Why Does the Blue Spring Daily Manatee Count Change? The primary factor in manatee migration is their need to leave cold water and find warm water. At Blue Spring, the main reason for the changing number of manatees from day to day relates to the difference between the River and the Run temperatures. Listen to Ranger Wayne explain: Audio Clip (Click here .aif format, 1521 K) or (Click here .wav format, 1521 K) Ranger Wayne Measuring Water Temperature at Blue Spring "The magic number is in the river, its 68 degrees F. When the River temperature gets down to 68 as the cold weather comes on, the manatees start coming into the Run. The lower it gets below 68, the more manatees you're going to see." Copyright 2003-2004 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form