By Rick Mikula (January 2019)
Let’s start with the ugly, the weather. While most of us are stuck inside because of the double digit below zero wind chills there is nothing else to do but think of warmer days. Too early to start seeds for most of us and too cold to search outside for chrysalis and silk moth cocoons. Next month I will cover how to find and care for any cocoons that you may discover. You’ll be very surprised where you can find them. Many of them in obvious places that you may pass by every day. How every ugly the winter may seem right now, hopefully next week Punxsutawney Phil will deliver some encouraging news.
Now for the Good. The latest reports from the roosting colonies at El Rosario are larger than last year and the Monarchs are more active than usual for this time of year. Much of that is due to the warmer than normal temperatures.
Daytime highs for Angangueo are in the low 60s with night time lows ranging from 39-49. While being in the 60’s is a normal daytime temperature 39-49 is about 10 degrees above normal. Sounds like that should be good for the Monarchs but in actuality it is not. The cooler night temps puts them into a suspended state and their metabolic rate drops to conserve their stored body fat. So while warmer temperatures increase activity but too much activity could burn too much fat. A reduction of these lipid reserves will affect egg production by the females as they return to Texas. Less eggs laid early in Spring migration means smaller succeeding generation that may eventually affect the overall numbers of migrants next Fall.
But for now, the overwintering numbers in Mexico look pretty encouraging. Some field researchers have estimated that there may be 200 million individuals this year. In the past the number of Monarchs per hectare have ranged from 10 to 70 million. This year the numbers closer to 15 million per hectare. The World Wildlife Fund Mexico reported that this year the total area, occupied by overwintering Monarchs consisting of fourteen colonies, has increased to 6.05 hectares. That is a 144% increase from the previous five seasons.
So, no matter how slowly the numbers have been increasing for the past few years current reports indicator suggests that the numbers of Monarchs at the roosting sites in 2019 is one of the biggest we have had in a decade.
Woo Hoo everything is looking rosy in El Rosario! Let’s keep our tarsi crossed that is true and all will be well in the world. Except for one extra little problem. There are several colonies on the western slope of the volcano Popocatépetl and it has erupted. Since they are smaller colonies and very remote no one has been monitoring them. So, although we may never know if that population will be affected by the eruption or toxic fumes we can always hope that they won’t.
Unfortunately, that is not the Bad of this installment, California is. In 1981, more than one million Monarchs were recorded overwintering in eucalyptus trees along the Pacific coast. This year only 30,000 were recorded. That is a 86% decline since 2017 alone. Granted, that over the decades over use of pesticide and poor land management and climate change have all contributed to the decline of Monarchs in the California. But in 2018 they were also challenged with higher than normal amounts of rainfall, mudslides, devastating wildfires, and continued deforestation. It seems that those poor little guys just can’t catch a break.
In the long run, Monarchs are pretty amazing creatures and as they have shown over the past decades that they can rebound. They have populated the world and surprised us time and time again. But they do need our help to succeed. Not only in planting gardens and creating habitats, but in educating others as well. Who knows if we all work together we just might see the number of Monarchs increasing for years to come.
This entry was posted on February 25, 2019.