289 



Common Names Scientific Names 



Striped Gopher Citdhis tridcccmlineatus (Mitch- 



Gray Gopher Citdhis jrankhm (Sabine) 



Prairie Meadow-mouse Microtus austerus (LeConte) 



Skunk Mephitis mesomdas azna (Bangs) 



Weasel Putoriiis novehoracensis Emmons 



Short-tailed Shrew Blarina hrevicauda Say 



Common Mole Scalops aqiiaticiis machrinus 



(Rafinesque) 



RELATION OF THE PRAIRIE VERTEBRATES TO THEIR ENVIRONMENT 



The influences that seemed to be the most important in determin- 

 ing the character of the vertebrate fauna of Station I were its size, 

 its topography, its chmatic conditions, its vegetation, its invertebrates, 

 the interactions of the vertebrates themselves, and certain features in 

 the country surrounding the station. 



The small size of the area studied was undoubtedly an important 

 factor in giving the place a small vertebrate fauna. Any favorable 

 feature for a particular species in the way of food, shelter, nesting 

 place, and so on, could not be extensive enough to attract many indi- 

 viduals of the species. 



The topography was of such a character that a diversity of con- 

 ditions, chiefly hydrographic and vegetal, were brought about. A 

 varied fauna was thus produced, with some animals that were strictly 

 acjuatic and others that were entirely terrestrial. 



The weather has a marked effect on the vertebrate life. In win- 

 ter little activity is manifest, though a few roving winter birds may 

 search about the dead but standing herbs for seeds; shrikes and 

 sparrow-hawks may rest on the wires ; and a few rabbits may hide in 

 the dead, ground vegetation. In spring the wet weather, that usually 

 comes, causes the forming of pools where amphibians breed. In dif- 

 ferent summers the amount and frequency of rainfall differs greatly. 

 In 19 10 and in 19 12, small pools or areas of wet ground were pres- 

 ent most of the time, and acjuatic or partly aquatic animals were 

 prominent through the season; but in the summers of 1911 and 1913, 

 dry weather prevailed, and water animals, except crawfish in burrows, 

 seemed to be entirely absent. The appearance and slow disappear- 

 ance of the pools, especially of the large pool, bring about a succes- 

 sion of animal habitats — pond changing to mud flat and the latter to 

 low, dry, cracked ground with scant vegetation. Each of these has 



