There are three reasons to focus on the patterns of colouration on the hindquarters of jackals.
Firstly, only recently has the taxonomy of jackals been revised, with the recognition of not three but four species.
Secondly, the American Canis latrans is the closest counterpart to a jackal in the New World, which means that we can extend the list to five species – omitting for now South America where no jackal-like canid may be large enough to qualify.
Thirdly, all jackals have some sort of display of tonal contrast on the pelage of the hindquarters, a part of the body usually overlooked in descriptions of Carnivora because its displays are subtle relative to those familiar in ruminants.
In this Post, I compare Canis aureus of Asia and Canis anthus of North Africa. The former has most often been photographed in and near India, whereas the latter has most often been photographed in Tanzania and Senegal.
Although anyone with any familiarity with the fact that Canis anthus is a separate species from C. aureus will by now know that the two spp. can be identified by the size of the ear pinnae, there are two other immediate clues to identity.
Firstly, the tail of C. aureus is far shorter than that of C. anthus.
Secondly, the iris of the eye is noticeably pale in C. aureus but not so in C. anthus.
The patterns of tonal contrast on the hindquarters are nebulous and individually variable in both species, and I find negligible difference between them.
In both cases the tail tip tends to be dark, there tends to be a dark patch on the mid-dorsal part of the proximal half of the tail, and there is a dark diagonal separation on the haunch with the posterio-ventral section pale fawn, but not pale enough or consistent enough to qualify as a ‘blaze’.
So, in terms of a dichotomous key, the distinction between these two spp. resolves simply to:
tail reaching no farther than hock: Canis aureus
tail reaching beyond hock: Canis anthus
Canis aureus:
shows that dark-tipped tail just reaches hock:
http://cdn3.discoverwildlife.com/sites/default/files/imagecache/623px_wide/main/jackal_shimi_eni_iStock_623.jpg
shows the usual division of haunch into two by vaguely dark diagonal band; this individual has unusually dark tail:
https://drscdn.500px.org/photo/44612456/q%3D80_h%3D450/96e7ffce26211c418c481cee8f6343dd
shows that colouration pattern on hindquarters lacks noticeable tonal contrast:
http://m8.i.pbase.com/o4/09/881409/1/149277148.6QCyQSjf.sciacallodorato44.jpg
shows dark patch on dorsal surface of proximal part of tail:
http://www.thebetterindia.com/wp-content/uploads/2011/06/golden_jackal.jpg
shows that longest hairs of tail do not pass hock if hind leg is in standing position:
https://upload.wikimedia.org/wikipedia/commons/c/c0/Indian_Jackal_02.jpg
shows how short the tail can look relative to the length of the body; this individual lacks division of haunch:
https://upload.wikimedia.org/wikipedia/commons/9/9e/Flickr_-Rainbirder-_Golden_Jackal.jpg
shows slight ridge of dark hairs on mid-dorsal line of rump:
http://www.julienboule.com/golden-jackal-2#photo
shows individual with dark tail, not extending to lateral proximal part of tail:
http://www.canids.org/app/images/canids/golden-jackal/goldenjackal.jpg
shows relatively rich-hued individual with nondescript haunch:
http://4.bp.blogspot.com/-H5WR6jk4vaA/Tlx5BjcfxjI/AAAAAAAABnI/lQctB-n4mxc/s1600/_IGP7448.JPG
shows that, although tail is clearly the darkest part of the whole animal, there is no noticeable contrast with any pale part of haunch:
https://www.mindenpictures.com/cache/pcache2/80182228.jpg
shows shortness of tail and paleness of lateral surface of proximal tail:
http://media.gettyimages.com/photos/golden-jackal-portrait-ranthambhore-national-park-india-picture-id112191220?s=170667a
Canis anthus:
shows clearly that tail extends below hock:
http://rpguide.soulsrpg.com/public/images/subspecies/jackal/ca_anthus2.png
ditto but also shows how distinct the dark diagonal can be on haunch:
http://www.animalspot.net/wp-content/uploads/2012/09/Golden-jackal-Pictures.jpg
shows how pale and nondescript hindquarters can be:
http://www.safari-wangu.de/Afrikanischer_Goldwolf.jpg
shows again that tail reaches below hock:
https://s-media-cache-ak0.pinimg.com/originals/60/f7/83/60f783ace23f1a164bac271cd98abeac.jpg
shows that, as in C. aureus, lateral surface of proximal tail is pale:
https://c2.staticflickr.com/4/3297/3260783309_1c4c487bc5_z.jpg?zz=1
shows maximum development of dark diagonal on haunch:
http://rpguide.soulsrpg.com/public/images/subspecies/jackal/ca_bea3.png
shows unusually pale and nondescript individual, in which even tail tip not dark:
https://terrydarc.files.wordpress.com/2010/09/serengeti-iii-48.jpg
shows individual in which tail seems relatively short:
http://c8.alamy.com/comp/EG7CM2/common-or-golden-jackal-in-senegal-EG7CM2.jpg
shows full length of tail:
http://www.mundo.cz/sites/default/files/images/fauna-flora/sakal-obecny.jpg
shows individual with maximal tonal contrast between dark tail and pale posterio-ventral section of haunch; this is just vivid enough to qualify as a ‘blaze’ but is too variable individually:
http://wallpapersdsc.net/wp-content/uploads/2016/10/Jackal-Computer-Wallpaper.jpg
shows dark patch on dorsal surface of proximal half of tail, as in C. aureus:
http://media.gettyimages.com/photos/golden-jackal-djoudj-national-bird-sanctuary-senegal-picture-id537007683?s=170667a
shows how little tonal contrast there can be between tail and haunch:
https://senegalwildlife.files.wordpress.com/2015/12/palmarin_jackal1.jpg?w=624
Σχόλια
Photo showing that Canis anthus is less countershaded on legs than Lupulella mesomelas:
Canis anthus bea:
https://s-media-cache-ak0.pinimg.com/originals/e7/33/d4/e733d4c0972c658dbd289e41c4d9801b.jpg
Προσθήκη σχόλιου