SIGHT — FIELDWORK AND EXPERIMENTS 4I 



in SO far as the difference in agility and the size of the toad 

 reflects some variations. It will be clear to the observer that 

 a really large toad such as the South American Giant Toad 

 will have a much longer tongue, and will, therefore, be able 

 to take in prey which may be two to five inches away from 

 it; while our own Natterjack Toad, being a running toad 

 capable of quite a good speed, will be able to compensate 

 for its much smaller size and shorter tongue by its quickness 

 of movement. Like frogs, all toads take only moving prey, 

 and stories that they will take prey which is still are due to 

 faulty observations. A moth at rest in good light conditions 

 may appear to be still, but its wings or the antennae, delicate 

 though they are, will be moving slightly. This is enough for 

 a toad to be stimulated to flick out its tongue and capture 

 the insect. A mealworm which is about to pupate is often 

 apparently motionless, but even if it is lying on its back tiny 

 movements of its legs will seal its doom. Many large tropical 

 toads will eat mice ; and if a mouse is put into a tank or cage 

 having been just previously killed, it will still produce small 

 reflex movements quite sufficient to attract the notice of the 

 toad. A live mouse in the wild will "freeze" if it senses danger, 

 but it will not stop breathing, and the almost imperceptible 

 breathing movements will again suffice to activate the toad. 

 At short distances a toad can see movement which would be 

 invisible to a hunting owl. 



One caution is necessary when carrying out experiments 

 of this nature. Toads being crepuscular and nocturnal 

 creatures, cannot instantly adjust themselves from natural 

 environmental Hght conditions to those brought about by 

 using a torch to aid in observations in the ordinary habitat ; 

 and still less can they make the necessary optical adjustment 

 when in captivity and where from being in a nice shady tank 

 in a dark room they are subjected to the sudden beam from 

 an electric lamp or torch. This means that before settling 

 down to make observations of feeding behaviour it is neces- 

 sary to give the toads at least five minutes to accustom them- 

 selves, or rather their eyes, to what to them must be a 

 dazzling light. I have also noticed that toads will often try 

 to take a moving insect soon after their light conditions have 

 changed, but they will miss their mark. This does not reflect 



