Nebraska Bird Review 
9 
Figure 2. Growth of feathers in eight tracts of Goldfinch nestlings; semi- 
logarithmic scale. 
ing a little earlier than Goldfinch 
nestlings. For instance, 100 percent 
of Redwing nestlings have alar 
feathers projecting and fringing by 
day three and seven, respectively, 
while for the Goldfinch this does not 
occur until day five and eight, re¬ 
spectively. However, the Redwing 
leaves the nest at a mean age of 9.5 
days while the Goldfinch does not 
leave until 12.3 days of age. This 
gives Goldfinches nearly three more 
days in the nest for feathering. 
Figure 2 shows growth curves for 
eight feather tracts when means 
(shown in Table 5) were plotted in 
a semi-logarithmic fashion. Growth 
rates were calculated and are shown 
in Table 6. The alar, humeral, capi¬ 
tal, and caudal tracts had values 
that remained about the same or had 
an increase in relative growth rate 
in the first three days of growth 
and then declined. The other four 
feather tracts had a high rate of 
growth during the first few days 
and then declined. 
An index was calcuated similar to 
that for other measurements except 
that it was the mean of R values 
for only the first six days of feather 
growth. This was done so that com¬ 
parisons could be made between in¬ 
dex values for Goldfinches and Red¬ 
wings. If an index was calculated 
for the entire growth period, there 
would be no way of comparing values 
between tracts in the same species 
