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!)

Growing up barred – Part 3: Strife and affection

In the nest, baby barred owls (Strix varia) are vulnerable to predators including hawks, weasels, raccoons and other owls. When they are out on their own and already able to fly, they eventually have less to fear. Their main predator becomes the one owl larger than they are in North Carolina, the great horned owl.

As pointed out in the previous blog, however, they can be fearsome predators to many other species of animals including songbirds, woodpeckers and other avian species. On a few occasions, I noticed the young owls at the Mason Farm Biological Reserve gazing about with expressions that seemed to express wonder and confusion.

It turned out that they were being dive-bombed by members of a very small bird species, the blue-gray gnatcatchers (Polioptila caerulea). The owlets seemed to have no interest in pursuing the gnatcatchers, but they were perching in areas where the small birds had had their nests so the little gnatcatchers did their best to drive the owls away.

  

One day, they succeeded. The owls flew to the other side of a path through a bog. One landed on a branch right over my head and looked down at me with what I imagined was an expression of “Hey, what did I do???”

The young owls were very affectionate with one another. They often perched next to or near one another.

 

They often sat close together, expressing what looked to me like affection.

 

 

When they were apart, they would vocalize. It would have been cool to be privy to the meaning of their communications.

 

The young birds seemed to enjoy nuzzling and grooming each other.

 

  

When I stopped seeing the young owls in their usual haunts, I figured the time had come for them to separate and seek out a mate and new territory. Mated owls usually establish nests about 400 yards away from other barred owls although some nests have been observed as close as 100 to 200 yards apart. The young owls may not have flown very far away but they did need to leave their parents’ area. I hope they made it and was happy to have had the opportunity to watch them mature. My next goal for owls – to see a species in the wild that I have not yet seen (e.g., great grey owl, screech owl, barn owl, etc.). I hope you, too, have the chance to see members of this avian group up close!

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. 😊

 

Gracious and gorgeous grebes nurturing newborns

After birding now for some six or seven years, I’ve come to appreciate all birds since each species can be fascinating to watch. I do have some favorites though that have captured my interest. In 2012, I fell in love with great-crested grebes (Podiceps cristatus), whom I first noticed during a trip to Switzerland. A pair was engaged in their courtship dance, which was simply delightful to see. They circled one another, stretched out their necks, ruffled their feathers and arose on the water facing one another. Their beauty enchanted me, and I felt that I had witnessed something very special.

The rust and black-tinted head plumes and ruff are gorgeous, making these birds very attractive indeed. This led to their being hunted almost to extinction during the 1800s in the United Kingdom because the feathers were desired as decorations or hats. This led to the establishment of the Royal Society for the Protection of Birds in that country and their numbers fortunately rebounded.

Fast forward six years to this past July, and I discovered that these birds are quite common in my land of birth, where I just had not noticed them before. Granted, I was not a birder while living in The Netherlands (I currently live in the USA), but I had managed to take note of house sparrows, mute swans, Eurasian coots and moorhens when walking along canals and ditches. Now, as a much more observant wildlife observer, it was thrilling to see many grebes along the dike bordering the Gouwzee (a body of water bordering Monnickendam that is part of the larger Markermeer nature area). And even better – they were all tending young ones at different stages of development.

The great-crested is Europe’s largest grebe species and the adults are stunning with their reddish-orange head plumes. (They are also found in Australia, New Zealand and African countries.) I discovered that the young look quite different – mostly light in color with black stripes on their heads and pink markings near the eyes.

Their floating nests are often found along reed beds, which were abundant along the dike and a ditch across a road from the dike. A couple mothers had chosen the ditch as their home area and the early morning light made for some nice photos in my opinion as they preened and relaxed.

  

   

The water in the lake on the other side of the dike was less calm but the young ones managed to swim well in the waves; they can already dive shortly after leaving the nest.

Their feet are set back far along their bodies and they cannot walk well. I did not ever see one on land during the week that I was observing them.

According to the literature, pairs tend 1-9 eggs, which hatch after about 27-29 days. The mothers carry newborns on their backs as they swim along, offering a safe perch for sightseeing in safety. The babies fledge after 71-79 days. I did not see any pairs with more than two young, so some were probably lost during the previous weeks.

The grebes eat fish, crustaceans, mollusks, amphibians and insects. Their fishing technique, which was more in evidence in the open water of the Gouwzee, includes skimming the water with outstretched necks and diving underwater. (The neck-to-the-water pose is also used to show aggression but in these cases no other birds were near and they would subsequently dive under to come up with some food.)

The parents demonstrate and the young imitate them, mostly coming up empty-beaked. Occasionally, a parent would fly away and return later with food. The babies eagerly grab the meals offered by both mama and papa.

After breeding, the adults gather together during a molting period, during which they do not fly. Perhaps one day, I’ll be able to watch them in winter and find out new things about them. In the meantime, if you’d like see what happens when they are feeling perturbed, check out my next blog on “The gorgeous grebes when aggrieved and grumpy!”

My hummer summer, part 1 – guarding the home front!

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Just like human beings, some birds like to hang out in groups, while others are more solitary in nature, coming together mainly to reproduce. A prime example of the latter group are the ruby-throated hummingbirds (Archilochus colubris).

 

 

ruby-throated-hummingbird-i77a7336-maria-de-bruyn-res2This past summer, some health and other problems led to my spending a good deal of time at home. The upside was that being a bit home-bound gave me plenty of opportunities to observe the comings and goings of these gorgeous little flyers and to learn more about their behavior towards one another.

I had at least four ruby-throats – and probably more as I couldn’t distinguish them all – visiting my feeders and yard regularly. A couple had a distinctive trait that helped me identify them, like some white feathers on top of their heads or at the bottom part of their gorgets.

ruby-throated-hummingbird-i77a1237-maria-de-bruyn-res   ruby-throated-hummingbird-i77a9185-maria-de-bruyn-res

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I usually had three or four nectar feeders up in my back yard and two in my front yard. In addition, as the summer progressed, the gardens were filled with increasing numbers of nectar-filled flowers so my home site was a fairly well-stocked larder for them.

The ruby-throats are among the more competitive hummingbirds and don’t really like to share their feeding space with others, although a friend and I visited a birder in a nearby town who had more than a dozen feeders up and many dozens of hummers visiting his back yard every day, feeding right next to one another. At my house, I suppose guarding their food source is an instinctual imperative, since they do consume half their own weight in nectar each day.

ruby-throated-hummingbird-i77a0514-maria-de-bruyn-res

ruby-throated-hummingbird-i77a8255-maria-de-bruyn-resThe tiny birds were quite intent on protecting their territory from intruders. Only thing was, several of them considered my feeders THEIR territory, so there was a continual rotation of birds perched in nearby trees and shrubs to watch for “invaders”. Once spotted, the newly arrived hummers would have the current “resident” bird swoop down on them (at up to 60 miles per hour!), frequently chittering like mad as a warning to “get out of here.”

Sometimes, they would have a little “challenge flight ballet” as they confronted one another, until one gave up and flew off – sometimes across the street, sometimes to the yard on the other side of the house, and sometimes to a nearby tree or shrub at the side of the house.

ruby-throated-hummingbird-i77a8257-maria-de-bruyn-res   ruby-throated-hummingbird-i77a8256-maria-de-bruyn-res

ruby-throated-hummingbird-i77a9443-maria-de-bruyn-resThere was one particular male hummer who seemed particularly aggressive – or perhaps possessive is a better term as I never saw him body slam a rival; he just made sure that the other bird would leave. I recognized him as he often chose exactly the same spots on a nearby Rose of Sharon, a willow oak and a cedar as his watching posts,

Some of those who were run off didn’t travel far, however. They would fly to a nearby tree or shrub and wait to see if Hummer No. 1 would leave.

ruby-throated-hummingbird-i77a0290-maria-de-bruyn-res       ruby-throated-hummingbird-i77a1099-maria-de-bruyn-res

ruby-throated-hummingbird-i77a5725-maria-de-bruyn-resScientists have determined that the brain section responsible for memory and learning – the hippocampus – is five times larger in hummingbirds than in woodpeckers, seabirds and songbirds. They memorize where feeders and nectar flowers are and can remember when they last fed there. They can even estimate how long it will take each flower to fill up with nectar again.

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The hummers’ memory is long-term, too – they recall not only where feeders are placed in their breeding territories but also in places along their yearly migration routes! Wouldn’t it be nice if we had such great memories making GPS and maps less of a necessity?

 

 

 

ruby-throated-hummingbird-i77a7716-maria-de-bruyn-resAnother behavior I observed several times was a hummer hovering in front of me, especially when the nectar feeders were getting low. Scientists have determined that they can recognize the people who replenish their food sources, which makes for a delightful encounter as one chirps at you while suspended in front of your face with its wings flapping at 60 beats per second!

While guarding their home turf, they may stick out their tongues briefly after feeding.

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However, if you see one with its tongue stuck out permanently, this can be a sign of a fungal infection (often acquired from dirty feeders). Their tongues swell with the infection and they can no longer drink with these anatomical, elastic micro-pumps.

 

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Often death ensues, so it’s important to keep the nectar feeders clean!

 

 

 

Coming up in part 2: the beauty of the hummingbirds at rest and in flight