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

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.

Redunca arundinum:

https://www.inaturalist.org/observations/134474169
https://www.inaturalist.org/observations/134399092
https://www.gettyimages.com.au/detail/video/shot-0f-reedbuck-male-running-at-okavangoforest-stock-video-footage/477433085
https://www.mindenpictures.com/stock-photo/southern-reedbuck-(redunca-arundinum)-male-running-rietvlei-nature-reserve/gallery-132-2442-1961-0/detailmodal-0_00559122.html
https://www.inaturalist.org/observations/134398932
https://www.inaturalist.org/observations/120770948
https://www.inaturalist.org/observations/112575487

Redunca redunca:

https://www.inaturalist.org/observations/107742724
https://www.dreamstime.com/female-bohor-reedbuck-running-female-bohor-reedbuck-redunca-redunca-endemic-to-ethiopia-running-prairei-dinsho-wetland-image145413945
https://www.dreamstime.com/female-bohor-reedbuck-running-female-bohor-reedbuck-redunca-redunca-endemic-to-ethiopia-running-prairei-dinsho-wetland-image145414156
https://www.agefotostock.com/age/en/details-photo/jumping-reedbuck-masai-mara-national-reserve-kenya/WE109495/1
https://www.flickr.com/photos/timmelling/33417983882
https://www.artranked.com/topic/Reedbuck#&gid=1&pid=17
https://www.artranked.com/topic/Reedbuck#&gid=1&pid=6
https://kenya.hsmagazine.digital/reedbuck-the-african-antelope-article-by-gareth-jones-3/

Redunca fulvorufula:

https://www.alamy.com/stock-photo-side-view-of-a-mountain-reedbuck-leaping-through-long-grass-31832023.html
https://www.shutterstock.com/image-photo/southern-mountain-reedbuck-redunca-fulvorufula-running-1024727896
scroll to several photos in https://dewetswild.com/tag/rooiribbok/

The only photo I have found, that supports the notion of a caudal flag in alarm, is https://www.inaturalist.org/observations/129680116.

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 scroll in https://brucewatsonsafaris.com/hunting/trophy-animals/reedbuck-hunting/ 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). However, 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?

(Also see https://www.inaturalist.org/posts/53474-a-comparison-of-adaptive-colouration-between-lookalikes-grey-rhebok-and-mountain-reedbuck#.)

Posted by milewski milewski, 25 August, 2020 00:26

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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.

Posted by milewski over 1 year ago (Flag)

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".

Posted by milewski over 1 year ago (Flag)

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?

Posted by milewski over 1 year ago (Flag)

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".

Posted by milewski over 1 year ago (Flag)

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

Posted by milewski over 1 year ago (Flag)

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/.

Posted by milewski over 1 year ago (Flag)

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.

Posted by milewski 8 months ago (Flag)

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.

Posted by beartracker 8 months ago (Flag)

@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

Posted by milewski 8 months ago (Flag)

@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."

Posted by milewski 8 months ago (Flag)

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.

Posted by beartracker 8 months ago (Flag)

The following (https://www.inaturalist.org/observations/109676221) is one if the few photos showing clearly the colouration on the buttocks, in Redunca arundinum.

The following (https://www.inaturalist.org/observations/104986782) suggests that the pattern is different in Redunca redunca, with negligible whitish on the buttocks.

Posted by milewski 3 months ago (Flag)

The tails of bushbucks (Tragelaphus scriptus and Tragelaphus sylvaticus) are similar in size, shape, and colouration to those of reedbucks (Redunca spp.).

Unlike reedbucks, bushbucks do flag the tail in alarm.

The following video clip (https://latestsightings.com/single-post/wild-dogs-eat-bushbuck-alive-as-it-fights-back-malamala) is remarkable, showing a male individual of Tragelaphus scriptus defending itself (unsuccessfully) from a group of Lycaon pictus.

The tail is held conspicuously curled over, qualifying for a caudal flag in this species in an anti-predator context. This posture of the tail differs from that of Odocoileus virginianus, which erects the tail, rather than curling it over.

Also, the tail is sometimes loosely flapped up and down when fleeing, in bushbucks. However, this does not produce a particularly striking display in terms of colouration, because the white hairs on the lower surface of the tail seem not to be pilo-erected.

Tragelaphus scriptus:

https://www.alamy.com/stock-photo-bushbuck-tragelaphus-scriptus-male-running-pendjari-national-park-59453232.html?imageid=6CEF78B4-0EC4-4B3D-82A1-4DDC26A538E2&p=86574&pn=1&searchId=c4807554bb1a466cf282cc8091f3a683&searchtype=0

https://www.alamy.com/stock-photo-bushbuck-tragelaphus-scriptus-male-running-pendjari-national-park-57894269.html?imageid=C5206842-7555-4CAA-8165-505C66069A9B&p=86574&pn=1&searchId=c4807554bb1a466cf282cc8091f3a683&searchtype=0

I have never seen the tail displayed in any species of reedbuck, in the ways shown above.

Bushbucks, like reedbucks, also display the tail socially. This qualifies as a caudal flag, deployed in a context other than an anti-predator context.

Tragelaphus sylvaticus:

https://www.alamy.com/a-male-bushbuck-tragelaphus-sylvaticus-flashes-its-white-rump-in-warning-arusha-national-park-arusha-tanzania-image376767209.html?imageid=F73C6249-52C3-45C2-A887-3B5FD5ECC2F6&p=39397&pn=1&searchId=c4807554bb1a466cf282cc8091f3a683&searchtype=0

https://www.alamy.com/the-bushbuck-tragelaphus-scriptus-is-a-common-and-a-widespread-species-of-antelope-in-sub-saharan-africabushbuck-are-found-in-a-wide-range-of-habit-image472642359.html?imageid=D949EE38-316D-484B-96C5-C0A1B5584126&p=203037&pn=3&searchId=860819a898d0b3e353b6310d1e861c73&searchtype=0

Posted by milewski 3 months ago (Flag)

@beartracker @capracornelius @tandala

The following describes an encounter I had with Redunca arundinum, as I drove near the entrance to Ithala Game Reserve (https://en.wikipedia.org/wiki/Ithala_Game_Reserve), Kwazulu-Natal, in August 2000.

(The closest observation in iNaturalist is https://www.inaturalist.org/observations/19794658.)

Group of six individuals (4 females plus 2 subadult males), encountered at 4:30 pm, in grass up to 1 m high, in a small drainage line (similar to https://www.inaturalist.org/observations/98521497).

When I stopped the car, the animals stopped grazing, and stood and watched the car for more than 10 minutes, whistling repeatedly (taking turns among individuals), without any caudal flagging, or any locomotion beyond a few walking steps.

The body and head hardly moved during the utterance of the whistling sound (in contrast to the impala during sneeze-snorting, see elsewhere).

The whistle was loud, but thin and reedy (nasal).

I was surprised that such a forceful whistle was produced without any noticeable contraction of the body or nose, or any jerking of the head.

After 10 minutes, it was as if the animals' nerve broke, and first one individual, then all but one of the rest, ran a short distance, in 'display mode' (stotting).

This did not involve any erection of the tail at all, although one or two individuals wagged the tail a little at the first moment of running.

The stotting consisted of a few exaggeratedly high (but not long) bounds, with short, decreasing whistles in a series of about four. The effect of this soft, stacatto whistling was to emphasise the up-and-down movements in the locomotion. (I heard no sound from the inguinal pouches.)

(The following gives some indication of the gait: https://www.inaturalist.org/observations/9971.)

The individuals ran in the same general direction, but not cohesively (despite their having been encountered in a single, tight group). They were not coordinated in flight, but they did not scatter, either.

The stotting gait was one of moving up and down without much progress, done individually rather than collectively, followed by stopping and standing stationary.

My impression was that the displays/announcements (both whistling and stotting) were directed at us, not at each other.

This running took them about 50 m upslope, to where the standing figures were more or less obscured in grass taller than 1 m.

In this view (by the light of late afternoon), the whitish patch at the crook of the throat of one individual was somewhat conspicuous, serving as a possible (subtle) flag above the grass. (The following gives an indication: https://www.inaturalist.org/observations/125708555.)

At that point, I drove on, leaving the scene.

I was struck by two aspects of this series of reactions to the appearance of a potential predator.

Firstly, the initial whistling was a purely auditory announcement, being unaccompanied by any bodily movement, even though the figures were in plain view. However, the subsequent whistling, uttered as part of stotting, was integral to the exaggerated gait, as if 'pumped' by the limbs.

Secondly, there was no significant display of the tail, in either the initial standing or the subsequent stotting.

What I did NOT observe, at any time in this encounter, was anything resembling https://www.inaturalist.org/observations/129680116. The latter is caudal flagging, but in the category of social (intraspecific), not anti-predator.

Posted by milewski about 1 month ago (Flag)

Redunca arundinum, showing caudal flag in social (not anti-predator) context:

https://www.inaturalist.org/observations/139267618

https://www.inaturalist.org/observations/137558106

Posted by milewski about 1 month ago (Flag)

Going through my field notes from a visit to Ithala Game Reserve, Zululand, in August 2000, I find the following six entries:

"Juvenile male Redunca arundinum arundinum, with horns still short enough to resemble those of Redunca fulvorufula, alone, less than 1 km from Thalu camp. Located on short green grass in a previously burnt area ('green-pick foraging'). When it runs, it curls up the tail in a similar way to Strepsiceros strepsiceros, showing the white underside."

"Juvenile Redunca arundinum arundinum. As I drive past, this individual, resting in a thicket, allows my car to approach it to 10 m, before it stands up, then fleeing several seconds later. It runs off with the tail up, showing white. Having thus been flushed from a thicket, it runs, without stotting, for at least 50 m."

"Just after sunset, two juvenile male individuals of Redunca arundinum arundinum, out in the open, inconspicuous in the dim illumination, despite their exposure. When we approach on foot, they initially trot for a short distance, in mild alarm, separating somewhat (i.e. not fleeing cohesively). I see no displaying of the tail, even when they gallop off at a fair speed. I heard no whistling during this encounter."

"A subadult male individual of Redunca arundinum arundinum, with horns only 1.5-fold the length of its ear pinnae, encountered in early afternoon. When it runs in mild alarm, with the usual kudu-like, bounding gallop, it does not raise the tail. However, some white shows at the sides of the tail, possibly because the pelage of the tail is slightly spread horizontally."

"Subadult male individual of Redunca arundinum arundinum (with horns 0.75 of full length) on short, green grass. As we drive past it, at a distance of 50 m, it lies down, as if to hide from us, although still right out in the open (beyond a few low boulders which might partly hide the animal, but are >10 m from it). In the recumbent position, it does not lower the head or ears completely. When we approach in the car, it stands up and bounds off for 50 m, but does not erect the tail, and does not disappear into cover."

"Subadult male individual of Redunca arundinum arundinum, mildly alarmed by my car, bounds slowly out of a donga. It does not raise the tail."

Posted by milewski about 1 month ago (Flag)

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