58 
JOURNAL OF MAMMALOGY 
that the graysquirrel population in the palmy days of 1800 may easily 
have numbered several billions. 
These great movements have never been clearly observed. The only 
way at present possible to fill the gap is by collecting the testimony of 
eyewitnesses — the old-timers who are passing away — for I have little 
faith in any great emigration since 1870. That was about the latest 
date at which primitive conditions continued anywhere in the northern 
Mississippi Valley. 
Will not our young naturalists render service now by interviewing 
all available old-timers — the men who joined in the squirrel hunts of 
the ’60’s — and make as full a record as possible of the time, place, 
extent, direction, etc., of every emigration that can be traced, together 
with facts that bear upon its cause and results or that in any way offer 
interesting light? 
AN APPARENT EFFECT OF WINTER INACTIVITY UPON 
DISTRIBUTION OF MAMMALS 
By Hartley H. T. Jackson 
INTRODUCTION 
It was the writer’s pleasure during the past summer (1919) to spend 
a few weeks investigating the terrestrial vertebrate fauna of the Apostle 
Islands, Wisconsin, as a part of the general study of the land vertebrates 
of the state now being undertaken by the United States Biological 
Survey, the Wisconsin Geological and Natural History Survey coope- 
rating. My first visit to the islands was from June 22 to 26, when all 
the time was spent on Madeline Island. I again visited the islands 
July 3 to 24, accompanied by Mr. Harry H. Sheldon and Mr. Arthur 
J. Poole who assisted in the work. On this second visit careful investi- 
gations were made on Madeline Island, July 3 and 4, 12 to 15, 20 and 
21; Outer Island, July 5 to 11; Presque Isle or Stockton Island, July 
15 and 16; Gull Island, July 18; Little Manitou Island or Gull Rock, 
July 18; Michigan Island, July 18; and Sand Island, July 23. Obser- 
vations of a more or less superficial nature were also made on other 
islands, but physiographical conditions were such that the more intensive 
work on the islands selected undoubtedly gave us a fairly accurate 
idea of the mammalian fauna of the islands as a whole. Mr. Sheldon 
and Mr. Poole returned to the islands September 4 and remained until 
