Observation on Sand-Martins at the Nest

in the Sand-Martin (Riparia r. riparia) is said to be " by both sexes but positive data scanty" (F. C. R. Jourdain, 1938)* ; males had been found on eggs by Stoner {1936), but the nature of their participation in the brooding was not ascertained. We had a nest containing eggs under observation for 7 hours on July 1st and z hours on July 2nd, in fine weather. The most usual thing was for the birds to...