Mating behavior of the Southern three-banded armadillo (Tolypeutes matacus) in Brazil

Mating systems vary widely among species and populations. Intrasexual and intersexual competition are common. Behavioral, physiological, and morphological traits can influence individual reproductive success. Little is known about the mating biology of the Southern three-banded armadillo Tolypeutes matacus (Desmarest, 1804). This study describes the behavioral repertoire and a physiological trait related to mating of free-ranging armadillos in midwestern Brazil. We captured and marked 58 males (56 adults) and 39 females (33 adults). Female reproductive status was characterized through external morphological traits and 27 of them were radiotracked daily. Mating behaviors were recorded through focal group observations. Four monitored females entered estrus and were recaptured after mating for vulvar characteristics assessment. Estrous females started races and were actively chased by males attempting to mate (events we named rallies). A conditional logistic regression analysis evidenced a positive relationship between body mass and the likelihood of a male winning a ‘rally.’ We observed intense competition and agonistic encounters among males to access receptive females, with up to 14 males around one female in estrus. All four females presented copulatory plugs in the advanced estrous phase. Finally, we observed a female mating with multiple males, indicating a promiscuous mating system.不同物种及种群的交配系统差异显著，同性竞争与异性竞争均普遍存在。行为、生理与形态特征均可影响个体的繁殖成功率。目前关于南方三带犰狳（Southern three-banded armadillo，*Tolypeutes matacus* (Desmarest, 1804)）的交配生物学研究仍较为匮乏。本研究针对巴西中西部地区的野生犰狳，对其与交配相关的行为谱及生理特征展开描述。研究共捕获并标记58只雄性个体（其中56只为成体）与39只雌性个体（其中33只为成体）。研究人员通过外部形态特征判定雌性繁殖状态，并对其中27只雌性开展每日无线电追踪监测。交配行为通过焦点组观察法进行记录。4只被监测的雌性进入发情期（estrus），并在交配后被重新捕获以评估其外阴特征。处于发情期的雌性会发起奔跑，随后被试图交配的雄性持续追逐——该类事件被我们命名为“追逐赛（rallies）”。条件逻辑回归分析结果显示，雄性体重与其赢得“追逐赛”的概率呈显著正相关关系。研究观察到雄性间为获取与发情雌性交配的机会存在激烈竞争与对抗性互动，最多曾有14只雄性聚集在同一只发情雌性周围。4只雌性在发情后期均出现了交配栓（copulatory plugs）现象。最后，研究观察到一只雌性与多只雄性交配，表明该物种的交配系统为混交制。