Filed under Monarch Population Status | 9 Comments »
As many of you know, the fall monarch migration is well underway. In July when I wrote the text for the Premigration Newsletter (available for download at monarchwatch.org/tagging) it was already clear that the fall migration would be modest and certainly no larger than the migrations we have seen for the last several years. It is now clear that the migration this year will be smaller than any seen since the fall of 2004, a migration that resulted in an all-time low overwintering population in Mexico of 2.19 hectares.
The overwintering population this winter will probably be less than 4 hectares and could be much less if the long term drought that has persisted in much of Texas and northeastern Mexico doesn’t abate. Monarchs are highly dependent on nectar and sources of water to fuel the migration through this region in October and November and, if the drought persists and nectar resources are scarce during this period, the number of monarchs reaching the overwintering sites will be reduced. There have been some recent rains in Texas but it is not yet clear whether these rains have been sufficient or widespread enough to provide the fall flowers needed by the monarchs.