Food consumption of the American merganser. (Fisheries research report: 1661)

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respectively, were killed during patrols. A 9. 3-inch brook trout with
a girth of 5 inches was forced down the gullet of the smaller bird with
firm pressure. Extreme pressure was needed to insert a 10. 2-inch
brook trout of 6-inch girth into the guiilet of the largest female bird; a
10. 8-inch brook trout with a 6. 5-inch girth was inserted into the male's
gullet. Size of the merganser and girth of the fish apparently limit
the size of fish eaten.
Two observations of the eiapsed time from consumption of
trout to elimination of fecal remains were imade for merganser i. On
the first occasion, March 2, at the start of feeding, elapsed time was
22 minutes. She had been starved for the previous 6 days and it was
assumed that her digestive tract was empty. In the second trial,
April 2, after the merganser had not been fed for the previous 2 days,
elapsed time was 20 minutes.
On March 12, merganser I was given a surfeit of trout. She
had been fed only about 4 ounces of trout per day for the previous 10
days and had lost more than one third of her body weight. In 24 hours
she ate 29 ounces of trout, more than 100 per cent of her body weight.
On March 20 and 21, after several days on a ration of 9 or 10 ounces
per day, she was again presented with a surfeit of trout. In the first
24-hour period she consumied 17.5 ounces of trout, or 50 per cent of
her body weight, and in the second 24-hour period her consumption
dropped to 11.5 ounces, or 23 per cent of her body weight.