Journal archives for June 2024

June 02, 2024

A new interpretation of the evolutionary and ecological strategy of whiteyes/silvereyes (Zosterops), part 2: a nectarivorous species (Z. chloronothos) as an exception proving a rule

...continued from

In general, the genus Zosterops has combined great speciation with minimal adaptive radiation.

This is explained partly by the facts that

  • Zosterops is capable of inhabiting islands as small as one square kilometer, and
  • most of the species are restricted to islands of various sizes, up to the size of Madagascar, New Guinea, and mainland Australia.

In other words, speciation in Zosterops has been nominal, with minimal modification of a morphological kind.

In this Post, I explore one example - on the island of Mauritius in the Indian Ocean - in which two sympatric spp. of Zosterops have separated in terms of diet.

This example is 'an exception that proves a rule', in the sense that

  • there is a clear specialisation in nectar in one of the spp., including a significant lengthening of the beak, but
  • the adaptation has been more behavioural than morphological, i.e. it reflects a change in 'software' rather than 'hardware'.


Zosterops chloronothos (, which is naturally restricted to Mauritius, has

The diet is mainly nectar and flying insects. Fleshy fruits and gleaned insects, normally part of the diets of Zosterops, are hardly taken by Z. chloronothos.

Zosterops chloronothos is not merely a 'cheat' in the sense of taking nectar without pollinating the plants. Unusually for its genus, it also collects pollen on the forehead.

Plant spp. possibly pollinated by Z. chloronothos ( include

I interpret the nectarivory of Z. chloronothos as follows.

On one hand, it is true that

  • Z. chloronothos deviates from the norm in its emphasis on exudates (nectar and sap), to the near-exclusion of other dietary components normal in its genus, viz.
  • fleshy fruit-pulp, and
  • insects, such as Homoptera (, gleaned from plants.

On the other hand, it is also true that

What this means is that the deviation from the norm in Z. chloronothos is open to interpretation. It is simultaneously true that here we have an island-effect, in which Zosterops has 'filled in for' the paucity if true nectarivores - particularly Nectariniidae ( - in the avifauna of Mauritius.

Delphacidae occur on Oceanic islands and produce honeydew

to be continued in

Posted on June 02, 2024 05:21 AM by milewski milewski | 8 comments | Leave a comment

Contrary to field guide-books, reedbucks (Redunca spp.) do not flag the tail in alarm, part 2: further illustrations

...continued from

Since I wrote part 1, many further photos have emerged of Redunca spp., further illustrating the fact that, in general, reedbucks do not raise the tail in anti-predator alarm.

At the same time, many photos show caudal flagging in social contexts.

Some photos are ambivalent, deserving closer scrutiny.


last photo in


Showing tail socially
(showing caudal flag in social, not anti-predator, context):


Second and third photos in

Showing tail socially:



The following deserves close scrutiny:


Additional photos showing that Redunca fulvorufula does not raise its tail when fleeing:
third photo in

Posted on June 02, 2024 05:08 PM by milewski milewski | 2 comments | Leave a comment

Subtle differences among reedbucks (Redunca spp.) in size of tail and colouration on the hindquarters

The proportional size of the tail varies, among the three spp. of Redunca, in the order fulvorufula > arundinum > redunca.

The following show that the tail is proportionately larger in Redunca arundinum than in Redunca redunca:

The following shows how small the tail can be in Redunca redunca.

The following shows Redunca arundinum for comparison:

In the latter photo, note the bare, dark skin at the junction of flank and knee, a feature shared (approximately) with Aepyceros melampus.

Redunca arundinum:

Redunca redunca:

The following ( is one if the few photos showing clearly the colouration on the buttocks, in Redunca arundinum.

The following ( suggests that the pattern is different in Redunca redunca, with negligible whitish on the buttocks.

Posted on June 02, 2024 10:59 PM by milewski milewski | 2 comments | Leave a comment

June 05, 2024

A new interpretation of the evolutionary and ecological strategy of whiteyes/silvereyes (Zosterops), part 3: encephalisation (braininess)

@tonyrebelo @jeremygilmore @ludwig_muller @jwidness @zarek @hirons @ldacosta @lukedowney @moxcalvitiumtorgos @carasylvia @rion_c @nwatinyoka @shauns @baldcoot @karoopixie @gareth_bain @justinponder2505 @christiaan_viljoen @bushbandit

...continued from


Zosterops is among the more encephalised ( of birds.

This is based on brain mass relative to body mass (corrected allometrically,

This braininess may help to explain how Zosterops has adapted to various biomes, on many islands as well as on mainlands, with minimal morphological modification.

Adaptation in this genus seems to be mainly a matter of behavioural versatility, i.e. via 'software' rather than 'hardware'.

The cognitive capacity of Zosterops may be evident, for example, in

  • vocal mimicry,
  • discrimination among subspecies, allowing these coexist for part of the year without loss of subspecific integrity, and
  • ability to stitch a cup-shaped nest between adjacent flimsy stems in the crowns of various trees, despite various stem-configurations according to the type of tree.

There is a correlation between vocal mimicry and encephalisation ( and and

Birds capable of mimicking the calls of other birds tend to be relatively brainy.

A noteworthy phenomenon, in Zosterops lateralis ( in southeastern mainland Australia, is that several subspecies overlap in geographical distribution.

In the normal concept of subspeciation, geographical separation is necessary to maintain the distinctiveness of subspp. In Z. lateralis, the nomadic/migratory movements in the non-breeding season mix several subspp. ( However, this has not compromised the subspecific distinctions.

This ability to coexist without interbreeding seems to reflect cognitive capacity, possibly extending to 'culture'.

All of the above raise the question:
How brainy is Zosterops, compared to other like-size, small birds?


In this Post, I compare Zosterops with other birds in terms of encephalisation, i.e. braininess.


My reference for body mass and brain mass in various spp. of birds is the data-set compiled by Andrew N Iwaniuk ( The data refer to adults of both sexes, in all spp.


I searched the entire data-set for bird spp. with body mass similar to that of Zosterops, viz. about 10.4 g. I then compared the brain masses on the basis of body masses similar to that in Zosterops.


The mean data for Zosterops are

  • body mass 10.2 g, brain mass 0.54 g in Zosterops japonicus (n=10), and
  • body mass 10.6 g, brain mass 0.47 g in Zosterops lateralis.

This shows that Zosterops has brain mass 0.50 g, at body mass 10.4 g.

Let us now compare this brain mass with those of various other birds with similar body masses.

Families are in alphabetical order.

Apodidae ( :

I found two spp., in two genera, with body masses 9.9-13.6 g. Brain masses were 0.28-0.30 g, indicating that Zosterops clearly exceeds apodids in braininess.

Apodids attain brain mass of 0.5 g only at body masses > 25 g, e.g. in Chaetura pelagica (, which has brain mass 0.46 g at body mass 23.6 g. (n=8).

Certhiidae ( :

I found four spp., in four genera, with body masses 9.8-11.0 g. Brain masses were 0.51-0.53 g, indicating that certhiids exceed Zosterops in braininess.

Cisticolidae ( :

I found two spp., in one genus, with body masses 10.0-10.3 g. Brain masses were 0.43-0.51 g, indicating that Zosterops slightly exceeds cisticolids in braininess.

Fringillidae ( :

I found 15 spp., in 14 genera, with mean body masses 8.9-12.0 g. Brain masses were somewhat variable, with particular braininess evident in Melopyrrha nigra (, which had brain mass 0.84 g at body mass 10.9 g (n=7).

Overall, the data indicate that Zosterops resembles fringillids in braininess.

Hirundinidae ( :

I found two spp., in two genera, with mean body masses 9.7-11.2 g. Brain masses were 0.36-0.43 g, indicating that Zosterops exceeds hirundinids in braininess.

Lybiidae ( :

I found only one comparable species, with body mass 15.5 g and brain mass 0.44 g, indicating that Zosterops exceeds lybiids in braininess.

Maluridae ( :

I found three spp., in one genus, with mean body masses 9.8-11.4 g. Brain masses were, on average, about 0.48 g, indicating that Zosterops slightly exceeds malurids in braininess.

Melanocharitidae ( :

The data indicate that Zosterops exceeds melanocharitids in braininess.

Meliphagidae ( :

I found nine spp., in seven genera, with mean body masses 7.8-11.9 g in Myzomela, and 10.3-11.4 g in other genera. Brain masses were somewhat variable. However, they indicate that, overall, Zosterops exceeds meliphagids in braininess.

Monarchidae ( :

I found two spp., in two genera, with mean body masses 10.2-11.0 g. Brain masses were 0.52-0.59 g, indicating that monarchids exceed Zosterops in braininess.

Muscicapidae ( :

I found five spp., in five genera, with mean body masses 7.5-15.4 g. Brain masses were 0.31-0.6- g. One species, viz Ficedula albicollis (, n=10), closely resembled Zosterops in mean body mass (10.3 g), and had brain mass 0.45 g.

Overall, these data indicate that Zosterops exceeds muscicapids in braininess.

Nectariniidae ( :

I found two spp., in two genera, with mean body masses 8.9-11.7 g. Brain masses were, on average, about 0.45 g, indicating that Zosterops exceeds nectariniids in braininess.

Pardalotidae ( :

I found three spp., in two genera, with mean body masses 9.2-11.6 g. Brain masses were, on average, about 0.45 g, indicating that Zosterops exceeds pardalotids in braininess.

Paridae ( :

I found three spp., in one genus, with mean body masses 10.2-11.3 g. Brain masses were, on average, about 0.65 g, indicating that parids are brainier than Zosterops.

Passeridae sensu lato, including Estrildidae ( and :

I found seven spp., in six genera, with mean body masses 9.2-10.9 g. Brain masses were, on average, about 0.45 g, indicating that Zosterops exceeds passerids in braininess.

Petroicidae ( :

I found three spp., in two genera, with mean body masses 9.6-11.4 g. Brain masses were, on average, about 0.52 g, indicating that petroicids are slightly brainier than Zosterops.

Picidae ( :

I found two spp., in two genera, with mean body masses 8.1-11.0 g. Brain mass was 0.58-0.60 g, indicating that picids exceed Zosterops in braininess.

Rhipiduridae ( :

I found one species, with body mass 10.2 g (n=7). Brain mass was 0.36 g, tentatively indicating that Zosterops exceeds rhipidurids in braininess.

Sittidae ( :

There is only one genus in this family, represented in the data-set by Sitta canadensis (body mass 10.5 g, brain mass 0.57 g, n=6). This indicates that sittids exceed Zosterops in braininess.

Sylviidae ( :

I found only one species (n=7), with mean body mass 10.8 g. Brain mass was 0.45 g, tentatively indicating that Zosterops exceeds sylviids in braininess.

Thamnophilidae ( :

I found four spp., in four genera, with body masses 9.3-11.2 g. Brain masses (means) were 0.45-0.7 g, indicating that thamnophilids are slightly brainier than Zosterops.

Trochilidae ( :

I found only one species large-bodied enough to be comparable, with mean body mass 10.2 g. Brain mass was 0.32 g, indicating that Zosterops exceeds trochilids in braininess.

Tyrannidae ( :

I found eight spp., in eight genera, with mean body masses 8.6-11.9 g. Brain masses were, on average, about 0.37 g, for six of the spp., indicating that Zosterops exceeds tyrannids in braininess.

The brain mass of Zosterops (about 0.5 g) is attained in these tyrannids only when body mass reaches about 14 g, which is >3.5 g heavier than Zosterops.

However, apparently brainier than other tyrannids are two spp., viz.


Brain mass, relative to body mass, varies up to 2.5-fold in small-bodied birds about the size of Zosterops. This can be seen in the following three carefully chosen examples:

The percentage value for Zosterops, viz. 4.8%, falls approximately in the middle of the above range (2.8-7.7%) of values.

However, Zosterops is somewhat brainier than most birds that are comparable on a basis of matched body mass but different familial affinity.

The following summarises the ranking of Zosterops in braininess, relative to like-size, small birds, family by family.

Zosterops is less brainy than

  • monarchids,
  • parids,
  • picids, and
  • sittids.

Zosterops is somewhat/slightly less brainy than

  • petroicids,
  • thamnophilids, and
  • one or two genera of tyrannids.

Zosterops is similar in braininess to

  • fringillids.

Zosterops is somewhat/slightly brainier than

  • cisticolids, and
  • malurids.

Zosterops is brainier than

  • certhiids,
  • hirundinids,
  • lybiids,
  • melanocharitids,
  • meliphagids,
  • muscicapids,
  • nectariniids,
  • pardalotids,
  • passerids,
  • rhipidurids,
  • sylviids,
  • trochilids, and
  • most tyrannids.

Zosterops seems much brainier than

  • apodids.

This means that Zosterops is brainier than like-size birds in most avian families.

However, Zosterops is less brainy than like-size birds in perhaps seven families, of which parids (tits) are the most renowned for their cognitive capacity (

Posted on June 05, 2024 03:28 AM by milewski milewski | 3 comments | Leave a comment

June 07, 2024

June 08, 2024

June 16, 2024

The black-and-tan pattern differs between the dingo and the kelpie breed of the domestic dog (Canis familiaris)


The dingo is colour-polymorphic, with a black-and-tan morph.

Various breeds of the domestic dog (Canis familiaris) also feature black-and-tan patterns of colouration.

The black-and-tan pattern is significant, in evolutionary terms, because it represents an 'wild-type' colouration,

  • adaptive to the original niche of an ancestral species of Canis, and
  • different from the colouration of any subspecies, or individual, if the wolf (Canis lupus,

The kelpie breed ( is particularly comparable to the dingo, because it has


In this Post, I compare the black-and-tan configurations between the dingo and the kelpie.


The dingo and the kelpie differ considerably, in the following ways:

  • The pale eyebrow-spots are smaller in the dingo than in the kelpie.
  • The pectoral pale patches are less divided (between left and right) in the dingo than in the kelpie.

Posted on June 16, 2024 04:35 PM by milewski milewski | 1 comment | Leave a comment

June 19, 2024

Data on braininess in mammals, part 1

Data on brain mass (g)/body mass (kg) in Raichlen and Gordon (2011,

Antilocapra americana 145.8 g/35.4 kg
Nanger granti 148.7 g/49.0 kg
Capra hircus 110.5 g/28.8 kg
Bos taurus 454.4 g/490.5 kg
Connochaetes taurinus 364.3 g/156.6 kg
Equus caballus 702.5 g/412.4 kg
Kobus defassa 314.6 g/229.6 kg
Madoqua kirkii 34.3 g/4.46 kg
Neotragus moschatus 33.2 g/3.29 kg
Ovis aries 132.5 g/51.9 kg
Sus scrofa 186.6 g/132.0 kg
Taurotragus oryx 460.0g/480.0 kg

BODDY ET AL. (2012)

Encephalisation quotients according to

Elephas maximus 1.46
Loxodonta africana 1.09
Note: Shoshani et al. (2006, report the values 1.13-2.36

Equus asinus 0.77
Equus quagga 1.03

Tapirus bairdii 1.21

Aepyceros melampus 0.88
Boselaphus tragocamelus 0.77
Connochaetes taurinus 0.84
Damaliscus pygargus 1.20
Eudorcas thomsonii 0.88
Kobus ellipsiprymnus 0.60
Madoqua kirkii 1.23
Syncerus caffer 0.52
Tragelaphus eurycerus 0.65
Tragelaphus scriptus 1.01

Alces alces 0.86
Axis axis 0.80
Cervus elaphus 0.81
Odocoileus virginianus 0.96
Rangifer tarandus 1.18

Giraffa camelopardalis 0.36

Moschiola meminna 1.04
Tragulus napu 0.96

Tayassu pecari 1.13

Phacochoerus africanus 0.57
Sus scrofa 0.63

Hippopotamus amphibius 0.34

Procavia capensis 1.07

Leopardus pardalis 1.21
Leptailurus serval 0.91
Lynx canadensis 0.95
Lynx rufus 1.69
Panthera leo 0.98
Panthera pardus 0.78
Panthera tigris 0.54
Puma concolor 0.81

Crocuta crocuta 0.83

Lupulella mesomelas 1.20
Otocyon megalotis 1.10
Urocyon cinereoargenteus 1.44
Vulpes vulpes 1.92
Mean value for Canidae: 1.41

Bassariscus sumichrasti 2.05
Nasua narica 1.16
Nasua nasua 1.63
Procyon lotor 1.28

Ichneumia albicauda 0.97

Genetta tigrina 1.16
Paradoxurus hermaphroditus 1.25

Mustela erminea 1.88
Mustela putorius 0.87
Mean value for Mustelidae: 1.41

Mephitis mephitis 0.63

Helarctos malayanus 2.33
Melursus ursinus 0.71
Ursus americanus 2.25
Ursus arctos 0.91
Ursus maritimus 0.71
Mean value for Ursidae: 1.38

Ailurus fulgens 1.34

Arctocephalus australis 0.99
Arctocephalus forsteri 0.99
Arctocephalus galapagoensis 1.73
Arctocephalus gazella 1.16
Arctocephalus philippii 1.07
Arctocephalus pusillus 0.80
Arctocephalus tropicalis 1.07
Callorhinus ursinus 0.82
Eumetopias jubatus 0.55
Neophoca cinerea 0.80
Otaria byronia 0.93
Phocarctos hookeri 0.62
Zalophus californianus 1.44

Cystophora cristata 0.70
Erignathus barbatus 0.71
Halichoerus grypus 0.62
Histriophoca fasciata 0.91
Hydrurga leptonyx 0.94
Leptonychotes weddellii 0.69
Lobodon carcinophaga 1.07
Mirounga leonina 0.43
Monachus monachus 0.74
Neomonachus schauinslandi 0.82
Ommatophoca rossii 1.06
Phoca largha 0.90
Phoca vitulina 1.32
Pusa caspica 0.76
Pusa hispida 0.86
Pusa sibirica 0.68

Odobenus rosmarus 0.83(?)

Gerbillurus dasyurus 2.48
Gerbillurus paeba 1.40
Rattus lutreolus 1.00
Rattus nitidus 0.97
Rattus norvegicus 1.78
Rattus tunneyi 0.99
Tamiops mcclellandii 2.26
Tscherskia triton 2.09
Mean value for Rodentia (258 spp.): 0.98

Neurotrichus gibbsii 2.92 (body mass 9-11 g)
Talpa europaea 0.97
Mean value for Talpidae: 1.69

Lepus americanus 0.74
Lepus arcticus 0.56
Lepus californicus 0.73
Lepus capensis 0.58
Lepus europaeus 0.90
Lepus nigricollis 0.72
Lepus timidus 0.64
Ochotona hyperborea 1.11
Ochotona princeps 0.93
Ochotona rufescens 0.80
Oryctolagus cuniculus 0.65
Sylvilagus auduboni 0.75
Sylvilagus bachmani 0.87
Sylvilagus brasiliensis 0.86
Sylvilagus floridanus 0.76

to be continued in

Posted on June 19, 2024 11:14 PM by milewski milewski | 2 comments | Leave a comment

June 22, 2024

Is the pronghorn (Antilocapra americana) inferior to like-size bovid ruminants, in braininess?

@ptexis @variani18 @tonyrebelo @jeremygilmore @oviscanadensis_connerties @hutan123 @nyoni-pete @capracornelius @tandala

For an index to my Posts on Antilocapra americana (, please see


In this Post, I assess the size of the brain, relative to body size, in a peculiar species of ruminant (, namely Antilocapra americana.


O'Gara (1978, gives body masses as follows:

Alberta: adult females, mean 50 kg, range 47-56 kg
Alberta: adult males, mean 57 kg, range 47-70 kg
New Mexico: adult females, mean about 40 kg

Wikipedia ( states that adult females weigh 34-48 kg, and adult males weigh 40-65 kg.

My commentary:

Antilocapra americana seems to conform to Bergmann's rule (,to%20many%20mammals%20and%20birds.).

DATA ON BRAIN MASS IN BEAR et al. (1973, Colorado Game, Fish and Parks Dept internal report: also see first comment below for individual measurements)

Adult females: brain mass mean 108 g (n=19) at body mass mean 46.4 kg
Adult males: brain mass mean 114 g (n=12) at body mass mean 50.4 kg

Yearling females: brain mass mean 107 g (n=8) at body mass mean 42.9 kg
Yearling males: brain mass mean 108 (n=7) at body mass mean 41.8 kg

My commentary:

The above data seem reliable.


Kopperud (2017, contains the following data for various wild ruminants.

Brain mass (g)/body mass (kg), in decreasing order of body mass (*cervids are asterisked):

Addax nasomaculatus 200 g/113.5 kg
Kobus leche 208.5 g/105.0 kg
*Rangifer tarandus 290 g/96.0 kg
*Rucervus eldi 198 g/88.0 kg
*Cervus nippon 109 g/73.0 kg
Damaliscus pygargus 305 g/70.0 kg
*Odocoileus hemionus 191g /68.0 kg
*Axis axis 134 g/67.5 kg
*Odocoileus virginianus 166 g/67.0 kg
*Rusa timorensis 169 g/62.0 kg
Nanger dama 150g/59.3 kg
Redunca arundinum 143 g/58.1 kg
Aepyceros melampus 178 g/55.3 kg
*Dama dama 194 g/54.7 kg
Nanger granti 151 g/50.0 kg
Tragelaphus spekii 156 g/48.1 kg
*Axis porcinus 156 g/43.9 kg
Tragelaphus scriptus 167 g/42.2 kg
Antilope cervicapra 138 g/37.4 kg
Saiga tatarica 111 g/38.6 kg
*Ozotoceros bezoarticus 92 g/38.2 kg
Rupicapra rupicapra 123 g/37.4 kg
Capricornis crispus 136 g/37.1 kg
Antidorcas marsupialis 136 g/36.0 kg
Litocranius walleri 134 g/34.5 kg
Rupicapra pyrenaica 114 g/33.9 kg

My commentary:

Among bovids:

An alcelaphin (Damaliscus pygargus) is brainy; see comment below

However, caprins (Rupicapra spp.) and a saigin (Saiga tatarica, seem somewhat below-par in braininess.

Among *cervids:

The data for Cervus nippon, Axis axis, and Ozotoceros bezoarticus presumably refer to mature males, whereas that for Rangifer tarandus may refer to adult females.

All these spp. are sexually dimorphic in body mass. The apparently greater braininess of R. tarandus than of C. nippon, A. axis, and O. bezoarticus may possibly be owing to the brawniness of mature males. The brain may cease to grow when adulthood is reached, despite body mass continuing to increase for several more years, in males ( and

Also see

However, this caveat does not seem to apply to Axis porcinus (


These authors give brain mass and body mass for A. americana as 145.8g and 35.4 kg.

My commentary:

The value for body mass is puzzlingly small, indicating that juveniles, not adults, were sampled. However, the value for brain mass is anomalously great, relative to the above two references.


Two caveats are that

  • the data presented by Raichlen and Gordon (2011) seem anomalous, in that the value for brain mass is as great as in like-size bovids, and
  • the data for cervids (in Kopperud 2017) are ambivalent, owing to the complications of sexual dimorphism.


  • two of the three references seem congruent, and
  • there seems to be no sexual dimorphism in the mass of the brain, relative to body mass, in A. americana.

According to the interspecific allometry of brain mass to body mass in wild bovids, the brain mass of Antilocapra americana is predicted to be about 165 g, at body mass about 53 kg.

The real brain mass of A. americana has a mean no greater than 114 g.

This means that the brain of A. americana, relative to that of bovids,

  • shows a shortfall of at least 50 g, and
  • is no more than 70% of the mass predicted.

Based on gazelles, Aepyceros melampus, and Tragelaphus spp. in Kopperud (2017), we would predict the brain mass of Antilocapra americana to be at least 150 g. In reality, the value is 114 g or less, viz. 75% or less of the predicted value.

Even Rupicapra (, at body mass of only 34 kg, has the same brain mass (114 g) as A. americana of body mass 53 kg.


The results suggest that Antilocapra americana is less brainy than are like-size bovids, with a noteworthy exception in Saiga tatarica (

This shortfall is surprising, because A. americana is

Posted on June 22, 2024 03:14 PM by milewski milewski | 10 comments | Leave a comment

June 23, 2024

Data on braininess in mammals, part 2

...continued from

Encephalisation quotients (as per Jerison), according to Wroe and Milne (2007, and

Dasyurus geoffroii 0.66
Dasyurus maculatus 0.24
Dasyurus viverrinus 0.61
Sarcophilus harrissii 0.35
Thylacinus cynocephalus 0.45

Thylacoleo carnifex 0.45

Didelphis virginianus 0.17

Myrmecobius fasciatus 0.59

Isoodon obesulus 0.31
Macrotis lagotis 0.51

Canis dirus 1.17
Canis latrans 1.52
Canis lupus 1.24
Otocyon megalotis 1.13
Lupulella adusta 0.92
Lupulella mesomelas 1.19
Lycaon pictus 1.47
Vulpes chama 1.27

Acinonyx jubatus 0.66
Caracal caracal 0.94
Panthera atrox 0.54
Panthera leo 0.66
Panthera pardus 0.76
Panthera onca 0.86
Panthera tigris 0.84

Crocuta crocuta 1.04
Parahyaena brunnea 0.80
Proteles cristatus 0.91

Aonyx capensis1.24
Gulo gulo 1.33
Meles meles 0.91
Mellivora capensis 1.62

Procyon lotor 1.22

Ursus americanus 1.02
Ursus arctos 0.72
Ursus maritimus 0.90
Ursus thibetanus 1.06

Arctictis binturong 0.57
Paradoxurus hermaphroditus 0.70
Viverricula indica 0.60

My commentary:

The mean encephalisation quotient for the above felids is 0.75. By contrast, that for canids is 1.24.

COZZI ET AL. 2014 (

Encephalisation quotients (as per Jerison), relative to that of Equus caballus:

0.78 according to Cozzi et al. (2014)
0.91 according to Shultz and Dunbar (2010,

Felis catus 1.0
Lynx lynx 0.85
Panthera leo 0.63
Panthera tigris 0.78

Canis lupus 0.74-1.55
Vulpes vulpes 0.90

Sus scrofa 0.60

Bos taurus 0.55
Capra hircus 0.71
Ovis aries 0.80

Camelus bactrianus 0.61

Loxodonta africana 1.67

Gorilla gorilla 1.76
Homo sapiens 6.62
Hylobates sp. 2.55
Macaca mulatta 1.86
Pan troglodytes 2.48

My commentary:

This study is disappointing despite its detail, because the allometric analysis is poor. Cozzi et al. (2014) obtained good original data on brain size in Equus caballus, but lack a firm grasp of allometry.

However, what this paper does nicely show is the convolution of the cerebrum in E. caballus. And apparently Equus quagga is even more extreme in the number of sulci on the brain. This convolution in equids seems to exceed that in Bos.

Braininess in Equus caballus is

  • much greater than in Bos taurus,
  • greater than in Camelus bactrianus and Sus scrofa, and
  • similar to that in Capra hircus and Ovis aries.
Posted on June 23, 2024 05:48 PM by milewski milewski | 0 comments | Leave a comment