Monarch Survey - "We Have Enough Data Now To Say That We Are Seeing A Long-term Decline”

[hatrack]

EDIT

During the past 17 years, the area of Mexican forest patches covered by overwintering butterflies has been shrinking overall, says conservation biologist Ernest Williams of Hamilton College in Clinton, N.Y. He and his colleagues use the area occupied, which has averaged 7.24 hectares since the end of 1994, as a rough index of winter monarch population size. Several menaces, including habitat loss, confront monarchs but the researchers focused on assessing trends in the populations instead of confirming the causes.

Within the overall downward trend, seven of the 10 below-average years in the study followed one another in a worrisome streak through the winter of 2010–11, the researchers say. The downward trend did not appear to be a fluke based on a couple of good or bad years; it still showed up when researchers removed the largest area (20.97 hectares in 1996–97) or the smallest (1.92 hectares in 2009–10) from the data, Williams and his colleagues report online March 21 in Insect Conservation and Diversity.

“We have enough data now to say that we are seeing a long-term decline,” Williams says.

That trend in winter populations may be statistically significant, says monarch researcher Karen Oberhauser of the University of Minnesota in St. Paul, but she and other researchers are now working on a broader analysis of monarchs and the challenges the insects face throughout the year to get a better handle on whether the population is declining and, if so, why. “I am not arguing that monarch populations are not facing threats, nor am I saying I’m not concerned,” she says. “I don’t think the trend data clarify the situation.”

EDIT

http://www.sciencenews.org/view/generic/id/72187/description/Worries_grow_over_monarch_butterflies

[Yo_Mama]

1. Ah, there's only one thing....

http://www.monarchwatch.org/news/021102.html

UPDATE: Links to other online articles added (see below)

11 February 2002

A massive moisture-bearing weather system moved into central Mexico late on 11 January 2002 which was followed by clearing skies and overnight lows in the mid to low 20s on the mornings of 14-16 January. What followed was unprecedented mortality at the monarch overwintering sites. In the following text I will summarize what is known at this time and will try to provide a perspective for this catastrophic event. --Dr. O. R. Taylor | Director, Monarch Watch

http://monarchwatch.org/blog/2010/07/monarch-population-status-9/
More bad weather hit them in 2010.

I've also seen a number of articles about deforestation in Mexico being the problem, but I don't think so. I think it is just the cyclical cold. This has all happened a number of times before and it will a number of times again.