This weekend is the Loudoun County 15th Annual Butterfly Count and one of the things we look for through this count is population increases and declines.
I just saw this posting by Monarch Watch (quoted below) about the state of Monarch Butterfly populations and I wanted to share it with you.
I have just started seeing Monarch butterflies in our yard in the last week. In the past, I’ve seen them through June and July.
It will be interesting to see what our butterfly count bears out.
A lot has happened since Monarch Watch was created in 1992. We’ve seen the overwintering population in Mexico increase each year from 1994 to 1996, only to crash inexplicably in 1997. We have seen ups and downs in overwintering numbers – but mostly downs since 2003. In fact, the population has been below the long-term average for the last seven years. The downward trend is now statistically significant (Brower, et al. 2011) and it is clear that we have entered a new era of monarch numbers.
The great migrations of the 90s are a thing of the past. In the future, we can expect overwintering populations in Mexico of 2-6 hectares. The main reason for the decline is loss of habitat. Monarch habitat has been reduced by at least 140 million acres in the last 10 years – about a fifth of the total breeding area available to monarchs has been lost. At least 100 million acres of habitat has been lost due to the adoption of herbicide resistant corn and soybeans.
So, where does this leave us and what does this mean for tagging? We can expect a low year for monarchs, perhaps not as low as 2009 (1.92 hectares) or 2004 (2.19 hectares) but close to these numbers.
The migration should be particularly low in the New England area and the numbers at Cape May will be low as well. The central region (Ontario, MI, OH, IN, IL) will see a modest migration and could produce more monarchs than the area defined by the eastern Dakotas, MN, WI, and IA. Even though the population will be down from historical highs, there will still be plenty of monarchs to tag.