76 
Till*: CONDOR 
Vol. XIV 
of flowers among which they can disport themselves and from which they secure the nectar 
and small insects which compose most of their food supply. 
Unlike the Black-chinned Humminghird or their larger cousin, the Anna Hummingbird, 
they seem to enjoy each other's company, and it is nothing unusual to find them almost in 
colonies, as many as five nests being located in a radius of fifty feet in an unusually well sit- 
uated grove of oaks. 
For the most part they arc cpiiet : but prior to tbe nesting season a short time are quite 
noisy, chasing each other up, down and around through the surrounding hushes and trees. 
Their note consists of a few sharp squeaks, given out more often when in very rapid flight 
than otherwise. During the breeding season the male has a very peculiar way of disporting 
himself before the female. When he locates his mate sitting on a tree, or more often on a 
low bush, he will ascend to an elevation of about one hundred feet and to one side of the 
female and will then turn and swoop down at a fearful speed, passing perhaps within a few 
inches of the watching female and ascending in the air to complete a half circle. This he 
keeps up until the female becomes impatient and endeavors to escape : then perhaps all that 
Fig. 27. KEM.'VLE COSTA hummingbird; nest in lemon- 
tree AT ESCONDIDO, APRIL, 1911 
one will see is a streak, and a sharp squeak or two is heard as they flash up the hillside, 
d'he noise that the male makes in doing his fancy dive is easily heard at some distance and 
quite often heard when the bird himself is not visible on account of the extreme speed at 
which he travels on his downward plunge. 
For nesting places Costa Hummingbirtls most commonb' select some bush on a cliff, or 
steep hank on a hillside, hut thej" are also to he found nesting in the orange and lemon groves, 
in olive trees, in dead cockle burrs in a river bottom or in dead trees: in fact they seem 
to prefer a dead limb rather than a live one for a n^-sting site. I think that is due to the 
fact that the nesting material they use harmonizes better with the dead branches. 
'I'he nest is made of plant down and weed leaves principally, bound together with cob- 
webs and lined with plant down and an occasional feather. A typical nest measures : inside 
depth, one half inch; outside depth, one and one-quarter inches; inside diameter, three- 
fourths of an inch; outside diameter, one and one-half inches. I'he female selects the nest- 
ing site and as far as 1 have observed, docs all the work on it, also all of the incubating, the 
