In stotting its bleeze, the Patagonian mara (Dolichotis patagonum) may be the most ungulate-like rodent on Earth

@gonsaro @r-a-p @kfinn @jeremygilmore @santiagoramos @enricotosto96 @nicoolejnik @paradoxornithidae @botswanabugs @tonyrebelo

The Patagonian mara (Dolichotis patagonum, https://academic.oup.com/mspecies/article/doi/10.2307/0.652.1/2600781?login=false) is a relatively cursorial caviid rodent (https://en.wikipedia.org/wiki/Caviidae), with a body mass of about 10 kg.

Please see https://www.researchgate.net/figure/Photo-of-a-mara-Dolichotis-patagonum-with-some-adaptations-for-running-being-highlighted_fig3_333504431 and https://go.gale.com/ps/i.do?id=GALE%7CA609539093&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=03279383&p=IFME&sw=w&userGroupName=anon%7E9e205385&aty=open+web+entry.

This may be the only rodent on Earth that

  • stots (https://en.wikipedia.org/wiki/Stotting) by means of stiff-legged, bouncing locomotion, and
  • possesses a bleeze (defined as a dark/pale pattern so bold that it makes the whole figure conspicuous, even at distance, and even when stationary).

The combination of stotting and displaying a large-scale conspicuous pattern on the hindquarters is associated with ruminants, from Ourebia ourebi (about 15 kg, https://www.dreamstime.com/oribioribi-sprinting-across-savannah-slightly-longer-shutters-speed-to-capture-motion-oribi-sprinting-across-image143323292) to Alcelaphus caama (about 130 kg, https://www.flickr.com/photos/neeravbhatt/6191239661/).

Among animals featuring this combination, the Patagonian mara is possibly

  • the only rodent, and
  • the smallest of all mammals.

(Please also see https://www.argentinat.org/journal/milewski/64011-flags-as-features-of-adaptive-colouration-in-lepus-part-2-other-species-of-semi-arid-north-america#.)

The following show that the bleeze of the Patagonian mara

  • is situated on the hindquarters, from the base of the tail to each haunch,
  • has a mainly horizontal orientation,
  • shows dark/pale contrast, independent of sheen/anti-sheen effects, and
  • subsumes but is not contributed to by the tail, which is short and bare.

https://www.inaturalist.org/observations/152145094

https://www.inaturalist.org/observations/149507669

https://www.inaturalist.org/observations/74038522

https://www.inaturalist.org/observations/143733867

The following shows that, in some individuals, there is a whitish patch near each knee (at the junction of flank and hindleg). In posteriolateral view, this extends the bleeze in an anterior direction (https://www.inaturalist.org/observations/51901419).

The following show that the bleeze of the Patagonian mara is conspicuous even when the standing figure is viewed in full profile (https://www.inaturalist.org/observations/116824024 and https://www.inaturalist.org/observations/35690755).

The following suggests that the white band of the bleeze can be flared/erected (https://www.inaturalist.org/observations/131837234).

The following shows the appearance of the bleeze when the animal flees (https://www.inaturalist.org/observations/73664556 and https://www.inaturalist.org/observations/147930616).

The following shows that the bleeze is concealed by sitting, which is a frequently used posture in the Patagonian mara (https://www.inaturalist.org/observations/126838562 and https://www.inaturalist.org/observations/109675491).

The following show the stotting gait of the Patagonian mara:

https://www.debrecensun.hu/local/2023/03/24/the-patagonian-mara-of-the-debrecen-zoo-got-a-partner/

https://www.inaturalist.org/observations/106457844

https://www.alamy.com/patagonian-mara-cavy-dolichotis-patagonum-stotting-valdes-peninsula-chubut-patagonia-argentina-image263028463.html

https://www.mindenpictures.com/stock-photo-patagonian-mara-cavy-dolichotis-patagonum-stotting-valdes-peninsula-naturephotography-image90672455.html

https://www.gettyimages.ie/detail/photo/rabbit-in-patagonia-argentina-royalty-free-image/1331275428?phrase=patagonian+hare&adppopup=true

https://www.alamyimages.fr/cavi-de-patagonie-dolichotis-patagonum-peninsule-de-valdes-site-du-patrimoine-mondial-de-l-unesco-province-de-chubut-patagonie-argentine-image396012030.html?imageid=67D29AC8-2DDD-4730-BA46-8F64B855A9A5&p=1360155&pn=4&searchId=fdf407efb395ee4e1da5818b4f0aac6e&searchtype=0

https://www.alamy.com/stock-photo-patagonian-mara-cavy-dolichotis-patagonum-stotting-valdes-peninsula-86749556.html?imageid=518140A7-DE66-4D56-AC01-B56AB482092B&p=269381&pn=1&searchId=589d9d24beda2dcae20b7ee79d560a38&searchtype=0

The Patagonian mara has long, slender legs for a rodent, and might be described as a 'cavy on high heels'. However, it remains digitigrade (https://en.wikipedia.org/wiki/Digitigrade), not unguligrade (https://en.wikipedia.org/wiki/Ungulate).

The following show the walking gait of the Patagonian mara:

https://www.inaturalist.org/observations/164868054

https://www.inaturalist.org/observations/104542547

https://www.inaturalist.org/observations/62059798

https://www.inaturalist.org/observations/38340582

https://www.shutterstock.com/image-photo/patagonian-mara-dolichotis-patagonum-rodent-genus-1207058716

https://www.shutterstock.com/image-photo/patagonian-mara-dolichotis-patagonum-599052566

https://www.alamyimages.fr/photo-image-mara-de-patagonie-81921558.html?imageid=A36AB68D-A326-4319-8811-EE760D18CF22&p=46571&pn=1&searchId=3f16e8ad5731abf977a4bcd41d46be22&searchtype=0

The following show the similarity in walking gait between the mara and a like-size African bambi, Raphicerus campestris (about 10 kg):

https://www.shutterstock.com/image-photo/patagonia-mara-portrait-while-running-grass-399321796

https://www.alamy.com/stock-photo-steenbok-raphicerus-campestris-walking-south-africa-krueger-national-76132028.html

DISCUSSION

Bambis (ruminants with body mass 15 kg or less) occur in South America. However, all of these depend on cover, and have inconspicuous colouration. The niche for a bambi in open vegetation has been usurped by a rodent, on this continent.

With the possible exception of one species/subspecies of Ourebia (which is marginal to the body mass criterion for bambis, anyway), no bambi on Earth possesses a bleeze.

(Please see https://colombia.inaturalist.org/journal/milewski/70050-the-three-main-types-of-oribi-ourebia-at-a-glance.)

The steenbok possesses a conspicuous white patch on the buttocks. However this qualifies as a flag rather than a bleeze, because it is

Furthermore, the steenbok does not stot.

Aspects of the Patagonian mara that are evolutionarily convergent with bovid bambis include

  • extremely large eyes, adapted for good vision by day,
  • hue-differentiation in the ground-colour
  • monogamy, and
  • precociality at birth.

However, there is negligible convergence with bovid bambis in

in view of the limited convergence between the Patagonian mara and ungulates, its possession of a well-developed bleeze is surprising. In displaying this conspicuous pattern, particularly by stotting, it outdoes its bovid counterparts - despite being otherwise only superficially ungulate-like.

Publicado el 5 de junio de 2023 00:39 por milewski milewski

Comentarios

@michalsloviak

Have you ever seen a photo showing stotting in Cervus canadensis?

Conceptual framework:

Cervus elaphus is well-known to stot, and is said to be so closely-related to C. elaphus that they may be a single species/superspecies.

However, it occurred to me for the first time today that I have never seen stotting in C. canadensis, which instead reacts to attacks by Canis lupus by something approaching a 'proud trot' with the muzzle held conspicuously high (https://www.shutterstock.com/image-photo/bull-elk-trotting-across-prairie-landscape-108061352).

If this is a real difference, it might be further evidence that C. canadensis is more different from C. elaphus than was realised in the past.

Your thoughts?

I suspect that the following shows stotting in C. canadensis:

https://www.shutterstock.com/image-photo/young-elk-spots-zooming-through-tall-2288865627

https://www.shutterstock.com/image-photo/young-elk-zooming-across-meadow-great-2289380621

Publicado por milewski hace 6 meses

Clear illustration of auricular flags and buccal semet in Cervus canadensis:

https://www.youtube.com/watch?v=2FNFyy0Hhic

Publicado por milewski hace 6 meses

Cervus elaphus and Cervus canadensis may indeed be conspecific, after all, there's zero problem when they hybridise. The definition of species in the genus Cervus is as trivial as the genus Canis.

Publicado por paradoxornithidae hace 6 meses

@milewski
Interestingly, Elaphurus can readily hybridise with Cervus without any fertility complications, producing seemingly normal offspring when crossed, with the hybrids being fully fertile. It's reasonable to assume Cervids are over-split by taxonomists.

Source: https://www.researchgate.net/publication/15431638_A_New_Gene_Mapping_Resource_Interspecies_Hybrids_between_Pere_David's_Deer_Elaphurus_Davidianus_and_Red_Deer_Cervus_Elaphus

Publicado por paradoxornithidae hace 6 meses

@paradoxornithidae @dejong

POSSIBLE BLEEZES IN PRIMATES

Conspicuous colouration is unusual in rodents, for the obvious reason that these mammals tend to rely on hiding at, or under, ground level.

We can expect conspicuous colouration to be unusual also in primates, for different reasons. This order of mammals tends to be arboreal.

So, are there any examples of bleezes on the hindquarters of primates, particularly those forms most adapted to terrestrial activity?

One possible candidate is Nasalis larvatus (https://www.inaturalist.org/taxa/43538-Nasalis-larvatus), which is often seen on the ground among mangroves.

In mature males of N. larvatus, the hindquarters have a conspicuous pattern (https://www.inaturalist.org/photos/70541169 and
http://www.shahrogersphotography.com/detail/11668.html and https://www.mediastorehouse.com/auscape-photo-library/photographer-galleries/attila-bicskos-kaszo/bic01099-24396015.html).

The main element of this pattern is the tail, but its whitish extends to the rump, where there is a remarkably sharp border with the brown of the back.

The conspicuous pattern in N. larvatus is plausibly more effective when the figure is sitting arboreally (https://www.inaturalist.org/observations/3735448).

Another possible candidate is Erythrocebus (https://www.inaturalist.org/observations?place_id=any&taxon_id=43461&view=species), the most terrestrial monkey on Earth.

As in N. larvatus, the conspicuous pattern is restricted to mature males, and consists mainly of whitish pelage. However, unlike N. larvatus, the pale surface is not on the tail and rump, but instead on the hindlegs, extending to the buttocks.

https://www.researchgate.net/figure/Back-and-front-views-of-adult-male-patas-monkey-Erythrocebus-patas-of-the-study-group_fig2_272337939

https://animalimages.net/patas-monkey/

https://zooinstitutes.com/animals/patas-monkey-monkey-park-tenerife-109545.html

https://www.semanticscholar.org/paper/Ecology%2C-behaviour-and-threats-of-Patas-monkey-A-Menbere/6d6390d22707b8ceb294f5d20f795280bea68872

https://www.semanticscholar.org/paper/Ecology%2C-behaviour-and-threats-of-Patas-monkey-A-Menbere/6d6390d22707b8ceb294f5d20f795280bea68872/figure/0

https://onlinelibrary.wiley.com/doi/abs/10.1002/ajp.23316

So, do these monkeys possess a bleeze, comparable to that of Dolichotis patagonum?

My verdict is no, because a) the pattern in the rodent is consistent with anti-predator display, whereas those in the monkeys are instead consistent with social/sexual display, and b) the patterns are not as conspicuous in the monkeys as in the rodent, partly because the environments of the monkeys tend to be cluttered with vegetation, and partly because there is no dark element on the hindquarters in Erythrocebus, limiting the pale/dark contrast.

I would, therefore, tentatively describe the patterns in these primates as a caudopygal flag in N. larvatus, and a fibuloischial flag in Erythrocebus.

(For a reminder of the appearance of a fibular flag, please see the comment above titled 'Fibular flag in Alces alces.)

Publicado por milewski hace 6 meses

Interesting that the Proboscis monkey of Kalimantan/Borneo has such a pattern

Publicado por paradoxornithidae hace 6 meses

Aren't members of Papionini (Baboons) also quite terrestrial?

Publicado por paradoxornithidae hace 6 meses

@paradoxornithidae
Erythrocebus is more specialised for terrestriality than is any species of Papio. Theropithecus is as terrestrial as Erythrocebus while foraging, but remains dependent on climbing in cliffs.

No species of Papio or Theropithecus has a conspicuous pattern, in terms of dark/pale contrast, on the hindquarters that would be a candidate for a bleeze (https://www.agefotostock.com/age/en/details-photo/two-olive-baboons-walking-lateral-papio-anubis/SSJ-120977).

Publicado por milewski hace 6 meses

@paradoxornithidae

The closest I have found to a dark/pale contrast on the hindquarters of a papionin is the following, of mature male Papio hamadryas:

https://depositphotos.com/79002692/stock-photo-wild-hamadryas-baboon.html

The pink does not count w.r.t. my definitions of bleeze, because it is conspicuous by means of hue, not tone. It can be considered a flag, intraspecifically (because papionins see this hue).

Publicado por milewski hace 6 meses

Dolichotis patagonum has body mass 8-9 kg.

For comparison, here are the body masses of other large rodents, in decreasing order:

Hydrochoerus hydrochaeris 60 kg (https://www.inaturalist.org/taxa/74442-Hydrochoerus-hydrochaeris)
Castor fiber 25 kg (https://www.inaturalist.org/taxa/43793-Castor-fiber)
Myocastor coypus 13 kg (https://www.inaturalist.org/taxa/43997-Myocastor-coypus)
Erethizon dorsatum 5 kg (https://www.inaturalist.org/taxa/44026-Erethizon-dorsatum)
Coendou prehensilis 5 kg (https://www.inaturalist.org/taxa/44021-Coendou-prehensilis)
Lagostomus maximus 4 kg (https://www.inaturalist.org/taxa/43824-Lagostomus-maximus)
Cavia aperea 0.5 kg (https://www.inaturalist.org/taxa/43813-Cavia-aperea)

Publicado por milewski hace 6 meses

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