The information in this state update was provided by Dr. David James, david_james@wsu.edu.  Please contact him for additional information about the update.

We Monarch aficionados in Washington State look forward to the first week in June, because that is invariably the time that we see the first Monarch butterflies of the season!  At least this was the case up until 2018, when they didn’t come.  They didn’t come in 2019 either. 

The well-documented and staggering decline in Monarch overwintering numbers in California during the 2018/19 winter is testament to the decline in western Monarch numbers since the summer of 2018.  I actually saw the warning signs on the Memorial Day weekend in 2018 when I only spotted half a dozen Monarchs flying along the Trinity River.

In previous years on this weekend, I had seen up to 120 Monarchs flying.  The indications are that Washingtonians will again not see many if any Monarchs this summer in our state.

David’s daughter Rhiannon checking for Monarch eggs near the Trinity River in N California, Memorial Day weekend 2017 (photo by David James)

However, I remain hopeful that the situation may turn around for two reasons: 1) The ‘Brower Effect’ and 2) the lack of late winter storms in coastal California in 2020.  Late winter storms are likely to have been an important reason for the decline in Monarch populations during 2018 and 2019, hitting them when they were most vulnerable, at the end of overwintering.  Together with a known shortage of early season milkweeds in California, it is likely that the egg production of overwintered Monarchs was severely curtailed.

This year, however, overwintered Monarchs experienced mostly benign conditions and they may have had better opportunities to reproduce.  I will know if that was the case when I visit the Trinity River in late May.  The ‘Brower Effect’ describes the ‘leakage’ of overwintering Monarchs in Mexico to the west of the Rockies. This can be amplified, by high overwintering populations and certain wind conditions. 

A large influx of Monarchs from Mexico may potentially enhance western populations, a scenario first described by the late Professor Lincoln Brower.  There is some evidence this happened to a small degree last year with better populations of Monarchs in Utah and Idaho than in Oregon and Washington.

Monarch at Trinity: Monarch female laying eggs on milkweed along the Trinity River on Memorial Day weekend in 2017 (photo by Linda Kappen)

For now, Monarch lovers in Washington must wait with bated-breath to see if Monarchs come our way or not.  A group of Washingtonians with a particular interest in seeing Monarchs this year, are the inmates at Washington State Penitentiary in Walla Walla.  Since 2012, dedicated inmates have reared Monarchs with loving care during August and September.

Over the years, they have reared many thousands and have tagged each one, contributing to our rapidly growing database on Monarch migration in the PNW.  Monarch lovers will not be surprised to know that these inmates rank Monarch rearing above kitten and puppy rearing when it comes to extra-mural activity choices in the prison!

Butterfly Wrangler's

Hands used for crime now nurturing a struggling species (KXLY News, September, 2018)

Western Monarch Mystery Challenge

Dr. Cheryl Schultz of Washington State University in Vancouver, WA is continuing her Monarch studies by enlisting citizens through social media to provide images of Monarchs seen in California from the middle of February to the end of April.  This is a critical period for Monarchs after they leave overwintering sites searching for milkweeds and laying their eggs.

To date, we have very little data on Monarch occurrence during this period and Dr Schultz is trying to rectify this using the talents and observations of the general public!  This project commenced on February 14 2020 and by the end of the ‘Western Monarch Mystery Challenge’, many data points on Monarch occurrence had been submitted. 

Monarch Butterflies in the Pacific Northwest Facebook page

MONARCH NEWS IN WASHINGTON

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