Wing chord (mm) Mass (g) 
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THE WILSON JOURNAL OF ORNITHOLOGY . Vol 123, No. 4. December 2011 
RESULTS 
The MPK of nestling Tree Swallow blood 
varied with nestling age (Kruskal-Wallis f = 
19.48, df = 2. P < 0.001) (Fig. 1 A). The Mood of 
only one of 10 ND6 nestlings killed E. coli (MPK 
= 0.45). The MPK of NDI2 nestlings was 0,21 r 
0.13 (n = 16). The MPK of NDI8 nestlings (0.42 
± 0.31, n = 22) was less than that of adults (0.83 
± 0.25, n = 79) (Mann-Whitney U = 267.5. P< 
0.001) (Fig. 1A). 
ND6 nestlings (n = 118) weighed 12.96 ± 
2.77 g and had right wing chords of 20.63 r 
4.06 mm. There were no differences between 
ND12 (21.13 ± 4.05 g, n = 16) and ND18 (20.75 
— 1.07 g, n = 22) nestlings in mass (r-test t'nr 
unequal variances, / = 0.37, df = 16.5. P = 0.72) 
(Fig. IB). The wing chords of ND12 nestlings 
(54.00 ± 7.01 mm) were shorter than those of 
NDI8 nestlings (83.59 ± 4.49 mm) (Student's i- 
test = 15.68, df = 36. P < 0.001) (Fig. 1C). 
There were no correlations between mean brood 
mass or mean brood wing chord length and mean 
brood MPK for both ND12 and ND18 nestlings 
(all P > 0.09), 
There were differences in mass (ANOVA, F = 
13.61, df = 2.96, P < 0.001) among ND18 
nestlings (20.75 ± 1.07 g). adult females (19.18 
— 1.30 g), and adult males (19.70 ± 0.98 g); 
ND18 nestlings weighed more than adults (Bon- 
ferroni multiple post hoc comparisons, both P < 
0.01) (Fig. IB). Adult females and males did not 
differ in mass (Student’s r-test = -1.95, df = 75. 
P = 0.06). 
There were differences in wing chord length 
(ANOVA. F = 805.10, df = 2.95. P < 0-0011 
among NDI8 nestlings (83.59 ± 4.49 mm), adult 
females (113.64 ± 3.10 mm, n = 44). and adult 
males (118.88 ± 2.79 mm, n = 32): the wing 
chords of males were longer than those of females 
and ND18 nestlings (Bonferroni multiple post hoc 
comparisons, both P < 0.001) (Fig. 1C). 
Midnestling MPK-midparent MPK regression 
produced an estimate of h 2 = 0.92 ± 0.66 (SE) 
FIG. 1. (A) Mean ± SD proportion kill (MPK) ability of 
whole hlood to kill E. coli in different age classes of Tree 
Swallows. (B) Mean ± SD mass of different age classes ol 
Tree Swallows. ND12 (n = 16). NDI8 (n = 22), Female^ 
= 44), Male (n = 32). (C) Mean ± SD flattened right wing 
chord of different age classes of Tree Swallows. NDI2 (n = 
16), NDI 8 (n = 22), Female (n = 44), Male (n = 32). 
