Canelillo
Wednesday, March 18, 2026
Canelillo :: Pleodendron costaricense
Bad at Goodbyes :: Episode 070
On today’s show we learn about the Canelillo, a critically endangered broadleaf evergreen rainforest tree native to the Pacific coast of Costa Rica in Central America. Its scientific name is Pleodendron costaricense and it was first described in 2005.
- (00:05) Intro
- (02:05) Species Information
- (21:02) Citations
- (22:57) Music
- (27:41) Pledge
For more information about Canelillo conservation see Osa Conservation at https://osa-arboretum.org.
Research for today’s show was compiled from:
- Bezanson S, Curtis S, Mata-Quiros M, Mata-Quiros MJ, Durst T (2024) Phytochemistry of the Fruit of the Critically Endangered Tree Pleodendron Costaricense (Canellaceae). JSM Environmental Science and Ecology 12(1): 1091. – https://www.jscimedcentral.com/jounal-article-info/JSM-Environmental-Science-and-Ecology/Phytochemistry-of-the-Fruit-of-the-Critically-Endangered-Tree-Pleodendron-Costaricense-(Canellaceae)—11736#
- Endress, P. K. (2010). The evolution of floral biology in basal angiosperms. Philosophical Transactions of the Royal Society B: Biological Sciences, 365(1539), 411–421. – https://doi.org/10.1098/rstb.2009.0228
- Hammel, Barry E., and Nelson A. Zamora. 2005. “Pleodendron costaricense (Canellaceae), a New Species for Costa Rica.” Lankesteriana 5 (3): 211–218. – https://doi.org/10.15517/lank.v5i3.19758
- Mata, M., and Calvo Guerrero, M. Preformulación teórica de un producto natural antifúngico a partir de extractos obtenidos de las hojas del árbol Pleodendron costaricense. Revista Ciencia Y Salud, 6(6). – https://doi.org/10.34192/cienciaysalud.v6i6.554
- Müller, Sebastian, Karsten Salomo, Jackeline Salazar, Julia Naumann, M. Alejandra Jaramillo, Christoph Neinhuis, Taylor S. Feild, and Stefan Wanke. 2015. “Intercontinental Long-Distance Dispersal of Canellaceae from the New to the Old World Revealed by a Nuclear Single Copy Gene and Chloroplast Loci.” Molecular Phylogenetics and Evolution 84 (March): 205–19. – https://doi.org/10.1016/j.ympev.2014.12.010
- Osa Arboretum. n.d. “Pleodendron costaricense.” – https://osa-arboretum.org/plant/pleodendron-costaricense/
- Pillco Huarcaya R, López Morales M, Álvarez-Alcázar L, Whitworth A. The First Ex-Situ Germination and Dispersal Mechanisms of the Rare, Critically Endangered Tree, Pleodendron costaricense. Tropical Conservation Science. 15 (1). 2022.– https://doi.org/10.1177/19400829221104572
- Rivers, M.C. 2019. Pleodendron costaricense. The IUCN Red List of Threatened Species 2019: e.T136055038A136055040. – https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T136055038A136055040.en
- Roque, Roger Moya; Salazar, Manuel Morales; Wiemann, Michael C.; Alvarez, Luis Poveda. 2007. Wood anatomy of Pleodendron costaricense (Canellaceae) from Southern Pacific, Costa Rica. Brenesia. Vol. 68 (2007): p. 25-28. - https://www.fpl.fs.usda.gov/documnts/pdf2007/fpl_2007_roque001.pdf
- Smith, Paul. 2021. “The Need for Horticulturist Expertise in Plant Conservation: Challenges and Opportunities”. Sibbaldia: The International Journal of Botanic Garden Horticulture, no. 20 (June): 45-56. – https://doi.org/10.24823/Sibbaldia.2021.316
- Zimmer, Elizabeth A., Y Suh, and Kenneth G Karol. 2012. “Phylogenetic Placement of a Recently Described Taxon of the Genus Pleodendron (Canellaceae).” Phytologia 94 (3): 404—412. – https://www.biodiversitylibrary.org/part/184468
Please find us on the web at Bad at Goodbyes and on instagram. Please subscribe and rate/review Bad at Goodbyes wherever you listen to podcasts. Please help spread the word about the show and about the species we feature. Please take care of each other, and all of our fellow travelers.
A note on accuracy: I strive for it! These episodes are well-researched and built from scholarly sources, hoping to provide an informed and accurate portrait of these species. That said, I’m a musician! I am not an academic and have limited scientific background. I may get things wrong! If you are using this podcast for scholarship of any kind, please see the cited sources and double-check all information.
Rough Transcript
Intro 00:05
Welcome to Bad at Goodbyes.
On today’s show we consider the Canelillo.
Species Information 02:05
The Canelillo is a critically endangered broadleaf evergreen rainforest tree native to the Pacific coast of Costa Rica in Central America. Its scientific name is Pleodendron costaricense and it was first described in 2005. It has an ancient lineage, we have fossil evidence of Pleodendron pollen in Costa Rica from roughly 28 million years ago.
Description
Pleodendron costaricense, the Canelillo, is an enormous, tall, tropical, canopy tree that can reach heights between 50 and 115 feet, with trunk diameters exceeding 20 feet. They grow a single straight cylindrical main trunk, typically clear of branches until the upper bounds of their height. The crown is dense, rounded, or somewhat spreading once those upper branches reach the canopy.
Their outer bark is thin, gray and white with a scaly, cracked texture. Then the next layer just below, the inner bark, is a pale pink color and smells of sweet mint and cinnamon, from a concentration of oils stored throughout this tissue. Their heartwood and sapwood, the innermost layers of the trunk are dense, and white to pale yellow.
The Canelillo’s leaves are oblong, measuring 3 to 6 inches in length and 1 to 2 inches in width. The leaf surfaces are smooth and have entire margins, meaning smooth edges. The leaves have a spicy, peppery flavor.
Reproduction
The Canelillo flowers in February or March, producing small pale greenish-yellow blooms of twelve petals arranged in a series of three layers. The outer petals are thick and fleshy (succulent); the inner petals are thin and delicate (membranaceous), marked by light lines.
The flowers are bisexual, meaning that both male and female reproductive organs occur in the same bloom. The
Canelillo’s male reproductive pollen-producing parts, the stamen, are fused together in a staminal column, a tube that surrounds the upper part of the ovary, the female reproductive organ. At the top of the ovary, the pollen-receiving stigma is rounded and divided into six lobes.
Though unconfirmed by observational research, the Canelillo is likely pollinated by small beetles and flies. These small insects are pollen-feeders, attracted to the Canelillo’s spicy aroma. The insects feed, the flower’s succulent petals and fused stamen protect the ovary from being consumed, and when the insects move from flower to flower, pollen is spread.
Once fertilized, the flower produces a green, smooth berry about an 1 inch in diameter, containing many small, black, shiny seeds. The Canelillo fruits in July and August, and their seeds are spread by zoochory, by animals, in this case, mammals. Camera trap studies have observed that Kinkajou and Olingo (these are small tree-dwellers in the racoon family), White-nosed Coati (these are small ground dwellers, also in the raccoon family) and Central American Woolly Opossum, a marsupial, will consume the berries and disperse the seeds in their feces.
The Canelillo’s seeds are also distributed by White-faced Capuchin Monkeys. The monkeys do not eat the fruit, instead they engage in “social anointing”. The monkeys bite into the berry, releasing essential oils and then rub the pulp onto their fur and onto the fur of their companions. Scientists believe this is a kind of communal medicinal behavior. The fruit’s oils are a topical fungicide that the monkeys use to prevent skin infections caused by fungus. Additionally the oils are an insect repellent, deterring mosquitoes and biting flies. And the oils may also be a social olfactory cue, the scent application and scent itself serve as a kind of social bonding. We have camera trap evidence of this behavior and it appears the monkeys seek out the Canelillo specifically, like they do not do this with other fruit, suggesting that they have some understanding of the fruit oil’s medicinal properties and/or have a preference for its scent.
In The Dream
————
In the dream,
Collecting seeds, climbing a hundred feet, into the canopy
My hands, my skin upon the bark of this ancient tree
Listening for the soft echos of its long story,
Gathering green verses to planted anew,
In hopes its song continues.
In the dream.
————
Habitat
The Canelillo is native to Costa Rica, in Central America, near the Pacific Coast, specifically found in the southwest of the country, in the Parrita district and on the Osa Peninsula. This is a tropical lowland rainforest, and the Canelillo is found on the slopes of coastal hills, from roughly sea-level to 1000 feet in elevation. Much of this habitat is old-growth forest, having never been cleared: old tall thick trees and a dense understory of palms and giant ferns. The soil is generally a deep red, acidic clay and the forest floor is dense with leaf litter.
The climate is consistently tropical with year-round highs in the low 90s°F, and nighttime lows rarely dip below 70°F. Rainfall is wildly abundant. Precipitation averages roughly 190 inches per year. That is almost 16 feet of rain, over a foot of rain per month, resulting in a verdant rainforest of lush vegetation.
The Canelillo shares its rainforest home with:
White-nosed Coati, Diesel Tree, Central American Squirrel Monkey, Cedrón, Spiny Palm, Ocelot, Spiral Ginger, Silk Cotton Tree, White-faced Capuchin, Scarlet Macaw, Passionflower, Mantled Howler Monkey, Balsa, Rubber Tree, Root-Spine Palm, Central American Woolly Opossum, Eyelash Palm Pit Viper, Olingo, Kinkajou, Jaguar, Garlic Tree, Black-cheeked Ant-Tanager, Silky Anteater, Red-eyed Tree Frog, Baird’s Tapir, Puma, Walking Palm, Three-toed Sloth, and many many more.
Threats
The primary current threat to the Canelillo is simply low population. The tree is rare and some of its few remaining individuals are very spread out. So low population first results in a lack of genetic diversity, which reduces the species’ ability to adapt to new pests, new diseases, or changing climate conditions. And their low population density imperils natural regeneration. The Canelillo, like many plant species, dedicates significant resources to producing a very large quantity of reproductive material, relying on abundance and chance - hedging bets that given ample opportunity a beetle or a fly will in fact transfer pollen from one individual to another. But when there are less individuals and those individuals are spread out, the odds, the chance, the likelihood of successful fertilization, goes down. This is called pollen limitation.
Additionally human habitat degradation and destruction threatens the remaining Canelillo population. Across the 20th century, segments of the Canelillo’s habitat were clear-cut for agriculture: oil palm plantations, cattle ranching, and pineapple farming. Infrastructure, specifically new roads in the Parrita region, have also fragmented this habitat. And though there is no evidence of direct effect yet, camera trap studies accidentally captured evidence of illegal logging in the same forests where the Canelillo grow.
And lastly, human induced climate change, due to persistent over-reliance on fossil fuel burning, is an imminent threat. As global warming results in sea level rise, low-lying coastal and near coastal vegetation is at risk.
Conservation
Fortunately about a quarter of the Canelillo’s remaining population is on government protected land.
An off-site propagation program in 2021 was able to successfully germinate and grow roughly 150 seedlings, 59 of which were replanted in the tree’s natural habitat on the Osa Peninsula. A follow up study in 2022 observed that about 40 seedlings survived that first year.
Nevertheless the Canelillo has been considered critically endangered on the IUCN Red List since 2019 and their population is currently in decline.
Our most recent counts estimate that less than 15 Canelillo remain in the wild.
Citations 21:02
Information for today’s show about the Canelillo was compiled from:
Bezanson S, Curtis S, Mata-Quiros M, Mata-Quiros MJ, Durst T (2024) Phytochemistry of the Fruit of the Critically Endangered Tree Pleodendron Costaricense (Canellaceae). JSM Environmental Science and Ecology 12(1): 1091. – https://www.jscimedcentral.com/jounal-article-info/JSM-Environmental-Science-and-Ecology/Phytochemistry-of-the-Fruit-of-the-Critically-Endangered-Tree-Pleodendron-Costaricense-(Canellaceae)—11736#
Endress, P. K. (2010). The evolution of floral biology in basal angiosperms. Philosophical Transactions of the Royal Society B: Biological Sciences, 365(1539), 411–421. – https://doi.org/10.1098/rstb.2009.0228
Hammel, Barry E., and Nelson A. Zamora. 2005. “Pleodendron costaricense (Canellaceae), a New Species for Costa Rica.” Lankesteriana 5 (3): 211–218. – https://doi.org/10.15517/lank.v5i3.19758
Mata, M., and Calvo Guerrero, M. Preformulación teórica de un producto natural antifúngico a partir de extractos obtenidos de las hojas del árbol Pleodendron costaricense. Revista Ciencia Y Salud, 6(6). – https://doi.org/10.34192/cienciaysalud.v6i6.554
Müller, Sebastian, Karsten Salomo, Jackeline Salazar, Julia Naumann, M. Alejandra Jaramillo, Christoph Neinhuis, Taylor S. Feild, and Stefan Wanke. 2015. “Intercontinental Long-Distance Dispersal of Canellaceae from the New to the Old World Revealed by a Nuclear Single Copy Gene and Chloroplast Loci.” Molecular Phylogenetics and Evolution 84 (March): 205–19. – https://doi.org/10.1016/j.ympev.2014.12.010
Osa Arboretum. n.d. “Pleodendron costaricense.” – https://osa-arboretum.org/plant/pleodendron-costaricense/
Pillco Huarcaya R, López Morales M, Álvarez-Alcázar L, Whitworth A. The First Ex-Situ Germination and Dispersal Mechanisms of the Rare, Critically Endangered Tree, Pleodendron costaricense. Tropical Conservation Science. 15 (1). 2022.– https://doi.org/10.1177/19400829221104572
Rivers, M.C. 2019. Pleodendron costaricense. The IUCN Red List of Threatened Species 2019: e.T136055038A136055040. – https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T136055038A136055040.en
Roque, Roger Moya; Salazar, Manuel Morales; Wiemann, Michael C.; Alvarez, Luis Poveda. 2007. Wood anatomy of Pleodendron costaricense (Canellaceae) from Southern Pacific, Costa Rica. Brenesia. Vol. 68 (2007): p. 25-28. - https://www.fpl.fs.usda.gov/documnts/pdf2007/fpl_2007_roque001.pdf
Smith, Paul. 2021. “The Need for Horticulturist Expertise in Plant Conservation: Challenges and Opportunities”. Sibbaldia: The International Journal of Botanic Garden Horticulture, no. 20 (June): 45-56. – https://doi.org/10.24823/Sibbaldia.2021.316
Zimmer, Elizabeth A., Y Suh, and Kenneth G Karol. 2012. “Phylogenetic Placement of a Recently Described Taxon of the Genus Pleodendron (Canellaceae).” Phytologia 94 (3): 404—412. – https://www.biodiversitylibrary.org/part/184468.
For more information about Canelillo conservation see Osa Conservation at https://osa-arboretum.org.
Music 22:57
Pledge 27:41
I honor the lifeforce of the Canelillo. I will commit its name to my record. I am grateful to have shared time on our planet with this being. I lament the ways in which I and my species have harmed and diminished this species. I grieve.
And so, in the name of the Canelillo I pledge to reduce my consumption. And my carbon footprint. And curb my wastefulness. I pledge to acknowledge and attempt to address the costs of my actions and inactions. And I pledge to resist the harm of plant and animal kin and their habitat, by individuals, corporations, and governments.
I forever pledge my song to the witness and memory of all life, to a broad celebration of biodiversity, and to the total liberation of all beings.
Slender-billed Vulture
Wednesday, March 4, 2026
Slender-billed Vulture :: Gyps tenuirostris
Bad at Goodbyes :: Episode 069
On today’s show we learn about the Slender-billed Vulture, a critically endangered avian raptor, a bird of prey, native to South and Southeast Asia, specifically Nepal, India, Bangladesh, Myanmar, Cambodia, and Laos. Its scientific name is Gyps tenuirostris and it was first described in 1844.
- (00:05) Intro
- (02:05) Species Information
- (27:51) Citations
- (29:43) Music
- (37:03) Pledge
For more information about Slender-billed Vulture conservation please see Saving Asia’s Vultures from Extinction at https://save-vultures.org.
Research for today’s show was compiled from:
- BirdLife International. 2021. Gyps tenuirostris. The IUCN Red List of Threatened Species 2021: e.T22729460A204781113. – https://dx.doi.org/10.2305/IUCN.UK.2021-3.RLTS.T22729460A204781113.en
- BirdLife International (2021). Species factsheet: Slender-billed Vulture Gyps tenuirostris. – https://datazone.birdlife.org/species/factsheet/slender-billed-vulture-gyps-tenuirostris 25/02/2026
- del Hoyo, J., N. Collar, and J. S. Marks (2020). Slender-billed Vulture (Gyps tenuirostris), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.– https://doi.org/10.2173/bow.slbvul1.01
- Hille, Sabine M., Fränzi Korner-Nievergelt, Maarten Bleeker, and Nigel J. Collar. “Foraging Behaviour at Carcasses in an Asian Vulture Assemblage: Towards a Good Restaurant Guide.” Bird Conservation International 26, no. 3 (2016): 263–72. – https://doi.org/10.1017/S0959270915000349
- Jackson, A. L., Ruxton, G. D., & Houston, D. C. (2008). The effect of social facilitation on foraging success in vultures: a modelling study. Biology letters, 4(3), 311–313. – https://doi.org/10.1098/rsbl.2008.0038
- Mundy, P. J., 2022. Measurements and shape of the Slender-billed Vulture Gyps tenuirostris. Indian BIRDS 18 (3): 82–85. – https://indianbirds.in/vol-18-no-3/
- The Peregrine Fund. n.d. “Slender-billed Vulture.” Explore Raptors. – https://peregrinefund.org/explore-raptors-species/vultures/slender-billed-vulture
- Prakash, Vibhu, Hemant Bajpai, Soumya S. Chakraborty, Manan Singh Mahadev, John W. Mallord, Nikita Prakash, Sachin P. Ranade, Rohan N. Shringarpure, Christopher G. R. Bowden, and Rhys E. Green. “Recent Trends in Populations of Critically Endangered Gyps Vultures in India.” Bird Conservation International 34 (2024): e1. – https://doi.org/10.1017/S0959270923000394
- Ranade, Sachin P. 2025. “Time Activity Budget of White-Rumped Vulture and Slender-Billed Vulture During Breeding in Captivity.” bioRxiv. – https://doi.org/10.64898/2025.12.09.693217
Sound Recording by Phil Gregory. 2024. Xeno-Canto. XC899521 – xeno-canto.org/899521 - Virani, M., P.C. Benson, M. Gilbert, and S. Thomsett. 2004. A survey of the reproductive activities at some Gyps vulture nests in Kanha, Bandhavgarh and Ranthambhore National Parks, India, in the 2002/2003 breeding season. Pages 263-268 in R.D. Chancellor and B.-U. Meyburg (Eds.) Raptors Worldwide. World Working Group on Birds of Prey and Owls, Berlin and MME/BirdLife Hungary, Budapest. – https://assets.peregrinefund.org/docs/pdf/research-library/2004/2004-Virani-vultures.pdf
- Wikipedia – https://en.wikipedia.org/wiki/Slender-billed_vulture
- Wildlife Institute of India (2018). National Studbook of Gyps Vultures (Gyps bengalensis, G. indicus and G. tenuirostris), Wildlife Institute of India, Dehradun and Central Zoo Authority, New Delhi.TR. No2018/38 Pages: 142. – https://cza.nic.in/uploads/documents/studbooks/hindi/Gyps%20Vultures%20(Gyps%20spp).pdf
Please find us on the web at Bad at Goodbyes and on instagram. Please subscribe and rate/review Bad at Goodbyes wherever you listen to podcasts. Please help spread the word about the show and about the species we feature. Please take care of each other, and all of our fellow travelers.
A note on accuracy: I strive for it! These episodes are well-researched and built from scholarly sources, hoping to provide an informed and accurate portrait of these species. That said, I’m a musician! I am not an academic and have limited scientific background. I may get things wrong! If you are using this podcast for scholarship of any kind, please see the cited sources and double-check all information.
Rough Transcript
Intro 00:05
Welcome to Bad at Goodbyes.
On today’s show we consider the Slender-billed Vulture.
Species Information 02:05
The Slender-billed Vulture is a critically endangered avian raptor, a bird of prey, native to South and Southeast Asia, specifically Nepal, India, Bangladesh, Myanmar, Cambodia, and Laos. Its scientific name is Gyps tenuirostris and it was first described in 1844.
Description
The Slender-billed Vulture is a medium-sized vulture, about 3 feet in length, weighing roughly 12 pounds, with a roughly 8 foot wingspan.
Their plumage is primarily dark brown and grey, with downy whitish grey feathers on the thighs, rump and at the base of the neck. They have a long, skinny, dark grey to blackish neck and head, with large dark eyes, and relatively large outer ear openings, on each side of the head. They have an imposing, squat, hooked bill, also dark grey, with two nostril slits at the upper base. Their legs, feet and toes are dark gray too, the toes are arranged in an anisodactyl formation, so three toes facing forward and one, the hallux, facing back, all with talons. Though unlike say an eagle or owl, vulture talons are relatively blunt, adapted for walking and stability, rather than grasping and killing.
The Slender-billed Vulture’s neck, head, legs, and feet are featherless. This is a kind of hygienic adaptation. They are deep-cavity scavengers; when they feed, they’ll often insert their heads deep into the cavities of rotting carcasses. Their bald neck and head means blood, rot, bacteria does not get stuck in feathers, helping protect the vulture from germs and potential disease.
Diet and Behavior
The Slender-billed Vulture is a carrion-eater, meaning they eat animals, generally mammals, which are already dead. They do not hunt and kill prey themselves, instead scavenging abandoned carcasses for the leftover, often rotting flesh, muscle, tissue, etc. They feed on the remains of larger mammals: cattle, buffalo, deer, and will visit human produced waste sites, seeking scraps in dumpsters and open landfills.
Vultures, including our Slender-billed Vulture, have highly acidic stomachs, so they can safely digest decaying meat contaminated with toxins, bacteria, and viruses that would be lethal to other animals.
This may sound a little gross. That’s because our species, humans, cannot digest these nutrients without getting sick. In the millenia of human evolution, individuals who consumed rotting food were more likely to die and hence, not reproduce as frequently or successfully. So, while my explanation here is a kind of simplified version of natural selection, basically human individuals who recoil, who are repulsed by spoilt food, have historically been more likely to live longer and healthier to produce more and healthier offspring. So our instinctive reaction, that feeling of being grossed out, was ingrained over time, it is an evolutionary adaptation.
Of course, carrion-feeders, for whom this food is not a danger, do not have this selection pressure and so do not share that revulsion. Instead, decaying discards, abandoned or avoided by other species, are vital energy and nutrient resources to the vulture. This in turn serves a vital ecosystemic role, removing, cleaning disease-bearing carcasses from their habitat.
And the Slender-billed Vulture has its own adaptations for this diet. The stomach acid, their bald head and neck, and their slender bill, for which they are named, that allows them to dig deeper into carcasses, providing greater access to additional sustenance. They employ a “gorge and fast” strategy; because food access is unpredictable and can be sporadic they will consume as much as they can in one feeding. They hold excess food in a specialized internal storage organ called the crop, and then slowly break down the meal over several days, even up to a week: digesting, resting, and fasting.
The Slender-billed Vulture finds its food sources through high-altitude, visual searches. Like many birds, they have specialized feathers called filoplumes that are extremely touch sensitive, mechanoreceptors that sense air temperature, air pressure and wind speed, allowing the vulture to ride warm air updrafts, to soar, to maintain flight without expending significant energy flapping their wings.
From above in the sky, they use their well developed eyesight to scan their habitat for potential food. Vulture eyes are large in relation to their head size, and have a high density of rods and cones, allowing them to see fine details and small movement from thousands of feet in the air.
And, Slender-billed Vulture use social strategies to aid in foraging. They rely on a behavior called local enhancement. So a single vulture does not have the time or energy to scan its entire range, so instead they monitor the behavior of other vulture. If one vulture spies food and begins a rapid descent, other vulture in eyeshot will follow to that location, resulting in a kind of game-of-telephone across the sky, a long distance, visual communication of food source location, that in a kind of chain reaction can draw others from miles and miles away.
At a feeding site, though there is evidence of some displays of social dominance, peeking and vocalizing, the Slender-billed Vulture is generally gregarious. Many Slender-bills will feed on the same carcass simultaneously and peaceably share feed sites with other vulture species and even mammals like jackal or wild dog.
We have an audio recording, made by Phil Gregory in 2024 of a group of Slender-billed Vulture feeding on a carcass from a site in Cambodia. It is, um unexpectedly mellow, for a crew of raptor gorging on carrion. Let’s listen.
[SOUND RECORDING]
The grunts, croaks and guttural hisses we heard there, are the vulture’s primary vocalizations. They do not have a syrinx. That is the vocal organ that many birds use to produce their songs, whistles, calls and caws. Instead, vulture can only produce sounds by forcing air through their upper respiratory tract: these clacks, grunts, and croaks; a short-range communication mainly used at feeding and roosting sites.
Outside of the breeding season the Slender-billed Vulture will roost, will gather in small groups on the branches of tall trees to preen, that’s clean themselves, and sun. Sunning is a behavior in which the bird spreads their wings wide, with their back to the sun. The sun’s heat has a restorative effect on their feathers and the UV radiation is a kind of disinfectant, killing bacteria on places where the bird can’t reach, like their head and neck.
Reproduction
During the breeding season, that is October to March, the roosts will split into mating pairs. Slender-billed Vulture form longterm, multi-seasons pair bonds, and are solitary nesters. Mating pairs construct their nests at a distance from other pairs, unlike say birds who nest in group colonies. Nests are large structures constructed by both the male and female, of sticks and twigs, lined with leaves and grasses, usually 30-80 feet off the ground in the branches of tall sturdy trees. We have observed evidence of nest site fidelity. So once a pair has successfully built a nest, they may return to the same nest in later years, refurbishing it, annually. They’ll add new sticks, reline the base with new greenery, and because they add on every year, the nests can get really big over time, reaching widths of 3 feet in diameter and 2 feet deep.
Nest construction, or refurbishment, begins in October, and then the female lays a single egg in November or December. Both parents take shared responsibility, splitting-time incubating the egg, defending the nest, and scavenging food for themselves. The egg incubates for roughly 50 days, and the young is born altricial, requiring parental care. Both parents share responsibility for feeding the hatchling, bringing it semi-digested meat. The young fledges, that is, learns to fly and leave the nest, after about 3 months. But parental care, protection, education and socialization continues for several months more. A juvenile Slender-billed Vulture reaches reproduction maturity at about 5 years of age and they live for up to 30 years.
In The Dream
————
In the dream,
To soar,
Isn’t this always the dream?
To soar
To be wind-kissed, to be sun-soaked,
On a cloudless morning
A patchwork of greens and browns and blues
stitched out below
Buoyant on the currents, surfing updrafts,
Effortlessly drifting above it all.
We dream to be free.
Here on earth, in the dirt,
among the craven war-makers
The sky and everyone in it
Looks holy.
In the dream.
————
Habitat
The Slender-billed Vulture is native to South and Southeast Asia, specifically Nepal, India, Bangladesh, Myanmar, Laos, and Cambodia, with most of the remaining population found in the Terai region of India and Nepal.
The Terai is a lowland belt across southern Nepal and northern India between the Himalayas and the Ganges River plains. This is a mix of open grasslands, subtropical deciduous forests, and wetlands, a mosaic of flat wide savannahs interspersed with scattered trees and major river systems.
The climate is humid, subtropical, significantly affected by the South Asian monsoon. Summer temps in the pre-monsoon months, April to June are intense with highs reaching above 110°F. Winter lows will drop into the mid-40s°F. Precipitation is also highly seasonal, with 80% of the year’s rain falling in June to September, monsoon season. Annual rainfall is high, averaging roughly 85 inches per year.
The Slender-billed Vulture shares its lowland home with:
Silk-cotton tree, White-rumped Vulture, Bengal Monitor Lizard, Haldu tree, Wild Boar, Munj Grass, Elephant Grass, Teak, Striped Hyena, Bengal Quince, Bengal Tiger, Spotted Deer, Asian Elephant, Sal tree, Golden Jackal, Indian Gooseberry, Indian Rock Python, Swamp Deer, Red-headed Vulture, Sloth Bear, Harro, Indian Vulture, Leopard, Greater One-horned Rhinoceros, Arjun Tree, and many many more.
Threats
In the late 20th century, the Slender-billed Vulture population suffered catastrophic decline, plummeting over 97% in about 15 years. The cause was the increased use of diclofenac, a non-steroidal anti-inflammatory drug human farmers used to treat inflammation in their livestock. Initially we did not know that the drug is toxic and fatal to vultures. So when scavenging the carcass of cattle treated with diclofenac, they also ingest the drug which in vultures causes rapid kidney failure. A vulture will generally die within 48 hours of consumption.
And because the vulture are social foragers, and share food sources, the threat escalates: a vulture might lead an entire local population to a toxic carcass, resulting in death for all.
Fortunately, in 2006 India and Nepal banned the use of diclofenac for domesticated livestock.
That said this threat persists today, as other anti-inflammatory drugs that are equally toxic to vultures, are still in use and there is evidence of use of cheap diclofenac labeled for human-use still being given to cattle.
Additionally, Slender-billed Vulture population is threatened by intentional poisoning by poachers. The sight of circling vultures can alert park rangers to the location of an illegally killed elephant or rhinoceros, so poachers will poison carcasses to kill vulture, reducing potential congregations.
Conservation
Fortunately, the Nepalese and Indian governments and local and international non-governmental organizations are taking these threats to the vulture seriously. Banning diclofenac and advocating against the use of other anti-inflammatory drugs.
Nepal and India have created Vulture Safe Zones, protected areas, in which populations are monitored, outreach programs educate locals on the vital role of vulture in the ecosystem, and even establishing Vulture Restaurants. These Community-managed Supplementary Feeding Centers are fenced-in areas where elderly cattle are purchased from farmers, kept in “quarantine” to ensure any drugs have cleared their systems, and then humanely slaughtered, put out for the vulture to feed upon.
Since 2009, local captive breeding programs have successfully raised Slender-billed Vultures. And recent reintroductions have found that some released birds have already begun to breed successfully in the wild.
Nevertheless the Slender-billed Vulture has been considered critically endangered on the IUCN Red List since 2002 and their overall population is generally in decline.
Our most recent counts estimate that less than 870 Slender-billed Vulture remain in the wild.
Citations 27:51
Information for today’s show about the Slender-billed Vulture was compiled from:
Information for today’s show was compiled from
BirdLife International. 2021. Gyps tenuirostris. The IUCN Red List of Threatened Species 2021: e.T22729460A204781113. – https://dx.doi.org/10.2305/IUCN.UK.2021-3.RLTS.T22729460A204781113.en
BirdLife International (2021). Species factsheet: Slender-billed Vulture Gyps tenuirostris. – https://datazone.birdlife.org/species/factsheet/slender-billed-vulture-gyps-tenuirostris 25/02/2026
del Hoyo, J., N. Collar, and J. S. Marks (2020). Slender-billed Vulture (Gyps tenuirostris), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.– https://doi.org/10.2173/bow.slbvul1.01
Hille, Sabine M., Fränzi Korner-Nievergelt, Maarten Bleeker, and Nigel J. Collar. “Foraging Behaviour at Carcasses in an Asian Vulture Assemblage: Towards a Good Restaurant Guide.” Bird Conservation International 26, no. 3 (2016): 263–72. – https://doi.org/10.1017/S0959270915000349
Jackson, A. L., Ruxton, G. D., & Houston, D. C. (2008). The effect of social facilitation on foraging success in vultures: a modelling study. Biology letters, 4(3), 311–313. – https://doi.org/10.1098/rsbl.2008.0038
Mundy, P. J., 2022. Measurements and shape of the Slender-billed Vulture Gyps tenuirostris. Indian BIRDS 18 (3): 82–85. – https://indianbirds.in/vol-18-no-3/
The Peregrine Fund. n.d. “Slender-billed Vulture.” Explore Raptors. – https://peregrinefund.org/explore-raptors-species/vultures/slender-billed-vulture
Prakash, Vibhu, Hemant Bajpai, Soumya S. Chakraborty, Manan Singh Mahadev, John W. Mallord, Nikita Prakash, Sachin P. Ranade, Rohan N. Shringarpure, Christopher G. R. Bowden, and Rhys E. Green. “Recent Trends in Populations of Critically Endangered Gyps Vultures in India.” Bird Conservation International 34 (2024): e1. – https://doi.org/10.1017/S0959270923000394
Ranade, Sachin P. 2025. “Time Activity Budget of White-Rumped Vulture and Slender-Billed Vulture During Breeding in Captivity.” bioRxiv. – https://doi.org/10.64898/2025.12.09.693217
Sound Recording by Phil Gregory. 2024. Xeno-Canto. XC899521 – xeno-canto.org/899521
Virani, M., P.C. Benson, M. Gilbert, and S. Thomsett. 2004. A survey of the reproductive activities at some Gyps vulture nests in Kanha, Bandhavgarh and Ranthambhore National Parks, India, in the 2002/2003 breeding season. Pages 263-268 in R.D. Chancellor and B.-U. Meyburg (Eds.) Raptors Worldwide. World Working Group on Birds of Prey and Owls, Berlin and MME/BirdLife Hungary, Budapest. – https://assets.peregrinefund.org/docs/pdf/research-library/2004/2004-Virani-vultures.pdf
Wikipedia – https://en.wikipedia.org/wiki/Slender-billed_vulture
Wildlife Institute of India (2018). National Studbook of Gyps Vultures (Gyps bengalensis, G. indicus and G. tenuirostris), Wildlife Institute of India, Dehradun and Central Zoo Authority, New Delhi.TR. No2018/38 Pages: 142. – https://cza.nic.in/uploads/documents/studbooks/hindi/Gyps%20Vultures%20(Gyps%20spp).pdf
For more information about Slender-billed Vulture conservation please see Saving Asia’s Vultures from Extinction at https://save-vultures.org.
Music 29:43
Pledge 37:03
I honor the lifeforce of the Slender-billed Vulture. I will commit its name to my record. I am grateful to have shared time on our planet with this being. I lament the ways in which I and my species have harmed and diminished this species. I grieve.
And so, in the name of the Slender-billed Vulture I pledge to reduce my consumption. And my carbon footprint. And curb my wastefulness. I pledge to acknowledge and attempt to address the costs of my actions and inactions. And I pledge to resist the harm of plant and animal kin and their habitat, by individuals, corporations, and governments.
I forever pledge my song to the witness and memory of all life, to a broad celebration of biodiversity, and to the total liberation of all beings.