The Wibon Journal of Ornithology 124(2):253 264, 2012 
APPARENT FORCED MATING AND FEMALE CONTROL IN 
SALTMARSH SPARROWS 
JON S. GREENLAW 1 * - 4 AND WILLIAM POST 3 
ABSTRACT.—Saltmarsh Sparrows (Ammodramus eaudacum) arc non-territorial, lack pair-bonds, and practice 
promiscuous mating behavior and obligate maternal care of young. Behavioral details of mating behavior and associated 
intermale aggressive behavior are poorly understood in the species. We report the results of an observational study of 
mating and agonistic behavior of individually marked breeding birds in New York. We witnessed 1,265 sexual and 
agonistic interactions within and among males and females from 1977 through 1985. We found no evidence of male mating 
aggregations, and male aggressive behavior was prevalent only in male-initiated sexual interactions. Females solicit 
matings from males during nest-building, but the behavior is inconspicuous and not associated with male aggression. Males 
spend the morning patrolling their home ranges, and chase or approach females they encounter anywhere in their breeding 
habitat Males often concentrate patrol activity in the vicinity of nests under construction, but we found little evidence they 
know the location of most nest sites. Some males seek to forcibly mount females on the ground at any breeding stage, 
despite female resistance. Females thwart forced mountings in 579/ of cases either by fighting w ith die males, or by uttering 
an aggressive call. When a more persistent male suppresses a female's resistance, she then crouches passively as he 
assumes a copulatory position on her back. We discuss this behavior in terms of female control of forced mountings, female 
choice of mates, and forced mating as a tactic of males that appear not to know the fertility status of females. Males have a 
large cloacal protuberance, which suggests sperm competition is strongly developed in the species. We caution that 
evolution of the unusual mating behavior in Saltmarsh Sparrows must he understood in relation to the different sexual 
behaviors of its closest relatives. Received II April 2011. Accepted IS January 2012. 
Historically, behavioral ecologists interested in 
evolution of mating systems in birds often focused 
their attention on species that practice unusual, 
minority forms of mating behavior, Various 
expressions of social monogamy represenl the 
mainstream among known types of mating 
systems in birds, while different forms of social 
polygamy are relatively rare; overall, promiscuity 
is rarest among passerines (Lack 1968). Saltmarsh 
Sparrows {Ammodramus cotulacutus) arc unusual 
if not unique among North American passerines in 
lacking territoriality, pair-bonding, and paternal 
care (Woolfenden 1956, Post and Greenlaw 19X2, 
Greenlaw and Rising 1994). However, details of 
sexual interactions and intermale agonistic be¬ 
havior in the species remain largely unexplored. 
These details must he known before we can 
understand the selective forces and environmental 
constraints that influenced the evolution of its 
mating system (Emlen and Oring 1977. Clutton- 
Brock 1989). 
Montagna (1940. 1942) observed aggregations 
of sharp-tailed sparrows in Maine and Virginia; he 
described these as “curious tangle! s|“ (1940:192) 
Jon S. Greenlaw. Biology Department, Long Island 
University, Greenvale. NY 11746. USA. 
Current address: 10503 Mist Power Lane, Tampa. FL 
33647, USA. 
1907 I'On Avenue. Sullivan's Island, SC 29482. USA. 
4 Corresponding author; e-mail: jgreenlaw@earthlink.net 
or as “tangled, fighting mass res]” (1942:117). 
His collecting activities and observations of males 
al Popham Beach, Maine, convinced him they 
were fighting over females. These meetings were 
temporary and evidently involved several males 
attempting to copulate with a single female. 
Montagna (1940) thought the multi-male-female 
aggregations in Maine involved Nelson's Spar¬ 
rows {A. nelsoni), bill Saltmarsh Sparrows also 
occur at Popham Beach (Montagna 1942; Rising 
and Avise 1993; JSG, pets. obs.). Greenlaw and 
Rising (1994:10) and Shriver et al. (2007) found 
no evidence that male Nelson's Sparrows aggre¬ 
gated around females while mating; Montagna 
(1940) presumably described the behavior of 
Saltmarsh Sparrows in Maine. He (1942) ob¬ 
served similar social groups in Saltmarsh Spar¬ 
rows in Virginia: he described sparrows flushing 
to a perch where they “chipped softly" (a specific 
call of females [Greenlaw and Rising 1994]) and 
often were “immediately assailed" by one or 
more other birds, resulting in u fight on the ground 
(1942:116-117). 
Woolfenden (1956) was (he first (o characterize 
the divergent social system of Saltmarsh Sparrows 
duiing his work in New Jersey. He reported 
promiscuity by females, but his observations of 
male-female interactions involved only a few 
birds. He thought fighting occurred in both male- 
female groups and ali-nia/e groups. Hill (1968) 
witnessed males that flew to feeding females and 
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