Contrary to field guide-books, reedbucks do not flag the tail in alarm

@ludwig_muller

It is stated repeatedly in field guide-books that reedbucks (genus Redunca, https://en.wikipedia.org/wiki/Reedbuck) raise the tail in alarm, thus displaying the white underside.

There is little evidence of such flagging, during either standing or running (see https://www.dreamstime.com/female-bohor-reedbuck-running-female-bohor-reedbuck-redunca-redunca-endemic-to-ethiopia-running-prairei-dinsho-wetland-image145413945 and https://www.mindenpictures.com/stock-photo/southern-reedbuck-(redunca-arundinum)-male-running-rietvlei-nature-reserve/gallery-132-2442-1961-0/detailmodal-0_00559122.html and https://www.gettyimages.com.au/detail/video/shot-0f-reedbuck-male-running-at-okavangoforest-stock-video-footage/477433085 and https://www.dreamstime.com/female-bohor-reedbuck-running-female-bohor-reedbuck-redunca-redunca-endemic-to-ethiopia-running-prairei-dinsho-wetland-image145414156 and https://kenya.hsmagazine.digital/reedbuck-the-african-antelope-article-by-gareth-jones-3/ and https://www.shutterstock.com/image-photo/southern-mountain-reedbuck-redunca-fulvorufula-running-1024727896 and https://www.agefotostock.com/age/en/details-photo/jumping-reedbuck-masai-mara-national-reserve-kenya/WE109495/1 and https://www.flickr.com/photos/timmelling/33417983882 and https://www.artranked.com/topic/Reedbuck#&gid=1&pid=17 and https://www.artranked.com/topic/Reedbuck#&gid=1&pid=6).

Is this an example of an error, once published, being mindlessly passed from one author to another like a meme, decade after decade?

(Incidentally, among those who have been misled are taxidermists: see https://www.zululandtaxidermy.com/mountain-reedbuck and https://africanwildlifeartistry.co.za/mountain-reedbuck-floor-base-full-mount/).

Instead, one of the most interesting aspects of reedbucks is how little they raise the tail in alarm, given that:

Several of the ruminant species that stot are known to raise the tail or pilo-erect the fur on the hindquarters as part of the show. However, I have never seen evidence that reedbucks do either.

The way that two of the three species do advertise themselves when alarmed is by loud whistling and the production of popping sounds from the hindquarters, presumably from the inguinal glands. This suggests that reedbucks rely on communicating with their predators by sound and smell rather than visually.

So, is olfactory communication in reedbucks related to the fact that waterbucks (Kobus ellipsiprymnus and K. defassa), unusually among ruminants, discourage predation by means of disgusting substances on the skin and fur (http://www.gunsite.co.za/forums/showthread.php?35742-Correct-way-to-butcher-a-Water-Buck-bull and https://www.sahunters.co.za/index.php/hunting-articles/179-waterbuck-to-eat-or-not-to-eat)? Waterbucks belong to the same bovid tribe, namely Reduncini (https://en.wikipedia.org/wiki/Reduncinae), as reedbucks.

The mountain reedbuck (Redunca fulvorufula) is particularly puzzling in this way. I have certainly heard it whistle loudly (https://sounds.bl.uk/Environment/Listen-to-Nature/022M-LISTNAT00076-0001V0), but in which ways does it display to predators? It does not seem to have been recorded stotting, flagging its tail in alarm or flight, or popping its inguinal glands.

Thinking about this more deeply: it seems to me that an overarching oddity of reduncin bovids is that they have largely transferred their glandular communications from the social realm, normal for other antelopes, to the anti-predator realm. Unlike many antelopes, reduncins do not mark socially by means of preorbital or interdigital glands. They do possess well-developed glands - in the case of reedbucks including a bare patch below the ear-base (see https://www.inaturalist.org/observations/65592013) - but it seems possible that the smells produced are more for communication with predators than for intraspecific communication.

If so, would this help to explain the apparent redundancy of caudal flags - in the context of predation - in reedbucks?

Publicado por milewski milewski, 25 de agosto de 2020

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The following photos of Redunca reveal the white underside of the tail to varying degrees, but these are social postures as opposed to postures of alarm in reaction to the appearance of a potential predator: https://www.istockphoto.com/photo/reedbuck-male-gm1219279543-356595464 and https://www.istockphoto.com/photo/reedbuck-ram-in-showing-off-tail-gm177381327-20576575 and https://www.istockphoto.com/photo/bohor-reedbuck-on-the-sand-river-banks-in-the-masai-mara-national-reserve-kenya-gm860000138-142190049 and https://wildlifevagabond.com/wildlife/mammals/ungulates/even-toed-ungulates/bovids/antelopes/wetland-antelopes/mountain-reedbuck/ and https://www.sciencephoto.com/media/389642/view/female-mountain-reedbuck. Reedbucks obviously do qualify for possessing a 'caudal flag', but this seems to be social, not anti-predator, in its communicative function.

Publicado por milewski hace 12 meses (Marca)

This is how Haltenorth and Diller (1980) describe the sounds made by Redunca arundinum: "whistle with closed mouth through nostrils (as in Chamois) when excited; depending on degree of excitement a little or as much as 150 times, one after another. Rattling sound at beginning of bouncing leap. Sharp sound before the whistling only in female, if excited only moderately. Smacking sound in flight said to be produced by high hind leg sudden opening of the inguinal glands". Estes (1991) states "A disturbed reedbuck may whistle intermittently for as long as quarter-half hour, especially at night after getting wind of, say, a stalking leopard. In the bohor reedbuck, whistling may precede and follow, and often accompanies and emphasises, the typical rocking gallop. Stotting, in which the reedbuck bounds up and down almost in place, represents a higher state of excitation and usually involves 3-8 jumps...the common reedbuck does not whistle while galloping, but instead a snorting sound is produced at each jump as the head is thrown back and air is forced through the nostrils...fleeing reedbucks make strange popping sounds...attributed to the sudden opening of the pocket-like inguinal glands. At the height of a bound, disturbed common reedbucks of both sexes have been seen to throw the hindlegs backward and outward, which coincided with a double pop at each jump".

Publicado por milewski hace 11 meses (Marca)

To my surprise, I have just found for the first time these photos of Redunca fulvorufula: https://www.facebook.com/permalink.php?id=1092977137534522&story_fbid=1713459962152900 and https://www.facebook.com/WeekDaySafaris/photos/pcb.1713459962152900/1713455738819989. They certainly show caudal flagging while running, and perhaps while stotting. But was this a social display, as opposed to a display to potential predators?

Publicado por milewski hace 10 meses (Marca)

Haltenorth and Diller (1980) state for Redunca redunca, which has proportionately the smallest tail in the genus: "Tail...ending in thinly bushy tip, whitish underside conspicuous when exposed (in flight)." I find this statement particularly puzzling because the same authors state of R. arundinum "flight...with...tail close to body".

Publicado por milewski hace 10 meses (Marca)

The following video shows clearly that Redunca fulvorufula lacks any caudal flag while fleeing: https://www.youtube.com/watch?v=9fFt75Evdvo.

Publicado por milewski hace 10 meses (Marca)

The following gives an alarm-call of the white-tailed deer (Odocoileus virginianus), which is a 'sneeze-snort' less shrill than the whistling of reedbucks: https://vimeo.com/113800047. Also see https://targetcrazy.com/hunting/deer-sounds-meanings/.

Publicado por milewski hace 10 meses (Marca)

Vesey-Fitzgerald D (1967) Dance of the bohor reedbuck. Black Lechwe 6(4), page 24. This author reports an observation of extreme gregariousness and exuberance in Redunca redunca. More than 225 individuals were together, including 90 mature male individuals. Juveniles of the year were running around, stirring up much dust. Their gaits included high bounds with legs extended and the tail held erect. This suggests that there is indeed a caudal flag in R. redunca, but only for social communication, not for communication in reaction to potential predators.

Publicado por milewski hace 2 meses (Marca)

Very interesting. I have heard the alarm-call of the local blacktailed deer. It is a snorting sound, like blowing the air out of the mouth forcefully. They often do it before they move off in a stotting gait.

Publicado por beartracker hace 2 meses (Marca)

@beartracker Could you please tell me: when the black-tailed deer stots, does it erect its tail or does it leave its tail hanging inert?

Please see https://www.alamy.com/a-black-tailed-deer-stotting-across-a-winter-field-image235857060.html

Publicado por milewski hace 2 meses (Marca)

@beartracker

Another reduncin bovid, namely Kobus kob thomasi (https://en.wikipedia.org/wiki/Ugandan_kob), also stots (Buechner and Roth 1974), and I note that, as in the related reedbucks, anti-predator stotting is not accentuated by a caudal flag. So it seems that one of the hallmarks of Reduncini is that anti-predator stotting is unaccompanied by caudal flagging, either because the caudal flagging is purely social (as in reedbucks) or because the tail is too narrow and plain-coloured to constitute a flag even when erect (as in kobs, waterbucks, and lechwes).

While we are on the topic of Buechner and Roth (1974), it is food for thought that these authors assume stotting to make the stotting individual more, not less, likely to be targeted by the predator concerned. I would argue that this is close to being the opposite of the truth. This is because stotting, as an honest display of individual fitness, has evolved as a mechanism whereby the scanning predator can unselect fit individuals in a process of elimination.

Here is a quote from Buechner and Roth (1974) that, I suggest, shows how they have misinterpreted stotting as boosting the risk of predation for the stotting individual.

"Altruistic behavior among territorial males may contribute to kinship selection, and the individual kob behavior in response to predation suggests that altruism may have a bearing on the regulation of predation...In response to the presence of lions, females and males were observed stotting (stiff-legged bounding), a display that in the kob appears to be a highly specific signal for the presence of a predator. Besides conferring a survival advantage on the individual by inducing the predator to chase while it is well outside the prey's flight distance, as Smyth (1970) proposes, stotting seems to be a type of altruistic behavior. Not only do individuals expose themselves to attack by a lion (and presumably other predators) by stotting but they also approach, at least in daytime, to within ca. 75 m of a lion and whistle loudly."

Publicado por milewski hace 2 meses (Marca)

As far as I have seen, the tail can be raised or lowered when stotting in blacktailed deer. I've seen both. Most often raised.

Publicado por beartracker hace 2 meses (Marca)

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