94 THE SENSES OF ANIMALS 



times, of course, all these scents may be combined in what 

 is commonly referred to as "body scent". 



Whether the odour given off by a mammal is on the 

 ground, or in the air — due to the mere passage of the beast — 

 it is the degree of moisture and temperature that controls 

 the diffusion of scent particles, plus the effect of the wind 

 currents. All "scent" is vapour, and it is the intake of this 

 vapour and its consequent warming up as it travels along 

 the nasal passages of a mammal that finally guides or 

 stimulates that mammal in one kind of activity or another. 

 It is not possible to go into all the aspects of scenting con- 

 ditions here, but some reference to what are known as 

 micro-climates must be made. A micro-climate may, perhaps, 

 be described non-technically as the conditions of damp, heat 

 and cold, and wind currents prevailing in a small area of 

 ground within a larger area. For instance, we may be inspect- 

 ing a piece of waste land of uneven character with a ditch 

 or two, perhaps some patches of scrub and so on. Now the 

 general weather conditions over the whole of that area may 

 well be changed in one way or another due to shelter from 

 the wind, the presence of water, or some conformation of 

 the ground ; and in certain spots the degrees of moisture or 

 warmth or cold, and even the direction of wind currents 

 will differ again from those of the whole area. These micro- 

 climates will affect scent to some degree and will confuse 

 the observer's conclusions if not taken into consideration. 



It is not only humans who may be deceived by conditions 

 in micro-climates, some wild animals may themselves be 

 handicapped — at least momentarily — in this way. Naturally 

 in these small areas where wetness or dryness and wind 

 currents may differ from the general weather prevailing it is 

 the part of the area nearer to the ground that is most 

 affected. 



All the points mentioned will, I hope, be made clearer 

 when various groups of animals are discussed in the next 

 chapter. 



