364 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



Costa's biinuningbird builds its nest in a great variety of situa- 

 tions and in many different kinds of trees, shrubs, and weedy plants. 

 Among the trees recorded are various oaks, alders, bays, walnuts, 

 willows, gums, sumacs, cypress, sycamore, hollyberry, hackberry, 

 orange, lemon, olive, avocado, and Paraguay guava {Feijoa sellow- 

 iana). It has also been found nesting in sage and various other 

 bushes, in dead yuccas, in Opuntia eGhinocarpa^ O. ramoshsima^ and 

 other branching cacti, and in various weeds, as well as in a hammock 

 hook and a wire loop under a porch, 



James B. Dixon writes to me : "Its range is in the more arid regions 

 and the nesting locations are often a long way from known water. 

 They often nest close by water also, and in favored locations are prone 

 to colonize. I have found as many as six pairs nesting within a 100- 

 foot radius in a dead cocklebur thicket near the edge of open water. 

 One of their favorite nesting locations is the dead yucca stalks, Avhere 

 the nest is placed in the hard, dead framework of the last year's dead 

 stalk, and usually some 4 or 5 feet from the ground. I have noted 

 nest locations in dead trees, on top of thistle leaves, on clinging vines 

 on cliff' faces, and in citrus trees in open orchards, but not near houses. 

 It does not seek nesting sites near habitations and seems to like the 

 wild isolated areas the best." 



Major Bendire (1895) says that "in the desert regions of south- 

 eastern California various cacti, the different species of sage {^Arte- 

 imsia) and greasewood bushes {Larrea)^ while in the canyons ash, 

 sjT^camore, scrub oak, palo verde, cottonwoods, and willows, furnish 

 their favorite nesting sites." 



In the Thayer collection in Cambridge, there are 24 nests of this 

 hummingbird, all of which I have examined. One of these was lo- 

 cated in a sage over a stream, another in a weed over a road, and 

 another over a stream in a white-alder bush, as well as many others 

 in more usual locations. One nest was built on the top of an old 

 nest of the previous season, the buffy color of the new nest contrast- 

 ing with the dull, faded gray of the old one. The nests in this series 

 show great variation in size and shape and in the material used in 

 their construction. Most of them are rather shallow. The nests are 

 not handsome or even neat in appearance, being rather loosely made, 

 as a rule, of a great variety of materials, plant down of different 

 colors giving a mottled appearance, shredded material from the sage, 

 bits of gray lichens, scales of bud-s or flowers, thistledown, vegetable 

 fibers, thin strips of bark, willow or yucca down, the whole tightly 

 bound together with cobwebs or fine plant fibers. Many nests are 

 more or less profusely lined with small, soft feathers of different 

 colors, and some are decorated with these on the outside. Some nests 

 are almost as simple as those of the black-chinned hummer, but even 



