For more information on the Monarch Watch program:
http://www.monarchwatch.org/in...
----------------------------------------------------------------
Monarch Population Status
----------------------------------------------------------------
In the last update of the eastern monarch population (late September,
we noted that it would be interesting to see how monarchs cope with
the lack of nectar and water in Texas. We knew that the migration would
make it through Texas (and Northern Mexico) but we didn't know what
impact the drought conditions would have on it.
Modest numbers of monarchs have already arrived at the overwintering
sites in Mexico and they will continue to arrive through the end of
the month. Preliminary reports indicate that the monarchs are spread
out over an area of four hectares or so at this time but we expect
this area to shrink in the coming weeks as the masses of monarchs
become more consolidated.
Our predictions regarding the size of the overwintering monarch
population still stand (down this year*); official measurements will
be done in late December and we will report the findings in an update
after the first of the year.
Stay tuned!
*It is too late for rains to change the situation in TX and northern MX. Monarchs will make it to the overwintering sites but their numbers will be significantly reduced by these conditions. My expectation is that that the overwintering numbers will be the lowest ever (previous low 1.92 hectares) and that the arriving butterflies will be in relatively poor shape with low fat reserves. If the average condition (mass) of the overwintering monarchs is lower than average, mortality during the winter could also be high. Other scenarios could include low returning numbers next spring with a reduced reproductive capacity due to low fat reserves. Keep your fingers crossed that there are no winter storms in MX that could make matters worse.
It will be interesting to see how monarchs cope with the lack of nectar and water as they move through TX. Monarchs, like most insects, have hygroreceptors (sense organs that are sensitive to humidity gradients); therefore, when conditions are extremely dry, we might expect monarchs to seek out the darkest and most humid habitats. If this plays out, most monarchs will accumulate in drainages, along rivers, move in an out of forests, and concentrate around other water sources.
