Tuesday, February 2, 2010

Free Science Classes: Orca Communities

Every winter the Marine Science Center opens its doors to hundreds of elementary school students, offering classes about exciting topics in current science.  A grant from the Institute of Museum and Library Services (IMLS) enabled us to provide bussing stipends and offer the program free of charge.  As a result, we've been able to schedule almost eight hundred 4th and 5th grade students from public schools across the Northern Olympic Peninsula! 

In accordance with our Killer Whale-themed year, these courses are all about the ecology and behavior of Orcas. Each group attends two distinct classes during their visit; "Orca Communities" and "Orca Food & Habitat".  Today this blog's spotlight shines on the Communities class, but stay tuned for another blog about Food & Habitat!

The aim of the "Orca Communities" course is to familiarize students with the two types of Orcas we have in our area (The Salish Sea).  These two groups, "Southern Residents" and "Transients", differ radically in their diet, behavior and range.  As such, they are considered separate "ecotypes" and some researchers believe that they should actually be classified as subspecies. Transients travel in small groups, exclusively eating marine mammals.  Residents travel in much larger groups called "pods" and only eat fish (salmon is their favorite).

We begin the "Orca Communities" class by differentiating the two groups based solely on diet: fish eating vs. marine-mammal eating.  Once the students are clear about this distinction, we discuss morphological differences between the groups, while also discussing how individual Orcas are identified:

The bulk of the class, however, is dedicated to the marked behavioral differences between Transients and Residents. Each table of students is given a gridded map of the Salish Sea (including Vancouver Island) and a packet of "information from scientists".  In reality, the packets were complied by us, but they are indeed comprised of real, current data from researchers. Each group of students uses these handouts to trace the movements of Resident pods or of one of three Transient whales. The packets provide dates, locations and map coordinates for these movements based on visual sightings or data from satellite tags.

An example of a "research report" handout:
The first step is to sort the "research reports" by date:
Students From Jefferson Elementary
Each group then plots their respective Orca's movements on their maps (all fall within the date range of September 15-30, 2009):
Students From Jefferson Elementary
Finally, we call each group to the front of the room to share their discoveries with the whole class (each velcro dot represents the location of one Orca sighting):
Students from Jefferson Elementary

The result: the students who mapped the geographical movements of Residents find that they have very small, localized movements, almost exclusively along the West coast of San Juan Island.  The shock-and-awe part of the lesson comes when the groups with Transients begin to plot their whales' movements: one circumnavigates Vancouver Island!  Another transient moves all the way from South Puget Sound to Neah Bay, all within the course of a few days!

We also spend time speculating about the reasons behind these drastic differences. For those who are interested: the answer seem to lie in their respective diets.  Residents feast on the migrating salmon that pass by San Juan Island, while Transients must track down the smaller groups of marine mammals (like seals) which are more widely dispersed. In the case of Orcas, the classic idiom "you are what you eat" ought to read "you move like what you eat"!

Stay tuned for another blog about the second class, "Orca Food and Habitat"

Special thanks to the scientists who shared their research for this class:  Robin Baird, Gregg Schorr, and Brad Hanson for the transient sattelite tagging information, The Center for Whale Research for the orca photo identification, and OrcaNetwork for the resident orca sighting data.

-Jess Swihart
Natural History Exhibit Education Coordinator

For more information about these two ecotypes and their taxonomy check out these sites:

Here's one of our sources for the mapping activity (for our handouts I condensed the sightings for September 2009 to reduce complexity and minimize confusion):

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