It's Monarch season in Monterey County
Monarch butterflies are small insects — with a particularly complicated natural history. They're particularly active in Monterey County, and there's plenty of chances here to see them.
Migration patterns
One thing that makes Monarch butterflies special is that they migrate. Normally, the Monarchs we see along West Coast states like Oregon, Washington and Nevada are solitary animals. But when autumn comes around, so does an entirely new generation of Monarchs that behave differently.
These autumn Monarchs are the ones that migrate down to coastal California in very dense, beautiful clusters that are very easy to spot. Their migration from their northern grounds starts around September and they begin to arrive near Salinas in mid-October. Then peak butterfly season is between November through January, as by that point they have finished migrating and are here just to settle throughout the winter. Around mid-February, they start getting ready to migrate back north.
"So around mid-February or so, we start seeing monarch mating behaviors where they're essentially chasing each other trying to find a good strong flyer. And it's pretty great," Natalie Johnston, volunteer and Community Science coordinator at the Pacific Grove Museum of Natural History, said.
"There are fewer monarchs during the mid-to-late February season, but they're so active," she said. "It's kind of a delight to see it. The fact that it does happen around Valentine's Day is not lost on many people."
Once these butterflies have mated, they're ready to get out of the Central Coast. But, first, they move about 5 to 10 miles inland, according to Johnston. So, people in Carmel Valley, Salinas and King City at that time are able to see Monarch females lay their eggs as well as Monarch caterpillars. And if they have milkweed (the leaves of which Monarchs exclusively feed on), they get to watch that next generation begin their multi-generational migration north.
These mating behaviors are generally seen between March and April but can continue through May, as every butterfly works at its own unique pace.
Summer and winter
According to Johnston, there are essentially two types of monarchs: A summer generation and a winter generation.
The summer generation includes all of the Monarchs that hatch from March until September. These are the ones visible around Salinas. They live for a total of six to eight weeks. However, this lifespan also includes the couple of days that it takes for the eggs to hatch and the two weeks that it takes for the little caterpillar to transform into their adult form, Johnston said. So the Monarch butterfly is only an adult for three to five weeks.
The winter generation spends the season in Coastal California. What makes them special is that, in addition to migrating and clustering together, they have a significantly extended lifespan compared to their summer counterparts, so much that they are called the "Super Generation." They can also store fat, which is something that most butterflies cannot do at all, explained Johnston.
They're also not ready to reproduce, so they live for six to nine months instead of six to eight weeks. In coastal California, what they generally do is cluster and wait out the winter, because back up in their Northern grounds -- in states like Washington -- it's freezing cold. And the milkweed that their caterpillars need is perennial. The Monarchs get around their loss of Milkweed up North by migrating to the greater Salinas area that has a nice, mild winter where they can hang out in the trees and wait for the winter to end.
Habitat loss and global warming
Climate change and habitat loss have significantly contributed to the decline of the Western monarch population. The butterflies we see today are limited.
Pacific Grove, where the Monarch sanctuary is located, has called itself Butterfly Town, USA since the 1930s. Since the 1930s as well, it has been illegal to harm or molest the Monarch butterfly. Today, the fine for doing so is about $1,000.
"So back in those days, even as late as the 1980s, people would tell stories. They would say 'there were so many monarchs I'd have to sweep them all of my doorstep every day' or that they would open up the door and it would seem like their entire garden would come into the door at once because of all the butterflies that were there," Johnston said.
"Sometimes they would say that there was just a thick cloud of monarchs migrating through."
But in the 1980s, people started to realize that they were not seeing as many monarchs as we remember, she explained. They then tried to organize some sort of counting system, because nobody had ever tried to keep track of the monarch butterfly or any insect population, and eventually made an official system in 1997 called the Electorate Monarch Count.
It finally got finalized in 1997 into what's called the electorate Monarch count. Every single winter season, around Thanksgiving, Monarchs are visible in coastal California and not moving due to being in their clusters -- which means organizations like the Pacific Grove Museum of Natural History can count them accurately.
According to Johnston, their graphs show that there has been a sharp decline in the number of Monarch butterflies ever since they started being counted in 1997 -- a decline of over 95%.
That's linked to habitat loss, as Monarch butterflies need a coastal habitat but most of the Central Coast has been developed over, which influences the supply of milkweed patches (many of which have been developed over for housing or agricultural purposes).
Another contributing factor is climate change. All species are impacted by climate change, including monarchs, because it affects the entire habitat that they need. The trees that they need to rest in and the flowers they eat are possibly less healthy than they were because of droughts.
Like other insects, Monarchs are also impacted by pesticides, which loom particularly large in the Salinas Valley. In addition to killing off pests, pesticides hurt insects like butterflies and other wildlife.
See the Monarch reign
Pacific Grove is one of the largest publicly accessible overwintering sites where monarchs will cluster in or hang out for the winter, according to Johnston. Other key spots include Natural Bridges State Beach in Santa Cruz to the North and the Pismo Beach Butterfly.
They are highly visible now in November as they are migrating through. Some may rest in trees as a temporary rescue stop on their journeys. Then, in the springtime, caterpillars will be visible as they turn into adults.
If you want to lure monarchs into your backyard, try planting some Central Valley native milkweed purchased from a trusted retailer -- that ensures there's no pesticides in the mix. Monarchs do, however, feed off all flowering nectar plants so any pesticide-free native plants -- espsecially ones that bloom in the fall and winter instead of only in the summer --- will help work against habitat loss for these special butterflies.
This article originally appeared on Salinas Californian: It's Monarch season in Monterey County
