Abies religiosa and Danaus plexippus

Abies religiosa is native to southern Mexico and western Guatemala at high altitudes: 2100m to 4100m (or thereabouts). According to the Gymnosperm Database entry for Abies religiosa, its common name of sacred fir is due to “its widespread use in Mexico to create decorations for use at religious festivals, especially Christmas”, though others have suggested it is because the tips of the branches form a cross. The common name of oyamel fir tends to be more widely-used in popular texts about the species, particularly with regard to its ecology and its relationship with the monarch butterfly, Danaus plexippus.

The oyamel fir forests of Mexico are the wintering grounds for the monarchs of eastern North America, where the insects can be found in densities of 10 million individuals / hectare (4 million individuals / acre). While the species Abies religiosa itself is in no conservation danger, deforestation (ranging from illegal clearcut logging to thinning of trees — see this documentary on illegal logging near the monarch reserves) is altering the ecological conditions of the oyamel fir forest such that the monarchs may one day no longer find suitable wintering habitat. Journey North explains the ecological requirements of the wintering monarchs in point form: The Monarch’s Forest Ecosystem: Mexico’s Oyamel Fir Forest. Simply put, deforestation is changing the humidity and temperature regime of the forest, such that the monarchs will not be able to meet their physiological requirements for wintertime survival.

You can learn more about monarch butterflies from these valuable sites: MonarchLIVE, the monarch butterfly page from Canadian Biodiversity (discusses threats and monarch migration) and Monarch Watch (blog) (these great folks also could use a little bit of financial help, if you’re so inclined).

Ah, one last thing — I apologize about the quality of the photographs. I forgot my polarizing filter for this trek to see the butterflies so the photographs have a lot of glare. I also wish I could’ve taken better photographs of the firs, but the butterflies kept getting in the way. Perhaps these videos I took will make up for it (one thing to note in the videos — what appear to be solid masses of black shaded foliage are actually clusters of butterflies resting on the branches):

Abies religiosa and Danaus plexippus
Abies religiosa and Danaus plexippus
Abies religiosa and Danaus plexippus

17 responses to “Abies religiosa and Danaus plexippus”

  1. sue

    Wow! Amazing videos Daniel! Thanks so much for posting them. 😀

  2. Linda Miller

    Daniel….this one is a pass along. I know that they head south….having lived in MI, NJ and now VA and seeing one here or there. These images are another reason why WE HUMANS need to turn off the tv and get outside.
    Thank you Linda

  3. Rita Thieme

    At first when I took a glance at the photos I thought to myself, “well, that’s not a beautiful plant”. I continued to read that the tips of the plants make a cross, and scrolled back to look, thinking that the tips of the plants didn’t resemble a cross at all.
    THEN I saw mention of the monarch butterflies. How lovely.
    About 10 years ago I was in NH during the summertime. The glacial river we were enjoying had a small (15 ft square) beach area. As I walked across, hundreds of monarch butterflies rose from the sand and became part of the air around me. It was a thrilling experience I have thought of often. Thanks for showing what a real swarm of monarch looks like.

  4. Anne

    You just couldn’t stand in the middle of all that and not be completely blown away by the beauty of nature.

  5. Peter

    I visited El Rosario Monarch Butterfly Sanctuary -6 kilometers from the village of Angangueo – in January 2006. There was frost on the ground as we were fortunate to be the first visitors to arrive by foot early that morning at one of these unfathomable gathering havens of the Monarchs. I would say it was one of the most magical moments of my adult life. If you go, go early – before others arrive (noisily) in the mid-morning so you can enjoy the quiet spectacle of orange waterfalls of these creatures cascading off of the limbs as the sun warms them to flight.

  6. Eric in SF

    I can’t view today’s posting using the MacOS Dashboard Widget. Flash complains about a security violation. I had to navigate directly to the blog.
    The documentaries you link paint a bleak picture. If the Mexican government cannot stop the deforestation of the overwintering area very very soon the monarchs will not survive a winter there.

  7. Annie Morgan

    Wonderful videos and pictures. Thanks!

  8. Elizabeth Montgomery

    Oooh. Thank you so much for posting the videos (with sound!) of this incredible and beautiful end-of-migration spot. Here’s hoping the world will see to the preservation of this (sacred to the locals as well as to us) event.

  9. SoapySophia

    Funny it is used for religious ceremonies. That’s why “religiosa”. Before reading the description I thought “religiosa” sounded religious :*) Beautiful. I’ve seen pictures of trees so covered in Monarchs you can’t tell it’s a tree!

  10. Daniel Mosquin

    Eric, I suspect the security violation is due to the embedding of the youtube videos, since that’s the only difference between this and any other entry.

  11. Don Fenton

    I am no sort of Botanical/Insect Biology specialist, but – apparently – Monarch butterflies made it to Australia shortly before European colonization. They are quite common in Australia south of the tropics, and I understand that at least one migration-route has been mapped. Could we please manage a specialist update?

  12. Chungii V


  13. Chris


  14. elizabeth a airhart

    wonderful just wonderful
    i just came back from you tube
    i have an account and found the
    videos easily
    iam in florida central west coast and in
    the pathway it was chilly here freezeing 32
    the news is they may have returned early
    to our north lands thank you

  15. Jenn

    Gives me lots to think about:
    I wonder if anyone’s studied their gene pool diversity. Do they mate while they are down there? Or is all mating local to their summering areas?

  16. Daniel Mosquin

    They definitely mate while in Mexico. In fact, they are shameless about it — one has to step around the ones that are mating on the ground (though occasionally they manage to mate while in the air).

  17. Pete B.

    I’m just back(March 3) from a visit to El Rosario and Sierra Chincua. Both places are as you see them in the photos….truly amazing. If you want to hear the sound of air..sit among millions of monarchs.

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