378 HISTRIONICUS HISTRIONICUS 



other insects are taken in summer. Vegetable matter is mentioned by a few writers, 

 but it probably is not an important part of the whole. 



Examination by our Biological Survey of 22 stomachs of the Harlequin Duck taken 

 in British Columbia and Alaska from November to April shows that the species is 

 almost exclusively carnivorous. Vegetable matter (algse) amounted to less than one 

 per cent of the total contents of these stomachs. The most important food items 

 were mollusks and crustaceans. Of the former both bivalves and univalves are taken 

 and no fewer than 165 of the latter were found in a single stomach. The mollusks 

 with jointed armor, known as sea-slugs (Chitonidce) are freely taken. Of the 

 crustaceans, water-fleas (Amphipoda) predominate, but crabs including hermits are 

 often eaten. Barnacles also rank high in frequency of occurrence. The sea-loving 

 Harlequin gets representatives of various other groups of marine organisms, in- 

 cluding hydroids, sea-spiders, bryozoans, sea-urchins, foraminifera, and tubicolous 

 worms (W. L. McAtee, MS. notes). 



There are, of course, many other references to food habits; thirty-nine small shells 

 (Columbella luneatd) and several small Littorince were found in one stomach (Whit- 

 field, 1894). L. M. Turner (1886) found that shellfish of all kinds, but especially the 

 common black mussel (Mytilus edulis), were taken in Alaska. In the same region 

 Belding (J. Grinnell, Bryant and Storer, 1918) found them feeding on isopod crusta- 

 ceans, gathered under stones on the beach. The summer food in Iceland is comprised 

 of the larvae of Ephemeridoe and Phryganeidce (Slater, 1901), the crab, Cancer pulex, 

 Nerita and other small mollusks, as well as water plants (Faber, 1822); Hantzsch 

 (1905) took from one stomach spindles and complete Littorince, larger crustaceans, 

 as well as numerous complete eggs of a bone-fish, two millimeters in diameter. 



In the Pribilov Islands the contents of eleven well-filled and eight nearly empty 

 stomachs showed that the commonest foods in a region especially rich in inverte- 

 brate life were amphipods which were taken in the proportion of 51.4%. Hermit 

 crabs composed 25.1% and mollusks 19%. The vegetable food was less than 1% 

 and may very well have been taken accidentally (Preble and McAtee, 1923). 



It seems that Harlequins, like Scoters and Eiders, are occasionally caught by large 

 mussels or clams into whose open shells they have pushed their bills. L. M. Turner 

 (1886) speaks of finding them drowned by mussels in Alaska. 



They do not obtain all of their food by diving. In shallow streams they are often 

 seen walking along on the bottom merely plunging their heads under rocks or be- 

 tween boulders. They can often be seen shoving themselves along on the bottom 

 against a strong current with their feet alone in much the same manner as the Dip- 

 per (Johnstone, 1921). Their ability to take food under the strongest breakers has 

 already been mentioned. In summer they feed in just as dangerous places, right 

 under the foot of a waterfall where tons of white water fall from above, churned up 

 by jagged rocks below (Millais, 1913). 



