The peculiar ordinariness of the larynx of the impala

The impala (Aepyceros melampus) is a strange antelope appearing as an ordinary antelope. This is partly because its peculiarities are small-scale anatomically, such as the nature and arrangement of its fur and the grooming apparatus of its teeth and gums.

Little-known is how odd it is that the impala can roar without obvious modification of the larynx (see https://www.youtube.com/watch?v=IqzBw9EWhjU and https://www.youtube.com/watch?v=X5ifYPaDGXo and https://www.youtube.com/watch?v=B0Kxm5kgLMA and https://www.youtube.com/watch?v=6fBYZDOUJas and https://www.youtube.com/watch?v=Ywnn2TPMyDQ and http://ourlifeinkruger.co.za/2019/05/21/the-rutting-season-when-impalas-get-busy/).

Several ruminants are, like the impala, capable of roaring or loud grunting during masculine display, i.e. during the rut (https://onlinelibrary.wiley.com/doi/10.1111/j.1469-7580.2011.01361.x). These are the goitred (Gazella subgutturosa) and mongolian (Procapra gutturosa, see https://link.springer.com/chapter/10.1007/978-4-431-76933-0_1 and http://www.bioacoustica.org/expedition/dauria2017_eng.html) gazelles and the red (Cervus elaphus, see https://www.youtube.com/watch?v=RduhVcBn-0M and https://www.youtube.com/watch?v=K4aG93vZImg) and fallow (Dama dama, see https://www.youtube.com/watch?v=oxHvwrwyuso and https://www.youtube.com/watch?v=I9enG3Tz96E) deer.

However, all have obvious modifications of the larynx of the male in season. In the goitred gazelle and red deer the larynx descends so far that it can abut the sternum. In the goitred and mongolian gazelles the larynx is so enlarged that the very names of the species refer to the swelling. And in all these species, the larynx recoils far down the neck during roaring.

The rutting male impala shows none of these specialisations (see https://onlinelibrary.wiley.com/doi/full/10.1111/joa.13114 and https://pxhere.com/en/photo/1600574), yet manages to excel in several ways. It roars more loudly than the goitred gazelle, it roars as loudly while running as deer roar while standing, and it somehow intersperses its roars with loud snorts made non-vocally.

The result is that the impala is one of the loudest of ruminants while retaining a larynx which looks no different in the rutting male from that in the female. And the female impala has not, as far as I know, been recorded vocalising loudly, although she - like the male - certainly snorts loudly when alarmed by predators (see https://www.youtube.com/watch?v=U_GbVH8AOEY).

Publicado por milewski milewski, 24 de abril de 2021

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