Monarch butterflies are moving south, beginning their migration to Mexico overwintering colonies. Early reports indicate a large number of butterflies on the wing and gathered in tree roosts overnight. You can track their migration on the map at Journey North and report your own sightings.
The Daily Bucket is a nature refuge. We amicably discuss animals, weather, climate, soil, plants, waters and note life’s patterns spinning around us.
We invite you to note what you are seeing around you in your own part of the world, and to share your observations in the comments below.
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Monarch Watch Director Chip Taylor sees 2018 conditions as similar to those of 2001, when spring migration and summer conditions (temperature) were favorable. He sent a message to a monarch email list explaining his observations.
Yesterday, while going over the year to year summaries of the tagging data, I discovered another similarity between 2001 and 2018 - the timing and likely pace of the migration. It turns out that the migration of 2001 was the earliest during the 18 year period from 1998-2015. Overall, that migration was 3-6 days ahead of most of the migrations during that interval.
Why is that relevant? It turns out the 2018 migration shaping up now is on the same time schedule. The leading edge of the migration should be at or near 45N (Twin Cities) on this date. Clusters (overnight roosts) are being seen as far south as 43N over a wide area. But, most importantly, there is nothing in the long range forecasts to suggest that the migration will be delayed. In fact, the forecasted temperatures favor a rapid pace for the migration with most of the monarchs gone from the Upper Midwest sooner than we have seen over a number of years. Some migrations have a long “tail” as the last of the monarchs trickle southward. That may not be the case for the Upper Midwest this year. Again, we’ll see.
The last point is this - migrations on a early pace tend to result in large overwintering populations. In 2001 the population went from 2.83 hectare to 9.38 hectares. This year [winter 2017-18] the overwintering number was 2.48 hectares. While there isn’t as much milkweed in the midwest now as there was in 2001, my guess is that there is still enough milkweed to produce a monarch population in the 5 hectare range.
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