. This was obviously not the case for the two pairs that I observed; their young appeared to be several weeks past fledging age.

The birds first caught my eye when they faced one another, lying low in the water. This is said to be a common aggressive posture.

Suddenly, they erupted upwards, calling loudly and flapping their wings strongly to intimidate one another. (You can see larger versions of photos by clicking on them.)

  

 

   

 

A couple times, they surged upwards from the water to clash their chests together.

   

One appeared to have dunked his opponent in the water, although this happened so quickly that I didn’t really see how it occurred.

They would take a few second pause, making their mutual displeasure apparent.

This would be followed by another bout of confrontation. At one point, one grebe’s mate and young one swam closer to the action.

Finally, after a couple minutes, one “combatant” was driven off by his opponent.

He was joined by his mate and offspring and peace returned. And I walked away elated at having witnessed the behavioral exhibition, glad that no injuries had been sustained. 😊