We’ve had three separate sightings of monarch butterfly in our flower beds this year. The most recent visitor was skittish and soared up and over the neighbor’s house before I even came close, but an earlier guest cruised around our beds for a good 15 minutes, sampling from quite a variety in the front beds but favoring the butterfly weed the most (though it is also one of our more prolific species – kudos to my wife for getting us started on them!)
This three (and hopefully counting!) tally is more than the previous five years combined. I think I spotted one monarch last year at a different garden, but don’t think we’ve had any at all for at least three years. Not surprising given the fairly well known plight of this glorious creature – habitat loss, heavy herbicide use that is leaving crop fields an efficient but biologically sterile monoculture, and climate change that is beginning to be felt by numerous species. The U.S. Fish and Wildlife Service is a good starting resource to learn about the monarch’s situation and how to help.
The slight rebound seen here jives with what was seen at the overwintering sites in Mexico, with just over 4 hectares covered by the hibernating critters during the 2015-2016 winter, up from the low of 0.67 (!) hectares over the 2013-2014 season but still significantly lower than the 7+ hectares typical of the previous two decades. Detailed surveys are also found on the F&WS web site.
Even with the glimmer of hope with more sightings I have to say that I’m very pessimistic long term. Unfortunately, Danaus plexippus may have painted itself into an evolutionary corner. Dependence on a single food source, the milkweed, is a burden many other species have evolved towards (classic example? Panda bears and eucalyptus). Monarchs have a second critical dependency: overwintering grounds in Mexico that must have the “Goldilocks zone” of temperature. Too warm and they become too active and burn off critical energy reserves; too cold and they freeze. These overwintering grounds are on the peaks of a tiny handful of mountains. As the planet warms from man’s impact those peaks will warm. No problem, they can just roost at higher elevations, right? Sorry – they’re at the tops, there isn’t any “higher” to go.
So unless temperatures attenuate faster than the most optimistic goals for CO2 emission reductions it may already be too late for at least the eastern population of monarchs, having specialized so much that they’ve boxed themselves in, and mankind may only be able to enjoy these truly royal creatures in that exact way – in a box.