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JOUKNAL OF MAMMALOGY 
THE YOUNG OF THE CALIFORNIA GRAY SQUIRREL 
The large arboreal nests of the California gray squirrel (Sciurus griseus griseus 
Ord) are not uncommon in the Transition Zone forests of California but the find- 
ing of young in one of these nests is a rather unusual event. In fact, I have not 
been able to find any published account of the young of this species except general 
statements relative to the number to a litter and approximate season at which 
they are dropped. 
On April 13, 1919, while in the hills near Lake Lagunitas, Marin County, 
California, I examined a number of arboreal nests of mammals. Some of these 
were the work of the brown-footed woodrat, but the majority of those investi- 
gated had been made by gray squirrels as attested by their smaller and more 
rounded form, more compact structure, and greater height above the ground. 
In the Sierra Nevada nests of the gray squirrel are more often placed in conifers, 
but in the coast redwood belt the animals use the live oak, California laurel, and 
madrone. The nest discussed here was about 40 feet above the ground in a live 
oak, just within the crown of green leaves at the top of the tree. It came to 
attention only when the tree was examined from directly beneath. The nest 
tree was in a grove of live oaks on a slight rise of ground between two rather 
level small valleys. 
This nest was about 50 centimeters in outside diameter. The form of the base 
of the nest suggested that it might originally have been constructed by a western 
crow, a bird which is common in many parts of Marin County. There were 
portions of several flight feathers of a crow in the nest but these could well have 
been picked up on the ground by the parent squirrel when gathering material 
for the nest lining. The central soft portion of the nest was about 25 centi- 
meters in diameter. At the bottom it was made up of shredded oak bark pre- 
pared by the parent squirrel in the manner common to many rodents, and much 
of this material was in very short lengths. Above this was a soft mass of gray 
lichen, chiefly XJsnaa florida but with some Evernia prunastri and a slight amount 
of a moss, Alsia longipes. Over the moss and lichen were some live oak twigs 
cut green to which the leaves were still adhering. In the central soft part 
of the nest were the two young squirrels where they could easily keep warm while 
the female was away. 
The young squirrels were packed in an “egg’’ box and taken to Berkeley where 
they were kept alive for a few days, being sheltered in a box lined with cotton. 
They were fed on “Carnation” condensed milk, diluted with three parts of water. 
This diet was obviously unsuitable as it caused a violent digestive disturbance, 
more or less constipation, followed by a profuse diarrhea, and so weakened the 
young that they had to be killed and preserved as specimens. Upon autopsy 
of one of the squirrels the caecum was found to contain much caseated milk 
and to be bloated with gas. Possibly cow’s milk would have been more suitable. 
Instances have been reported where a cat whose young have been removed has 
acted as foster parent for young squirrels. Great difficulty was experienced in 
keeping the young squirrels sufficiently warm. 
When the nest was first opened a finger thrust at the young squirrels was 
eagerly seized and sucked — an obvious feeding reflex. Later, in captivity, 
whenever they were touched, their forefeet would work around and eagerly 
