@christiaan_viljoen @dewald2 @matthewinabinett @jacqueline_llerena @simontonge @paradoxornithidae @tonyrebelo
The relationship between age and appearance is potentially informative in any species of ungulate. However, it is particularly so in the red hartebeest (Alcelaphus caama), because
Please see the illustrations in https://www.researchgate.net/publication/316165747_Focus_on_the_Red_Hartebeest_Alcelaphus_buselaphus_caama
Newborn
https://www.dreamstime.com/addo-elephant-national-park-south-africa-image201995623
https://www.dreamstime.com/red-hartebeest-calf-southern-african-savanna-image145519702
INFANTS HIDE FOR TWO WEEKS, helping to explain why there are so many photos of infants slightly older than 2 weeks, as follows.
2-3 weeks
https://www.inaturalist.org/observations/34703540
https://stock.adobe.com/images/id/6354853?tduid=86f6bb255d68643c6d65a89810a8b212&as_channel=affiliate&as_campclass=redirect&as_source=arvato
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-at-waterhole-kalahari-botswana-africa/ISO-IS09B64Z9
https://www.inaturalist.org/observations/127790132
https://www.dreamstime.com/red-hartebeest-calf-red-hartebeest-calf-wet-rain-shower-southern-african-savanna-image107666150
https://www.dreamstime.com/red-hartebeest-calf-southern-african-savanna-image145519842
https://www.dreamstime.com/stock-image-baby-red-hartebeest-antelope-image13753251
https://www.dreamstime.com/royalty-free-stock-images-baby-red-hartebeest-antelope-mom-image11720999
https://www.dreamstime.com/stock-photo-juvenile-red-hartebeest-southern-african-savanna-image93776386
https://www.dreamstime.com/stock-photo-juvenile-red-hartebeest-southern-african-savanna-image93776491
https://stock.adobe.com/images/red-hartebeest-alcelaphus-buselaphus-caama-or-a-caama-juvenile-young-baby-antelope-portrait-with-one-eye-shut-as-if-winking/421088757?as_campaign=ftmigration2&as_channel=dpcft&as_campclass=brand&as_source=ft_web&as_camptype=acquisition&as_audience=users&as_content=closure_asset-detail-page
https://www.alamy.com/a-red-hartebeest-alcelaphus-buselaphus-caama-calf-or-small-baby-antelope-running-to-catch-up-image213086330.html
https://www.inaturalist.org/observations/127619182
BY ONE MONTH OLD, the horns are not yet noticeable, but body mass has doubled since birth.
1 month
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-young-kgalagadi-transfrontier-park-kalahari-desert-south-africa/YD4-2933940
https://www.pikist.com/free-photo-sqetz
https://www.dreamstime.com/red-hartebeest-calf-southern-african-savanna-image145519513
https://www.dreamstime.com/red-hartebeest-calf-southern-african-savanna-image145519750
https://www.alamy.com/alert-young-kudu-calf-image65992949.html?imageid=F7972E69-9122-4D9B-A1DC-A5CB20701C31&p=40848&pn=2&searchId=b0dfc14786b5fa6ae25dfd03aa754a21&searchtype=0
https://www.inaturalist.org/observations/80401764
2 months
https://www.dreamstime.com/red-hartebeest-calf-southern-african-savanna-red-hartebeest-calf-image138194762
https://www.dreamstime.com/royalty-free-stock-photography-red-hartebeest-standing-open-field-calf-image29300867
https://www.dreamstime.com/royalty-free-stock-photos-red-hartebeest-standing-open-field-calf-image29300908
3 months
https://www.pond5.com/stock-footage/item/36490409-red-hartebeest-calf
https://www.inaturalist.org/observations/86069654
https://www.inaturalist.org/observations/22357084
The appearance of suckling juveniles of this age can be seen
4 months
https://www.dreamstime.com/juvenile-red-hartebeest-calf-mist-juvenile-red-hartebeest-calf-misty-morning-addo-elephant-park-south-africa-image228762287
https://www.dreamstime.com/hartebeest-female-calf-kgalagadi-transfrontier-park-south-africa-specie-alcelaphus-buselaphus-family-bovidae-hartebeest-image240044359
https://www.dreamstime.com/hartebeest-female-calf-kgalagadi-transfrontier-park-south-africa-specie-alcelaphus-buselaphus-family-bovidae-hartebeest-image240044372
https://www.dreamstime.com/stock-photo-juvenile-red-hartebeest-southern-african-savanna-image93776768
https://www.dreamstime.com/royalty-free-stock-image-hartebeest-red-animal-moms-cow-her-calf-drinking-water-photo-taken-game-ranch-namibia-africa-image30435926
https://www.robertharding.com/preview/764-3238/young-red-hartebeest-alcelaphus-buselaphus-addo-elephant-national/
https://www.robertharding.com/preview/764-5930/red-hartebeest-alcelaphus-buselaphus-cow-calf-addo-elephant/
https://www.alamy.com/stock-photo-red-hartebeest-alcelaphus-caama-50919189.html?imageid=04C1D099-3F70-4A05-8C57-E2ABED2E5322&p=170574&pn=1&searchId=9602590878ee9911fc12a6e1486d6e22&searchtype=0
https://www.alamy.com/young-red-hartebeest-alcelaphus-buselaphus-running-in-grassland-mountain-zebra-national-park-south-africa-image472233605.html?imageid=AB82AC72-0091-4A2F-803B-421A23B37322&p=70019&pn=1&searchId=9602590878ee9911fc12a6e1486d6e22&searchtype=0
BY SIX MONTHS,
6-7 months
https://www.flickr.com/photos/arthur_chapman/7600869392/in/photostream/
https://stock.adobe.com/fi/search?k=%22red+hartebeest%22&asset_id=368460805
https://www.inaturalist.org/observations/103543206
https://www.inaturalist.org/observations/96453015
https://www.inaturalist.org/observations/32475264
https://www.inaturalist.org/observations/24431929
https://stock.adobe.com/fi/search?k=%22red+hartebeest%22&asset_id=510930262
https://www.inaturalist.org/observations/87422880
8 months
https://pixabay.com/photos/red-hartebeest-antelope-hartebeest-4114705/
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=hartebeest&order=relevance&safe_search=1&limit=100&search_page=14&search_type=pagination&get_facets=0&asset_id=480986151
https://stock.adobe.com/fi/search?k=%22red+hartebeest%22&asset_id=411186967
https://stock.adobe.com/fi/search?k=%22red+hartebeest%22&asset_id=480174251
https://www.inaturalist.org/observations/84420586
https://www.inaturalist.org/observations/33775370
https://www.agefotostock.com/age/en/details-photo/hartebeest-alcelaphus-buselaphus-in-the-early-morning-etosha-national-park-namibia-africa/IBK-1082236
ABOUT NINE MONTHS OLD, THE HORN TIPS TOUCH EACH OTHER before growing apart again
9 months
https://www.pikist.com/free-photo-siesm
https://pixabay.com/photos/red-hartebeest-hartebeest-antelope-4757941/
https://www.dreamstime.com/stock-images-red-hartebees-front-dead-trees-image29369634
https://www.inaturalist.org/observations/121590665
https://www.inaturalist.org/observations/94453196
https://www.inaturalist.org/observations/18412388
https://www.inaturalist.org/observations/7274278
https://www.agefotostock.com/age/en/details-photo/hartebeest-alcelaphus-buselaphus-in-the-early-morning-etosha-national-park-namibia-africa/IBK-1082234
10 months
https://www.shutterstock.com/image-photo/female-red-hartebeest-walking-her-young-1475515883
https://www.dreamstime.com/royalty-free-stock-photo-red-hartebees-family-young-calf-standing-green-fields-image35903145
https://stock.adobe.com/fi/search?k=%22red+hartebeest%22&asset_id=198816863
https://www.inaturalist.org/observations/63478415
https://www.inaturalist.org/observations/42748058
https://www.inaturalist.org/observations/35942310
https://www.inaturalist.org/observations/20177206
https://www.shutterstock.com/image-photo/red-hertbeest-savannah-alcelaphus-caama-200785607
The following shows adult female with 10 month-old male, probably its son:
https://www.shutterstock.com/image-photo/adult-hartebeest-her-adolescent-young-kalahari-113169034
AT ONE YEAR OLD, THE HORN-TIPS BECOME HORIZONTAL. The dark patches on shoulder and ventral part of haunch are not yet fully-developed.
12 months
female:
https://stock.adobe.com/fi/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=%22red+hartebeest%22&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=367151611
https://www.inaturalist.org/observations/117569311
https://www.inaturalist.org/observations/54496645
https://www.inaturalist.org/observations/24431982
male:
https://www.shutterstock.com/video/clip-11340560-red-hartebeast-4k-footage-namibian-savannah
https://es.123rf.com/photo_91529230_an-alert-red-hartebeest-antelope-on-the-african-grassland.html
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-close-up/SLR-IS098Y6W3
https://www.inaturalist.org/observations/104693518
https://stock.adobe.com/fi/search?k=%22red+hartebeest%22&asset_id=63615660
https://www.inaturalist.org/observations/35819422
1.5 years, female
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-walking-in-grass/SLR-IS098Y6W2
https://www.inaturalist.org/observations/116586348
1.5 years, male
AT TWO YEARS OLD, THE FOREHEAD FINALLY BECOMES DARK
Estes (1991, page 139) states: "Male hartebeests often accompany their mothers for up to 2.5 years, a year longer than other alcelaphines, yet mature no later than wildebeests, at 3-4 years (Gosling, 1974). The basis of this unusual arrangement is continuous breeding: female hartebeests calve every 9-10 months (gestation 8 months), too early for the last calf to become independent".
2 years
https://www.imago-images.com/st/0152431666
https://stock.adobe.com/fi/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=%22red+hartebeest%22&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=63615658
https://stock.adobe.com/fi/search?k=%22red+hartebeest%22&asset_id=522906968
https://www.inaturalist.org/observations/40968903
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-caama-adult-male-standing-in-the-high-grass-kgalagadi-transfrontier-park-northern-cape-south-africa-africa/ZI6-3572633
https://www.inaturalist.org/observations/52142300
AT 2-2.5 YEARS OLD, FEMALES REACH SEXUAL MATURITY
Males become sexually mature at about 3 years, but socially mature only some 5 years later
3 years, female
https://www.inaturalist.org/observations/201786
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-caama-adult-running-across-a-dirt-road-close-of-day-kgalagadi-transfrontier-park-northern-cape-south-africa-africa/ZI6-3564222
https://www.inaturalist.org/observations/95198707
https://www.inaturalist.org/observations/27721560
AT THREE YEARS OLD
3 years, male
https://www.inaturalist.org/observations/103543206
https://www.agefotostock.com/age/en/details-photo/kuhantilope-red-hartebeest-alcelaphus-buselaphus-etosha-namibia/ZON-8871375
First photo in https://www.inaturalist.org/observations/62680448
5 years, female
5 years, male
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-mountain-zebra-national-park-south-africa-africa/RHA-764-988
https://stock.adobe.com/fi/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=%22red+hartebeest%22&order=relevance&safe_search=1&limit=100&search_page=2&get_facets=0&search_type=pagination&asset_id=113541552
https://www.inaturalist.org/observations/116565592
https://www.inaturalist.org/observations/11076946
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-standing-in-the-savanna-side-view-south-africa-western-cape-karoo-national-park/BWI-BS443380
https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-caama-kgalagadi-transfrontier-park-kalahari-south-africa/EEA-SS2255514
10 years, female
AT TEN YEARS OLD, MALES REACH THEIR PRIME becoming noticeably darker than mature females
10 years, male
https://www.inaturalist.org/observations/102666578
https://www.inaturalist.org/observations/99463527
https://www.inaturalist.org/observations/57816678
https://www.inaturalist.org/observations/47862767
https://www.inaturalist.org/observations/11111379
12 years, male
https://www.inaturalist.org/observations/117556686
https://www.inaturalist.org/observations/49832745
https://wildlifesafari.info/hartebeest_red.html
15 years, male
https://www.inaturalist.org/observations/86376921
https://www.inaturalist.org/observations/66735467
DISCUSSION
The colouration on the hindquarters is far more precocial than that on the head.
The bleeze on the hindquarters (including darkness of the tail) appears (https://www.inaturalist.org/observations/18676884) long before the full set of dark markings on the head appears (https://stock.adobe.com/fi/search?k=%22red+hartebeest%22&asset_id=522906968).
The ontogenetic sequence of colouration on the head is intriguing.
In infants, the head is plain except for dark on the lower lip, pale on the anterior surface of the ear pinnae, and pale immediately around each eye (https://stock.adobe.com/images/red-hartebeest-alcelaphus-buselaphus-caama-or-a-caama-juvenile-young-baby-antelope-portrait-with-one-eye-shut-as-if-winking/421088757?as_campaign=ftmigration2&as_channel=dpcft&as_campclass=brand&as_source=ft_web&as_camptype=acquisition&as_audience=users&as_content=closure_asset-detail-page and https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-young-kgalagadi-transfrontier-park-kalahari-desert-south-africa/YD4-2933939).
By six months old, the pale around each eye has largely been replaced by a dark patch (https://www.agefotostock.com/age/en/details-photo/red-hartebeest-alcelaphus-buselaphus-standing-in-the-savanna-side-view-south-africa-western-cape-karoo-national-park/BWI-BS443379). This small-scale 'mask' remains throughout life.
However, dark on the forehead takes about another 1.5 years to appear (https://www.shutterstock.com/image-photo/two-red-hartebeest-looking-camera-early-1712872699).
It may be worth pondering why dark on the tail is present already at birth (https://www.istockphoto.com/photo/red-hartebeest-and-calf-gm1216185417-354538365?phrase=juvenile%20red%20hartebeest), whereas dark on the forehead is delayed until adolescence.
I hypothesise that this is because the colouration on the hindquarters is adaptive mainly against predation, whereas the colouration on the head is adaptive mainly socially.
Comments
https://www.dreamstime.com/royalty-free-stock-photo-red-hartebeest-wildlife-background-speed-power-runs-across-green-grass-field-as-seen-wilds-africa-image37860795
https://www.agefotostock.com/age/en/Stock-Images/red-hartebeest-running.html
https://stock.adobe.com/fi/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=%22red+hartebeest%22&order=relevance&safe_search=1&limit=100&search_page=3&search_type=pagination&get_facets=0&asset_id=430858768
https://www.inaturalist.org/observations/9562867
https://www.inaturalist.org/observations/9287765
https://www.inaturalist.org/observations/5609759
https://www.inaturalist.org/observations/4927264
ORYX GAZELLA
https://stock.adobe.com/images/id/295818146?tduid=86f6bb255d68643c6d65a89810a8b212&as_channel=affiliate&as_campclass=redirect&as_source=arvato
Shift to Post on bontebok among flowers
https://www.agefotostock.com/age/en/details-photo/bontebok-damaliscus-pygargus/WR2048913
unusually clear comparison of infant and juvenile
https://www.shutterstock.com/image-photo/female-red-hartebeest-walking-her-young-1475515883
https://www.shutterstock.com/image-photo/red-hartebeest-antelope-south-africa-126171779
https://www.shutterstock.com/image-photo/namibia-etosha-national-park-red-hartebeest-649009471
https://www.shutterstock.com/image-photo/red-hartebeest-standing-grass-starring-camera-645605965
https://www.shutterstock.com/image-photo/two-red-hartebeest-antelope-296368655
The following shows how close to adulthood A. caama can be before the forehead turns dark:
https://www.shutterstock.com/image-photo/red-hartebeest-alcelaphus-buselaphus-caama-walking-1590963340
https://www.shutterstock.com/image-photo/red-hartbeest-alcelaphus-buselaphus-kgalagadi-transfrontier-1411796342
https://www.shutterstock.com/image-photo/red-hartebeest-lat-alcelaphus-buselaphus-caama-618821711
Mislabelled
Damaliscus lunatus lunatus
https://www.shutterstock.com/image-photo/group-hartebeests-savanna-moremi-game-reserve-1442216207
https://www.dreamstime.com/stock-photo-cokes-hartebeest-family-aka-kongoni-standing-savanna-olare-orok-conservancy-bordering-masai-mara-kenya-all-looking-image83117687
INFANT OF ALCELAPHUS COKII:
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=hartebeest&order=relevance&safe_search=1&limit=100&search_page=63&search_type=pagination&get_facets=0&asset_id=96970655
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