ON RATS
[To the Editor, of the SrEcraTon.]
Sia,—With regard to Mr. Oliver Warner's inquiry about black rats and brown squirrels, in the Spectator of March 9th, •the black rat is still frequently found in the ports of East Anglia, and occasionally in London -docks. At Yarmouth and Ipswich there appear to be permanent eolonies independent of introduction from ships : an Ipswich rat-catcher reports catching several this winter. It is difficult to say, however, whether these colonies are true survivals of the old population or merely invaders from shipping, as the black rat is still a very common resident of most merchant vessels. The black rat is• holding its own on Lundy, but in nothing approaching its former numbers. -
The present scarcity of the brown squirrel may, in some districts, be due to the grey-squirrel invasion, but the facts show that in the greater part of the country decreases have occurred where the alien has never been seen. From the evidence so far to hand, it appears that the most potent factor influencing our native, squirrel population is the periodic occurrence of disease.
As many'of your readers are aware, we are now investigating the whole problem of fluctuations in numbers and epidemic diseases of rodents, and we should be greatly interested to hear from anyone who may be able to give any information bearing on this subject. The main points on which evidence is particularly required are : 1. Sudden increases in numbers and years of abundance of any rodent. 2. Decreases in number, ' and years of scarcity. 3. Disease of any kind among rodents. —I am, Sir, Ake.;
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