Tag Archives: mixed-species flocks

Arenal for Antbirds: Birding Costa Rica, Part 2

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After our surprising morning birding near San Jose’s Juan Santamaría International Airport (see our previous post), Braden and I wasted no time heading into the heart of the region where we would spend the next nine days—the northern Caribbean slope of Costa Rica. Our first destination? The flanks of Arenal Volcano.

Despite having spent more than two months in Costa Rica back in 1994 (when I was writing my books The Forest in the Clouds and Monteverde: Science and Scientists in a Costa Rican Cloud Forest), I had never before explored this region. During his semester abroad here, however, Braden had thoroughly scoured the country for birds and had put together an itinerary that would give us the most bang for our birding buck. The Arenal area—near the bustling tourist town of La Fortuna—held many avian riches, but Braden and I had one group of birds we especially wanted to see: antbirds.

**The area around Arenal Volcano was the first major destination of our nine-day itinerary. Unfortunately, heavy rains greeted us during this supposed dry season!**

If you’re unfamiliar with them, antbirds are a group of birds that shadow army ant swarms—not to eat them, but to snag the many other invertebrates that the swarms dislodge during their ravenous raiding parties. I had seen many ant swarms during my time in Costa Rica, but again (and tragically), that was before I became a birder and if any antbirds were around, I had cluelessly overlooked them. Braden had, of course, been more alert and seen several kinds of antbirds—but never in the classic “insect-palooza” situation one reads about in scientific narratives.

**Braden and I looked forward to finding an antbird flock as much as any other birds on our trip. Note the army ants below the leaf upon which this Bicolored Antbird stands.**

We got our first shot at antbirds on our second morning in the country when we birded the internationally famous Arenal Observatory Lodge & Trails, a rather pricey destination with a fabulous sweep of nature to offer visitors. Fortunately, you don’t have to book a room to bird the place, but can simply pay a fee to spend the day. Unfortunately, waves of heavy rain greeted Braden and me when we arrived. Don’t get me wrong. We still had an incredible day here, including bird lists totaling more than 100 species and a fantastic sighting of a northern tamandua, a small, incredibly shy species of anteater—a first for both of us. Alas, we got only a brief glimpse of a single antbird—a Spotted Antbird—and encountered no army ant swarms where more antbirds might be plying their trade.

**On our first day of antbird searching, we saw only a single Spotted Antbird that didn’t happen to be following any army ants. Still, a gorgeous creature, verdad?** **(Note: the featured image at the beginning of this post shows a female Spotted Antbird!)**

Still hopeful, the next morning we headed to another nearby spot, a combo nature area and zip-lining destination called Sky Adventures. And guess what? It was again pouring down rain! After spending the previous day pretty much soaked, neither of us looked forward to another day of damp garments and soggy boots. A ray of hope was that one of the Sky Adventures guides told us that he had seen antbirds only the day before and even told us where to look.

**Braden wondered if he would see any life birds on this Costa Rican adventures, but quickly spotted this Black-headed Tody-flycatcher, the first of FOUR lifers he would collect this day!**

In this kind of weather, we had the trails pretty much to ourselves, and we realized that there was no shortage of birds around us. I should backtrack a bit and explain that while more than a third of the Costa Rican birds I was seeing were lifers, Braden had already seen so many birds in the country that he wondered if he’d get any lifers on our entire trip. That question got answered pretty quickly as we began crossing a spectacular hanging bridge over a lush ravine. Almost immediately, Braden said, “Black-headed Tody-Flycatcher!” Sure enough, on a branch hanging over the bridge, we spotted one of the cutest birds in the tropics—and a lifer for both of us! In fact, a huge variety of amazing birds seemed to be hanging out around the bridge, and before long a yellow and black bird landed just below us. Braden got even more excited by this one. “Black-thighed Grosbeak!” he exclaimed. Ka-ching! His second lifer in ten minutes!

Braden’s second life bird of the day, a Black-thighed Grosbeak, put in a leisurely appearance just below the hanging bridge. Look closely and you can even see the black thighs—though this is still one of the worst bird names ever!

Still, we hadn’t forgotten the antbirds and pressed across the bridge and up a winding trail. And at a sharp left, suddenly, there they were. Antbirds!

I confess that it took both of us a few minutes to embrace exactly what we were looking at. Columns of army ants marched along both sides of the trail, and the antbirds skittered and skaddled all about us.

**Braden, looking happily in shock at finding his best antbird mixed-flock ever!**

According to Vallely’s and Dyer’s Birds of Central America, Costa Rica hosts nine species of antbirds and we recognized four working the ant columns around us. These included Bicolored, Spotted, and Zelodon’s. It also included the one we both most wanted to see. “I’ve got an Ocellated!” Braden shouted with glee—his third lifer of the day.

**One of our top targets of our entire trip, Ocellated Antbirds gave us extensive, if very quick, looks for our full ant swarm visit.**

Why were we so excited about this bird? All antbirds are subtly beautiful, but Ocellated has the most distinct patterns of any Costa Rican species. It sports gorgeous blue, black, and rufous colors around the face and eye, and a remarkable scalloped pattern of feathers down its back and chest. As thrilled as we were to find it, we were even more thrilled to watch what the antbirds were doing.

**Only a single female Zeladon’s Antbird joined the ant swarm, and apparently these do not usually follow mixed flocks, and are not obligate ant swarm feeders. Males are black instead of brown.**

Back and forth they darted snagging insects, spiders, and other arthropods that were startled by or fleeing from the army ants. Braden and I paced back and forth, mesmerized by this performance. At least fifteen or twenty antbirds surrounded us, the most abundant being the Bicolored, who were also the least shy. WATCH THE VIDEO BELOW!

Antbirds, though, aren’t the only birds that join in on following army ant columns. As we watched, we also saw Wedge-billed Woodcreepers, Northern Barred-Woodcreepers, and Fawn-throated Foliage Gleaners. As a bonus, the rain had let up by now, letting us fully enjoy what might be for me a once-in-a-lifetime spectacle. In fact, we spent at least half an hour with these remarkable birds, trying to grasp exactly what they were doing and just appreciating that things like this could still happen in the world. Finally, as the trail’s foot traffic increased, we moved on.

**Woodcreepers can be intimidating birds to identify, so I relished spending time with several species at the ant swarm, including this Northern Barred-Woodcreeper.**

We, of course, saw many more species on this outing—including Braden’s fourth lifer of the day, a White-throated Shrike-Tanager—but it was the antbirds that would stay with us as we headed to our next, equally spectacular destination, Caño Negro wetlands.

Our Sky Adventures checklist: https://ebird.org/checklist/S303092147

The Social Lives of Birds (Book Review)

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With single-digit temperatures in Montana this week, it is still very much book reading season, a time when all birders can—and should—beef up our birding resumés by tapping into the vast wealth of research and experience of the global birding and scientific communities. This past week, I delved into a topic that intrigues most birders by picking up Joan E. Strassmann’s The Social Lives of Birds: Flocks, Communes, and Families (Tarcher, 2025).

**Joan Strassmann’s The Social Lives of Birds is packed with delightful revelations for beginning and experienced birders alike. (Click on the cover for ordering info.)**

A well-regarded professor and scientist, Strassmann has created a comprehensive resource that introduces readers to almost every aspect of bird society. She begins by answering the simple question “Are Birds Social?” (You can probably guess the answer to that!) Then, chapter by chapter, she explores topics that fascinate beginning birders as much as they do veteran scientists. These include flocking behavior, mixed-species flocks, the predilection of many birds to roost and/or nest in colonies, the pros and cons of nesting and/or roosting together, lekking behavior, and more.

**The author devotes an entire chapter to the fascinating and intriguing world of seabird colonies, such as those of one of the world’s most popular birds, the Blue-footed Booby.**

I learned something fascinating with each chapter. For instance, I was first drawn to the book because the cover showed a line of six Long-tailed Tits packed tightly together on a branch. I had had the pleasure of observing these birds in the Netherlands (see our post Layover Birding in Amsterdam), Japan (see our post Birding Japan: Kyoto), and Spain (see our post Birding Barcelona, Part 1: The Urban Core), but had no idea that they lived and foraged in stable flocks that are often built around a main breeding pair and its offspring. In her book, Strassmann recounts a study that showed that on chilly nights, the tits nestle tightly together to stay warm, and that often it is the lowest birds on the “tit totem pole” that have to endure the chillier end positions. This is no trivial matter since the birds lose about 9 percent of their total body mass in a single, chilly night.

**After observing Long-tailed Tits in Europe and Asia, I was fascinated to learn more details of their highly social behavior in *The Social Lives of Birds*.**

Similar revelations emerge with every chapter, examining birds from a wide variety of terrestrial and aquatic habitats. My favorite chapter was the last, “Supersocial Groups: Birds That Are Always Together.” That’s probably because it featured one of my favorite birds, the Acorn Woodpecker (see our post College Search Birding in California), and three other species I was fascinated to learn more about: White-winged Choughs, Sociable Weavers, and a bird Braden and I are always delighted to see, Pinyon Jays. Regarding the latter, Braden and I have seen Pinyon Jays only a handful of times here in Montana, and I had wondered why they aren’t more common. Strassmann explains that the birds need extremely large territories to guarantee a dependable food supply. Unfortunately, their main food source, the pinyon pine, has suffered extreme losses from clearing for agriculture and other reasons. Warmer temperatures driven by climate change have also impacted the production of pinyon pine seeds, leading to large-scale die-offs of these beautiful, dynamic, gregarious birds.

**Strassmann devotes much of the final chapter on one of Braden’s and my favorite birds, Pinyon Jays, shown here in a cemetery in Helena, Montana.**

The Social Lives of Birds struggles a bit over whether it wants to be a comprehensive resource or an engaging narrative in the vein of the recently reviewed The Great Auk or A World on the Wing. The author mentions her personal connections to many of the topics, but I found these more distracting than engaging. Still, that will not prevent readers from enjoying the book and harvesting a wealth of information—knowledge that will help you look at birds with greater understanding and appreciation each time you head out to bird.

Review copy provided by the publisher.

Best Fall Warbler Flock Ever!

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After a couple of slightly disappointing birding outings in a row, Braden and I were feeling a little down, especially because we felt like we’d missed our chances to see some uncommon fall migrants as they make their all-too-brief passages through Montana. Nonetheless, I continued taking my binoculars with me on my morning dog walks just to keep an eye on things and learn more about how fall birds behave. Early last Sunday, I decided to take Lola on one of our Top Secret routes—places we can’t tell you about or we’d have to kill you—and had just started down a street near Pineview Park when I saw activity in weird poplar-type trees up ahead. I unslung my binocs and focused.

**You Californians are probably used to this, but sixty Yellow-rumped Warblers in Montana? Almost unheard of!**

I saw about eight or ten little birds, and the first two I identified happened to be Ruby-crowned Kinglets, so I at first assumed they were all kinglets. Rookie mistake. Upon further study, I realized that many of them were Yellow-rumped Warblers (Banding Code: YRWA). What’s more, many more birds filled the surrounding trees. “Hm . . . This could be serious,” I thought and settled in for a better look. For the next twenty minutes, I did my best to identify the frantically-moving targets, finding Red-breasted Nuthatches, Black-capped Chickadees, Evening Grosbeaks—and about twenty Yellow-rumped Warblers. As I was looking at the top of a spruce tree, however, a shocking black-and-yellow face suddenly popped up: a Townsend’s Warbler! By now, TOWAs were supposed to be long gone and when I punched it into eBird, well, the app flagged it as RARE.

**Anyone know what this tree is? Whatever it is, it apparently hosted a lot of insects because the birds loved it!**

Lola and I hurried home and woke Braden. “You don’t have to come,” I told him, “but there’s an amazing mixed-species flock down by Pineview, including a Townsend’s Warbler.” Five minutes later, cameras and binoculars in hand, we zoomed down there in our ’86 4-Runner. To our relief, the birds hadn’t left, and we spent the next seventy minutes following them. My major goal was for Braden to see the Townsend’s, but together, we soon began making other discoveries. For one thing, there weren’t just twenty YRWAs. There were at least sixty of them, along with at least ten Ruby-crowned Kinglets. It wasn’t long before Braden found a Wilson’s Warbler and we both began detecting an occasional Orange-crowned in the crowd. Thanks to Braden’s ears, we also heard Pine Siskins, Red Crossbills, a Song Sparrow—even a pair of Sandhill Cranes in the distance!

**Full Disclosure: I still confuse Cassin’s Vireos with Ruby-crowned Kinglets. The white “spectacles” are the key to IDing the Cassin’s.**

Not to be outdone, vireos made an appearance. Braden spotted a pair of one of our favorite songbirds, Cassin’s Vireo, while I saw another surprise bird face, that of a Warbling Vireo—also flagged as RARE for this time of year.

The species kept piling up with Hairy Woodpecker, flickers, and another surprise, Red-naped Sapsucker. But where was that sneaky Townsend’s Warbler? Had I been imagining it? Had it struck out on its own? Finally, after almost an hour, Braden shouted, “I’ve got the Townsend’s!” I hurried over and sure enough, there it was. I even managed a poor, but unmistakable, photo of it. As the flock made its way slowly down Rattlesnake Creek, Braden and I climbed back into the 4-Runner. “Wow,” I said, “I think that’s the best mixed-species flock we’ve ever seen in Montana!” After some thought, Braden agreed. It hadn’t provided us any Year Birds or Lifers, but had been something we would never forget—and almost in our back yard. Birding doesn’t get better than that.

Click here for our complete list: https://ebird.org/checklist/S74123665