(me) Erika Mako (the old
man)
Sitting at the edge of our nation...
I saw orca whales in the wild for the first time. It is amazing to finally see the creature
whose mysterious sounds I have been analyzing for months now.
The Team:
Erika Danforth, senior, environmental science major
Matthew Ayres, senior, biology major
The Mission:
Our goal is to listen to the southern resident orca vocalizations with respect to boat noise.
Our question is if the orcas are disturbed by the boats, and do they make specific vocalizations in reaction to
this diturbance? We hope to correlate specific calls with the presence of boats. We will also be noting call density
in calls per minute to see whether calls increase as boats are present. There is very little known about the effects
of loud boats and other man-made noise on the orca whale. It is important to investigate the well-being of the
orcas as soon as possible, because their population is at a critical level. The sooner we can discover the effects
of man-made noise on the orca, the sooner we can make well-informed decisions about smart mangement techniques
in order to assure the viability of the species.
Background:
The southern resident population of orca whales (J, K, and L pods) makes a fairly distinct set
of 23 calls. There are few conclusive studies on the meaning of the vocalizations. Colorado College physics professor
Val Veirs has a research station on the west side of San Juan Island in Puget Sound, waters the southern residents
frequent for the spring and summer months. There are 8 hydrophones located along a 200 meter stretch of shoreline
at the research station. When the whales swim past, the hydrophone picks up their sounds, and the sounds are fed
to a computer which records the good ones (ideally).
Methods:
We collected as much data as possible from recordings made in 2001. Because the hydrophones
pick up the noise from the boats as well as the Orca vocalizations, we concentrated specifically on the Orca vocalization
recordings that have boat noise in the background. As we listened to the recordings, we kept track of which calls
we heard, how frequently they occurred, and whether or not trhere was boat noise present. We compiled a data set
that allowed us to quantitatively determine which calls occur most frequently when boats are present. The data
was divided into sections called pass-by's. These ranged from one inute to one hour when vocalizations were relatively
constant. Then we determined which pod was present during each pass-by. We used pod identification data collected
during that same time period by the Center for Whale Research for most of the pod identifications, and analyzed
the calls we had identified in a pass-by to determine the rest. This was possible because J and L pod each have
a handful of calls that are unique to the pod. Matching up the presence of these unique calls with specific pods
filled in the gaps left by the CWR pod ID data.
In the end...
We were not able to find any conclusive results that pointed to a specific call being used more
frequently when the whales heard boats. This was not surprising, considering there has never been any correlations
determined between a specific call and behavior. However, I learned a good deal about how Orcas communicate. I
was able to hear subtle differences in specific calls that seemed to show different moods or states of excitement.
For more information about variations within a specific call, visit Molly's webpage.
starfish
Mike and Mila, 2 salty dogs
This webpage last updated April 15, 2002
