Biological Papers. 121 



THE mole's guests. 



Whether willing or not, the mole finds himself compelled to act 

 as host to a large number of guests that throng his hallways. The 

 maze of passages that thread the soil everywhere furnishes conceal- 

 ment and lines of traffic to several species of small mammals not 

 favored by nature with the means for digging runways of their own. 

 What the mole's attitude towards each species of these intruders 

 may ba I have not been able to discover. In the case of the shrew, 

 I would infer it to be one of hostility, for the shrew and the mole 

 are on the lookout for the same kinds of food. The shrew is gen- 

 erally supposed to do some burrowing on his own account, but I 

 have trapped any number of the little animals in runways that 

 from their size and general appearance were undoubtedly con- 

 structed by moles. In fact, I have more than once found a trap 

 holding a dead shrew pushed up by fresh mole work almost out of 

 the small excavation I had made. Whether tolerated or not, the 

 shrew by no act contributes to blackening the reputation of his 

 host as do the other guests — mainly voles (meadow mice), white- 

 footed field mice and the common house mouse. These latter are 

 directly responsible for most of the thefts of grain, seeds and tubers 

 commonly laid to the charge of the mole. 



BREEDING HABITS. 



Though one of the most abundant of our small mammals, the mole 

 is a slow breeder. This we would expect of an animal withdrawn 

 from the strife and competition that reddens tooth and claw in the 

 world above his secluded burrows. As will be seen from the ac- 

 companying table, the number of young at a birth is normally 

 four, and but one litter is produced anually. These facts were 

 ascertained from the examination of a large number of females — 

 101 — taken in all months of the year. Thirty-three of these were 

 either pregnant or gave indisputable evidence of having recently 

 born their young. The first specimen of this latter number was 

 trapped February 27; the last April 20. 



It would appear, then, that in this vicinity (Manhattan) the 

 young are produced within a period of three to five weeks, mainly 

 in March and early in April. The period of gestation must be 

 comparatively short, for signs of pregnancy did not appear until 

 about five weeks before the first females gave evidence of having 

 born their young. I must admit, however, that my data on this 

 point are not full enough to warrant a positive conclusion; for, of 

 the twenty-five moles trapped during the months of December and 

 January, and up to February 27, only five were females. This fact 



