Monday, September 18, 2006

Spatial Landmarks for Foraging Columbian Ground Squirrels

We’ve all seen these cute little creatures scurrying through the grass or jumping the trees to find food for winter, but how is it they seem to know exactly where the food is that they want? How are they able to tell which food will be the most nutritious and essential for survival? Many experiments have been done in labs to answer these questions, but there is always the chance the results are due to unnatural conditions that are not the same as out in the wild. In the January 2006 edition of Animal Cognition, Anna Vlasak published her findings from a study done with Columbian Ground Squirrels. She tested the global and local spatial landmarks they used to find food in a natural location.

In her study nine identical platforms were evenly spaced in a meadow in Alberta, Canada surrounded by a forest. Results were concluded from fourteen adult free-range females that completed both the training and the tests. Experiments were done to test if squirrels responded to local landmarks (vegetation pattern, burrows, rocks, bushes), global landmarks (forest edge, the outline of the mountains), both local and global, or a familiar route to find the platforms with the correct food. To rule out olfactory all platforms were made to smell the same, the only differences were the landmarks around the platforms. Artificial landmarks (flags, ball, log) were put out to serve as local landmarks so they could be easily manipulated. After training the squirrels on the platforms six trials were done. Trials 1-4 were used to test the manipulation of artificial landmarks and trials 5 and 6 were used to test the importance of natural landmarks. After trials 1-4 were complete the data showed that squirrels seemed to ignore the local artificial landmarks and had memorized the food location by a mixture of natural and/or global landmarks. Even when the artificial landmarks had been moved the squirrels were still able to find the correct platform. When trials 5 and 6 were complete fewer squirrels were able to find the correct platform because the platforms were shifted in a way to change the global landmarks. However, the fact that some squirrels were still able to find the correct platform proves that they also use a familiar route when finding food. Vlasak concluded “that squirrels disregarded information provided by artificial local landmarks when a familiar route, natural local, and global landmarks were available to them.” She also found that “when known global landmarks were not present, animals seemed to be able to refer to the spatial arrangement of the [platforms].”

This idea of spatial recognition has been tested on other animals and found to be true. Foraging honeybees are able to find more sugar feeders when visual cues are given with scent cues. There have also been tests on the results of animals that have had their memories impaired. A study by Annabelle Belcher and her colleagues was done on adult male Sprague-Dawley rats and the effects of methamphetamine (mAMPH) on their memory. Scent cues seem to play a role in animal recognition, but an animal’s spatial recognition seems to be the most important factor for an animal’s survival.

Posted By REC (3)


At 10:37 AM, Blogger CatherineS said...

I found this post to be thought provoking and highly relevant to the current material in lecture. The juxtaposition of the Vlasak field experiments with Belcher's work in the lab covers a lot of pertinent territory. The manipulation of landmarks and the demonstrated ability of the test subjects to find the food platforms despite changes in the landscape, does seem to indicate memory/cognition skills. Belcher's work with Sprague-Dawley rats is equally fascinating from a physiological perspective, in that it examines the role of the hippocampus in the recognition/memory abilities of subjects in the presence of compromise and deficit. e inclusion of the Reinhard paper re: Honeybees was also enlightening, specifically the aspect of chemical olfactory cues and the process by which they are distributed. The confluence of papers on observable behavior within the framework of a manipulated environment, measured physiological responses to altered anatomy and the examination of the effect of chemical cues on feeding behavior was well done.

At 7:53 PM, Anonymous kaykay said...

This post seemed to be very informative. It was very clear and precise. I was just wondering if the experiment would make much of a difference if male squirrels were being tested as well as females. I found it interesting that when “known global landmarks were not present, animals seemed to be able to refer to the spatial arrangement of the platforms.”

At 10:20 PM, Blogger PWH said...

I found these tests to be very interesting and very informative. I found a few other experiments on this type of behavior, but none seemed to be as helpful in understanding the information. At the end of Vlasak's article she says there may have been a difference in how male squirrels reacted to this experiment, but that she had not done any tests on this theory. An article by Eileen Lacey and Nancy Solomon describes some of the studies done over the years on rodents and what conclusions some scientists have come up with. This can be found in the Journal of Mammalogy; Volume 84, Issue 4 (November 2003).

I hope this has helped and thank you so much for the comments.

Posted by REC


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