The topi of the Serengeti vs the blesbok of the Highveld: a comparison

The genus Damaliscus is represented in the Serengeti ecosystem of Tanzania and Kenya by the topi (Damaliscus jimela, https://www.inaturalist.org/observations?taxon_id=132769), and on the Highveld of South Africa by the blesbok (Damaliscus pygargus phillipsi, https://www.inaturalist.org/observations?taxon_id=129724).

Both forms are well-known, with thousands of photos on the Web. However, they have never been directly compared in the literature.

BODY SIZE AND SHAPE

The topi weighs about twice as much as the blesbok. The head is proportionately larger in the blesbok than in the topi.

HORNS

The horns of the topi are proportionately shorter than those of the blesbok. This is mainly because the former lacks the straight distal section of the latter (https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=blesbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=195859381)

https://www.alamy.com/stock-photo-blesbok-damaliscus-pygargus-phillipsi-grazing-at-mlilwane-wildlife-94425541.html?imageid=1DCCBA66-A144-4361-813B-D4E707694249&p=14406&pn=1&searchId=83e975b8ad7ac652d6ed41669818bca7&searchtype=0

Furthermore, only in the blesbok are the horns sexually dimorphic in colour, those of males being pale.

SEXUAL DIMORPHISM

Mature males are noticeably stockier than adult females in the blesbok. In the topi, the sexual difference is hardly noticeable.

https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=blesbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=916919

https://www.alamy.com/stock-photo-blesbok-damaliscus-dorcas-phililipsi-mountain-zebra-national-park-59197488.html?imageid=C70BA866-741D-49E7-9406-EF8C73152CCA&p=22059&pn=1&searchId=83e975b8ad7ac652d6ed41669818bca7&searchtype=0

COLOURATION ON THE HEAD: ADULTS

The rostrum of adults is blackish in the topi (https://www.inaturalist.org/observations/3677807), vs whitish in the blesbok.

https://www.freeimages.com/premium/topi-antelope-780234
https://www.mindenpictures.com/stock-photo-topi-damaliscus-lunatus--masai-mara-kenya-naturephotography-image00544100.html

https://www.istockphoto.com/photo/topi-antelope-in-the-savannah-gm590065986-101395729
https://www.istockphoto.com/photo/topi-antelope-gm501136375-43414418

This difference in tones applies also to the forehead. However, the marking on the forehead is broader in the topi than in the blesbok, with no constriction separating it from the marking on the rostrum (https://www.freepik.com/premium-photo/topi-antelope-masai-mara-national-park-kenya_12972508.htm and https://www.dreamstime.com/royalty-free-stock-image-topi-antelope-masai-mara-national-park-kenya-image39514446).

There is a facial bleeze in the blesbok, but the corresponding markings in the topi do not qualify as a bleeze. This is because whitish is more conspicuous than blackish.

This facial difference is so great that it makes the whole figure of adults of the blesbok conspicuous in the field (https://www.alamy.com/stock-photo-herd-of-blesbok-in-field-africa-87078020.html?imageid=86BEBDEB-C18F-4079-8D07-AFF1F8FF92C7&p=269694&pn=1&searchId=83e975b8ad7ac652d6ed41669818bca7&searchtype=0). In this sense, the blesbok is more committed/specialised, in terms of adaptive colouration, for conspicuousness to both predators and conspecifics.

A minor difference is that the whitish of the rostrum extends all the way to the rhinarium in the blesbok, whereas the corresponding blackish does not reach the rhinarium in the topi.

The posterior surface of the ear pinnae of adults tends to be conspicuous in the blesbok, but not in the topi. This is because the back-of-ear in the blesbok tends to be pale, owing partly to sheen.

Only in the topi does the distal section of the back-of-ear tend to be (inconspicuously) dark.

The presence of a posterior auricular flag in the blesbok means that the head of the blesbok is more conspicuous than that of the topi, whether viewed from the front, the side, or the rear.

The complex, subsidiary markings on the sides of the face are pale in the blesbok (https://zooinstitutes.com/animals/blesbok-berlin-zoological-garden-6020.html and https://www.istockphoto.com/photo/blesbok-gm469912880-62692804?phrase=pics%20of%20a%20blesbok), vs dark in the topi (https://www.inaturalist.org/observations/147820582 and https://www.inaturalist.org/observations/147820583).

Furthermore, these tend to appear already in juveniles in the topi (https://www.istockphoto.com/photo/closeup-of-a-beautiful-topi-antelope-gm480066601-36403576), vs only in full maturity in the blesbok.

Only in the blesbok do these subsidiary markings extend to the orbits (https://www.shutterstock.com/it/image-photo/antelope-wild-blesbok-blesbuck-lying-down-2223739221).

COLOURATION ON THE HEAD: JUVENILES

One of the greatest, and most surprising, differences is that only in the blesbok is there a distinct facial pattern of colouration in juveniles.

https://www.robertharding.com/preview/764-6170/topi-tsessebe-damaliscus-lunatus-calf-kruger-national-park/

https://www.shutterstock.com/image-photo/young-blesbok-south-africa-2119574858

https://stock.adobe.com/search?k=blesbok&asset_id=545134999

https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=blesbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=53965073

https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=blesbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=200580481

https://www.alamy.com/juvenile-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-image65490812.html?imageid=E925F6B0-7DB8-4381-90A4-A1DB36C2A783&p=94604&pn=1&searchId=83e975b8ad7ac652d6ed41669818bca7&searchtype=0

COLOURATION ON THE HEAD: INFANTS

In the blesbok, the whitish extends on to the cheeks (with a clear differentiation from the fawn of the rostrum, https://www.afripics.com/image/detail/a-blesbok-lamb-running) and on to the forehead. In the topi, whitish on the face is hardly noticeable (https://www.shutterstock.com/image-photo/four-adorable-baby-topi-antelope-lying-524553010).

https://www.shutterstock.com/image-photo/young-hartebees-rhino-lion-park-south-2240015263
https://stock.adobe.com/search?filters%5Bcontent_type%3Aphoto%5D=1&filters%5Bcontent_type%3Aillustration%5D=1&filters%5Bcontent_type%3Azip_vector%5D=1&filters%5Bcontent_type%3Avideo%5D=1&filters%5Bcontent_type%3Atemplate%5D=1&filters%5Bcontent_type%3A3d%5D=1&filters%5Bcontent_type%3Aaudio%5D=0&filters%5Binclude_stock_enterprise%5D=0&filters%5Bis_editorial%5D=0&filters%5Bfree_collection%5D=0&filters%5Bcontent_type%3Aimage%5D=1&k=blesbok&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=59763469
https://stock.adobe.com/search?k=blesbok&asset_id=544432933

https://www.belfasttelegraph.co.uk/entertainment/news/pictures-belfast-zoo-celebrates-birth-of-betty-bantu-the-blesbok/37149489.html

COLOURATION OF THE HINDQUARTERS

https://www.alamy.com/blesbok-damaliscus-phillipsi-damaliscus-dorcas-phillipsi-damaliscus-pygargus-phillipsi-group-in-savanna-south-africa-eastern-cape-mountain-zebra-national-park-image255390769.html?imageid=7333E975-7610-47E1-8C86-820F3594D64E&p=851122&pn=1&searchId=83e975b8ad7ac652d6ed41669818bca7&searchtype=0

TAIL

The tail-tassel is proportionately longer and laxer in the blesbok than in the topi. Furthermore, the distal part of the tassel tends to be pale only in the blesbok.

https://www.inaturalist.org/observations/32009259
https://www.inaturalist.org/observations/32620006

about 15 seconds in https://www.youtube.com/watch?v=VWM5FJCLLfs

COLOURATION OF THE TORSO

In the topi, the torso has uniform colouration (https://www.inaturalist.org/observations/15397878 and https://www.inaturalist.org/observations/141365278 and https://www.inaturalist.org/observations/110747003).

In the blesbok, it is differentiated into a dorsal section (including the withers), an intermediate section (on the flanks), and a ventral section (narrowest on the chest and broadest on the belly). These are, respectively, medium in tone, dark, and whitish (https://www.agefotostock.com/age/en/details-photo/bontebok-blesbok-damaliscus-dorcas-stands-in-african-savanna-south-africa-eastern-cape-mountain-zebra-national-park/BWI-BS420963 and https://es.123rf.com/photo_27663869_a-blesbok-antelope-damaliscus-pygargus-standing-in-grassland-south-africa.html).

COLOURATION OF THE LEGS

The main difference is that the legs of the blesbok have extensive depigmentation, whereas no part of the legs of the topi is paler than medium tone.

Furthermore, there are individually variable dark markings on the outer surfaces of the lower legs in the blesbok (https://zooinstitutes.com/animals/blesbok-zoo-plzen-19988.html and https://zooinstitutes.com/animals/blesbok-zoo-barcelona-6897.html). These are absent in the topi.

https://www.inaturalist.org/observations/149688457

GAITS

The topi trots occasionally, usually in a demonstrative way. I have seen this

• by males during courtship, in conjunction with holding out the head and tail, and
• by adults during defensive action against Acinonyx jubatus.

Trotting occurs occasionally in the blesbok (https://www.sciencephoto.com/media/1112128/view/blesbok-running-on-a-mountain-ridge), but it remains unknown whether the circumstances match those in the topi.

The following shows non-demonstrative trotting in the topi (https://www.inaturalist.org/observations/29316820 and https://www.inaturalist.org/observations/40344454 and https://www.inaturalist.org/observations/107687028).

POSTURES OF HEAD AND NECK

The blesbok frequently nods its head while walking, and holds the head down, with the horns forward, while standing or lying, facing the sun, in the heat of the day.

The topi only infrequently nods its head, and postures of the head in reaction to heat may occur (https://www.inaturalist.org/observations/103099619 and https://www.inaturalist.org/observations/79119693), but are hardly noticeable.

https://upload.wikimedia.org/wikipedia/commons/5/5d/Topi%2C_Maasai_Mara_%2846196374375%29.jpg

https://www.alamy.com/stock-photo-two-blesbok-damaliscus-pygargus-phillipsi-mountain-zebra-national-27089126.html?imageid=C6D7D661-8F8A-4F6B-80E2-7B00468FBCDF&p=40779&pn=1&searchId=83e975b8ad7ac652d6ed41669818bca7&searchtype=0

https://www.shutterstock.com/image-photo/baby-topi-antelope-standing-grass-serengeti-1296795187

https://pixels.com/featured/baby-topi-dorothy-nelder.html

https://www.istockphoto.com/photo/baby-topi-new-horn-is-coming-under-the-skin-gm503151635-44513508

https://www.agefotostock.com/age/en/details-photo/topi-damaliscus-lunatus-female-with-new-born-calf-massai-mara-kenya/K77-687571/1

https://www.agefotostock.com/age/en/details-photo/topis-damaliscus-korrigum-mother-and-baby-grazing-the-lush-grasslands-ishasha-sector-queen-elizabeth-national-park-uganda-africa/D88-3698849/1

https://www.agefotostock.com/age/en/details-photo/the-topi-antelope-in-the-kenyan-savanna-in-the-middle-of-the-grass-landscape/ESY-055382511/1

https://www.agefotostock.com/age/en/details-photo/topi-damaliscus-lunatus-jimela-adult-female-with-calf-standing-masai-mara-kenya/FHR-11182-00120-125/1

https://www.dreamstime.com/topi-calf-its-mom-maasai-mara-national-reserve-kenya-baby-topi-its-mom-african-savannah-image166656081

DISCUSSION

The colouration of the blesbok is more complex, and more individually variable, than that of the topi.

For an index to my many Posts about the genus Damaliscus, please see https://www.inaturalist.org/journal/milewski/78238-an-index-to-my-posts-on-genus-damaliscus#.

Posted on Απρίλιος 13, 2023 0111 ΠΜ by milewski