SHORT COMMUNICATIONS 
615 
reproductive success of both males and females 
(Zack and Stutchbury 1992. Both and Visser 
2000. Rolando 2002). Males defend territories 
with song and active monitoring, presumably to 
protect resources for their offspring and to guard 
against extra-pair fertilizations (EPFs), while also 
moving outside of their defended territory to 
potentially seek their own EPFs or other resources 
(Moller 1987. 1991). Males of most socially 
monogamous species also contribute to care of 
young, but females often perform a larger portion 
of parental care including incubation, brooding, 
and provisioning (Trivers 1972. Bennett and 
Owens 2002). Male spatial activity and home- 
range size, despite differing in territorial and 
parental behavior from females, have received 
much more attention than female home-range 
size, particularly during incubation and nestling 
provisioning (Whitaker and Warkcntin 2010). 
Female songbirds encounter a variety of chal¬ 
lenges during the nesting cycle. Females are not 
limited in use of space by incubation or nestling 
care during their fertile period and should have 
their largest home ranges at that time (Moller 1987, 
1990). Females of many species are known to 
undertake 'forays' outside of their mate’s territory 
in addition to foraging and nest building during the 
fertile period, potentially resulting in EPFs as well 
as female home ranges that are much larger than 
territories defended by their social males (Neudort 
et al. 1997, Pedersen et al. 2006. Stapleton and 
Robertson 2006, Evans cl al. 2008; but see Akc^iy 
et al. 2011). 
Female home-range size is predicted to de¬ 
crease as incubation begins as females no longer 
seek copulations and make shorter movements oft 
the nest to forage and engage in nest defense. 
However, the abundance and proximity of re¬ 
sources to the nest can alfect home-range size, 
and females may maintain larger home ranges 
depending on food availability (Moller 1990). Hie 
subsequent transition from eggs to nestlings marks 
a period of increased effort as females begin to 
forage for nestlings in addition to themselves and 
may continue to devote a large amount ol time to 
brooding. This increase in time spent toraging 
during the early nestling period predicts an 
increase in female activity but presents contrast¬ 
ing predictions about home-range size. Females 
may forage close to the nest and maintain smallei 
home ranges than during the fertile period to 
minimize energy expenditure and maximize lime 
spent regulating nest temperature through blood¬ 
ing. which can impact nestling fitness (Dawson 
et al. 2005. Butler et al. 2009). Conversely, fe¬ 
males may increase their home-range size to use a 
variety of foraging locations or to gather higher 
quality food items (Zach and Falls 1979. Grundel 
1992, Garcia-Navas and Sanz 2010). 
We quantified female home-range size during 
the nestling period for Dark-eyed Juncos (Junco 
hyemalis) to examine if female home-range size 
declines between the fertile and nestling periods. 
We compared our home-range estimate to previ¬ 
ously published data from Neudorf et al. (2002), 
collected from the same junco population, which 
estimated female home-range size during the 
fertile period. 
METHODS 
Study System and Site .—'This research was 
conducted at Mountain Lake Biological Station 
(MLBS) and adjacent grounds of Mountain Lake 
Hotel in Pembroke. Virginia (Giles County; 
37 22' N, 80 32' W). USA between 29 April 
and 24 July 2007. Vegetation on the study site was 
largely mixed deciduous and coniferous forest that 
supports an abundant population ot Dark-eyed 
Juncos (J. li. ccirotinensis) (Chandler et al. 1994). 
All juncos cm the study site received unique color 
bands and the population has been continuously 
monitored since 1983. 
Dark-eyed Juncos are socially monogamous 
(28% of 187 offspring sampled in our study 
population were sired by an extra-pair father. 
Ketterson ct al. 1998) and only females incubate 
and brood while both sexes contribute to provi¬ 
sioning of nestlings (Nolan et al. 2002). Juncos 
spend the majority of the breeding season near the 
ground as they are a ground-nesting species and 
forage for seeds and insects in the leaf litter as well 
as in the understory vegetation (Nolan et al. 2002). 
Radiotelemetry .—Radiotelemetry has been used 
in previous studies to monitor activity of both male 
and female juncos (Chandler et al. 1994. 1997; 
Snntlders et al. 2000; Neudorf et al. 2002). We 
used a modified leg-loop harness (Rappole and 
Tipton 1991) to attach BD2A transmitters (Holohil 
Systems Ltd., Woodlavvn, ON. Canada) to seven 
female juncos in the morning (0500-1000 hrs EST) 
when their nestlings were 3 days post-hatch. The 
average (± SE) combined w eight of the transmitter 
and harness was 0.9 ± 0.005 g and average female 
mass was 21.5 ± 0.38 g. We tracked females 
opportunistically to maximize our sample and all 
