to Challenge Question #8:
Last time you calculated the number of days on the wintering ground for the HY2005 chicks as 106, the shortest time in five years of data. Sixth grade homeschooler Marcus gave you Challenge Question #8:
Marcus did some great thinking about factors that could affect the length of the Eastern flock's stay on the wintering grounds. He wondered whether they are heading north earlier because of earlier seasonal warming or because the cranes are learning that there is less available nesting habitat. Nick and Kathryn from Iselin Middle School also thought that global warming could shorten winters and send cranes packing earlier. Good reasoning!
However, scientists need to look at all the variables that influence their data.
Here's what Tom Stehn said:
The analysis of the WCEP whooping cranes spending a shorter winter in Florida over the past 5 years might be meaningful if the ultralight arrived in Florida on the same day each year. But the ultralight's arrival is partly determining the length of stay on the wintering grounds. The ultralight's arrival, however, depends not only on when the migration leaves Wisconsin, but also on the weather en route. Thus, to me, the students have done a good job compiling data and calculating length of stay, but conclusions aren't meaningful. It might be meaningful if the departure date from Chassahowitzka was getting earlier and earlier every year.
we add: You
can see the annual departure dates listed here. While
it is interesting to keep track of days on the
wintering grounds, we have learned something important! We need
to look at all the variables before deciding if it's a meaningful conclusion. Which
variables would need to be controlled in order for the conclusion to
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