32 UNIVERSITY OF COLORADO. 



The tiny hummingbirds, "glittering fragments of rainbows," as Audubou 

 called them, are of great aesthetic and scientific interest, and entitled to 

 preservation. Economically they have few bad habits, though they do destroy 

 some parasitic Hymenoptera, offsetting the damage they thus do by their good 

 work in pollenizing flowers and destroying harmful insects. Their chief 

 food is the nectar of flowers, which does not show in analyses of stomach 

 contents. One stomach examined by Aughey (114) contained 4 small locusts. 

 Warren (according to Sullivan) found spiders, beetles and other insects in 

 62 stomachs (115). Stomachs of 59 ruby-throated hummingbirds contained 

 (ignoring the nectar item) Hymenoptera 36% (largely parasitic and hence 

 useful), bugs 8.8%, gnats 2.5%, spiders 43.4%, vegetation 5.6%, while stom- 

 achs of 111 Anna's hummingbirds contained gnats and small flies 45%, bugs 

 17%, spiders 2%, Hymenoptera 35% (116). 



PASSERES- Perching Birds (Song Birds) 



The order Passeres includes over two-fifths of all the bird species found in 

 the United States and Canada. Their food habits are varied, and our space 

 permits only a brief summary of each family. 



Tyrannidae. The flycatchers feed mostly upon flying insects taken on 

 the wing, though true flies constitute only a minor item of their diet. 

 Stomachs of 3,398 specimens, representing 17 species, contained an average of 

 94.99% animal matter (chiefly insects), and only 5.01% vegetation. The 

 percentages of the various elements of their food are tabulated as follows, 

 omitting the fractions of percent which occur in the original table (117) : 



(114) Aughey, Ibid., p. 39. 



(115) Sullivan, Ibid., p. 32. 



(116) Beal and McAtee, U. S. Dept. Agric., Farmers' Bull. No. 506, pp. 15-17. 



(117) Beal, Food of Our More Important Flycatchers, U. S. Biol. Surv., Bull. No. 

 44, pp. 5-6, 1912. 



