May 22, 2024

Description of a nest and clutch of the harlequin quail (Coturnix delegorguei delegorguei) in what is now Nairobi National Park, Kenya

On 15 July 1988, I found a nest of a species of quail, presumably Coturnix delegorguei (https://www.inaturalist.org/observations?place_id=10957&subview=map&taxon_id=790), near the laundry-drying wire at the School for Field Studies camp at Wildlife Ranching and Research, on the Athi-Kapiti plains, Kenya.

This site is now within Nairobi National Park.

The nest was located in a patch of herbage that had been slashed by machete, to keep it short, 5-6 weeks previously. I infer that the nest had been established after the slashing, i.e. in the open.

The nest consisted of a shallow, loose cup, about 10 cm diameter, of dry, curly grass-blades. This was a very simple structure, positioned near ground level.

The embryos were half-developed at the time of discovery.

The eggs were whitish, with a spattering of fine olive speckles of various sizes and intensities (most smaller than a large 'fly spot'), in some cases amounting to vague scribblings. One side of each egg tended to be hardly spotted, and the other side dark enough to be described as 'speckled fawn'.

The masses of the eggs were: 6.7 g, 6.7 g, 6.5 g, 6.1 g, 6.4 g, 6.5 g, and 6.3 g. The dimensions were (maximum length X maximum width of each egg): 2.9 X 2.2 cm, 2.93 X 2.24 cm, 2.94 X 2.17 cm, 2.99 X 2.22 cm, 2.94 X 2.22 cm, 3.05 X 2.22 cm, and 2.925 X 2.19 cm.

Although I resided in a tent in this campsite for more than 3.5 years, I do not recall ever spotting the harlequin quail here, except in the form of this single nest.

Posted on May 22, 2024 02:18 AM by milewski milewski | 0 comments | Leave a comment

May 20, 2024

Comparison of body composition in the Maasai ostrich (Struthio camelus massaicus) and a coexisting phasianid, the yellow-necked spurfowl (Pternistis leucoscepus)

INTRODUCTION

Ostriches (Struthioniformes, https://en.wikipedia.org/wiki/Struthioniformes) can in some sense be viewed as scaled-up galliforms (https://en.wikipedia.org/wiki/Galliformes).

Furthermore, the Maasai ostrich (Struthio camelus massaicus, https://www.inaturalist.org/observations?taxon_id=322201) coexists with various galliform families, genera, and spp., including the yellow-necked spurfowl (https://www.inaturalist.org/taxa/495989-Pternistis-leucoscepus).

However, ostriches can alternatively be viewed as quasi-ungulates, integrated into a complex guild of Artiodactyla and Perissodactyla in Africa and - historically - Eurasia.

This is mainly because - contrary to popular belief - ostriches are not so much omnivorous as specialised for herbivory.

AIMS

With this ambivalence in mind, I was curious to compare the Maasai ostrich (hereafter referred to as the ostrich) with the yellow-necked spurfowl (hereafter referred to as the spurfowl) with respect to the proportional sizes of various organs in its body.

Is it the case that the ostrich scales relative to the spurfowl as, for example, the lion (Panthera leo) scales relative to the domestic cat (Felis catus), as detailed in Davis (1962, https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1558-5646.1962.tb03240.x and https://www.jstor.org/stable/2406182 and https://onlinelibrary.wiley.com/doi/10.1111/j.1558-5646.1962.tb03240.x and https://academic.oup.com/evolut/article-abstract/16/4/505/6867898?login=false)? Or are there basic differences in the sizes of organs, unexplained by mere scaling?

STUDY SPECIES

For an introduction to the spurfowl in question, please see:

https://ebird.org/species/yenspu1/L3028880

https://www.google.com.au/search?q=Yellow-necked+spurfowl&sca_esv=f9529c069ef53509&sxsrf=ADLYWIKMXM1hF3wGgITFx8oJLiMSlJTHnQ%3A1716248001529&source=hp&ei=wd1LZu-rHtPs1e8PkqGECA&iflsig=AL9hbdgAAAAAZkvr0QCE8ho7MIAM1URxQ-8YOIC3NDCa&ved=0ahUKEwivkOeDsp2GAxVTdvUHHZIQAQEQ4dUDCBc&uact=5&oq=Yellow-necked+spurfowl&gs_lp=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_qnAg&sclient=gws-wiz#fpstate=ive&vld=cid:9f8d02bc,vid:EjzMyaiP_sU,st:0

STUDY LOCATION

Wildlife Ranching and Research, later Swara Plains Conservancy, now incorporated in Nairobi National Park
1987-1988

RESULTS

All of the following values are mean masses as % of mean body mass, except where stated otherwise.

The values are

  • first for the adults of the ostrich (for sample size see other Posts), and
  • second for the spurfowl (n = 3 adults).

Dressed carcass 49%, 67%
Total limb 49%, 33%
Feet 4%, 3%
Head 0.6%, 4%
Skin (includes skin of wings?) 4.5%, 4.5%
Skin and feathers 6%, 12%
Total visceral organs 6%, 3%
Cardiovascular organs 3%, 1%
Cardiovascular organs as % of total visceral organs (excluding gastrointestinal tract) 55%, 39%
Eyeballs 0.085%, 0.67%
Eyeballs as % of head (including eyeballs) 15%, 18%
Gastrointestinal tract 21%, 9%
Contents alone of stomach 3%, 6%

Length of small and large intestines as %o of total body length 193o/oo %o, 67.5%o

The following body components showed positive allometry:

  • legs including feet (ostrich 46%, spurfowl 22%)
  • internal organs including gastrointestinal tract and, specifically, intestines (organs: ostrich 6%, spurfowl 3%; intestine length: ostrich 52%, spurfowl 19%)

Despite the large, sturdy legs and feet of the ostrich, its feet are more simply constructed than those of the spurfowl, with only two toes instead of three.

The following body components showed negative allometry:

  • dressed carcass (ostrich 49%, spurfowl 67%),
  • head, including eyes (ostrich 1%, spurfowl 4%),
  • feathers (ostrich 6%, spurfowl 12%),
  • wings (ostrich 2%, spurfowl 8%), and
  • pectoral muscles (obvious).

The ostrich had a proportionately longer oesophagus than that of the spurfowl. However, the masses, relative to body masses, did not differ.

The full and empty proventriculus of the ostrich were statistically significantly heavier, relative to body mass, than the full and empty crop of the spurfowl. However, the volumes (measured by filling the emptied organs with water) did not differ, relative to body mass.

The full and empty gizzards did not differ in mass, relative to body mass, in the ostrich and the spurfowl.

The stomach (comprising crop, proventriculus, and gizzard) did not differ in mass, whether full or empty, relative to body mass, in the ostrich and the spurfowl.

In the case of the small intestine, lengths, and full and empty masses, did not differ, relative to body masses, in the ostrich and the spurfowl. However,

  • volume (as measured by filling the emptied organ with water) was statistically significantly greater in the ostrich than in the spurfowl, and
  • surface area was statistically significantly smaller in the ostrich than in the spurfowl.

The full mass, length, and volume (as measured by filling the emptied paired organs with water) of the caeca were statistically significantly greater, relative to body mass, in the ostrich than in the spurfowl. The surface area was statistically significantly smaller in the ostrich, relative to body mass, than in the spurfowl. The empty masses, relative to body masses, did not differ significantly.

The large intestine was statistically significantly greater in the ostrich than in the spurfowl, relative to body masses, in full masses, empty masses, and lengths.

The gastrointestinal tract may be divided into foregut and hindgut.

The foregut, consisting of the stomach in a loose sense, contributed a similar proportion of body mass in both spp. However, the stomach is composed of

  • two parts in the ostrich, compared to
  • three parts (thin-walled crop, tubular proventriculus, and gizzard) in the spurfowl.

In the hindgut, the large intestines show the greatest contrast between the two spp. of birds.

The small intestine contribute similar proportions of body mass in the two spp. However, that of the ostrich is irregularly constricted at intervals of about 20-25 cm, and the chyme tends to form boluses far drier than the fluid chyme of the spurfowl.

The caeca of the ostrich alone contains spiralled, mucus-lined septa, apparently restricting the movement of contents.

The large intestine is extremely long and bulky in the ostrich, weighing 42% of all visceral organs and their contents. By contrast, the large intestine is rudimentary in the spurfowl.

The first half of the large intestine of the ostrich is an exaggerated version of the caeca. The spiral septum is wider but has a tighter spiral, which restricts movement of the contents to the extent that I found, while collecting the data, that manual emptying of the tube was impossible.

In the ostrich, the contents of the caecum and initial section of the large intestine are fluid. By contrast, farther down the large intestine boluses are formed, with obvious progressive desiccation towards the cloaca, where fecal pellets occur.

DISCUSSION

For useful background, please see

The relationship between the ostrich and the spurfowl is unsurprising (in line with other animals of different size), in that the larger bird has proportionately:

  • smaller eyes and brain,
  • bigger bones,
  • bigger cardiovascular system, and
  • smaller metabolic organs.

Both the volumes of the proventriculus/crop and the combined masses of the stomach components are similar, relative to body masses, in the ostrich and the spurfowl.

The skin is also isometric in the two spp.

This is noteworthy, because the skins of larger animals are usually proportionately thicker than those of smaller animals, despite proportionately lesser surface areas.

For example, the mass of the skin (excluding that of head and lower legs), relative to body mass, is as follows (n = 20 for each species) in ruminants coexisting with the ostrich in the study area:

  • Eudorcas thomsonii thomsonii 0.56 kg/21kg = 2.7%
  • Nanger granti granti 1.34 kg/50 kg = 2.7%
  • Alcelaphus cokii 5.23 kg/130 kg = 4.0%
  • Connochaetes albojubatus 8.31 kg/200 kg = 4.2%

This positive allometry may be because larger-bodied spp. tend to

  • be vulnerable to parasites,
  • possess areas of bare skin (applicable also to the ostrich), and
  • experience greater stresses on the skin because of percussion/friction by/with extraneous objects.

The skin of the ostrich is proportionately thin, compared to that of like-size ungulates. However, it is proportionately heavier, probably because it is denser (as evidenced by the durability of ostrich leather).

The large legs and feet, and small wings and feathers (and body cage), of the ostrich could be owing to its large body size, or to its flightlessness. However, the two attributes are related anyway. (are the wings of large flightless birds positively allometric, thus emphasising the oddness of the ostrich?? - see literature).

It is remarkable that the pair of legs (including the feet) of the ostrich approaches half of body mass. The leg bones of the ostrich seem disproportionately heavy, possibly because of a disproportionate risk of shattering in such a heavy bird.

There is obvious convergence with ungulates in

Posted on May 20, 2024 04:34 PM by milewski milewski | 10 comments | Leave a comment

May 19, 2024

Size of the eyeballs relative to the size of the head in the Maasai ostrich (Struthio camelus massaicus)

@tonyrebelo @jeremygilmore @ludwig_muller @matthewinabinett @nyoni-pete

The largest eye of any land vertebrate is reputed to be that if the ostrich (body weight 63-104 kg, Cramp S, 1977, The birds of the western Palaearctic, vol. 1, Oxford University Press, London).

The ostrich (Struthio camelus) combines

Indeed, the combined mass of the pair of its eyeballs exceeds the mass of its brain (https://www.gulla.net/en/ai/the-curious-case-of-the-ostrichs-eye-and-its-pint-sized-brain/ and https://www.youtube.com/watch?app=desktop&v=THUDef6VyKA and https://www.reddit.com/r/Damnthatsinteresting/comments/t8auso/an_ostrichs_eye_is_bigger_than_its_brain_the/ and https://www.facebook.com/LAZoo/photos/a.304439135272/10165402741960273/?type=3 and https://www.facebook.com/familyfocuseyecare/posts/fun-fact-ostrich-eyes-are-bigger-than-their-brains-/2621767008132812/).

As with many factoids/memes, a risk arises of exaggeration and factual distortion.

In this Post, I record the exact dimensions of the eyeballs and head, which I myself carefully measured.

Subspecies: Struthio camelus massaicus, fully wild (no influence of captivity or domestication)

Location: Wildlife Ranching and Research, later Swara Plains Conservancy, now incorporated into Nairobi National Park

Sample size: n = 3 female adults, measured 9 October, 19 October, and 29 October, 1987.

EYEBALLS

https://www.flickr.com/photos/ceekay/3465110529 and https://www.deviantart.com/frankandcarystock/art/Ostrich-Eye-369635470 and https://www.pixoto.com/images-photography/animals/birds/ostrich-eye-4913795697213440 and https://www.dreamstime.com/stock-image-portrait-ostrich-image16965141

My measurements were similar for the left and right eyeballs.

Eyeball circumference: 151.5 mm, 154 mm, 155 mm
Eyeball diameter: - , 51 mm, 52 mm
Eyeball depth: - , 41.5 mm, 42.5 mm
Eyeball mass (each one, not the pair): 42.1 g (slightly flaccid), 45.2 g, 46.8 g

HEAD

https://unsplash.com/photos/an-ostrich-with-its-mouth-open-and-its-eyes-closed-cHcTA_HyXZ4 and https://www.discovery.com/nature/ostrichlandand https://stock.adobe.com/hu/images/ostrich-eyes-close-up-close-up-portrait-of-an-ostrich-with-big/390285270 and https://unsplash.com/photos/an-ostrichs-face-with-a-blurry-background-DOqXcvrrmSM and https://es.123rf.com/stock-photo/ostrich_eye.html

Head mass: 0.59 kg, 0.92 kg (skull haemorrhaged), 0.70 kg
Head length straight to occipital condyle: 19.4 cm, - , 20 cm
Head dorsal length along contour: 26 mm, 23 mm, 28 mm
Head ventral length along contour: 20 mm, 20 mm, 20 mm
Beak length along contour, tip to gape: 14.7 mm, 14 mm, 15.6 mm
Beak straight length, tip to gape: - , - , 14.6 mm
Beak length along contour, tip to cere (https://www.collinsdictionary.com/dictionary/english/cere): 68 mm, 67 mm, 84 mm
Beak straight length, tip to cere: - , 6.4 cm, 7.6 cm
Beak length along contour, tip to feathers: - , 71 mm, 88 mm
Beak straight length, tip to feathers: 67 mm, 67.5 mm, 81 mm
Beak width at gape: 80 mm, 82 mm, 88 mm
Beak width at cere: 57 mm, 55 mm, 59.5 mm
Head maximum width: 107 mm, 103 mm, 103 mm
Head depth: 93 mm, 90 mm, 92.3 mm
Orbit (bony) width: 60 mm, 58 mm, 64 mm
Tongue length: 20 mm, 20 mm, 12 mm (probably measured differently)
Tongue width: 42 mm, 38 mm, 38.7 mm

Mass of head (excluding horns) in coexisting ungulates:

The following values are means, in which the sexes are combined unless otherwise stated.

Eudorcas thomsonii thomsonii: females 1.1 kg, 1.4 kg (combined: 1.25 kg)
Gazella granti granti: 2.6 kg
Aepyceros melampus: 2.5 kg
Alcelaphus cokii: 5.75 kg
Connochaetes albojubatus: 10.2 kg
Equus equus boehmi (body mass 260.5 kg): 12.25 kg
Taurotragus oryx pattersonianus: 12.95 kg

Sundry notes from the literature:

No bird has eyes approximating the spherical form typically seen in the eyes of mammals.

The eyelids are feathered in the ostrich, rheas, and owls, but not in most birds.

The eyeball of the ostrich has a bulbar axial length of 50 mm (line passing through lens to retina). Please see https://www.perplexity.ai/search/Consider-the-axial-DYkJ039cSnGJ78vdJU4ZEw.

Typically, birds' eyes are so large, relative to the skull, that they meet in the middle of the head, separated by only a thin septum of bone.

Optically, the most important parameters of size are anterior focal length or posterior nodal distance.

Miller (1979) has shown that a large posterior nodal distance is essential if the vertebrate eye is to achieve the maximum theoretical limit of visual resolution. This is because there exists a finite limit on the size, and hence packing density, of the retinal photoreceptors which sample the retinal image.

Clearly if the image is spread over more photoreceptors, then there is an increase in the amount of detail resolved. However, this is limited by diffraction effects and aberrations within the optical system. "Thus, an eye any larger than that of the ostrich...may have little adaptive value, since although the image will be larger, its quality may deteriorate" (G H Martin, page 313, Notes from Form and Function in Birds, 1985, vol. 3, Ed. by A S King and J McLelland, Academic Press, https://books.google.com.au/books/about/Form_and_Function_in_Birds.html?id=gHQXAQAAIAAJ&redir_esc=y).

Posted on May 19, 2024 11:15 PM by milewski milewski | 10 comments | Leave a comment

The ostrich (Struthio camelus) has a small brain, perhaps even relative to phasianid birds

It is easy to show that the ostrich (Struthio camelus) has a small brain relative to like-size ungulates - with which it is ecologically comparable.

What is more subtle is an allometric comparison of brain sizes between the ostrich and trophically comparable but far smaller birds, particularly Phasianidae (https://en.wikipedia.org/wiki/Phasianidae).

In this Post, I suggest that the ostrich is, if anything, rather small-brained for a phasianid of its body size. It seems to be, in a sense, nicely preadapted for domestication.

Source: Hrdlicka A (1907) Brain weights in vertebrates. Smithsonian Miscellaneous Collections XLVIII: 89-112.

'Numida cristata' body mass 467 g, brain mass 3.0 g

Numida data in Crile and Quiring (1940)

Pavo cristatus female adult, body mass 3060 g, brain mass 6.7 g

Lophortyx californicus adults, body mass 151.8 g and 102 g, brain mass 1.22 g and 1.5 g

Callipepla squamata adult, body mass 99 g, brain mass 1.5 g

Bonasa umbellus female adult, body mass 299.3 g, brain mass mean 2.7 g

Colinus virginianus, both sexes, all adults, n = 20, body mass mean 125 g, brain mass mean 1.228 g

Gallus gallus data in Crile and Quiring (1940)

The brain of the ostrich is mean 42.11 grams at say 55% of body mass 123 kg, = 67.65 grams. Its head weighs mean 0.68 kg. at carcass mass 59.9 kg.

Casuariiformes: Dromaius novaehollandiae female adult body mass unrecorded, brain mass 20.3 g

Casuariiformes: Casuarius casuarius sex unknown adult body mass unrecorded, brain mass 31.7 g

My plotting of a regression, using the above data, suggests that a domesticated phasianid, viz. Gallus gallus, has been decephalised by selective breeding.

However, both the ostrich and Casuariiformes have brains smaller than expected, based on the allometry of wild phasianids.

Posted on May 19, 2024 09:15 PM by milewski milewski | 0 comments | Leave a comment

The ostrich as a quasi-ungulate, part 3

The ostrich (Struthio camelus) is the largest living bird.

It has an uniquely large intestine for a bird, resembling ungulates in this way.

In this series of Posts, I compare the ostrich with ungulates in terms of

  • body sizes,
  • organ sizes,
  • habitats, and
  • diet.

This provides a basis for ecological comparison between the ostrich and African ungulates.

I find that the ostrich shares the same body mass as several coexisting ungulates, but not

  • other monogastrics, or
  • ruminants avoiding a grass diet as the ostrich does.

Major body-parts and organs are similar in size in the ostrich and like-size ungulates, except for head and e.g. spleen.

The gastrointestinal tract of the ostrich resembles that of monogastric hindgut-fermenters. However, its relatively heavy gut-walls are linked to its lack of teeth.

The ostrich prefers dry plains, also inhabited by various ruminants of which like-size spp. tend not to rely on forbs as the bird does.

The diet of the ostrich is qualitatively and even quantitatively similar to those of ruminant concentrate-selectors or 'mixed feeders', particularly coexisting gazelles smaller-bodied than the bird.

I hypothesise that the ostrich is extremely adapted for a combination of

  • tolerance to dry heat,
  • mobility,
  • food selectivity, and possibly
  • tolerance of silica-rich dicotyledonous plants, contributing to its ecological separation from ungulates.

COMPARISON WITH COKE'S HARTEBEEST (Alcelaphus cokii, adult females, which resemble the coexisting ostrich in body mass):

Mass of feet: about 1.8-fold greater in ostrich (two combined) than in hartebeest (four combined)

My commentary: The skeleton contributes similarly to body mass in birds and mammals (Anderson et al. 1979, Prange et al. 1979 https://www.journals.uchicago.edu/doi/abs/10.1086/283367 and https://www.jstor.org/stable/2459945).

However, the mass of the skeleton is differently distributed in birds vs mammals, and the above difference in the feet is consistent with this trend.

Mass of full stomach: about 2.5-fold smaller in ostrich than in hartebeest

Length of small intestine: about 2.0-fold less in ostrich than in hartebeest

BUT

Mass of small intestine (full): about 1.5-fold greater in ostrich than in hartebeest

Mass of small intestine (empty): about 2.33-fold greater in ostrich than in hartebeest

Mass of heart statistically significantly (Mann-Whitney U) greater in ostrich than in hartebeest

Mass of liver statistically significantly (Mann-Whitney U) greater in ostrich than in hartebeest

Mass of lungs NOT statistically significantly (Mann-Whitney U) different between ostrich and hartebeest

The entire gastrointestinal tract of the ostrich, full or empty, was relatively heavier in ostrich than in hartebeest (my commentary: this seems counterintuitive), and this is true for each component except for the full stomach.

The heart is generally heavier in birds than in mammals, relative to body mass (Pettingill, https://books.google.com.au/books?hl=en&lr=&id=livLBAAAQBAJ&oi=fnd&pg=PP1&dq=Pettingill+birds&ots=CR34Xkbq9L&sig=qfGvTiTD9jR8IRYp22BrCc1Zj0w#v=onepage&q=Pettingill%20birds&f=false).

The liver is the heaviest visceral organ in birds (Pettingill).

The lungs of birds are relatively small (Villee et al.).

Among liver, heart, and lungs, it is the liver that differs most between ostrich and hartebeest.

The mass of each eyeball is 7.07% of the mass of the head in the ostrich, vs 0.36% of the mass of the head in the hartebeest.

Thus, relative to the mass of the head, each eyeball is 19.64-fold heavier in ostrich than in hartebeest.

Posted on May 19, 2024 06:02 AM by milewski milewski | 13 comments | Leave a comment

May 18, 2024

The ostrich as a quasi-ungulate, part 2: proportional sizes of organs in ostrich-size, yearling juveniles of the eastern white-bearded wildebeest (Connochaetes albojubatus) near Nairobi, Kenya

The following illustrate juveniles of the eastern white-bearded wildebeest (Connochaetes albojubatus, https://www.inaturalist.org/observations?taxon_id=525438) at an ontogenetic stage corresponding in body mass approximately to adults of the coexisting Maasai ostrich (Struthio camelus massaicus, https://www.inaturalist.org/observations?taxon_id=322201).

Please note that the body mass has just exceeded half of maternal body mass, but the horns - albeit much longer than the ears or mane - are still simple spikes directed dorsally.

https://www.inaturalist.org/observations/7898982

https://www.inaturalist.org/observations/110103601

https://www.inaturalist.org/observations/124808683

https://www.inaturalist.org/observations/102212589

https://www.inaturalist.org/observations/189131122

https://www.inaturalist.org/observations/191952637

Scroll in https://fossilrim.org/animals/common-wildebeest/

Scroll in https://www.zootierliste.de/en/?klasse=1&ordnung=121&familie=12115&art=1160826

Compare with

Sample size large, of both sexes

Location:
Wildlife Ranching and Research, later Swara Plains Conservancy, and now incorporated into Nairobi National Park

Time:
1986-1989

The following are mean values of percentage of body mass, followed by the actual masses in parentheses.

Body mass 111 kg

Carcass mass = 54.22% (60.184 kg)

Skin = 7.92% (8.788 kg)

Feet = 2.93% (3.253 kg)

Head = 7.29% (8.088 kg)

Brain = 0.267% (0.296 kg)

Eyeballs = 0.0438% (2 X 0.0243 kg)

Tongue = 0.23% (0.259 kg)

Masseter muscle = 0.266% (2 X 0.148 kg)

Heart = 0.726% (0.806 kg)

Lungs = 1.55% (1.726 kg)

Spleen = 0.35% (0.392 kg)

Liver = 1.28% (1.422 kg)

Kidneys = 0.265% (2 X 0.147 kg)

Rumen = 1.67% (1.859 kg)

Reticulum = 0.275% (0.305 kg)

Omasum = 0.43% (0.480 kg)

Abomasum = 0.34% (0.375 kg)

Total intestines (full?) = 4.83% (5.363 kg)

Total stomach = 2.72% (3.019 kg)

DISCUSSION

Elsewhere in this series of Posts, I compare the Maasai ostrich with a coexisting alcelaphin ruminant - namely Alcelaphus cokii (https://www.inaturalist.org/observations?taxon_id=132649) - of similar adult body mass to the bird.

The values presented here - except for brain and skin - exceed those of adults of A. cokii, of similar body mass, in their overall resemblance to the Maasai ostrich.

The ostrich is constituted in some ways like juveniles of a ruminant, with big organs and feet (suggesting emphasis on mobility and foraging and rapid metabolism).

Posted on May 18, 2024 03:19 PM by milewski milewski | 16 comments | Leave a comment

Some ungulates have bigger eyeballs than others

Relative to body mass, the following have exceptionally large eyeballs:

This is remarkable for various reasons, e.g.

The Maasai giraffe (https://craftfineart.com/sink-c-jeffrey-maasai-giraffe-ido-129120) also has notably large eyeballs for an ungulate, relative to its body mass.

Wild, non-bovin bovids in Africa have larger eyeballs than do like-size cervids on other continents, as is apparent if one merely looks at photos of the animals (https://www.istockphoto.com/photo/a-close-up-profile-portrait-of-a-female-black-faced-impala-gm1218530588-356087085).

However, the trend is borne out by the regression below for the red deer, and by information on Axis axis (https://creatures-of-the-world.fandom.com/wiki/Chital_Deer?file=Ftd-axis-deer.jpg) and Odocoileus virginianus (https://www.alamy.com/profile-of-a-white-tailed-deer-image209768621.html and https://pixels.com/featured/whitetail-doe-face-brook-burling.html).

The proportionately small eyeballs of the red deer (https://www.masterfile.com/image/en/700-06758256/portrait-of-a-red-deer-cervus-elaphus-female-bavaria-germany) seem at odds with its unusual orbital prominence, and the fully lateral placement of the eyes (https://stock.adobe.com/images/a-close-up-head-and-shoulder-portrait-of-a-female-red-deer-staring-forward/298586849).

Bovin bovids (https://en.wikipedia.org/wiki/Bovini) have eyeballs smaller than expected for their body mass.

This is particularly noteworthy in the African savanna buffalo (https://www.masterfile.com/image/en/841-06446194/cape-buffalo-syncerus-caffer-with-redbilled and https://www.dreamstime.com/profile-portrait-cape-buffalo-wild-side-view-profile-portrait-cape-buffalo-african-wilderness-image277091409), which scores 20% below par, in contrast to the 50% above par scored by the common eland.

Perhaps the most puzzling of all these findings - despite being well-known - is how small the eyeballs are in the hook-lipped rhino (https://upload.wikimedia.org/wikipedia/commons/6/69/Black_Rhino_at_Working_with_Wildlife.jpg).

It is evident that domestication has led to a diminution of the eyeballs in both

In the latter case, the resulting eyeballs (https://www.dreamstime.com/profile-view-animal-portrait-big-domestic-pig-big-domestic-pig-profile-view-image186895256) are even smaller, proportionately, than in rhinos, because even wild suids have small eyes.

In the case of the common warthog, there is the same incongruity as in the red deer: the orbits are noticeably prominent (in this case dorsally, not laterally, https://www.dreamstime.com/head-profile-common-warthog-phacochoerus-africanus-image153887595). However, the eyeballs remain small relative to like-size, coexisting bovids (https://www.dreamstime.com/stock-photography-warthog-image2002732).

The following are the quotients, calculated relative to adult body mass from the interspecific regression, in decreasing order of eyeball mass:

Equus caballus +0.5
Taurotragus oryx +0.5
tragelaphin bovids (small sample of two spp., Crile and Quiring 1940) +0.4
Giraffa tippelskirchi +0.3
Equus quagga +0.25
Aepyceros melampus +0.2
alcelaphin bovids including Connochaetes +0.1
reduncin bovids +0.1
gazelles (Eudorcas thomsonii and Nanger granti) +0.05
Oryx (small sample, Crile and Quiring 1940) 0
neotragin bovids (small sample, Crile and Quiring 1940) 0
Bos taurus -0.05
Syncerus caffer (small sample, Crile and Quiring 1940) -0.2
Cervus elaphus -0.2
Ovis aries -0.2
elephantids -0.3
Phacochoerus africanus -0.5
Diceros bicornis -0.7
Sus scrofa domesticus -0.9

https://en.wikipedia.org/wiki/Alcelaphinae

Posted on May 18, 2024 12:40 AM by milewski milewski | 0 comments | Leave a comment

May 17, 2024

The ostrich as a quasi-ungulate, part 1

The ostrich does not coexist with any monogastric or ruminant species sharing both its body size and its avoidance of a grass diet.

The diet of the ostrich is qualitatively and even quantitatively similar to those of ruminant concentrate-selectors or 'mixed feeder', particularly coexisting gazelles smaller than the ostrich.

The ostrich seems tolerant of silica-rich forbs, contributing to its ecological separation from ungulates.

The ostrich, in its most extreme habitat, coexists with

  • a grazer larger-bodied than itself, viz. Oryx,
  • a grazer/browser smaller-bodied than itself, viz. Gazella.

Both are adapted to reduced intakes (ruminants) and have advantages of foraging at night.

The grazer accepts up to 40% of the diet as browse, fruits, tubers, and forbs, largely for their water-content. The grazer/browser accepts up to 30% of the diet as the same, though smaller, items, and probably some insects too. Neither eats faeces, nor relies on forbs. Both avoid competition with the ostrich partly by foraging at times when atmospheric moisture condenses, and partly by resorting to landforms avoided by the ostrich.

The grazer is the arid-zone counterpart of semi-arid-adapted alcelaphins, which are more specialised grazers, partly because they can drink (and ultimately mesic hippltragin and large reduncins).

The grazer/browser is the arid-adapted counterpart of small-bodied reduncins and tragelaphins, because neither grass nor browse will support a specialist.

Where two spp. of gazelles coexist with the ostrich, the smaller-bodied one eats more grass (cannot reach much browse, and does not depend on forbs), and the larger-bodied eats more browse because it can reach it. They have about the same dietary quality, in terms of protein.

The more browsers extend into the arid zone, the ganglier they become (giraffes, gerenuk, dama gazelle). Nanger granti is the last outpost of a 'normal browser' towards dry country, after all the tragelaphins have expired.

Spatial separation and limited bulk demands/food quality are two sides of the same strategy. If a species can survive the shortage in the desert, then the quality is likely to be fair. If physical separation is hard, and coexistence is inevitable, then the animal must eat as little as possible in order to avoid competition and to exploit microspatial separation based on advantages in economy of movement. I.e. do what browsers do, but on the ground floor = go 'down and out'. If the animal can afford to pick and choose, then it can wait to find items others have found too awkward to eat.

The ostrich does not enhance mobility by reducing ingesta mass in body, but rather maximises this (compensating with e.g. reduction of toes) and draws indirect benefits from digestive power and hence reduced bulk demands, allowing it to move instead of having to eat so frequenty.

The ostrich differs from ungulates in the following:

  • small head/lack of teeth/small brain
  • gastric mill/hindgut fermentation/double caeca/cloaca
  • feathers/uric acid/salt gland
  • bipedality/air-sacs
  • diurnality/high body temperature (1 degree Celsius or less higher than in ruminants)
  • omnivory/carnivory/coprophagy
  • large clutch/collective breeding/seasonal breeding.

Concentrate-selecting ungulates differ from roughage grazers in the following morphological features:

  • small head and narrow muzzle
  • smaller teeth and reduced dental occlusion
  • long neck
  • long legs
  • small stomach (fermentation vat)
  • large caecum
  • short small intestine
Posted on May 17, 2024 06:32 AM by milewski milewski | 14 comments | Leave a comment

May 16, 2024

Summary of life-history strategies of African bovids (Bovidae)

Most bovids have gestation periods of

  • about 6 months in the smallest-bodied, fastest-growing spp.,
  • about 7 months (relatively small-bodied spp.),
  • about 9 months (relatively large-bodied spp.),
  • 11 months (Syncerus caffer).

Compare the above values with

  • 5 months in Phacochoerus,
  • 7 months in Hippopotamus,
  • 12 months in Equus quagga,

Most bovids have birth-weight percentages of about 5-10%, exceeding 10% in the most precocial spp. The values for Phacochoerus and Hippopotamus are less than this.

Most bovids reach sexual maturity at

  • about 9 months in relatively small-bodied spp.,
  • 1.2-1.4 years in Connochaetes,
  • 2.5 years in large-bodied, slow-growing spp.,
  • 2.75 years in Syncerus caffer.

Compare the above values with

  • 1.5 years in Equus quagga and (check) Phacochoerus,
  • 4 years in Hippopotamus (exceeding the value for Giraffa)
Posted on May 16, 2024 10:20 PM by milewski milewski | 0 comments | Leave a comment

How do the niches differ between the ostrich (Struthio camelus) and a coexisting ungulate, Grant's gazelle (Nanger granti)? part 2

Crude protein estimation for Grant's gazelle
Values are weighted means (% crude protein X % of diet*).
Harpachne schimperi https://www.inaturalist.org/taxa/343051-Harpachne-schimperi leaves 1220 (8.6%); stems 22.4 (4.2%)
Cynodon dactylon/nlemfuensis leaves 152.7 (4.2%); stems 16.8 (2.3%)
'Harpachne lin' leaves 130.6 (9.2%); stems 12.2 (2.3%)
Microchloa kunthii https://www.inaturalist.org/taxa/165373-Microchloa-kunthii leaves 54.7 (3.85%); stems 12.2 (2.3%)
Themeda triandra leaves 4.2 (0.4%); stems 0.3 (0.1%)
Sida sp. indet. https://www.inaturalist.org/observations?place_id=56881&subview=map&taxon_id=54996&view=species leaves and stems 210.0 (14.0%)
Unidentified leaves 5.5 (0.4%
); stems 28.6 (5.4%)
Indigofera leaves and stems 340.2 (14.0%
)
Solanum leaves 123.2 (6.2%) fruits 26.2 (1.54%)
Leguminous seeds and pods 127.5 (5.1%)
Asteraceae indet. 76.5 (5.1%
)
Balanites aegyptiaca 72.8 (2.6%*)

Total = 1583
Mean = 15.83% crude protein

Posted on May 16, 2024 05:52 PM by milewski milewski | 3 comments | Leave a comment