Take time out to read this
Google book from True Stetson, I came across it from recent notes inside
'Chasing the Sun': How scientists diminished the Sun by Richard Cohen
Richard goes on to say... "
In 1937 the memorably named scientists H. True Stetson, of MIT and Harvard, came up with new evidence - Rabbit skins. The pelt records of the Hudson Bay Company showed remarkable variations in the number of Fox, Lynx and Rabbit taken over periods of ten to eleven years. Nearly every peak corresponded "quite closely" with the scarcity of spots. "If sunspots have anything to do with Rabbit popultion," Dr. Stetson continued, "and sunspot years have been favorable for tree growth, one might wonder why Rabbits appear most numerous near sunspot minima and most scarce near sunspot maxima".