80 
THE CONDOR 
Vol. XI 
September Nidologist for 1894, which measured .87X.53; .88X.53; .88X.52; 
.86X.50. 
Nest no. 1 and the set of eggs are now in the Museum of Vertebrate Zoology 
of the University of California. 
Nest no. 2 was discovered June 15, when by moving a rock hanging to the 
face of the quarry, a crevice was exposed where several feet back in the solid rock 
out of our reach a nest with three young birds could be seen. I think the birds 
were a week or ten days old at this time, and they seemed to be of different sizes 
and without feathers. The birds were feathered on June 25 and on June 27 the nest 
was empty. The nest was located about fifteen feet from the floor of the quarry 
and fifty or sixty feet from the top. 
Nest no. 3 was also discovered on June 15. Four feet of decomposed rock 
were moved and a crevice in the solid rock exposed. Several feet back in the 
crevice we could see part of a nest on a shelf and hear the young. We could see 
parts of the feathered birds on June 25; but on June 27 the nest seemed to be 
empty. 
Probably there were at least twenty-five pairs of birds nesting in one large 
crevice in the solid rock, but it extended so far that it would have been impossible 
to secure the nests or even get a glimpse of them. 
I believe that the birds are residents on Slover Mountain during the entire 
year but they do not seem to be plentiful during August and September. Some 
days the birds are numerous and on other days not a sign of them can be seen or 
heard. The birds seem to know that they are safe while “in the rocks’’, for when 
I have surprized them in the quarry, I have seen the birds which were at the open- 
ings to narrow crevices crawl on out where they could turn around and then crawl 
back into the crevices out of sight. 
When not in the crevices they spend most of their time soaring above the 
mountain, probably feeding on insects. They can soar with much ease and can 
remain almost stationary in the air even in a strong breeze. No doubt the White- 
throated Swifts are the swiftest birds on the wing when they choose to “speed up”, 
and with rapidly vibrating wings and bullet-like speed they seem to enjoy passing 
within a yard of a visitor to their haunts. 
The swifts do not seem to have any musical ability, but their notes or calls are 
pleasing, especially to one who is studying them. One series of peculiar shrieks is 
given while the bird is in rapid flight and is suggestive of joyous freedom. Another 
series of notes is given when the birds are in the crevices, which sound very much 
like the twitterings of small chickens as they cuddle under their mother’s wings, 
only the swifts’ notes are much louder. These twitterings are quite a contrast to 
the wild shrieks, and they can not help but suggest comfort and satisfaction. 
The swifts are not alone on Slover, for many other birds find enjoyment here. 
Cliff Swallows ( Pctrochclidon lunifrons) and a few Barn Swallows ( Hirundo 
erythrogaster ) are frequently noticed flying about with the swifts in May and June 
altho they do not nest on the mountain. Rock Wrens ( S alp in ties obsoletus ) are 
common on the mountain during the entire year, and on useless trips to the old 
quarry there w ? as some satisfaction gained when I could see this little wren bobbing 
on a rock or hear its little song and sometimes find a nest in some convenient 
pocket in the rocks. Barn Owls ( Aluco pratincola ) monopolized the large 
crevices in different parts of the mountain and, due to their ignorance in choosing 
some places, it was not uncommon to smell burning flesh and feathers after blasts 
in the quarries. Intermediate Sparrows (. Zonotrichia leucophrys gambeli ) are 
common in the winter time. California Towdiees ( Pipilo crissa/is senicula) are 
