THE WHITE-MOUTHED DIGGER WASP A C T I V I T I E S C U R T A I L E D BY W E A T H E R ,
T h e unsettled weather which set in on the 12th of July and continued for the rest of the year brought a sudden and early end to the activities of this wasp. They made three attempts to continue their work between the 12th and 18th of July, but each time they were overcome by the cold winds. T h i s was shown in the evenings when I observed one or two crawling about and was able to pick them up. They eventually succumbed to this weather and none were observed after the 18th. HENRY J.
MOUSE RESEARCH IN SUFFOLK ALTHOUGH the house -mouse (Mus musculus L . ) is one of the best known mammals in the world, surprisingly little is known about its habits. Volumes have been written about laboratory strains used for physiological experiments, but until the outbreak of war in 1939, the wild mouse received almost no attention in this country. Then it became clear that large stocks of c o m and flour would have to be held for long periods, often in makeshift buildings from which mice could not be efficiently kept out. T h e rapid increase in numbers of mice living in these stores became alarming, and damage to ricks also became a problem of national importance. Throughout the war biological research on the mouse, and on the brown and ship rats, was carried out by the Bureau of Animal Population, but after 1945 this work was taken over by the Infestation Control Division of the Ministry of Agriculture and Fisheries. Members of the Society may be interested to learn that the Ministry's mouse research is partly being carried out at Rougham near Bury St. E d m u n d s in an ex-R.A.F. building. T h e s e buildings erected in East Anglia for the services have been put to some odd uses since the war, but surely one of the queerest conversions has been this development of a building designed for the training of bomber pilots into an official residence for a colony of wild house mice. Here the mice can be watched without disturbing them and information about their innate behaviour is being gained which may assist in designing intelligent control measures. T h e structure contains a ground floor room 20 feet Square and fifteen feet high, in which the mice are ailowed to roam about freely, and an upper room, fitted with Observation holes in the
MOUSE RESEARCH IN SUFFOLK 186 floor, through which the observer can watch the mice. Stairs connect the twofloorswith an open landing which is a very suitable Observation post. There is also a small room adjacent to the groundfloorroom and connected with the landing by a ladder. Mr. H. N. Southern of the Bureau of Animal Population found that mice showed no objection to dim red light, so the main room is usually lit uniformly by red bulbsfixedto the high ceiling. Experience has shown that wild house mice behave quite naturally in this dim red light, and this was checked by also watching them in the absence of all visible light using an infra-red telescope. Flood lights arefittedfor cinematography, but mice must be patiently conditioned to these and to the sound of the camera before their normal behaviour can be photographed. One of the chief advantages of having wild mice available for direct Observation is that it enables us to clear up many populĂ¤r misconceptions about their behaviour. It is often claimed, for example, that mice avoid traps or baits handled by humans. Direct Observation reveals that this is not so. Conversely certain aromatic substances are claimed to attract mice. Those tested so far have had just the opposite effect. The aspects of this work of greatest interest to the naturalist are those which reveal details of the mouse's social life. It has long been known that laboratory micefightamong themselves, particularly if males which have previously been living in separate cages are brought together. There is little evidence, however, for or against the idea that wild mice behave similarly. The work at Rougham has shown that aggressive behaviour is very important in the life of the mouse, and that it probably functions as territorial behaviour, which is well known among birds. A mouse which has been living in the room for a day or more usually rushes at and chases any strĂ¤nge mouse which is introduced. After some hours, however, it may have established an amicable relationship with a mouse of the opposite sex. Two females similarly will not persist infighting,but when two males are confined together one becomes dominant and chases the other whenever they meet, and this State of affairs continues indefinitely. When a number of males live together in the room two types of social order may be seen. In thefirst,the mice become " sorted out " into a social heirarchy, which is rather similar to a peck order among chickens, except that in the mice the individuals do not recognize one another by sight, but by smell and behaviour. One mouse, in a social position half-way down the ladder will sometimes mistakenly attack one of his superiors, whose behaviour rapidly convinces him of his error. The females present do not appear to become involved in this social Classification. They are sometimes rushed at in error but their behaviour at once causes the attack to cease. The second type of Situation is that in which one male mouse is so superior in aggression and
MOUSE RESEARCH IN SUFFOLK
strength, that he becomes a despotic dominant while the other males become so cowed that, instead of fighting among themselves, they are all reduced to the same rank. This fighting does not usually seriously affect the health of the mice because of two interesting mechanisms. Firstly, house mice are very short sighted, and frequently, after beginning to chase one mouse, the dominant inadvertently transfers his attention to another, which allows the first victim to escape. The more mice present, the more this inability to confine attack to an individual tends to dissipate the aggression of the dominant male. Secondly, the so-called " home-cage " effect comes into play. This term was coined by workers with laboratory mice, after observing that a mouse tended to win fights in its own cage, and to lose in its opponents'. Similarly, among wild mice, it appears that a mouse low on the social scale may have one particular nest box within which he feels so secure that he can repel any attack. Here he is safe, and to this box he retums whenever chased by a mouse dominant to him. The attack ceases when he turns round on gaining his shelter and defends the entrance. The aggressive behaviour so prominent in artificial colonies of mice is absent in a mouse family. If a male is confined with one or two females and breeding occurs, a colony is obtained in which fighting is never seen. The mice spend much of their time sitting or feeding in little groups, and present a picture more consistent with the populĂ¤r conception of the meek, timid mouse. But if a strĂ¤nge mouse of either sex should venture into their joint domain the behaviour of the entire colony undergoes a striking change. Even very young mice, which have recently begun to take a few steps from the nest, rush at the stranger if it takes refuge among them. The grown mice of the family are soon all aware that a stranger is among them and their excitement grows visibly as they rush about searching for it. When two of the family meet a sniff establishes identity and they proceed on their respective paths, but when the stranger is encountered the sniff is followed by attack. When the others converge on the sounds of the scuffle the mechanism mentioned above comes into play, and the stranger may escape attention while two or three of the family chase one another for a few seconds. These and similar observations make it appear probable that families of mice maintain territories from which other mice are excluded, but many more details of their social life need investigation before we shall have a clear picture of the social Organization among the mice infesting a barn or a food warehouse, and this knowledge is necessary for practical reasons, quite apart from its considerable academic interest. W.