A new species of scale-covered marine worm, Sthenelais onca, has been documented along the Pacific coast of Costa Rica. It is characterised by a jaguar-like color pattern! Read more: zookeys.pensoft.net/article/1764...

NEW SPECIES ALERT! Researchers with the BioMar project have discovered a new species of marine worm in Área de Conservación Guanacaste. #newspecies #biodiversity #costarica #science #marineworm #marinebiodiversity Read more here: zookeys.pensoft.net/art.../17644...

Our latest newsletter is out today. Please read and share. Thank you! mailchi.mp/eee818ebe3bb...

Inspired by this @karaman.is #TidyTuesday example to use his format to plot elevation rather than depth! Here are three years of air temperature data across 1500 m of elevation in #ACG #CostaRica from sea level (outer band) to cloud forest (centre) 🙏 for the example!! @gdfcf.bsky.social

🌿✨ A new species for science! Meet Cryptocarya costaricana, a newly described tree in the family Lauraceae. 🇨🇷 Co-authored by botanist Nelson Zamora, who works closely with the parataxonomists on the ACG plant bioinventory. www.scilit.com/publications...

“What I see when I'm walking through the forest, I just do not feel that the birds are having any kind of food,” Dan Janzen says. “No insects.” Birds are vanishing from tropical forests. Is another ‘silent spring’ coming? | Science | AAAS www.science.org/content/arti...

Here’s a view of a deceased Costa Rican nightjar slowly being turned into Costa Rican ants in #ACG @gdfcf.bsky.social youtube.com/shorts/kqwsY...

🧪🪰🧪 More #ACG diversity described! Santarosamyia woodorum sp. nov. Fleming AJ, Smith MA, Hallwachs W, Janzen D (2025) A new genus and a new species in the tribe Eryciini ( #Diptera , #Tachinidae ) from Area de Conservación Guanacaste. @bdj.pensoft.net doi.org/10.3897/BDJ.... @gdfcf.bsky.social

🍃Our End of Year newsletter is just out today! Thank you to all of our supporters for helping us protect one of the most remarkable places on the planet: Área de Conservación Guanacaste. Happy Holidays! mailchi.mp/040b71d05c06...

Successful Master's thesis defense of my student Isabel Vargas at the University of Costa Rica. She studied environmental and forest structure factors affecting Wood Thrush occupancy in Northern Costa Rica Project funded by @gdfcf.bsky.social

"After 55 years, the world’s most ambitious caterpillar inventory will come to a close. This monumental project in ACG has reared 870,000 caterpillars, of 8,000 species of butterflies and moths, and 18,000 species of wasp parasites—all documented by a team that grew to 30 local parataxonomists."

Happy to share our latest newsletter! The latest GDFCF and Area de Conservación Guanacaste news is here: mailchi.mp/54601d57a15d...

🧪 Very honored/excited to take part in this paper analysing & releasing 🐛 caterpillar rearing info from #ACG #CostaRica collected by #DanJanzen and #WinnieHallwachs and the #parataxonomists of @gdfcf.bsky.social doi.org/10.3389/fevo... Figures from data available at doi.org/10.5683/SP3/...

🧪 🪰 Happy to see this large data release and analysis of decades of #tachinidae collected by #DanJanzen, #WinnieHallwachs and the #parataxonomists of #ACG @gdfcf.bsky.social in #CostaRica. So much diversity! Paper here: doi.org/10.3390/d170... Data here: doi.org/10.5683/SP3/... 🪰 🧪

Fascinating new research on spectral #bats conducted in Área de Conservación Guanacaste #hugs #murcielago #batconservation #science #costarica @plosone.org These Bats Like to Give Hugs and Play With Bugs www.nytimes.com/2025/08/20/s...

How do Rufous-and-white Wrens respond when this 3D-printed owl is presented near versus far from their nest? Find out in Dr. Natalie Sanchez' talk "Singing in the face of danger" today at 16:00 in Grand Ballroom A at #AOS2025. 🦉🇨🇷🎶 @natingui.bsky.social @gdfcf.bsky.social @lincolnsavi.bsky.social

New paper out in Frontiers in Ecology & Evolution on #caterpillar diet in Área de Conservación Guanacaste. Authors include GDFCF's taxonomists in Costa Rica, Dan Janzen and Winnie Hallwachs, @alexsmithants.bsky.social, and Scott Miller. #science #Lepidoptera www.frontiersin.org/journals/eco...

We are studying adult trees, saplings, and seedling composition in tropical dry forests, rainforests and the dry-wet ecotone in ACG Costa Rica to understand the future of these hyper diverse forests. #CostaRica @gdfcf.bsky.social

New article in Mongabay featuring Dan and Winnie and the future of the tropical dry forest. Their survival, Dan says, is “...going to depend on how much land is given back to it, as well as climate change.” news.mongabay.com/2025/06/will...

🧪 “There’s just no moths on that sheet.” @tessairini.bsky.social writes in the @theguardian.com about #InsectDecline with #DanJanzen, #WinnieHallwachs and the caterpillars of the Area de Conservacion Guanacaste #ACG in #CostaRica @gdfcf.bsky.social www.theguardian.com/environment/...

Featured prominently in this heartbreaking article are our very own Dan and Winnie. #insects #costarica #insectos #biodiversityloss #climatechange #cambioclimatico www.theguardian.com/environment/...

Half the tree of life’: ecologists’ horror as nature reserves are emptied of insects - A new point in history has been reached, entomologists say, as climate-led species’ collapse moves up the food chain even in supposedly protected regions free of pesticides www.theguardian.com/environment/...

Last April, we nano-tagged Swainson's Thrush in Monteverde, 🇨🇷 to contribute to understand their migration pathways. This is part of GDFCF @gdfcf.bsky.social BioAve project We detected them by our Motus stations at Área de Conservación Guanacaste and in their way North. @birdscanada.bsky.social

On #BiologicalDiversityDay I reflect on the privilege and responsibility I feel to work with the passionate people of ACG and @gdfcf.bsky.social to help to share stories of the tens upon tens of thousands of little things that run the world.

“Even protected areas aren’t spared,” says Daniel Janzen, a biologist studying ACG’s ecosystems. #abejones #beetles #pesticides #insects #areadeconservactionguanacaste #ACG ticotimes.net/2025/05/11/c...

🧪🪲🐞🗺️ 📢 a neat news piece from @respublications.bsky.social #RESEcolEnt about the @alexandreloureiro.bsky.social led global #meta-analysis of #elevation & #biodiversity for #beetle #Coleoptera families. www.royensoc.co.uk/news/do-beet... Read the paper here: doi.org/10.1111/een....

🧪 New paper led by Jose Fernandez-Triana of #CNC, builds on decades of Janzen & Hallwachs #ACG @gdfcf.bsky.social collections; A description of 102 new species of the #parasitoid #wasp genus #Dolichogenidea in @zookeys.pensoft.net including this 1 for @rpuschen.bsky.social doi.org/10.3897/zook...

And the 15 millionth insect was a Placosternus guttatus long-horned beetle from Área de Conservación Guanacaste! #DNAbarcoding #insects #DNA #beetle #species news.uoguelph.ca/2025/04/worl...

Our Late Dry Season newsletter is out today! Please read and share widely! mailchi.mp/cdb7585b1111...

Earth Day. Every Day. Celebrating Área de Conservación Guanacaste on this #earthday and everyone working to support our planet 🌎. #earthactionday @earthdayorg.bsky.social #earthdayeveryday

A new publication by GDFCF Science Advisor Roberto Fernández regarding a novel case of spider-snake predation in Costa Rica. #snake #spider #CostaRica #predation #reptiles #serpientes #arañas #behavior herpetologia.fciencias.unam.mx/index.php/re...

#tbt to 1986. Dan and Winnie in the field in Área de Conservación Guanacaste processing Lepidoptera specimens. Photo by Bill Fasth. #history #lepidoptera #biodiversity #mariposa #butterflies #moths #science

"The house is burning. We don’t need a more sophisticated thermometer, we need a fire hose" Dan Janzen & Winnie Hallwachs @paddywoodworth.bsky.social #IrishTimes re. #ACG and the crisis in #Insect #Biodiversity @gdfcf.bsky.social @irishrainforest.bsky.social www.irishtimes.com/environment/...

New article in the Irish Times highlighting the work of Dan and Winnie #biodiversity #biodiversityconservation #climatecrisis #insects #AreadeConservacionGuanacaste www.irishtimes.com/environment/...

Thank you, @alexsmithants.bsky.social! Glad to be here. Please give us a follow!

Yesterday, I returned from 3 weeks in Costa Rica, where I went to find out what can be learned from their spectacular success rewilding a country. I cannot overstate how awe-inspiring the trip was: nature loss CAN be reversed on a huge scale, benefiting *everyone*.