YELLOW-BELLIED SAPSUCKER 131 



amined the body of one of these birds and reported enlargement and 

 fatty degeneration of the liver. 



Mr. Bolles remarks that "the most probable cause of this enlarge- 

 ment of the liver, which seems to have been the reason for the death 

 of the three sapsiickers, was an undue proportion of' sugar in their 

 diet. In a wild state they would have eaten insects every day and 

 kept their stomachs well filled with the chitinous parts of acid in- 

 sects. Under restraint they secured fewer and fewer insects, until 

 during the last few weeks of their lives, they had practically no solid 

 food of any kind." 



Summarizing his observations, he says: 



From these experiments I draw the following conclusions: (1), that the 

 yellow-bellied woodpecker may be successfully kept in captivity for a period 

 corresponding to that during which as a resident bird he taps trees for their 

 sap, sustained during this time upon a diet of which from 90 to 100 per cent 

 is diluted maple syrup; (2), that this fact affords evidence of an extremely 

 strong character, in confirmation and support of the theory that when the 

 yellow-bellied woodpecker taps trees for their sap he uses the sap as his 

 principal article of food, and not primarily as a bait to attract insects. 



Winton Weydemeyer (1926) in Montana "observed a pair of red- 

 naped sapsuckers * * * gathering sap to feed their young in 

 the nest. A regular tree-route, followed alternately by the male and 

 female, included a quaking aspen, a larger alder, and a large willow, 

 in which borings had been made. The birds flew directly from the 

 nest to the aspen, and gathered the sap that had accumulated since 

 the last visit; then flew to the alder and to the willow, repeating 

 the process; and finally flew back to the nest, without hunting for 

 insects. Occasionally the male would vary the process by catching 

 a few flies from the air, eating some and carrying some to the nest." 



Forbush (1927) gives the incubation period of the yellow-bellied 

 sapsucker as "probably about 14 days." 



A. Dawes DuBois furnishes the following note: "Yellow-bellied 

 sapsuckers were observed feeding young in a nest, in Hennepin 

 County, Miiin., on July 5, 1937. The nest was about 25 feet above 

 ground in a partially dead tree at edge of willow-and-alder thicket 

 adjoining w^oods. Both parents were bringing food. The squeaky 

 note of the young was repeated with such regularity (about four times 

 a second) as to indicate that only one nestling was uttering it. Wlien 

 the nestling was being fed at the entrance, by the poking method, 

 these notes went up to a higher pitch, and were sometimes choked oJff 

 almost to inaudibility. 



"Two days later, the parents were still feeding very frequently. 

 The male, who on the first day had been seen to bring a bright red 

 berry about the size of a pea, again brought a bit of small red fruit. 

 On one occasion, when the parents were away, the nestling put its 

 head out of the hole ; but it did not do so when being fed. In gen- 



