Introduction
Social information plays an important role in the distribution of
wildlife across the landscape. Wildlife derive information on resource
availability from the occurrence of individuals (Danchin et al. 2004),
and the performance of conspecifics and heterospecifics, wherein habitat
patches conferring improved fitness attract more individuals (Doligez et
al. 2002, Campomizzi et al. 2008). Congregation of individuals within
resource patches is often driven by conspecific attraction (Stamps
1988). As such, clustering of species during the reproductive period has
shown positive fitness benefits via information transfer on resource
availability, predation risk, and mate availability (Alexander 1974,
Forbes and Kaiser 1994, Danchin et al. 1998, Strong et al. 2018). Thus,
social information is a known determinant of reproductive decisions and
underlies the coordination of the timing of reproduction (Brandl et al.
2019).
Coordination in timing of reproduction is driven by resource
availability for a wide array of species (Lack 1968, Perrins 1970) as
optimization of reproductive success hinges on matching reproductive
activities with environmental conditions (Ims 1990). As such, temporal
clustering of reproductively-active individuals is typically driven by
climatic seasonality (Ims 1990), especially when breeding seasons are
restricted to shorter temporal periods (Emlen and Demong 1975, Findlay
and Cooke 1982). The availability of social information, which underlies
spatial clustering, can influence temporal clustering (Helm et al. 2006)
and certain life history events (migration, reproduction) are inherently
clustered temporally (Lack 1968, Gochfeld 1980). Monogamous species
regularly demonstrate a high degree of reproductive synchrony (Emlen and
Oring 1977, Gochfeld 1980) as male investment in courtship limits
extra-pair reproductive activities (Grant and Kramer 1992) with the
consequence being synchronized reproductive activities (Knowlton 1979).
Colonial birds consistently demonstrate high degrees of clustered
nesting, (Darling 1938, Lack 1968, Gochfeld 1980), as individuals
synchronize reproduction to simultaneously reproduce (Gochfeld 1980),
resulting in higher rates of nest success (Di Maggio et al. 2013) by
reducing offspring mortality (Darling 1938). However, in non-monogamous
systems, social rank may dictate breeding access of individuals within a
local population (Robel and Ballard 1974, Foster 1981). Typically,
higher ranked males copulate with more females (Robel 1970, Buchholz
1997, Krakauer 2008), creating a pronounced reproductive skew (Emlen
1976, Mackenzie et al. 1995). When high-ranking males can more
effectively monopolize access to females, asynchronous breeding is
predicted to occur (Post 1992, Webster 1994). Thus, asynchronous
breeding may disproportionately affect fitness amongst individuals,
potentially increasing fitness of higher ranking individuals and
decreasing fitness of lower ranking individuals.
The eastern wild turkey (Meleagris gallopavo silvestris ;
hereafter, wild turkey) has a complex social structure, wherein flocks
exhibit social hierarchies where the highest ranking individual
dominates others and the lowest ranking individual dominates none (Watts
and Stokes 1971, Eaton 1992, Healy 1992). The establishment of dominance
hierarchies occurs through agonistic interactions within social groups
and rank seldom changes as long as the dominant bird survives (Watts and
Stokes 1971, Healy 1992). Male and female wild turkeys maintain separate
social hierarchies within and between flocks and dominance is influenced
by age (Watts and Stokes 1971) and various morphological and behavioral
attributes (Buchholz 1995, 1997, Badyaev et al. 1998). Wild turkeys use
a male dominance polygynous mating system comparable to exploded
lekking, wherein males communicate with females via elaborate courtship
displays and vocalizations (Krakauer 2005, Chamberlain et al. 2018,
Wakefield et al. 2020). The establishment of dominance hierarchies
determines access to mates for both sexes (Emlen and Oring 1977,
Williams and Austin 1988). In species that maintain social hierarchies,
higher-ranking females may prevent subordinate females from gaining
access to dominant males (Bro-Jørgensen 2002), and in some birds, higher
ranking females may realize fitness advantages associated with early
nesting (Robel 1970, Robel and Ballard 1974). In fact, social status can
influence the onset of laying activity and lower ranked females may
delay nesting attempts, causing asynchronous reproduction within social
groups of females during a single breeding season (Cristol 1995).
We evaluated reproductive synchrony within and between presumed social
groups of GPS-tagged female Eastern wild turkeys by inferring female
social rank based on timing of nest initiation (Watts and Stokes 1971,
Schmutz and Braun 1989, Healy 1992, Cristol 1995). We hypothesized that
the social rank of dominant females, inferred from the onset of nest
initiation, would influence the timing of reproduction in subordinate
females. We predicted that dominant females would nest first, and when
their initial nest failed, would rejoin their previous social group and
reinsert themselves in the reproductive hierarchy over remaining
subordinate females presumably attempting to mate. Therefore, we
predicted that dominant females who nested first would be more likely to
have subsequent renest attempts before subordinate females attempted
their first nest. We also predicted that dominant females would travel
shorter distances within their reproductive ranges prior to onset of
nest initiation.