RS Brown 1763 Great Frigatebird McKean Island 24 Oct The preceding samples were collected at about 1200. Many of the animals were exceedingly fresh and thus the young are being fed throughout the day. The percentages of fish to squid are arrived at by visual determination, which is a bit crude, but 1000 is better than nothing. Attempts to separate out the job from squid and merge with separately sampled fish (because after) that large error is obtained at any rate. In testing my ability to visually estimate the percentage of each food type, I find in a few samples which were clean cut and each weighed individually that I come within 5% of the actual percentages — thus for this type of determination, I feel that the results are acceptable. The systematic variation presented in the samples does not justify any attempt at finer distinction at any rate. This probably because the birds are feeding on an opportunistic basis for the most part. The frigate regurgitation samples (both species) contain squid and some birds of larger domination in most cases than the specimen of the same prey found in stern samples. Thus it should appear that the frigate are either garantying both or are feeding for chalupus. The frigate samples of both species were collected in open mouth plastic bags and disposed 1 after weighing since they could not be adequately sealed with alcohol in them.