More from Explorations of an Ecologist
I have recently returned from an excellent tour of northern Colombia for Quest Nature Tours. This was my fourth time guiding for Quest here, in the birdiest country in the world. Birdiest may be a bold claim, but eBird shows 1,956 species recorded for Colombia, while the Colombian Committee of Ornithological Records lists 1,969 species. Second and third place fall to Peru and Brazil, respectively, though neither country has reached 1,900 species yet. I've spent more time in Colombia than any other Latin American country, and I love coming back for more! Glaucous Tanager This tour was a short and sweet ten days visiting the Santa Marta mountains and the Caribbean coast in the far northern reaches of Colombia. One advantage of this tour is that it focused on a relatively small geographic area, meaning that we had no internal flights and minimal long drives. If you are going to pick just one area of Colombia to visit, this would be a pretty good one due to the high number of endemic species; that is, species found found just here and nowhere else in the world. The Santa Marta mountains present an interesting study in biogeography as they have been isolated from the main Andean chain for 10-15 million years. Many of the bird species found here (at least 28 species) are endemic to these mountains. A high ratio of endemism is found with its many plants, lizards, frogs, insects, and more. Vermilion Cardinal (male) Orange-chinned Parakeets In total we found nearly 340 bird species during our tour including a high percentage of the Santa Marta endemics. We also spent some time in the varied habitats along the north coast of Colombia, from the desert scrub of La Guajira to dry tropical forest of Tayrona National Park, from mangrove-lined estuaries filled with flamingos and shorebirds to productive freshwater marshes full of life. And of course there was so much to see besides the birds - we enjoyed endemic primates, a nice array of lizards and frogs, countless butterflies and beetles and abundant plant life. I set up my moth lights in a few montane locations which attracted quite a bounty. All in all it was a fantastic trip. Scaled Dove Cope's Ameiva (Ameiva bifrontata) Blue Ground-Dove We met up as a group at our hotel during the evening of March 13 for our welcome dinner, and discussed the possibilities of what the next week and a half would bring. It was good to reconnect with Cristian Daza who was to be our local guide for the duration of the trip. I have worked with Cris on numerous occasions in the past and it was wonderful to catch up with him. Before dawn the next morning we were on our way. Our first stop was a famous birding road called the Kilometre Four Road, just outside of a small village called Palermo. Russet-throated Puffbird Kilometre Four was a great way to kick off the trip. The habitats here consist of open farmland, stands of woodland, agricultural plots and wetland, and bird diversity is very high. In just a couple of hours we tallied around 90 bird species with our local guide, Omar. Many of them are localized to this region, including Colombian endemics like Turquoise-winged Parrotlet, Chestnut-winged Chachalaca and Sapphire-bellied Hummingbird, as well as other localized species such as Caribbean Hornero, Stripe-backed Wren and Northern Screamer. We also found a Belted Kingfisher here at the southern part of its wintering range. Black-crested Antshrike Chestnut-winged Chachalaca Northern Screamer Cattle Tyrants on a domestic buffalo Caribbean Hornero Stripe-backed Wren Our next stop was a boardwalk traversing through mangroves at Isla de Salamanca National Park. We improved our views of the localized Sapphire-bellied Hummingbird, and found some other interesting species like Bicolored Conebill, American Pygmy Kingfisher, Golden-green Woodpecker and Red-rumped Woodpecker. Several Prothonotary Warblers were flitting around the mangroves. In just a matter of days they will likely be winging their way north, perhaps as far north as where I live in southern Ontario. Birding at Isla de Salamanca Sapphire-bellied Hummingbird Golden-green Woodpecker We found a Spectacled Caiman and a Colombian Slider at Isla de Salamanca as well. The latter was a new species for me, so I was pretty happy with that! Butterfly and dragonfly diversity was also relatively high at this site. Spectacled Caiman (Caiman crocodilus) Colombian Slider (Trachemys callirostris callirostris) Caribbean Yellowface (Neoerythromma cultellatum) Eastern Amberwing (Perithemis tenera) Pin-tailed Pondhawk (Erythemis plebeja) Spot-tailed Dasher (Micrathyria aequalis) By midday we had exhausted our birding options here (it had been a successful morning) and so we drove east to Riohacha, our base for three nights. As we traveled along the coast past the imposing Santa Marta mountains to our south, the forests became noticeably drier and sparser, eventually turning to desert scrub before we reached Riohacha. This is the most arid part of Colombia and it shares many unique species with northern Venezuela. We had two full days to take in the sights and sounds here. Desert scrub in Camarones During both days we drove west for half an hour to the village of Camarones, home of the Wayuu people, an indigenous group found in the Guajira peninsula of Colombia and Venezuela. With our local guide Alvaro we got to work finding the special birds of this region. During both days we spent the early morning hours birding the scrub, finding specialties like Tocuyo Sparrow, Chestnut Piculet, Buffy Hummingbird, Orinocan Saltator and a selection of flycatchers. Orinocan Saltators Calephelis laverna, a type of metalmark butterfly Tocuyo Sparrow Melocactus curvispinus, a type of turk's-cap cactus Double-striped Thick-knee Opuntia caracassana, a type of prickly pear cactus One morning, we visited the property of local birding guide Jose Luis who I first met in 2015 during my inaugural Colombia trip (Jose had guided myself and a few friends in the Camarones area). Now, Jose has established a bird feeding station where the incredible Vermilion Cardinal appears regularly. This is a flagship species of the region and we couldn't have asked for better view of El Rey de la Guajira. Sipping cold drinks in the shade while watching the cardinals and other birds was not a bad way to spend a couple of hours! Vermilion Cardinal (male) Vermilion Cardinal (female) Black-faced Grassquit (male) Black-crested Antshrike (male) Camarones is positioned at the edge of a large wetland that drains into the Caribbean. As you can imagine from the town's name, shrimping is a productive industry here and we made sure to get our fill of camarones al ajillo (garlic shrimp) at local restaurants here. We also went for a boat trip into the mangrove-lined wetland one day. Seeing many hundreds of American Flamingos was a highlight, but I was more excited to see my first Mangrove Rail for Colombia. Of course the heron and shorebird diversity was quite high here as well. Sailing near Camarones American Flamingos American Flamingos Mangrove Rail We ventured back west towards the Santa Marta mountains, breaking up the drive with a morning spent in the beautiful forests of Tayrona National Park. Tayrona is very close to the mountains and receives more rain than the Camarones area, leading to a much higher forest canopy. Our main target was the critically endangered Blue-billed Curassow. Our local guide Wilson found one for us, but it remained heard-only, unfortunately. Gray-headed Tanager Fiery Skipper (Hylephila phyleus) Colombian Red Howler Monkey (Alouatta seniculus) Our morning at Tayrona was quite productive. Many of the birds here are shared with Central America and this would be our only chance for them during this trip. We teased out many interesting species including Pale-bellied Hermit, White-necked Puffbird, Military Macaw, Plain-brown Woodcreeper and Lance-tailed Manakin, to name a few. We also had wonderful experiences with Colombian Red Howler Monkeys and the recently-split Santa Marta White-fronted Capuchin, while I had fun chasing down and identifying various lizards and frogs. Santa Marta White-fronted Capuchin (Cebus malitiosus) Gaige's Rainbow Lizard (Cnemidophorus gaigei) Milk Frog (Trachycephalus macrotis) Gaige's Anole (Anolis gaigei) Argiope submaronica, a type of orbweaver spider Having done quite well in the coastal areas, it was time to trade in our Mercedes Sprinter van for 4x4 Toyota Land Cruisers for four days in the Santa Marta mountains. During our first morning we found ourselves at the Gairama reserve, listening to the last Rufous Nightjar of the night while waiting for dawn to break. The scenery along this road is outstanding and we tallied a number of dry-forest birds here including Black-backed Antshrike, Long-billed Gnatwren, Whooping Motmot and White-bearded Manakin, while we also enjoyed a pair of Military Macaws. Sunrise birding at Gairama Reserve Astraptes sp., a type of skipper Black-backed Antshrike Ochre-bellied Flycatcher Next on the agenda was breakfast at a little finca further up in the hills beyond Minca. We enjoyed our scrambled eggs, arepas, cheese, fresh fruit and coffee, all while watching an active feeder setup that was attended by Golden-winged Sparrow, Blue-black Grosbeak, Blue Ground-Dove and a plethora of hummingbirds and tanagers. We even had some flyover raptors including Great Black Hawk, Short-tailed Hawk, Zone-tailed Hawk, King Vulture and a distant Black-and-chestnut Eagle. Brown Violetear Cocoa Woodcreeper Blue-black Grosbeak (pair) Golden-winged Sparrow King Vulture Our first night in the Santa Marta mountains was spent at a little ecolodge called Colores de la Sierra. The birding was quite good here and in a relaxed afternoon we found around 60 species which included Black-headed Tanager, Scaled Piculet, Bran-colored Flycatcher and Pale-breasted Spinetail. The scenic viewpoint with panoramic views was a nice setting for us to go over our bird list, enjoy a few cold beverages, and watch the sunset before listening to a Collared Forest-Falcon and a Tropical Screech-Owl. Life is good. Doing our species checklist at Colores de la Sierra Bicolored Wren Swallow Tanager (male) Pale-breasted Spinetail Scaled Piculet One of the participants, Reiner and I also set up our insect-attracting lights at Colores de la Sierra and had a decent haul of moths and other insects to photograph. Copaxa multifenestrata, a type of silkworm moth Central American Paper Wasp (Apoica pallens) Dithecodes sp., a type of geometer moth Walker's Moth (Sosxetra grata), a type of cutworm moth Hylesia sp., a type of silkworm moth The next morning we ventured higher into the mountains, into the range of our first Santa Marta endemics. With local guide Jeider, we visited a local coffee farm called Finca Vista Nieves where a feeding station has been established for Black-fronted Wood-Quails. In recent days, a surprise Rufous-necked Wood-Rail has also been attending! This is a rare species that is typically found in coastal mangroves, not secondary forest high up in the mountains, and it was also a new species for both Cris and I. Though the Black-fronted Wood-Quails vocalized quite close to the feeding station, they just wouldn't come in. However, we did have excellent views of the Rufous-necked Wood-Rail and other endemics like Sierra Nevada Brushfinch, Santa Marta Brushfinch and White-lored Warbler, as well as a pair of Rusty-breasted Antpittas. White-lored Warbler Rusty-breasted Antpitta Sierra Nevada Brushfinch A walk along the edge of the coffee farm produced more endemics - Santa Marta Foliage-gleaner and Antbird - as well as a pair of Groove-billed Toucanets, a Black-and-chestnut Eagle seen well in flight, and a stunning male Rosy Thrush-Tanager. The latter is the only member of its family (Rhodinocichlidae), where its closest living relatives are the longspurs/buntings of Calcariidae. Santa Marta Foliage-gleaner Groove-billed Toucanet Highland Rubyspot (Hataerina cruentata) Rosy Thrush-Tanager We continued higher into the mountains, making birding stops along the way, until our arrival at the El Dorado Lodge situated at around 2000 m elevation. Upon arrival we were greeted by a pair of White-tipped Quetzals. Stunning birds, and a strong contender for bird of the trip. Santa Marta Blossomcrown El Dorado Lodge White-tipped Quetzal (male) White-tipped Quetzal (male) Anticipation was high the next morning. This would be the day that we explored the San Lorenzo ridge where many of the Santa Marta endemic species can be found. An early wake-up was in order, as the eight-kilometre drive takes just under two hours by 4x4. But the rough ride was worth it when we experienced an epic sunrise on the San Lorenzo ridge. Colombia's tallest peak, the snow-covered Pico Cristóbal Colón, loomed off in the distance. Sunrise on the San Lorenzo Ridge Though the winds were high, we managed to connect with most of the endemic birds over the course of the morning. We managed exceptional views of both endemic antpittas (Sierra Nevada and Santa Marta Antpittas), Santa Marta Warbler, Yellow-crowned Redstart, and White-tailed Starfrontlet, to name a few. Black-cheeked Mountain-Tanagers showed well, though the other endemic tanager, the Carriker's Mountain-Tanager, remained heard only. A couple of cheeky Crab-eating Foxes were lurking around, hoping to share our breakfast. The plant life and butterfly diversity was quite enjoyable up on the ridge. Southern Emerald-Toucanet (Santa Marta subspecies) Hermit Wood-Wren Sierra Nevada Antpitta Crab-eating Fox (Cerdocyon thous) Pedaliodes phazania Birding at the San Lorenzo Ridge We really enjoyed our two-night stay at the El Dorado Lodge and we lucked out with an amazing sunset one evening and sunrise one morning, despite being fogged out for some of our stay here. The birding opportunities were great around the lodge; highlights included Rusty-headed Spinetail, Brown-rumped Tapaculo, Lazuline Sabrewing and heard-only Barred Forest-Falcon. Some of the group had a lucky encounter with a Gray Tinamou, while an afternoon walk from the lodge back to the main road produced Gray-throated Leaftosser, Golden-breasted Fruiteater and Golden Grosbeak. Sunset at the El Dorado Lodge Masked Trogon Central American Agouti (Dasyprocta punctata) Lazuline Sabrewing At night, some of the group was successful with hearing a Santa Marta Screech-Owl, while we also experienced several endemic frog and lizard species as well as an endemic tarantula. Reiner and I each set up our insect-attracting lights. The bounty was incredible and we photographed around 200 species of moths in just one evening. Sphinx moths in particular were well-represented, with over 100 individuals of at least twelve species. Eulepidotis rectimargo, a type of erebid moth Sarosa helotes, a type of tiger moth Rhodochlora endognoma, a type of geometer moth Xylophanes titana, a type of sphinx moth Paromenia sp., a type of leafhopper Symphlebia citrarius, a type of tiger moth Wittinia zebra, a type of flannel moth Xylophanes ceratomioides, a type of sphinx moth Pityeja histrionaria, a type of geometer moth Idalus herois, a type of tiger moth Bertholdia albipuncta, a type of tiger moth Our final morning in the mountains was spent cleaning up some targets, including the endemic Black-backed Thornbill and the endemic subspecies of Cinnamon Flycatcher, before heading back down to the coast. Golden Grosbeak Black-backed Thornbill (immature male) City of Santa Marta, as seen through a hole in the clouds from the Santa Marta mountains Mimardaris aerata, a type of firetip skipper Cinnamon Flycatcher (Santa Marta race) Our last day of the tour was spent visiting Ciénaga Grande de Santa Marta. This is the largest wetland in Colombia (over 4,200 km2). Highlights during our day here included a Bare-throated Tiger-Heron, several "trip birds" in American Coot, Cocoi Heron, Fulvous Whistling-Duck and Black-collared Hawk, and a visit to the floating village of Buena Vista where we enjoyed a lunch of fresh caught snapper with lentils, smashed plantain (patacones) rice and blackberry juice. That evening we returned to Barranquilla where we enjoyed our farewell dinner. It was a wonderful trip and I can't wait to return in the future! Floating village of Buena Vista Cocoi Heron
The winter of 2025-2026 is shaping up to be a proper one. Since basically the start of December we have experienced below average temperatures and an abundance of snow. We haven't had much respite from the cold, other than a brief warm spell in January quickly followed by an unrelenting Arctic blast. As I write this in early February we are mired in a long stretch with temperatures oscillating between -20 and -5 degrees Celsius. Most regions of southern Ontario have several feet of snow piled on the ground, and nearly every body of water (other than parts of Lake Ontario) is frozen solid. Spruce Bog - Algonquin Provincial Park, Nipissing District In an attempt to stave off the seasonal depression that is common with many at this time of year, I have been spending more time outside this winter. One advantage of the crisp days is that the sun is often shining. Even on a bitterly cold day, the sun feels just a little stronger now than it did a month ago. And the days are growing noticeably longer, with today's sunset scheduled for 5:36 PM; a full 50 minutes later than what we were experiencing in late December. Red Squirrel - Algonquin Provincial Park, Nipissing District To continue reading on my other blog, click here.
Zapotén is a legendary birding area in southwestern Dominican Republic quite close to the Haiti border, and it is a must-visit site for any birder on Hispaniola. This rough track climbs high into the Sierra de Bahoruco, a beautiful mountain range cloaked in pine and broadleaf forests home to a high diversity of species. From a birding point of view, it is the most reliable site to find the localized La Selle Thrush as well as most of the other endemic species found in the mountains of the Dominican Republic. The only problem is that a high clearance 4x4 is required to traverse this road. But there is an easy solution for visiting birders. An ecolodge called Villa Barrancoli is situated only 40 minutes from the start of the rough road and its owner, Kate Wallace, regularly organizes 4x4 transport for birders. And so that is what we did. October 20, 2025 (continued) We arrived at Villa Barrancoli in the middle of the afternoon and were met by Kate. Originally from the United States, Kate is a passionate biologist and birder who has lived in the Dominican Republic for much of her life. Kate gave us a tour of the ecolodge and showed us to our cabins. We would be the only guests during our two night stay. Exterior of cabin - Villa Barrancoli Ecolodge, Independencia, Dominican Republic Interior of cabin - Villa Barrancoli Ecolodge, Independencia, Dominican Republic Washroom/shower building - Villa Barrancoli Ecolodge, Independencia, Dominican Republic The ecolodge is rustic but contains everything you need. Just don't expect luxury. The cabins were simple and came equipped with fans while the toilets and showers were in a nearby building. We found the price a bit steep (75 USD per person per night), but this included our meals and the location was perfect, even if the ecolodge itself was rather basic and in need of some upkeep. And having Kate organize our Zapotén expedition for the following morning was very helpful. Dan, Laura and I dropped off our bags and headed out for a pre-dinner walk. The ecolodge is situated next to a dirt road/trail called Rabo de Gato that probes deeper into the countryside, accessing dry forest and shallow wetlands. It is a very popular birding trail and many of the more difficult endemic bird species can be found here, including the Bay-breasted Cuckoo and White-fronted Quail-Dove. Rabo de Gato Trail, Independencia, Dominican Republic Laura came through with an excellent find. "I see a snake!" she yelled and I looked to see a sleek, striped snake vanish off the trail. Fortunately it did not go far. I saw it again and quickly pounced, coming up successfully with the serpent safely in my hands. A Cope's Antilles Snake. Cope's Antilles Snake (Hypsirhynchus parvifrons) - Rabo de Gato, Independencia, Dominican Republic Cope's Antilles Snake (Hypsirhynchus parvifrons) - Rabo de Gato, Independencia, Dominican Republic This is the same species of snake that Dan and I had seen road-killed that morning. The Cope's Antilles Snake is endemic to Hispaniola and it is closely related to several other species that are only found in the Caribbean. Like all Caribbean snakes, the Cope's Antilles Snake is nonvenomous and harmless. They prey mainly on small lizards such as anoles, of which there is no shortage of here. Cope's Antilles Snake (Hypsirhynchus parvifrons) - Rabo de Gato, Independencia, Dominican Republic Apart from the snake, our late afternoon walk at Rabo de Gato was fairly uneventful. We were unable to find our main target birds (White-fronted and Key West Quail-Doves, and Bay-breasted Cuckoo), though we managed a good look at a Zenaida Dove and a Scaly-naped Pigeon, both of which were new for Laura. We headed back to the ecolodge for dinner. Dominican Graceful Anole (Anolis distichus ignigularis) - Rabo de Gato, Independencia, Dominican Republic Despite a 3:15 AM wakeup call looming for the following morning, the three of us headed back out after dinner for an abbreviated night-hike. I manned the thermal camera while Dan and Laura scanned for herps and insects. I found a few heat signatures that turned into roosting birds - Broad-billed Tody and Black-and-white Warbler - while Dan and Laura found some interesting arthropods including a couple of vinegaroons. These arachnids are well-known for their defence mechanism of spraying acetic acid. This is the same compound found in vinegar, hence the common name. Hispaniolan Vinegaroon (Mastigoproctus proscorpio) - Rabo de Gato, Independencia, Dominican Republic Dan also spotted a couple of Brown Widow Spiders (Latrodectus geometricus), a species closely related to the Northern Black Widow which we have back home in Ontario. Though bites from Brown Widows are apparently painful, they are not as dangerous as bites from the Northern Black Widow. Brown Widow (Latrodectus geometricus) - Rabo de Gato, Independencia, Dominican Republic Unfortunately, despite using the thermal I was unable to find any Hispaniolan Solenodons (a large shrew-like creature that is one of only two species of terrestrial mammals native to Hispaniola), and Dan and Laura could not turn up any snakes. We checked the moth sheet once we returned to the ecolodge. It was covered with insects! Epitragus aurulentus - Villa Barrancoli Ecolodge, Independencia, Dominican Republic Unidentified crambid moth - Villa Barrancoli Ecolodge, Independencia, Dominican Republic Ethmia abraxasella - Villa Barrancoli Ecolodge, Independencia, Dominican Republic Insulatitan youngi - Villa Barrancoli Ecolodge, Independencia, Dominican Republic Hieroglyphic Moth (Diphthera festiva) - Villa Barrancoli Ecolodge, Independencia, Dominican Republic With the 3:15 AM alarm quickly approaching we called it a night and headed off to bed. The Blue Jays were losing 3-1 partway through the critical Game 7 of the American League Championship Series at this point. October 21, 2025 "The Jays won!!!" Those were the first words I heard in the morning. Laura must have woken a few minutes before me and checked the score - indeed, they had a massive come from behind win, thanks to a three-run home run by George Springer to erase the 3-1 deficit. I could hardly believe it - the Blue Jays were going to the World Series for the first time in 32 years. Needless to say, the early wakeup didn't seem so rough following that news. Today was a day that we had been anticipating for weeks as it would be our expedition up the Zapotén Road. Our driver, Rafael, arrived at 3:50 and we loaded the cooler containing sandwiches, cookies and a thermos of coffee into the back of his Toyota Land Cruiser. This is the gold standard vehicle in so many parts of the world for tackling the roughest roads. The reason for our early wakeup was simple. We needed to be above the third army checkpoint before dawn since La Selle Thrushes can be reliably observed on the road for just a few minutes around 7am. And given the state of the road, it would take around two hours to reach this location. We stopped only once on the drive up when Rafael heard an Ashy-headed Owl hissing from beside the road just after the first checkpoint. Mere seconds later, he had found it in his spotlight. Clearly, Rafael was more than just a driver - he was a keen birder as well. We bounced along, slowly making our way up the mountain. We passed the second checkpoint, and then the third. Finally, at 6 AM we had arrived at our destination. Zapotén, Pedernales, Dominican Republic We downed the hot coffee while waiting for the sky to lighten. Above us was a most incredible display of stars. Off in the distance the first Hispaniolan Nightjars begin their distinctive song, followed shortly by the Rufous-throated Solitaires. Dawn was imminent and we needed to get moving. Zapotén, Pedernales, Dominican Republic All four of us were on high alert as we tiptoed along the road. Up ahead was a famous bend in the road dubbed "La Selle Thrush Corner" for obvious reasons, and the day was brightening up far too quickly. Would we be late for our date with this rare mountain thrush? La Selle Thrush Corner - Zapotén, Pedernales, Dominican Republic Our first Western Chat-Tanager appeared in the roadside shrubbery, delaying us by a minute or two. But we shouldn't have worried. Right at La Selle Thrush Corner was a solitary La Selle Thrush, hopping along quietly. We crept around the bend in the road, enabling much better views. Not two minutes later it had slunk back into the woods where it would likely remain for the rest of the day. We were lucky. La Selle Thrush - Zapotén, Pedernales, Dominican Republic This was our first time in the mountains proper and so we soaked in the sights. Zapotén, Pedernales, Dominican Republic Despite the clear skies earlier in the morning, now that it was daylight we noticed clouds rolling down the mountainsides, ready to envelop us. This was not good news. It would make finding another big target, the Golden Swallow, nearly impossible. It would also likely quiet many of the other birds. We kept an eye out for quail-doves on the road but this was not meant to be. Surely, we would have more chances for the endemic White-fronted Quail-Dove near the Villa Barrancoli Ecolodge later that day or the following morning. Zapotén, Pedernales, Dominican Republic The birding remained steady and we quickly found a pair of White-winged Warblers. These are not actually true warblers - rather, they are in the family Phaenicophilidae which is endemic to Hispaniola and which also contains the two species of palm-tanager and the Green-tailed Warbler. White-winged Warbler - Zapotén, Pedernales, Dominican Republic We heard several Hispaniolan Euphonias but they refused to be seen once again. The birding was a bit quiet, possibly due to the gloomy conditions. This satyr was the only butterfly species that we observed at the upper elevations. Calisto archebates - Zapotén, Pedernales, Dominican Republic A Hispaniolan Trogon started singing next to the road, though it slipped away before Laura or I managed a look. Luckily, we found a second one at the next bend in the road. These trogons can be common during the breeding season, but at this time of the year they are quiet and unobtrusive. Hispaniolan Trogon - Zapotén, Pedernales, Dominican Republic Watching the Hispaniolan Trogon - Zapotén, Pedernales, Dominican Republic Rafael turned out to be an excellent birding guide; not "just" a driver as we had been led to believe. He knew every sound on the mountain and had locations to try for most bird species. He somehow managed to spot this day-roosting Hispaniolan Nightjar. We were incredulous as to how he managed this feat. Surely this is a known roosting spot? A check of eBird shows no photos of this species taken during the day from this mountain which leads me to believe that he just randomly found this one for us. Incredible. Hispaniolan Nightjar - Zapotén, Pedernales, Dominican Republic By the time that we returned to the pine forest around the third army checkpoint, the threat of rain had diminished and the sun even came out for a brief moment or two. Rafael and Dan heard an Antillean Siskin (Laura and I were further up the road and missed it), and then a nice mixed flock passed through that contained our first Hispaniolan Elaenia. Hispaniolan Elaenia - Zapotén, Pedernales, Dominican Republic As I write this a week later, following eBird's taxonomy update, this is one of the new species that my life list has gained. When we were looking at this elaenia it was called the Greater Antillean Elaenia. I had seen the Jamaican subspecies last year. But the Greater Antillean Elaenia has now been split - each island now has its own endemic species. Hispaniolan Elaenia - Zapotén, Pedernales, Dominican Republic One of my most-wanted bird for this trip was the Hispaniolan Crossbill and we lucked into a female here. Crossbills are nomadic birds of North America's coniferous forests and back home in Ontario we can find White-winged and Red Crossbills. The Red Crossbill in particular has quite a lot of variation, with several varieties that have slightly different vocalizations and bill shapes. These races specialize on different conifer seeds. One of them feeds on Lodgepole Pines in southern Idaho and it has been split off as its own species called the Cassia Crossbill; all of the other races are, for now, still lumped within Red Crossbill. And here in the pine forests of Hispaniola there is a crossbill that somewhat resembles the White-winged Crossbill. Hispaniolan Crossbill - Zapotén, Pedernales, Dominican Republic One theory is that a group of White-winged Crossbills remained trapped on Hispaniola near the end of the last ice age. As the temperatures warmed, pine forests retreated further north and the only pines that could survive in Hispaniola were these high elevation ones, now called the Hispaniolan Pine. In the thousands of years since, this resident population of crossbills remained and they are distinct enough to be considered their own species - the Hispaniolan Crossbill. It was really neat to spend a few minutes with this female Hispaniolan Crossbill and to observe its unique bill shape and listen to its distinctive calls. Hispaniolan Crossbill - Zapotén, Pedernales, Dominican Republic By this point we had found most of our bird targets from the upper elevations, though the Golden Swallow and White-fronted Quail-Dove still eluded us. We started back down the road as we had a few more targets - namely the Hispaniolan Loggerhead Kingbird and Bay-breasted Cuckoo, two of the toughest endemics on the island. Naranjos area, Independencia, Dominican Republic Beginning around 1000 m in elevation, we made frequent stops to play tapes for both of our target species. Our first handful of stops produced no hits, though we found our first Olive-throated Parakeets of the trip as well as a nice selection of butterflies. Trawling for cuckoos - Naranjos area, Independencia, Dominican Republic Olive-throated Parakeet - Naranjos area, Independencia, Dominican Republic Cloudless Sulphur (Phoebis sennae) - Naranjos area, Independencia, Dominican Republic Anasaitis locuples - Naranjos area, Independencia, Dominican Republic Banded Yellow (Eurema elathea) - Naranjos area, Independencia, Dominican Republic Finally, we lucked out with a Hispaniolan Loggerhead Kingbird that responded to the tape. It remained out of sight, though. I had read that this species is quite tape-responsive; perhaps this is only the case during the breeding season. Hispaniolan Violet Dung-Rolling Beetle (Canthon violaceus) - Naranjos area, Independencia, Dominican Republic One of our last stops produced a vocal Bay-breasted Cuckoo as well! It was also uncooperative, but we would have redemption at our final stop before reaching the first army checkpoint. We heard a pair of Bay-breasted Cuckoos vocalizing from somewhere off the road. I decided to enter the forest and, after following the sounds of the cuckoo, I found it perched just above eye-level. Luckily it stayed long enough for Dan and Laura to bask in its glory. Such an awesome bird! Bay-breasted Cuckoo - Naranjos area, Independencia, Dominican Republic With most of our targets in the bag, Rafael drove us back to Villa Barrancoli. But we made one final stop in some agricultural fields and quickly found a pair of Antillean Siskins, yet another endemic species down! Antillean Siskin - Puerto Escondido, Independencia, Dominican Republic We thanked Rafael profusely for such an excellent day. If anyone is planning a Zapotén expedition through Kate Wallace, ask for Rafael - you won't be disappointed.
I have recently returned from an eight-day blitz of the Dominican Republic with my wife, Laura, and good friend, Daniel Riley. Now October isn't really an ideal time for a birding trip to the Dominican Republic for a few reasons. First, October is the off-season and few birds are breeding. This means that bird song is relatively quiet and playback doesn't work very well since most species couldn't be bothered with the idea of defending a territory. Second, October is one of the hottest months of the year, especially compared to January or February which is when most birders visit the country. This makes birding in the lowlands that much more uncomfortable, especially for us Canadians who are used to the cold. And third, October is well within the window for hurricane season. Though the 2025 hurricane season had been relatively quiet prior to our trip, this would change halfway through and would cause us to change our itinerary. More on that later! That being said, we still had an amazing trip and found almost everything that we hoped to. The birds did not give themselves up easily, but we persisted and prevailed with almost every species. And the herping was phenomenal with many snakes, lizards, and frogs. Certainly, the rainier conditions assisted us in this regard. The mothing was also fantastic. As birds are only one of our interests, missing a couple of bird species in exchange for better herping and mothing conditions seemed to be a reasonable trade-off. Ashy-faced Owl - Caño Hondo, Hato Mayor, Dominican Republic October 18, 2025 One of the reasons why we picked the Dominican Republic in the first place is because of how easy it is to visit from Canada. Each day, there are multiple direct flights from Toronto and this was important as we only had an eight-day window to complete our trip. Laura's work rotation has a suitable gap, and so this was an opportunity for us to get away on a trip without her having to use any vacation time. Our flight arrived on time and we quickly sorted out the rental vehicle through Enterprise at the airport. By 3 PM we were on the road, heading north along the coast towards the town of Sabana de la Mar and Parque Nacional Los Haitises. We had added our first lifers while procuring the rental car, species that would prove to be common throughout our week in the DR: Hispaniolan Woodpecker was a lifer for Laura and I, while Antillean Palm-Swift was a new one for just Laura. Dan had been to a resort in the Dominican Republic previously and so he had already seen some of the common bird species. The drive was uneventful and we kept a close eye on the clock as we slowly made our way through coastal towns with their innumerable speed bumps. The high clearance SUV was necessary for the speed bumps alone! By 5:30 PM we arrived at Paraíso Caño Hondo, our hotel at the edge of the national park. Unfortunately the drive had taken too long to manage much birding before dark, and so our number one target species, the Ridgway's Hawk, would have to wait until the following morning. Still, it was exciting to walk around at dusk and see new species, such as Bark Anole (Anolis distichus) and a neat mantis called Gonatista major. Bark Anole (Anolis distichus) - Caño Hondo, Hato Mayor, Dominican Republic Gonatista major - Caño Hondo, Hato Mayor, Dominican Republic We checked into the hotel, set up the moth sheet, and went for a quick stroll around the property to familiarize ourselves with the area and to figure out where we needed to hike the following morning to search for the Ridgway's Hawk. Yellow Split-Toed Frogs (Eleutherodactylus flavescens) and Common Stout Anoles (Anolis hispaniolae) were quickly discovered. Both of these species are endemic to the island of Hispaniola. We also found our first of many tarantulas. This is one of the species in Phormictopus, a genus which is limited to Cuba and Hispaniola. Phormictopus sp. - Caño Hondo, Hato Mayor, Dominican Republic Yellow Split-toed Frog (Eleutherodactylus flavescens) - Caño Hondo, Hato Mayor, Dominican Republic Common Stout Anole (Anolis hispaniolae) - Caño Hondo, Hato Mayor, Dominican Republic The vast majority of the plant life was unfamiliar to us as well. I snapped a few photos, mainly of ferns that were growing along an embankment. Pyramid Maidenhair (Adiantum pyramidale) - Caño Hondo, Hato Mayor, Dominican Republic Fragile Maidenhair (Adiantum pyramidale) - Caño Hondo, Hato Mayor, Dominican Republic Tropical Resurrection Fern (Pleopeltis polypodioides) - Caño Hondo, Hato Mayor, Dominican Republic We wolfed down the hotel's buffet dinner (our first real food since breakfast) before procuring our gear for our first proper birding of the trip, a spotlighting session for Ashy-faced Owl. This species is closely related to the familiar and cosmopolitan Barn Owl, though it is restricted to the island of Hispaniola. Ashy-faced Owls are not particularly rare or range-restricted, but we hoped to find one here since the owling conditions were good this evening and a healthy population of owls resides in this area. If we struck out tonight, we would have to devote valuable evening or early morning hours later in the trip; hours better spent looking for boas, for example. Armed with flashlights, headlights and a thermal camera we headed out by car along the entrance road, making various stops to hunt for our target. The thermal camera picked up numerous heat signatures. Black Rats were the default culprits, though we also located a Black-whiskered Vireo, Limpkin and Bananaquit in this manner. Black Rats are introduced on Hispaniola and the population here sure seems to be quite healthy. I wonder if the Ashy-faced Owls are taking advantage of this relatively new food item on the menu. Black Rat (Rattus rattus) - Caño Hondo, Hato Mayor, Dominican Republic Finally, after over an hour of searching, we heard the characteristic hissing shriek of an Ashy-faced Owl. Success! Seeing them would prove difficult, but eventually a couple of dark shapes glided over the road, sihouetted by the moonlight. Our spotlight illuminated the pair of Ashy-faced Owls. Ashy-faced Owls - Caño Hondo, Hato Mayor, Dominican Republic We couldn't have asked for better looks of this handsome owl species and we took a few photos of them lit up by the spotlight beam. Owling can be difficult, even with the assistance of a thermal camera, and any victory is one to be celebrated. Happy with our excursion, we returned to the hotel. Ashy-faced Owls - Caño Hondo, Hato Mayor, Dominican Republic Though we were all pretty tired due to the early wake-up required to make our morning flight, we still had one task to complete before our beds beckoned. Mothing! (moths) It was obvious to us that this corner of Hispaniola had received a fair bit of rainfall recently as the vegetation was lush and the streams were flowing quickly. In our experience, increased rainfall has a positive correlation with diversity on the moth sheet. This evening was another data point in that favour as the sheet was dripping with moths. If only we had more time to stay out later, as many new moths were appearing even as we were taking the sheet down. But we needed some rest before the Ridgway's Hawk search began, and that took priority. October 19, 2025 Sunrise at this time of year arrives late, yet by 6 AM all three of us were geared up and raring to go birding. We sipped a coffee at the hotel while the sky slowly lightened and the morning's first birds called out from the darkness: Bananaquits, Palmchats and Hispanoiolan Woodpeckers. Finally, by 6:30 AM it was light enough to see the birds. Palmchat - Caño Hondo, Hato Mayor, Dominican Republic The Ridgway's Hawk is a species of Buteo that is most closely related to the Red-shouldered Hawk of Canada, the United States and Mexico. While formerly widespread across Hispaniola, this species has experienced a steady decline brought on by two strong factors: habitat loss (deforestation), and direct persecution by humans. When the hawks are hanging around homesteads and farms with chickens, they are often shot. The truth is that a fully-grown chicken is much too large a meal for a Ridgway's Hawk and these diminutive hawks primarily subsist on lizards, snakes and introduced rodents, but the unfair stigma has contributed to their decline. To make things worse, a botfly parasite has been found infecting Ridgway's Hawk chicks, causing reproductive rates to be barely sustainable to begin with. Only a few hundred Ridgway's Hawks survive in the wild with the population stronghold being Parque Nacional Los Haitises. In recent years, the Peregrine Fund has helped establish two introduced populations. One is thriving in the Punta Cana area, while the other has been recently set up in Los Brazos. Sunrise at Caño Hondo, Hato Mayor, Dominican Republic The vast majority of birders who cross paths with Ridgway's Hawks either do around the resorts in Punta Cana, or they visit the Caño Hondo area at the edge of P. N. Los Haitises. We were more interested in seeing the "wild" birds, which is why we added a night here at the start of our trip. We set off on a wide trail near the hotel complex which accessed the mosaic of woodland and pasture home to a pair of Ridgway's Hawks. Searching for Ridgway's Hawks - Caño Hondo, Hato Mayor, Dominican Republic Early on our search was unsuccessful, but the birding was exciting nonetheless. After all, we were in a novel environment and many of the species were new and interesting to us. Western Cattle-Egret - Caño Hondo, Hato Mayor, Dominican Republic Some were familiar to us - the Western Cattle-Egrets working the fields and the Gray Kingbirds twittering from dead snags, for example. Gray Kingbird - Caño Hondo, Hato Mayor, Dominican Republic Others, such as the Plain Pigeons that flew overhead all morning, were new for Laura and Dan. I had seen this species previously in Cuba, but it was nice to be reacquainted with them. Plain Pigeon - Caño Hondo, Hato Mayor, Dominican Republic Laura picked out a Hispaniolan Pewee, a lifer for all three of us. Drab flycatchers are not at all her favourite (who can blame her?) and so I was quite proud of her correct identification of the pewee! We were feeling anxious as the minutes ticked by and the sun rose higher in the sky. We had only budgeted one night here, and if we missed the Ridgway's Hawk this morning then it would be impractical to change our itinerary to spend an extra night. But Dan came through. His scanning of a distant hillside produced a curious small hawk sitting in a cecropia. Indeed, it was our first Ridgway's Hawk! Ridgway's Hawk in Trumpetwood (Cecropia schreberiana) - Caño Hondo, Hato Mayor, Dominican Republic Here is a slightly closer photo of the same bird. Though the views were a little bit distant, we were thrilled to see such a rare species. We heard a second Ridgway's Hawk vocalizing from the edge of a pasture and headed over there for a peek, but it vanished. As did the original one before we could approach for a closer view. That was all we were going to get from the birding gods, but our Ridgway's Hawk experience was much better than nothing. Ridgway's Hawk - Caño Hondo, Hato Mayor, Dominican Republic We all had more spring in our step as we headed back to the hotel for a well-deserved breakfast. Many other birds came out of the woodwork - Louisiana Waterthrushes along the creek, Yellow-faced Grassquits buzzing from the grasses, and White-winged Doves feeding on a fruiting tree. Louisiana Waterthrush - Caño Hondo, Hato Mayor, Dominican Republic Yellow-faced Grassquit - Caño Hondo, Hato Mayor, Dominican Republic White-winged Dove - Caño Hondo, Hato Mayor, Dominican Republic I even stopped to take a photo of one of the ubiquitous Turkey Vultures. It is definitely a bird species that gets better looking the further away it is. Turkey Vulture - Caño Hondo, Hato Mayor, Dominican Republic Another highlight was a group of Caribbean Martins cruising overhead. These birds vacate Hispaniola in October, though small numbers can hang around, and it was one species that could be easily missed on our trip. Caribbean Martin - Caño Hondo, Hato Mayor, Dominican Republic We also saw a few of the common endemic bird species including Hispaniolan Mango, White-necked Crow and Broad-billed Tody. The todies are a well-loved family of birds that only contains five living species, all found in the Greater Antilles. Todies are most closely related to the clade that includes motmots and kingfishers. Laura's favourite bird family is the motmots, so it was no surprise that she was enamoured by her first tody, too. Broad-billed Tody We enjoyed a hearty breakfast, packed up and headed out under blue skies and hot temperatures. We had a long driving day ahead of us but made sure to make a few birding stops along the entrance road to Caño Hondo. This paid off as Dan noticed a few Tricolored Munias feeding on roadside grasses, a life bird for him. This was the first time that Laura and I had seen this adaptable species outside of southeast Asia. Tricolored Munia - Caño Hondo, Hato Mayor, Dominican Republic Tricolored Munia - Caño Hondo, Hato Mayor, Dominican Republic Our time at the edge of Parque Nacional Los Haitises had been brief, but it had been immensely productive. Ashy-faced Owls and Ridgway's Hawks, lifer frogs and lizards, and even a great mothing session. The clock was ticking, and it was now time to drive through Santo Domingo to the southwestern part of the Dominican Republic.
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[Note that this article is a transcript of the video embedded above.] Have you ever thought about windows? Like really considered the idea? If we hadn’t been exposed to them our entire lives, it might seem like kind of a bizarre concept. On the face of it, windows are about light. But it’s more esoteric than that, especially now that we can make our own light. We want to be inside, but not all the way inside. So we put holes in the wall. It’s a heck of a trade-off: you get light and a view of the outdoors, but it comes at a cost. Not just the cost of the glass itself, but also the structural changes they require and their effects on ventilation, sound, cooling, heating, safety, and security inside a building. As simple as they seem, windows are a technology of sorts. And like a lot of building science, we’ve slowly been making progress, readjusting those tradeoffs and giving us the benefits without so many of the costs. I love to pick a relatively innocuous part of the built environment and really take a close look. So, I’ve built a few demonstrations in the garage to show you how far the science of glazing has come. I’m Grady, and this is Practical Engineering. Glass is not a good substitute for an exterior wall, in many respects. If you take some wall away and replace it with a window, you’re not trading like-for-like. For one, you never accidentally throw a baseball through a brick wall. But it’s especially true when it comes to heat. And this is a pretty big deal because we collectively spend vast sums of money, resources, effort, and energy on maintaining a comfortable thermal climate inside our buildings. Almost all the time, in almost all the places, the temperature outside of a building is different from the temperature we want it to be inside. But the laws of physics (also all the time in all the places) are constantly working to equalize those temperatures. We usually categorize the flow of heat into three separate modes. Conduction is heat moving through solid objects, atoms or molecules that are tightly packed, transmitting energy to their neighbors directly by vibrating against each other. Convection is heat transfer via the movement of a fluid like air or water. Radiation is heat transfer through electromagnetic waves. Since it is literally light, radiation doesn’t need a medium. All three play a role in the walls of buildings. And of course, it works both ways: sometimes it’s too hot outside and you want to keep that heat out. Sometimes it’s too cold and you want to keep the heat in. Any movement of heat from inside to out or vice versa is a flow of power, just like we measure with electricity. If you have 500 watts of heat flowing out of your house, you essentially need a 500 watt heater inside to make up for the loss and maintain a steady temperature. And just like voltage is a difference in potential that drives electrical current, heat flow is driven by a difference in temperature. The bigger that difference, the greater the flow of heat through a given wall. Continuing the electrical metaphor, insulation is the generic term we use to describe materials that resist the transmission of heat from one side to the other. It makes sense that we put it in our walls. In the US, we use R-value as a measure of this resistance. This is kind of a cursed unit of measurement, so I’m going to gloss over the scientific definition. But, a typical exterior wall assembly will usually have an R value between 10 and 25, depending on climate and how new the building is. A simple pane of glass has an R value of about 1. Let me show that to you. I built this box of foam insulation in my garage. Inside, I have a 25 watt ceramic heat emitter. I can close this up and wait for the temperature inside to stabilize. When that happens, we can assume that the heat going into the box is the same as the heat flowing out. Okay, this has pretty much settled out, and you can see that the difference between the interior and exterior probes is about 43 degrees Fahrenheit, I think that’s around 24 celsius. This is R-5 foam, soif you do the math for a perfectly sealed box with these dimensions that should be right around 50 F, 28 C, um, so accounting for the imperfections in my setup, like this, uh, terrible tape seal, that’s actually pretty close. Um, so now I’m going to swap this lid out with a pane of glass, and we’ll set this going again. Okay, this has settled out. And you can see that the temperature inside the shop hasn’t really changed, but the temperature inside the box has gone down a lot compared to the foam lid. The difference is about 22 F, which I think is around 13 C. So, just replacing one side of the box with glass instead of foam, it takes a much smaller difference in temperature to move that same 25 watts out of the box. I’m sure you see the issue here. If we want windows in our buildings, it comes at a cost of thermal efficiency. For every square foot or square meter of exterior wall that we swap with single pane windows, heat will move through that space roughly 10 to 25 times faster. So, we rarely use single-pane glazing anymore. Almost all modern windows use two, and sometimes even three panes of glass with a sealed air gap between them. Sometimes this gap is filled with a heavy gas like argon or krypton that has lower conduction and convection. There are even vacuum insulated panels that have no air inside, eliminating convection entirely. It seems like a simple change, but it makes a pretty big difference. I happen to have a double-pane glass unit, so we can try the experiment again. Okay, this demo has settled out now, and you can see that the temperature difference is right at 30 F, 17 C. Remember with the foam lid it was about 43 degrees and with the single pane it was around 23 degrees. So this is basically right in the middle. It’s not as good as when there was no window, but it’s a lot better than the single pane of glass. This varies a lot with details of the frame and coatings. But very generally, modern double-pane windows can double to quadruple the insulative value of a single pane of glass, and that can make a huge difference in a building with a lot of them. This idea of a sealed air gap between panes comes with one problem. If you’ve ever brought a bag of chips on an airplane, you know what I’m talking about. If the glass manufacturer is at a low elevation and the window’s going to be installed somewhere much higher, you end up with an overpressure situation between the panes compared to the barometric pressure. That can cause them to bow out and even fracture. In some cases, manufacturers will actually dial in the pressure for the altitude of the final destination. Another option is to install a capillary tube that equalizes the pressure inside and out. These are very narrow diameter and long tubes meant to reduce the amount of moisture that diffuses between the panes, which would otherwise lead to condensation inside the unit. Insulating glass panels help reduce heat conduction and convection, but that’s not the only way heat gets into and out of a building. The whole point of a window is to let in light, and we already learned that heat can move as electromagnetic waves. Of course, if we block visible light through a window to avoid heat transfer, that kind of defeats the purpose. But radiation also happens at other wavelengths on the electromagnetic spectrum. Specifically, for the temperatures we deal with on a day-to-day basis, most of the thermal radiation happens in infrared: wavelengths longer than visible light but shorter than microwaves. Even within that range, there are big differences in how the waves interact with matter. That’s particularly true for windows. Typical stuff at ambient temperatures like a sun-baked driveway or human body, emit thermal radiation mostly in the far-infrared spectrum. This is the stuff you can see on a normal infrared camera. And even though glass is designed to let visible light through, it is almost completely opaque to longwave infrared light. Try looking through a window with an infrared camera and you just see the window itself, not anything beyond. It’s cool to think that if our eyes worked a bit differently - if they were tuned to a slightly different part of the electromagnetic spectrum - a glass window would be entirely useless. And it seems like it would be a good thing for our thermal problem, preventing heat from transferring through. Unfortunately it’s not that simple. Glass isn’t just opaque to far-IR; it’s also highly emissive. That means it mostly absorbs thermal radiation rather than reflecting it. So, the radiation doesn’t come directly through, but it does warm the glass, which can then just conduct through the pane and reradiate it where you don’t want it to go, whether inside or out. It’s basically radiation with extra steps. On the shorter wavelength part of the spectrum we call near IR, it’s a little different. The main source of near IR radiation is the sun, and like visible light, that radiation can pass directly through most glass. This is how greenhouses work. The shortwave radiation passes right through where it can warm the stuff inside. But the stuff inside radiates longwave IR, which can’t pass back out through the glass. So, windows are kind of a two-way half-door for far infrared (since they absorb and reradiate it in both directions) and a one-way door for near infrared, but we can do better than that, mostly through low-emissivity or low-e coatings. These coatings essentially convert a pane of glass into a mirror for IR. And you can see the difference really well with an IR camera. You still get some reflections with an uncoated pane, but the difference is obvious when you put a coated pane next to an uncoated one. But this gets a little tricky, especially when it comes to near IR. If you live in a cold climate and your main use of energy is heating, you’re happy to invite as much sunlight as you can get inside. You don’t want to reflect the near IR. The opposite is true in warm climates. Fortunately, manufacturers can tune the coatings according to the climate. You can reflect shortwave radiation if you’re worried most about cooling, or you can let it in to gather more heat inside. Window manufacturers also sometimes vary which face is coated. In warmer climates, you can coat the inside of the outer pane, called “surface 2,” reflecting the IR before it crosses the gap to keep it from warming the air between the panes. In cooler climates, you can put it on “surface 3” to reflect the long-waveshort-wave IR back into your house without it having to cross the air gap. Making windows more thermally efficient isn’t the only use for glass coatings. If you’re like me, there’s a good chance you have the Merlin app installed on your phone. I think it’s a bit of an inevitability that once you reach a certain age, you start getting interested in birds. Unfortunately, one of the largest human-caused sources of bird mortality is actually windows. At certain angles, windows work essentially like mirrors, reflecting the trees and sky, and birds (bless their hearts) can’t always tell the difference. It can happen the other way too. Sometimes a bird will see something inside a building or all the way through two windows that they want to fly toward, not recognizing that there’s solid glass in the way. For you and me, walking into a glass pane like a sliding door is embarrassing, but for a bird flying at much higher speeds with tiny, hollow bones, it is often fatal. McCormick Place Convention Center on the lakeshore in Chicago may be the most famous case study. In an average year, monitors would find around 1,000 dead birds around the building from collisions with the windows. In October 2023, nearly 1,000 birds died in a single night. The owner finally decided to address the problem head on, installing a pattern of dots on all the glass surrounding the building. The solution cut the number of bird strikes by 95 percent. Awareness about bird safe glass is continuing to grow, and so are the number of solutions. Many glass manufacturers have bird-safe products that work in a similar way. The goal is to break the illusion of glass being a mirror or imperceptible as a solid surface, so most of the fixes involve patterns or designs on the glass. I think it looks pretty cool, actually. And because many bird species can see into the ultraviolet spectrum, you can even get dots and patterns that are practically invisible to humans, but still perceptible to birds to keep them from crashing into windows. Some cities are already including requirements for bird safe glass into codes, particularly in major migration corridors and for buildings that use large, uninterrupted facades of glass. This is a really common design for tall buildings and skyscrapers. Ever since I was a kid, I have always been impressed with this kind of facade. From the outside, it looks like a sleek, continuous column of glass. And it’s pretty interesting how it’s actually done. These are called walls, specifically curtain walls. But they’re also not walls in the traditional sense, at least when it comes to bearing loads. We typically think of a building’s exterior walls as the primary load path - the way forces from the building are transferred to the foundation. With curtain walls, that’s not true, and that name kind of gives it away. In buildings with curtain walls, the load bearing happens through interior columns. The exterior walls just hang there. Not that this needs another analogy, but it’s pretty much like the building is wearing a coat. This has a lot of advantages. A curtain wall is relatively lightweight, reducing structural loads on a building. It’s also thin, maximizing space in a building where it comes at a premium. They’re also unitized: you get very large pieces assembled in a factory so they go up quickly on a construction site. And, of course, you get a lot of light into the building when the entire exterior wall is a window. But how do you hold the glass in place? The process of installing glass, called glazing, is not like installing most other materials. You can’t use traditional fasteners like nails or screws. Glass is brittle, and the sharp point forces would induce too much stress. If you look at the windows of your house, the glass panes are usually sandwiched inside a frame with softer material that both seals against the glass to keep out the weather and spreads out the holding forces across a larger area along the edges of the glass. That’s sometimes called captured glazing. It’s done on large buildings with expansive glass facades too, but it’s not the only way. When you really want the outside of a building to look like only glass with no mullions or framing elements protruding beyond the panes, you can use structural silicone glazing, where the sealant does some or all the work to hold the glass in place. In 4-sided structural glazing, the glass panels are adhesively bonded on all four edges. You have nothing on the exterior except smooth glass. If you’re used to the silicone sealants sold at the hardware store, this might seem absolutely crazy to you. I definitely wouldn’t trust a tube of bathroom caulk to hold thousands of pounds of glass hundreds of feet in the air above sidewalks and roads full of people. To be fair, these systems do usually have some kind of mechanical clips or toggles that surreptitiously prevent panes from coming entirely loose if the sealant fails, but also, structural silicone is very different from caulk. Just to demonstrate this, I have a glass block. First I’m going to attach this to a metal plate using typical silicone caulk you might use in the bathroom. I’m starting with a 45-pound weight on the hook, which is probably a bit ambitious. And of course, the camera died right when that dropped, but it held 45 lbs for just about a minute before it dropped. And part of that’s cause, even after 2 weeks of curing, you can see, only the caulk around the edges actually cured. This stuff is just not designed for heavy weights like this. Now I’ll try it with structural silicone. This stuff comes from a few manufacturers in a variety of strengths, curing systems, and material compatibilities. After I let this cure for a week, which is when the manufacturer says it reaches 50 percent of its strength, I tried my little demo again. Wow. It’s holding 45 pounds just fine. So I added this small metal anvil just for good measure, and it’s still holding fine. Just a silly little experiment like this can give you a lot more confidence that those big insulated glass units on tall buildings aren’t going anywhere. But the engineering of windows doesn’t stop at holding them in place. We also have to think about what happens if they break. The most typical glass we think about with picture frames and windows is actually annealed glass. The manufacturing process is pretty impressive. The molten material is allowed to spread out and float atop a bed of molten tin, making it extremely flat and very consistent in thickness. Then the glass is allowed to cool slowly, which relieves internal stresses. That makes it possible to cut along clean lines and even drill holes in the material. But it also means that when annealed glass breaks, it usually fractures into large, razor-sharp shards that can be extremely dangerous. I think most people have enough experience with the issue that there’s hardly a need at all to say that broken glass is a serious hazard. And in many cases, it’s a simply unacceptable hazard: a slip in the shower that breaks the door, a toddler on a glass tabletop, even pushing too hard on a glass door. There are plenty of documented cases where a simple accident became fatal simply because of how annealed glass becomes jagged and razor-sharp when it fractures. One of the main solutions to the problem is tempering the glass. If you heat glass and cool it down quickly, often using a high-pressure blast of air, you can get the outside to cool a little quicker than the inside of the glass. The outside faces shrink. Then when the inside cools, it shrinks as well, pulling the outside faces of the glass into compression. If you use a polarizing filter, sometimes you can even see the stresses in tempered glass. This is a tricky process because if the cooling happens unevenly, the glass will crack or break. I’ve discovered this myself by accidentally setting a glass dish on the stove burner. But if you do it right, tempering glass makes it much stronger than typical annealed glass. Since the outer faces are in compression, cracks are less able to propagate. But even if it does break, tempered glass has a big advantage. Instead of the large shards, you tiny, relatively harmless pieces. These can still have sharp edges, but just being so much smaller means they’re much less able to injure someone. They have a lot less mass when they fall, and the edges are shorter, so it’s more like angry gravel and less like deadly knives and spears. That’s why tempered glass is often called safety glass, and lots of building codes require it in situations where broken glass can pose a safety hazard like glass doors, large windows close to the ground, and in bathrooms and showers. Most vehicles also use tempered glass on the side windows to reduce the risk of injury during a crash. One disadvantage of tempered glass is that it can’t be modified after the fact. All that built-up stress in the material makes sure it shatters into tiny pieces, but it also prevents you from cutting or drilling holes. Tempering has to be the final step. The other disadvantage also comes from its main advantage. Because tempered glass breaks in a relatively safe way, it doesn’t offer much security. And really it’s true for annealed glass too. Windows aren’t just a thermal weak point in buildings; they are also a security weak point. Why would a criminal struggle to break through a reinforced door if they can just quickly smash a window? That’s where laminated glass comes in. You can glue individual panes of glass together where they still retain almost perfect optical clarity. But even better than that, you can sandwich a tough plastic interlayer between those panes of glass, creating a composite material. And it behaves a lot differently when it breaks. Now you don’t have shards separating at all. Even completely cracked apart, the glass stays adhered to the plastic instead of flying apart. And more importantly, this is still a barrier even after it breaks. I’m not getting my hand through there. Laminated glass is ideal for overhead applications, where a break could otherwise rain down shards on people below. And it’s perfect for commercial buildings, especially on ground floors, to make it more challenging for someone to break in through a window or glass door. Laminated glass is also standard on vehicle windshields to offer more protection from a road hazard that could otherwise break through the glass and injure the driver or passengers. What’s kind of crazy is that I’m just scratching the surface of modern window technology, not to mention the glass itself, which can get a lot more complicated for applications like phone screens. But these are all innovations that are kind of hiding in plain sight, and to me at least, they make the view through a window just a little bit sweeter.
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Camillo Sitte’s blueprint for making beautiful cities seized the imagination of the world before falling into obscurity in the twentieth century. Here is his forgotten formula.
The French mathematician Nicolas de Condorcet was a passionate believer in democracy, but he also discovered a frustrating paradox within it: A majority can sometimes vote itself into a logical loop. Mathematicians have now found that this “logical loop” maps onto a strange topological shape: the Klein bottle, a surface with no distinct inside or outside. On this episode of The Quanta Podcast, host Samir Patel speaks with writer Alex Stone about this new connection between this centuries-old voting paradox and the Klein bottle — and how it illustrates just how difficult it is to translate a group of individual preferences into a single choice. This topic was covered in a recent story for Quanta Magazine. Each week on The Quanta Podcast, Quanta Magazine editor-in-chief Samir Patel and Senior Editor Hannah Waters speak with the people behind the award-winning publication to navigate through some of the most important and mind-expanding questions in science and math.