Filed under Monarch Population Status | 18 Comments »
The number of migrating monarchs this fall should be similar to those observed in each of the last three years and the total area occupied by monarchs at the overwintering sites in Mexico should once again be close to five (5) hectares.
The last two strong migrations in recent history occurred in 2005 and 2003. It appears that strong monarch migrations occur when the temperatures and rainfall are favorable during the breeding season, including the two periods of migration in the spring and early summer.
This year, the temperatures were a bit higher than normal during the March–April period but perhaps more important were the conditions during the period from late April through mid June. Temperatures in May and June were below normal in many areas, and Minnesota (one of the big production areas for monarchs) experienced below normal rainfall and moderate drought conditions. Overall, the production of monarchs in the south appears to have been moderate, followed by conditions that limited the numbers and reproductive success of the monarchs reaching the northern breeding areas.
Nevertheless, if you have been tagging over the last three years, you should expect to see and be able to tag a reasonable number of monarchs this fall.
Stay tuned for updates as the season progresses…