on Rearing Wild Finches by Foster-parent Birds. 355


of the young aggregating thirteen birds, all of which reached

maturity, and were strong vigorous examples of their kind.

This hen Canary seemed as solicitous for the young Song Spar¬

rows as she had been for the young of her own kind, and so far

as I could see she did everything in her power for her foster-

children. In spite of all her efforts, when the Song Sparrows

attained an age of about six days, and were just beginning to

show feathers, one by one they weakened and died, though

both the parent Canaries, cock and hen, fed and brooded them

constantly.


Later in the same season I secured a clutch of four Field

Sparrow’s eggs ( Spizella pusilla ), and' gave them to another

equally good pair of parent Canaries. The results were almost

identical with the case cited above ; the eggs were all hatched,

the young seemed strong and vigorous, the foster-parents

appeared to do everything conducive to their development, but

all of the young died during the first week after they were hatched

from the egg. This concluded my efforts in this direction for

the spring of 1901. In the month of May, 1902, I was able to

carry on a much more elaborate series of experiments, which I will

now summarize. Some of these, in the light of my former ex¬

perience, I conducted under slightly varying conditions, which I

thought might yield more definite results. On May nth, 1902, I

found in a field on the ground a nest of Field Sparrows, the

female sitting on four eggs, and there were, at the same time, two

larger eggs in the nest, which I took to be those of the Cowbird

(. Molothrns ater). The nest and eggs I brought to the house,

keeping them warm, and placed the four Field Sparrow’s eggs

under a hen Canary which was sitting, and the two Cowbird’s

eggs I gave to another Canary. Both females covered the new

eggs which had been inti'oduced into their nest, and brooded

them within a moment after I had left them. The four Field

Sparrow’s eggs, placed under the first Canary, began to hatch on

the morning of May 22nd. I had left one Canary bird’s egg in

the nest, and this also was hatched early the next day. Another

of the Field Sparrow’s eggs hatched late on May 22nd, and in

the morning of May 23rd there were in the nest one Canary and

three Field Sparrows, and one unhatched egg of a Field



