2,000 Butterflies Counted So Far, Western Monarch Takes an Astonishing Step Closer to Extinction.
Two years ago, when volunteers counted only 27,212 monarch butterflies in the Xerces Society’s annual Western Monarch Thanksgiving Count, it meant the butterflies had crossed a threshold identified by scientists as the point past which western migratory monarchs were likely to become extinct.
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I think there are a few factors contributing to the low counts here. Hands down pesticides and herbicides are having a huge negative impact on populations.
One other thing to note is that I have seen at least some Monarchs changing their life cycle behavior due to climate changes. For example here in Southern California it now stays warmer later into the year. Even native milkweed like our Narrowleaf Milkweed takes a lot longer to naturally die back. Its December in the 70's F still and some Milkweed were still green in our yard. There were still medium to large Monarch caterpillars on those plants a couple weeks ago and they are probably starting to pupate now. (just moved so I haven't checked back there at the old house) In past years I have seen Monarchs overwinter as a chrysalis rather than emerge in the colder weather and try to migrate to a coastal grove.
Hopefully the low counts are not an absolute population indicator but also are affected by changing Monarch life cycle behavior where the migration to coastal groves may be becoming less important or not needed as early in the year if the weather stays mild where the Monarchs are already at. That being said, the known contributors like GMO's, herbicides, and pesticides are still the main factors for Monarch populations decreasing.
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