ZOOLOGICAL NOTES 133 



certain) one of the dogs belonging to the lighthouse keeper killed 

 one at the head of the jetty, which was the first seen or heard of on 

 the island. At the time there was a lighter lying there discharging 

 coal for the Light Station, and it was supposed the rat had come 

 from her. On nth December 1889, Mr. Dawson, the second 

 keeper at the station, wrote me, saying, " It was said at one time 

 that rats would not live here, but we find that to be a mistake ; for 

 of late 48 have been killed, and as yet there seems to be plenty 

 more about the place." From this, it will be seen that at that date 

 they had obtained a firm footing on the island, which, being a 

 favourite breeding-place of sea- fowl, and with a fringe of rough 

 boulders and masses of rock round the base of its steep cliffs, had 

 all the essential requisites as a suitable home for the rat. In the 

 following year, Mr. Dawson (in lit. 3d March 1890) says, "The rats 

 are commencing to be a perfect nuisance here. Mr. Ross, the 

 keeper of the lighthouse station, killed one a few days ago which 

 weighed 18 ozs. ;" and again, a few months later, "it is not safe to 

 put your hand into a hole for a puffin, for the chances are that you 

 get a rat instead." So serious were matters beginning to appear that, 

 on i ;th November, Mr. Dawson wrote me, saying, "Rats are on the 

 increase : last Sunday, 59 were killed by one dog at the west side 

 of the island. We are going to have a regular field day amongst 

 them, all hands are to turn out with their dogs." From this time 

 on, constant warfare was waged against the vermin by the tenant who 

 rents the island, he being the chief sufferer, as the rabbits were eaten 

 in the traps and the strings cut by them. The eggs and young of 

 the sea-fowl also paid large tribute to the omnivorous rodent, so much 

 so, that fewer young, I believe, were reared than has ever been the 

 case before. On 2d November last, Mr. Ross wrote, saying, "last 

 year from the ist October till the end of December [i.e. in 1890], 

 while the keeper was catching rabbits, he killed over 900, and I am 

 sure my dog killed over 100 about the doors; since then we have 

 not been keeping count of the numbers we have killed until the first 

 of last month, and since then there has been over 300 killed, and 

 yet they seem as plentiful as ever. They are all over the island, 

 from the very top down to the water's edge. Meat is getting very 

 scarce for them now since the birds have left, so that they have 

 started to eat the ones that have been killed. There is bound to be 

 a good number poisoned as well, as the tenant mixes up arsenic 

 with all the rabbit offal, and it all disappears. We thought last 

 year, seeing they were getting so much poison and eating one 

 another, that they w r ould all disappear, but now they are thicker 

 than ever." As this was the state of matters within three years 

 after the introduction, or rather the invasion of the rat, it is not 

 difficult to see that Ailsa Craig will, like Puffin Island, on the Welsh 

 Coast, and the Copeland Islands in Belfast Bay, be ruined as a 

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