August 28, 1964 (cont.) traps when checked. The roof rats were very large and strong. Their general condition was very good. Of the 8 sexually mature females, 2 were pregnant (both had early pregnancies) 3 had been pregnant previously. Ten of the 12 males caught were sexually mature. One of the sexually immature males caught was large enough to be sexually mature. This phenomenen, which had been observed in several of the population, could be the result of intense population pres- sure, Roof rats seem generally distributed over the island in considerable numbers. Why reproduction is occurring here and not on some of the other reasonably comparable sites is not clear. Norway rats were not found, to be here. bution though they might be expected Their colonial habits might have produced a distri- pattern which would have been missed by the sampling pro- cedure used.