![]() ![]() Such behavior can be studied either by direct observation or inferred from wound/scar frequency in extant species but is difficult to document in extinct taxa, limiting understanding of its evolution. Intraspecific aggression, or agonism, is a widespread intrasexual selective behavior important to understanding animal behavioral ecology and reproductive systems. Further, displays in both groups can be directed at, or by, both sexes, although the meanings may differ between males and females (i.e., the same signal may represent a threat to members of the same sex and an advertisement to members of the opposite sex), making teasing out intra-versus intersexual selection more difficult (Payne 1984). 2020) that can cause injury/death (Müller et al. ![]() ![]() 2007 Dinets 2013), and many bird species do engage in intraspecific combat (Payne 1984 Hansen 1986 Simmons and Mendelsohn 1993 Marcuk et al. 1978 Vliet 1989 Thorbjarnarson and Hernández 1993 Wang et al. However, this dichotomy is simplified, as these behaviors are not mutually exclusive crocodylians do engage in vocal/ visual displays before, or instead of, combat (Garrick and Lang 1977 Garrick et al. ![]() Within Archosauria, extant crocodylians practice extensive intrasexual aggression, resulting in dramatic facial injuries (Cott 1961 Gorzula 1978), whereas birds rely primarily on visual/vocal intersexual display (Butcher and Rohwer 1989), resulting in fewer physical injuries. These results suggest the species uses short-range, underwater acoustic signals during courtship and mating, with little vocal activity outside of those events, and provide foundation for future studies of this rare crocodilian. schlegelii, which differed in duration, dominant frequency, and the presence of harmonic structure. We identified seven signal types produced by T. Courtship behaviour during 18 recorded mating events followed that observed in other crocodilians, but acoustic signals were restricted to mating activity and were only recorded in the two animals housed indoors. schlegelii housed indoors, as well as monitored 12 captive adults kept in a semi-natural outdoor enclosure over a period of two months. Using video and passive underwater acoustic monitoring we recorded a breeding captive pair of T. Here we provide the first classification of adult vocalisations in Tomistoma schlegelii – a rare gavialid inhabiting swamp forests in Southeast Asia – and describe the behaviour produced during courtship. Although acoustic communication is commonly used by adults during courtship and territory defence, the signals produced vary between taxa. Image via Judith Janischīottom line: A study suggests that the bellows of American alligators reveal their size.Many threatened crocodilians are shy and difficult to observe in the wild, limiting the current knowledge of their behaviour and ecology. Researchers measure the body length of a male American alligator. Larger alligators have longer vocal tracts and therefore lower resonances. Resonance frequencies depend on the length of the vocal tract. Study co-author Stephan Reber is a cognitive biologist at the University of Vienna. Their analysis found that the resonance frequencies of the bellows are almost perfect predictors of body size. Then they measured the head and total body length of all the alligators up close with measuring tapes and hand-held laser-distance-measurement devices. Augustine Alligator Farm Zoological Park in Florida. Image via Stephan Reber.įor the study, the scientists recorded the bellows of 43 adult American alligators at the St. Only male alligators produce a water dance, visible due to water droplets sprinkling over their backs, preceding the audible bellow. American alligators bellow year-round, but most frequently during mating season. Sub-audible vibrations produce the “water dance” above the animal’s back. A research team of cognitive biologists at the University of Vienna identified cues to body size in the alligators’ bellows. That’s why it’s advantageous if fights can be avoided by alligators reliably signaling their body size to potential mates and rivals early on. However, direct physical confrontations can lead to lethal injuries. Females only accept males larger than themselves as mates and larger alligators are much more likely to win territorial fights. In alligators, being bigger than other alligators can have decisive benefits. That’s according to a new study published in Scientific Reports on May 12, 2017 Alligators can use this information to avoid unpromising contests for mates and breeding areas. These rumbling roars communicate the animal’s body size to other alligators. American alligators produce loud, very low-pitched vocalizations called “bellows”. ![]()
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