This audio file contains a recording of the territorial vocalization emitted by North American red squirrels called a "rattle." This recording relates to a paper that appeared in the April 18, 2013, issue of Science Express, published by AAAS. The paper, by Ben Dantzer at Michigan State University in East Lansing, MI, and colleagues was titled, "Density Cues Trigger Maternal Stress Hormones That Increase Adaptive Offspring Growth in a Wild Mammal."
Please cite the owner of the recording when publishing. This recording may be freely used by reporters as part of news coverage, with proper attribution. Non-reporters must contact Science for permission.