1147. Riparia riparia ijimse

(1147) Riparia riparia ijimae (Lonnb.).
THE EASTERN SAND-MARTIN.
Riparia, riparia ijimae, Fauna B. I., Birds, 2nd ed. vol. iii, p. 234.
The Eastern race of the Sand-Martin is found within our area in Cachar, Sylhet and Upper Assam, Manipur, Burma and Shan States. In Sakhalin, whence the type was described, Professor Ijima found this bird breeding in the cliffs along the sea-shore. In Assam small colonies, seldom exceeding forty pairs, were common all along the Surrma and Brahmapootra wherever there were suitable banks, I also found them on the North of the Brahmapootra breeding in the streams wherever these had clear running water and sandy hanks. Where the banks were earth, or even earth and sand, there were no Sand-Martins. I did, however, also find a few birds breeding in sandy borrow-pits beside roads and, on one occasion, found them breeding in one of these in company with Bee-eaters and a Kingfisher.
Tunnels, nests and eggs differed in no single respect from those already described for the preceding bird, but it may be noted that the chambers, about 6 inches wide each way, wore never more than 3 inches in height.
In Assam the birds commenced tunnel work as soon as the rivers fell in September, and I have taken eggs as early as the 6th October. Most eggs were laid between the 15th of this month and the end of November, but there seemed to be a recrudescence of breeding in March and early April, though these nests were constantly flooded out before the young had flown.
The normal clutch was four to six, and I do not remember ever finding twos and threes showing any sign of incubation.
Unfortunately at that time the status of the different races of Sand-Martin was not known, and I did not trouble to take many eggs, and most of those I did take were given away.
The average of twenty eggs is 17.5 x 11.9 mm. : maxima 18.5 x 12.1 mm. ; minima 14.9 x 11.0 mm.
Both species of Riparia nested in the banks of the Brahmapootra within 100 yards of my bungalow in Dibrugarh, but each species kept entirely to itself and I never found them mixed.