Newsletters and Literature

• A research project from the Transportation Research Board on "Evaluating the Suitability of Roadside Corridors for Use by Monarch Butterflies" has been released as a pre-publication of the final report here; the research products are available from this Monarch Joint Venture webpage.

• Xerces has recently released a blog post with the results of their west-wide breeding habitat monitoring. At all but one state that has been monitored for the past 3 years, monarch breeding numbers were lower than the previous two years (note that Arizona was not included here).

• The US Fish and Wildlife Service recently released a paper titled "A Method to Project Future Impacts From Threats and Conservation on the Probability of Extinction for North American Migratory Monarch (Danaus plexxipus) Populations" (also attached). Quotes of particular note:

"Our quasi-extinction threshold collected from the literature ranged between 20,000 and 50,000 butterflies. Across this range, the probability of quasi-extinction for the western monarch population reached 99.99% (99.98–100.0) by 50 years in both the “current” or baseline model and all future scenarios tested." (NOTE: The western monarch population was estimated at 28,429 monarchs in 2018)

"In the western population, further protecting overwintering grounds and nectar resources could cause a large and positive population response by the species. However, those changes would need to be greater in scope than what our analysis viewed as plausible."

• Xerces has recently released a blog post with the results of their west-wide breeding habitat monitoring. At all but one state that has been monitored for the past 3 years, monarch breeding numbers were lower than the previous two years (note that Arizona was not included here).

• The US Fish and Wildlife Service recently released a paper titled "A Method to Project Future Impacts From Threats and Conservation on the Probability of Extinction for North American Migratory Monarch (Danaus plexxipus) Populations" (also attached). Quotes of particular note:

"Our quasi-extinction threshold collected from the literature ranged between 20,000 and 50,000 butterflies. Across this range, the probability of quasi-extinction for the western monarch population reached 99.99% (99.98–100.0) by 50 years in both the “current” or baseline model and all future scenarios tested." (NOTE: The western monarch population was estimated at 28,429 monarchs in 2018)

"In the western population, further protecting overwintering grounds and nectar resources could cause a large and positive population response by the species. However, those changes would need to be greater in scope than what our analysis viewed as plausible."

• There is a new paper discussing the decline of the western monarch: "Why are monarch butterflies declining in the West? Understanding the importance of multiple correlated drivers". Click above to view or download.

• A new publication titled "Best Management Practices for Pollinators on Western Rangelands" is now available!

• A new paper examining the effects of pesticides on pollinators ("An assessment of acute insecticide toxicity loading [AITL] of chemical pesticides used on agricultural land in the United States") and a National Geographic article about the study.

• A number of monarch papers were published in Frontiers in Ecology and Evolution under the topic: North American Monarch Butterfly Ecology and Conservation.

• A paper was recently published by the University of Nevada - Reno and the Xerces Society in Conservation Science and Practice titled "Declines in insect abundance and diversity: we know enough to act now".