Mariana Crow

I’m taking part in an art project called “Losing Altitude“.  It’s a collaborative art book project that will feature over 50 artists from around the world who work in a wide range of media. The book will feature threatened and endangered species of birds from all around the world!  The project is headed and organized by Arras Wiedorn who was kind enough to invite me and my husband to the project.  Naturally, I chose a corvid to illustrate, the Mariana crow (I’m particularly invested as I know several of the researchers who work on them!).  Here is the piece, with information about this critically endangered species below.

Species: Corvus kubaryi

Common Name: Mariana Crow, Aga (in Chamorro), previously known as the Guam Crow.

Distribution: Endemic to and only found on the islands of Guam and Rota in the Mariana Islands.

Habitat: Mature and second-growth forest and coastal strand vegetation. Birds tend to forage in the canopy, understory, and occasionally the forest floor.

Diet: Omnivorous, feeding on fruits, seeds, invertebrates, small vertebrates, and opportunistically on eggs.

Status: Critically endangered! The Mariana crow was down to seven individuals on Guam in 1999. Individuals were introduced to Guam from Rota, increasing the population to 16 individuals. However, in 2008 only two males remained. The last sighting of a Mariana crow on Guam was in 2011, and the species is likely extinct from the island. The decline on Guam is mostly attributed to the introduction, right after World War II, of the brown tree snake (Boiga irregularis), a highly invasive species that has devastated native vertebrate populations on Guam, among other issues. On the island of Rota the population has also been in decline. In 1982 the population was estimated to be just over 1,300 and in 2008 the population was down to an estimated 70-400 mature individuals. The brown tree snake is not yet established on Rota with only one dead specimen found in a Rota harbor. The decline on Rota is likely due to other invasive species (monitors, feral cats, rats), habitat destruction, disease, and direct persecution.

Conservation Efforts: Efforts to keep sections of remaining forests on Guam snake free, for further reintroduction attempts, have been established. On Rota, aggressive conservation plans are in progress. Predation control experimentation, public education, forest protection, captive breeding, refined population survey methodology, and research are all a part of efforts to prevent the Mariana crow from going extinct (predicted to happen within 75 years).


This piece depicts an adult Mariana crow picking out the soft parts of a hermit crab it has just opened. A juvenile, still with slightly blue eyes, light-colored bill, and feather sheaths on the growing tail feathers, watches the adult. The border depicts brown tree snakes in the upper corners, representing the main reason for extinction on Guam. In the snakes’ coils are crow eggs to represent predation. Below the snakes are transverse cross-sectional representations of a bread fruit, one of the fruits the crows consume. Below that are oceanic geckos and next to them at the bottom are leaf-rolling crickets, other typical foods for the Mariana crow.

I want to thank Sarah Faegre and Renee Ha of the Rota Avian Behavioral Ecology Program for sharing photographs and information with me. They are fantastic researchers and people. Please check out their website and follow what is happening to the Mariana crow!

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About The Corvid Blog

Hi, I am Dr. Jennifer Campbell-Smith and I love corvids (well, anything nature really, but these birds have a big place in my heart). I received my PhD in behavioral ecology studying the social structures and social learning of wild American crows (Corvus brachyrhynchos). I now teach at a STEM school while continuing to do research where I can and with my secondary students. My goal on this blog is to spread the corvid love by sharing information, photographs, and artwork, and dispelling common myths. Feel free to ask me anything, but note that it can take me a bit to reply. If you have an emergency with a captive corvid, please call a local avian vet. If you have an emergency with a wild corvid, please call a local licensed wildlife rehabilitation facility. Thanks! These are truly some of the most fascinating birds on the planet!

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