Mammals of Porter County 209 



NOTES ON THE MAMMALS OF THE DUNE REGION OF 

 PORTER COUNTY, INDIANA. 



Marcus Ward Lyon, Jr., South Bend. 



The following notes on the mammals of the dune region of Porter 

 County are based primarily on a small collection which was made dur- 

 ing a brief camping trip into the dunes during the autumn of 1922. 

 They are supplemented by observations on mammals seen but not cap- 

 tured during that trip and numerous Sunday excursions and on reports 

 of apparently good authority. So far as I am aware there are no 

 previously published comprehensive records of the mammals of Porter 

 County. These notes contain little of novelty, but it seems desirable to 

 publish them because owing to the invasion of the region by week-end 

 visitors, the erection of permanent cottages along the lake front, and 

 more or less extensive forest fires it is not unlikely that the biological 

 aspects of this very interesting region will be rapidly altered. Many 

 animals and plants now common in the region are probably destined to 

 disappear as completely as the once common Virginia deer. 



Our tent was pitched in a sheltered spot a few yards back from 

 the lake front and about 50 or 60 feet above its level, north of Mineral 

 Springs station of the Chicago, Lake Shore and South Bend Railway. 

 Traps were set in the neighborhood of our camp and westward to op- 

 posite Oak Hill station. 



Acknowledgement is here made of the valuable assistance of my 

 wife, Dr. Martha Brewer Lyon of South Bend, not only for help in 

 placing traps and looking for mammals but also for acting as chef, etc. 

 while I skinned specimens. Special thanks are also due to Mr. H. W. 

 Leman of Chicago, for the privilege of camping on his property, and 

 to Mr. Gerrit S. Miller, Jr., of the United States National Museum for 

 assistance in the identification of specimens. The specimens collected 

 have all been deposited in the National Museum. 



As is well known the sand dunes at the southern end of Lake Mich- 

 igan are not barren tracts of sand. They present a variety of physi- 

 ographic features and characteristic associations of plants, if not of 

 mammals. In a general way these may be briefly described as follows.* 



The beach proper: This is the area between the calm low water 

 level of the lake and the rough high water level. It is practically de- 

 void of permanent vegetation. While perhaps most of the beach area 

 is dependent upon the size of the breakers formed after every heavy 

 northerly wind on the lake, some of it is evidently due to actual changes 

 in the water level. Northern winds seem to blow the water shoreward 

 as well as to throw it into large waves, while an off shore wind blows 

 it away again. Differences in barometric pressure over different areas 

 of the lake may also have an effect in altering the water level. Even 



* For a detailed description of the various associations in the region see .1 Natural- 

 ist in the Great Lakes Region by Elliott Rowland Downing, 1922, and for topographic 

 features Band McNalhj's Map of Indiana Dunes by P. S. Goodman [1920]. 



"Proc. 38th Meeting, 1922 (1923)." 

 14—25870 



