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!)

“Wattle” I do to get a better photo of you?

In mid-August 2019, it was my privilege and good fortune to participate in an interesting, engaging and VERY fun “Birding Plus” tour in Costa Rica thanks to a great roommate, Nan, knowledgeable guide and tour organizer, Steve and Sherry, and group of fellow travelers (Ann, Art, Bill, Gordon, Len, Tom and Ylva). My next blogs will mostly focus on the birds, amphibians, mammals and insects we were fortunate to see there. The photos are not all great as taking shots in the rain and dark cloud/rain forests was challenging for multiple reasons. But they will give you an idea of the fascinating and beautiful sightings we had. (Clicking on photos enlarges them; then back arrow.)

One of the most difficult birds to “capture” in a good photo was likely the one about which I was most excited, the three-wattled bellbird (Procnias tricarunculatus). This species, which also lives in Honduras, Nicaragua and Panama, only breeds in the mountains of Costa Rica. These bellbirds are known to be shy, secretive and elusive as they remain mostly in the dense, high canopies of the forests. They apparently prefer to perch on uncluttered branches that are 33-72 ft (10-22 m) high and 0.98-2 in (25-50 mm) in diameter.

The males usually sing from March through June, so we were lucky that some of them were calling out in mid-August. Here we see a couple digiscoped photos of a male bird. The females look very different with olive coloring and a streaky yellow breast (we did not see a female). They are quite different in size, with males in one study having a mean wing length of 6.5 in (165.5 mm) compared to 5.7 in (145.1 mm) for the females.

 

 

The common name for these birds comes from the sound they make. In some articles, it is described as a 3-part song. To me, it sounded like they first made a high-pitched brief screech, squeak or whistle sound and then a deeper call.

 

Others have described their calls/songs as a “boink,” “bonk” or “Hee-aahh” sound. In any event, they obviously work at producing the sound. As we watched, “our” bird would open his mouth very wide, so that you could see the white and black lines surrounding the bill.

He seemed to be breathing in plenty of air as he sat there silently for a while. You could see his neck getting ridges, which I assumed was due to the oxygen he was gathering and holding to be expelled in the call. (This turned out to be a correct assumption according to one study!)

Then, he moved his head up and down a bit and you knew the sound was coming. It is unmistakable once you have heard it as in this brief video that fellow traveler Ylva made.

It is said that the bellbird’s sound is one of the loudest avian calls, audible to humans who are more than 0.5 miles (0.80 km) away. The calls and songs are not instinctive – the birds learn the calls and there are different “dialects” among the birds from different areas! One bird studied in Costa Rica could perform the song/call repertoires of Talamanca and Monteverde – in other words, he was bilingual!

 

Research has also shown that immature male bellbirds not only take 6 years to achieve their full adult plumage but also to perfect their entire song repertoire! Kroodsma et al. also note that: “Males appear to be highly attentive to the nuances of songs produced by their competitors, as both immatures and adults visit each others’ display perches, listening there for up to several minutes at a time.”

The other really striking characteristic of this species is the three wattles on the male’s head which begin growing when he is 6-12 months of age. One dangles from each side of the bird’s mouth and one is affixed to the base of the upper bill.

The wattles have been described as “wormlike”. Nan and I thought they looked a bit like hair-braids and on the flight home I sat next to a woman who had three braids ending in a point with interwoven gold thread that immediately made me want to give her the nickname “Bellbird”. (I didn’t tell her that though.)

The wattles are about one-third of the bird’s size (9.5-12 in or 25-30 cm). They cannot be controlled by muscles or made rigid, but they can be extended in length up to 3.9 in (10 cm) when the bird is interacting with others or singing.

The birds are frugivorous (eat only fruit) and prefer wild avocados (Lauraceae). They play an important role in the tree’s seed dispersal.

 

Due to habitat loss and hunting, the numbers of the three-wattled bellbird have declined to about 20,000 individuals and the International Union for Conservation of Nature (IUCN) has declared its conservation status to be vulnerable. They obviously inspire artists in Costa Rica, however, as witnessed by a mural at a restaurant where we stopped for lunch.

 

 

After three blogs in quick succession, I’ll now take a break to process and sort some more photos from Costa Rica to share with you. In the meantime, bye bye from the bellbird!

Further information

Summer hummers – entertainment for free: part 2

In my yard this summer, the ruby-throated hummingbirds (Archilochus colubris) came late to the feeders (similarly to what other people in the area had reported). Now, there are at least four vying for the four feeders, claiming territory for their own.

 

 

One bird in particular is most likely to be seen enjoying the garden flowers, including blue-black sage (Salvia guaranitica) and hot lips salvia (Salvia microphylla ‘Hot Lips’). In the first two photos below, you can see as his throat starts to bulge more as he sucks up the sweet nectar to complement his mostly insectivorous diet.

 

 

The airborne nectar droplets indicate that sometimes this hummer is a messy eater — or must leave quickly as another hummer is almost literally on its tail.

A couple of the birds spend a lot of time near the nectar feeders, perching close by to chase off anyone who comes near.

 

 

 

They each have favorite perching spots from which they can observe if an “intruder” is coming near the feeder they have claimed.

 

 

Sometimes, they fly up to a higher perch so they can see both the front and back yards – a necessary vantage point if they want to keep an eye on where everyone is.

 

Most ruby-throats have 940 feathers, all of which are replaced each year. As they take little rests, they stretch their feathers and may also groom them.

When a rival approaches, they spread their rectrices (tail feathers) – both when sitting and in the air.

 

Their feathers are beautifully arranged, looking like scalloped decorations.

 

They make frequent trips to the feeders and then occasionally “air out” their tongues.

 

The bill of the ruby-throated hummingbird is one of its most distinctive features. It measures about 0.59-0.79 in (15-20 mm) in length and is said to open no more than about 0.39 in (1 cm wide) at the tip. The hummers in my yard seem to be able to open their mouths to varying extents, however. They consume nectar by extending and contracting their tongues up to 13 times per second.

 

 

 

A quick, only few-second nap is also a frequent behavior. The hummers are almost constantly at the feeders and thus bulking up for their long migration, but they also expend considerable energy chasing one another away from feeders and flowers!

 

 

 

The hummers are not fazed by weather, zipping around rain or shine. Putting on weight and strength for their autumn migration down south is important for survival!

These minute marvels are such a pleasure to watch; I will certainly miss them when they begin their journeys to their wintering grounds.

 

Summer hummers – entertainment for free: part 1

 

When a hummingbird other than a ruby-throated hummingbird (Archilochus colubris) is seen in the Triangle area of North Carolina, it is listed as a rare bird on the Cornell Lab of Ornithology listserv. One year, I did have a chance to see a buff-bellied hummer visiting in a nearby town though; another year a rufous hummer frequented my own feeders in the winter. Mostly, however, it is the ruby-throats who take up residence at my address, which is just fine as these feisty tiny birds provide loads of entertainment.

 

During a trip to Quebec earlier this year, we also saw ruby-throated hummingbirds there – early arrivals during the spring migration.

 

A few years ago, one of my blogs focused on their preening and cleaning, so this time I’ll mostly feature some of my favorite photos of them taken this summer in various places. (When looking through the shots, I had a LOT I liked, so this is now going to be a 2-part blog!)

At Sandy Creek Park in Durham, one female hummer had made a coral honeysuckle (Lonicera sempervirens) one of her preferred dining spots.

 

 

A butterfly garden featuring blue-black sage (Salvia guaranitica) and bee balm (Monarda) also attracted her and some other hummers.

 

One female found the bee balm to be a good place to rest, understandable since these bundles of energy have a high metabolic rate. Their hearts beat up 1260 times per minute and they take about 250 breaths per minute even when they are resting! Taking a few sips while remaining perched has to be a welcome luxury.

 

 

 

 

The hummers’ main wing bone, the humerus, is adapted to hovering flight and they have very large deltoid pectoral muscles relative to their size.

 

 

Male birds produce sperm that flows through the vas deferens (sperm duct) to the cloaca. When they mate with a female, they transfer sperm by touching the tip of their cloaca to that of the female; they do not have a penis. Females only have a functional left ovary; the right one atrophies early in her development, which allows her to avoid the extra weight of a second ovary and makes her lighter for long migratory flights.

One big treat for me this year was finding two ruby-throated hummingbird females tending a nest, the first time I had been able to spot this.

 

Later, I was able to take a quick photo of one female collecting cattail fluff with which to line her nest.

Even when several ruby-throats are frequenting an area, the (temporary) coloring of their feathers can help distinguish them. This young male had a few olive-green dots under his eye and a bit of white on the crown of his head.

 

A somewhat more mature male has a little white patch behind his red gorget.

 

They are all little beauties! Second part of this blog is coming up and then on to Costa Rica!

Moth marvels

Some of the large moths, like the polyphemus (Antheraea polyphemus) and cecropia (Hyalophora cecropia, below) moths, definitely rival butterflies in their beauty and splendor. Before launching into a series on some Central American wildlife, I thought I’d share a couple recent moth-related spottings that I had.

The luna moth (Actias luna) is a large lepidopteran that entrances people and I recently saw one along a path in the Mason Farm Biological Reserve. Unfortunately, the insect had died but the cause was not apparent. Perhaps it was a parasitic fly that was originally introduced to help control invasive gypsy moths or perhaps it had simply reached the end of its life span.

This past year, I was fortunate enough to see the cocoons of both the polyphemus (left) and cecropia moths but I had not seen the large caterpillars associated with some large moths.

 

Then, just a few days before departing for a trip to Costa Rica, it was my good fortune to visit a garden that had two species of large hornworms. The tobacco hornworm is the immature form of the Carolina sphinx moth (also known as the tobacco hawkmoth; Manduca sexta). The tomato hornworm, the caterpillar of the brown and gray five-spotted hawkmoth (Manduca quinquemaculata) looks very similar except that it has a black or dark blue horn instead of the orange one sported by the tobacco hornworm.

The tomato hornworm is distinguished by v-shaped marks (right) while the tobacco hornworm has beautiful black-bordered straight white lines on its body. I find both species attractive but particularly like the tobacco hornworm caterpillars.

                    

They are so cute with their rounded heads and little suction-cup-like feet.

Both species of caterpillar can be found on either tomato or tobacco plants as they consume the foliage of various plants in the nightshade family. The presence of frass (insect larvae poop) alerts you to which plants may be hosting the hornworms.

These moth species originated in Central America and are now considered by some people to be garden pests, especially when they eat tomatoes. It seems that planting marigolds next to the fruit can repel the caterpillars, who eventually pupate and then overwinter underground where they have fallen off plants.

 

There are parasitic wasps that also prey on the hornworms. One species attacks the tiny hornworm eggs, which are laid on leaves; another wasp lays its eggs in the body of the caterpillars.

 

The Kingsolver Lab at the University of North Carolina (UNC) is researching the hornworms among other insects, examining how environmental changes caused by humans (agro-ecosystems, introduction of invasive species, climate change) are evoking responses in the caterpillars. It was a treat to see lots of these caterpillars at different stages of their development.

                

Next up: a blog on one bird species I’ve watched frequently this summer in NC and then a virtual trip to Costa Rica. 🙂