398 
THE WILSON JOURNAL OF ORNITHOLOGY • Vo/. !24. No. 2. June 2012 
TABLE 2. Distances (m) among six Veery nests in a Piedmont forest in Delaware, 2011. Nests A. D. and E were 
visited by multiple male feeders. Nests A-E were visited by a male that also attended another nest. Nest F was attended bv a 
socially monogamous pair. 
Nest 
A 
B 
c 
D 
E 
F 
A 
- 
169.1 
127.1 
55.9 
80.1 
357.4 
B 
169.1 
- 
290.2 
168.2 
216.1 
526.5 
C 
127.1 
290.2 
- 
126.8 
147.9 
244.3 
D 
55.9 
168.2 
126.8 
— 
134.8 
370.4 
E 
80.1 
216.1 
147.9 
134.8 
__ 
332.9 
F 
357.4 
526.5 
244.3 
370.4 
332.9 
et al. 2003) including: (I) males attending 
multiple nests, (2) multiple male feeders at 
single-female nests, and (3) a monogamous pair. 
We monitored >140 Vccry nests al our study site 
since 1998, but provisioning by multiple males was 
not confirmed until 2011. .Several observations 
suggested that Veeries at our site may have engaged 
in this behavior in previous years, but confirmation 
did not occur prior to use or video cameras. Our 
ability to confirm the presence of multiple male 
feeders was likely diminished by dense understory 
vegetation at nest sites (Hcckscher 2004) and the 
single-brooded nature of this species (Heckscher 
2007). These observatioas suggest multiple males 
provisioning single broods and provisioning simulta¬ 
neously at multiple nests is widespread in our 
population in at least some years. Parental care 
strategies may exhibit annual fluctuations in frequen¬ 
cy and distribution (Brown 1987. Davies 1992). 
Multiple male provisioning strategies at our study site 
may be facultative (i.c.. influenced by factors that 
vaiy from year to year, including breeding synchrony, 
sex ratios, density ot breeders, and availability of 
suitable habitat). Males that were detected provision¬ 
ing at multiple nests did not necessarily provision at 
the nearest available nest (Table 2), but asynchronous 
nestling periods do not make it possible to rule out 
nest proximity as a factor influencing helping 
behavior. 
Veeries at our study site have a social 
dominance hierarchy among males dependent on 
age or time spent in the population (Heckscher 
2007). Territorial aggression among male Veeries 
is common (Dilger 1956, Heckscher 2007), unlike 
Bicknell’s Thrush (Ritnmer et al. 2001. Goetz 
et al. 2003). However, Heckscher (2007) found 
dominant males tolerated nests of subordinate 
males within their territories while maintaining 
nests ol their own and continuing to defend 
against adjacent territorial males. This resulted in 
overlapping home ranges among male Veeries, a 
feature that has been shown to facilitate polyan- 
drous mating behavior in other species (Davies 
1992, Goetz et al. 2003). Aggressive behavior 
described in the context of intraspecific territorial 
exclusion (e.g., Dilger 1956) may also have a role 
in establishment of relationships among males 
that provision at the same nest (MRH. unpubl. 
data). Our discovery of multiple male feeders for 
a single clutch provides a new context for 
interpreting foundational studies of Veery behav¬ 
ioral ecology including intraspecific hostile inter¬ 
actions (Dilger 1956) and use of the vocal 
repertoire in communication (Heckscher 2007 1 . 
Ihe close phylogenetic relationship between 
Bicknell’s Thrush and the Veery (Ellison 2001. 
Outlaw ct al. 2003. Winker and Pmett 2006). and the 
general similarities between nestling care in these 
species, warrant a re-evaluation of hypotheses 
regarding the evolutionary history of parental care 
in Cailtanis thrushes. The evolutionary origin of this 
behavior is unlikely to bo explained by ecological 
constraints experienced by BickneU's Thrush alone, 
such as harsh montane weather (Goetz et al. 2003) or 
food shortage (Strong et al. 2004). as Veeries breed at 
lower elevations in broadleaf forests that lack these 
extreme conditions. Future studies of the pooriy- 
known Gray-cheeked Thrush (C. minimus) and the 
Ruddy-capped Nightingale Thrush (C Jruntzii) 
may help define whether parental care among these 
closely-related species is (1) recently evolved, (2) 
plesiomorphic within the bicknelli clade(Outlawct 
al. 2003), or (3) derived from a more distant 
Caiharus ancestor. Future studies of Veery breed¬ 
ing ecology may clarify or reveal the role of 
hierarchies, genetic relatedness among multiple 
male feeders, and extra-pair paternity within the 
mating system of this secretive forest thrush. 
ACKNOWLEDGMENTS 
This study was conducted with the support of the Center 
for Integrated Biological and Environmental Research. 
