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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 2, June 2011 
TABLE 3. Differences in provisioning rate of male and female Varied Tits by elevation 3 . Mt. Jiri, Korea. 2007. 
Variable Between 
Within 
Gender 
Period df 
p 
Post hoc (Tukeyl 
Provisioning rate Sites 
Nestling age 
Male 
All 2 
<0.001 
Pi-Si 
<0.001 
4* 
Si-No 
<0.001 
** 
Pi-No 
<0.001 
** 
Female 
Ail 
0.001 
Pi-Si 
0.005 
** 
Si-No 
0.033 
** 
Pi-No 
<0.001 
** 
Peak (day 8-10) 
0.676 
ns 
Both 
All 
<0.001 
Pi-Si 
<0.001 
** 
Si-No 
<0.001 
** 
Pi-No 
<0.001 
** 
3 Pi - Piago! (300 m). Si = Siainjae (900 m). No = Nogodnn (1.400 m). 
ns = not significant. *» = significant (P < 0.05). 
tions including ambient temperature and season¬ 
ality. It is known that relative nestling demand 
across avian species is larger at higher altitude 
because of cold temperature, rapid seasonality, 
and fluctuation in food availability which results 
in increased parental effort in provisioning 
(Badyaev and Ghalambor 2001). This increasing 
parental effort appears to be critical for survival of 
offspring, especially at higher elevation (Badyaev 
1997, Blacken horn 1997). We did not include 
other factors believed to affect provisioning rate 
such as habitat quality, prey population density, 
prey size, and food availability in our analysis 
(Nour et al. 1998; Tremblay et al. 2003, 2005). 
We assume our results that parental provisioning 
rate increased with elevation indicated that 
altitude did reflect the effect of those factors. 
The provisioning rate of females was not 
different from that at other times in the peak 
provisioning period (from 8 to 10 days after 
hatching); males, in contrast, were considerably 
different during this period (Fig. 2, Table 3). 
Females had a higher provisioning rate than 
males and had the greater burden of provisioning 
nestlings. Males appeared to increase their 
provisioning rates to reduce the cumulative 
TABLE 4. Relative rates of male to female provisioning 
(provisioning rate of male/to that of female) by age of 
nestlings, Mt. Jiri. Korea, 2007. 
Period 
Pearson 
Correlation 
Coefficients 
p 
Piagol 
Until day 10 
0.21 
0.5546 
Siamjae 
0.67 
0.0320 
** 
Nogodan 
0.70 
0.0500 
** 
ns no! significant, ** = significant (P < 0.05). 
pressure on females of increased provisioning and 
elevation restrictions. Males at high attitude may 
compensate for reduced fecundity by increasing 
their breeding effort (Badyaev 1997, Badyaev and 
Ghalambor 2001). The peak provisioning period is 
the most nutritionally demanding for nestlings 
(Gowaty 1983 ) and, it is assumed that by increasing 
their provisioning rate, males help compensate for 
the female’s threshold level of provisioning to 
increase the survival rate of nestlings. 
Monogamous males tend to provide more 
investment in raising a brood (Krebs and Davies 
1993). However, there are interspecific differenc¬ 
es in the extent and type of cooperation monog¬ 
amous males provide to their males (Beer 1963. 
Coulson and Wooller 1976). Female Varied Tib 
in our study were the main suppliers of food, but 
the relative ratio of male to female provisioning 
rates increased steadily until it reached a peak at 
10 days at the study sites, except at Fiagol 
(Table 4). Female and male provisioning rates did 
not equally increase as a brooding progressed. a> 
the provisioning rate of males increased more than 
that of females. The male's provisioning role 
gradually increased until 9-10 days of nestling 
age. Females have a higher provisioning frequen¬ 
cy relative to males, but it is more difficult lor 
females to increase provisioning frequency. Tht^ 
when males increase provisioning more dramati 
cally in response to the increase in nutritional 
demand of nestlings seems to be essential lor 
females and for the benefit of nestlings. Thus, 
parents can increase their provisioning frequency 
during short periods, but cannot maintain in¬ 
creased provisioning frequency for a long period 
(Leffelaar and Rovertson 1986). This strategy Has 
a significant impact on the potential survival ol 
