30 de mayo de 2023

Larks (Alaudidae) as indicative of ecological differences between nutrient-poor heathlands in Australia vs South Africa

In previous Posts, I have pointed out that fynbos (South Africa), although ostensibly the ecological counterpart of kwongan (Australia), is considerably more fertile.

One of the problems with intercontinental comparisons of this kind is that the biotas are so different that it is hard to disentangle phylogenetic constraints from ecological adaptations.

For example, the marsupial Notamacropus irma (https://www.inaturalist.org/taxa/1453435-Notamacropus-irma) metabolises, grows, and reproduces more slowly than its ostensible counterpart, the bambi Raphicerus melanotis (https://www.inaturalist.org/taxa/42376-Raphicerus-melanotis). Is this really because kwongan is nutrient-poorer, and more prone to wildfire, than fynbos, or is it merely because two fundamentally different clades of mammals are represented?

There are, however, a few genera of plants and animals are shared between these two continents, and these provide an opportunity for relatively straightforward comparison.

In the case of birds, the shared genera are mainly raptors and owls. This limits their relevance, because their position at the top of food-pyramids means that they have little interaction with soils and plants.

This reduces the relevant genera to Turnix (Turnicidae), Coturnix (Phasianidae), Zosterops (Zosteropidae), and Mirafra (Alaudidae).



Publicado el 30 de mayo de 2023 por milewski milewski | 4 comentarios | Deja un comentario

29 de mayo de 2023

Sundry notes (on vegetation, termites, and rainfall) from a visit to Namaqualand, South Africa

@tonyrebelo @jeremygilmore @kevinatbrakputs @craigpeter @jrebman @pietermier @botaneek

On 21-22 May 2006, a colleague and I visited Kleinzee (https://en.wikipedia.org/wiki/Kleinzee) in Little Namaqualand (https://en.wikipedia.org/wiki/Namaqualand) in Northern Cape province of South Africa.

Today, I dusted off my field-notes from that visit.

Little Namaqualand falls within the succulent karoo biome (https://pza.sanbi.org/vegetation/succulent-karoo-biome).

Approaching Kleinzee from the northeast:

At the turnoff to Kleinzee from the Steinkopf-Port Nolloth road (https://en.wikipedia.org/wiki/R382_(South_Africa)), we found a vast vista of blanket-like vegetation consisting of low (0.5 m), succulent shrubs (https://www.inaturalist.org/observations/162520809), on flats, slopes, and drainage lines alike (https://upload.wikimedia.org/wikipedia/commons/a/a5/Houthoop%2C_Kleinzee%2C_Namaqualand%2C_Northern_Cape%2C_South_Africa_%2810465408374%29.jpg and https://www.flickr.com/photos/south-african-tourism/10993794574/in/photostream/ and https://www.flickr.com/photos/south-african-tourism/10993845063/in/photostream/ and similar to https://www.inaturalist.org/observations/11048822 and https://www.inaturalist.org/observations/120312638 and https://www.inaturalist.org/observations/58090550).

This landscape is completely exempt from wildfire, and the vegetation had not burned for at least half a century, for hundreds of thousands of hectares.

What struck me as noteworthy about this vegetation was that it was both shorter and denser than expected for a semi-desert.

Both heuweltjies (https://en.wikipedia.org/wiki/Heuweltjie) and the termitaria of Trinervitermes (https://en.wikipedia.org/wiki/Trinervitermes) were absent.

Houthoop Guest Farm (https://www.flickr.com/photos/south-african-tourism/10993785134/in/photostream/) got its name (English translation: wood pile) from an interesting circumstance in terms of the regional vegetation. Trees and even tall shrubs being absent as far as the eye can see, any incidence of wood much larger than gnarled twigs is exceptional in this region.

A major family in succulent karoo vegetation is Aizoaceae (https://en.wikipedia.org/wiki/Aizoaceae), the plants of which are usually small. However, the genus Stoeberia (https://www.inaturalist.org/observations?place_id=any&taxon_id=575290&view=species) - although not arborescent - is large and woody enough to be remarkably solid in the local context. Simply collecting the occasional dead plant of this genus, the landowner here eventually accumulated a pile (?several hundred kg) of wood, which became noteworthy enough to form the initial basis for a tourist-attraction.

Although I recall seeing this pile during our visit in 2006, I have found no photos of it on the Web, suggesting that it has not proven to be durable or renewable.

I know of nowhere else on Earth where the vegetation is

  • perennial and technically woody (as opposed to herbaceous), and dense enough to appear to blanket the landscape, yet
  • so low that dead wood is so hard to obtain that the collection of even of a few hundred kg is remarkable enough to become an anthropogenic landmark.

Herbivory/folivory in succulent karoo:

The main herbivores/folivores in this succulent karoo ecosystem northeast of Kleinzee at the time were Raphicerus campestris (https://www.inaturalist.org/observations/144416187) and, probably, Microhodotermes viator (https://www.inaturalist.org/taxa/568761-Microhodotermes-viator).

I observed the former (of which extremely dense populations have been reported near the coast hereabouts), but not the latter.

Two other indigenous species with similar diets, viz. Antidorcas marsupialis (https://www.inaturalist.org/observations/135399878) and Struthio camelus (https://www.inaturalist.org/observations/10816345 and https://www.inaturalist.org/observations?taxon_id=154483), were relatively scarce over much of the area owing to management by pastoralists.

(Driving south from Kleinzee subsequently, over a distance of about 50 km, I observed both A. marsupialis and S. camelus, but not R. campestris. This suggests competitive release, in which the bambi (body mass 10 kg) compensates for the scarcity of the gazelle (body mass 30 kg) and/or the large bird (body mass 80 kg).)

I encountered vigorous seasonal growth of Mesembryanthemum crystallinum (https://www.inaturalist.org/observations/163481201 and https://www.inaturalist.org/taxa/49319-Mesembryanthemum-crystallinum) on an old track.

I tried it as food, and found it remarkably palatable, raw. It was extremely succulent and tender, with a content of probably >95% water in the leaves and shoots. It lacked the taste I associate with oxalates in e.g. Tetragonia and domestic spinaches, and was only slightly salty and only slightly sour. I describe it, in my field notebook, as 'basically salad-flavoured green water, but very close indeed to a table-standard palatable wild plant'.

Farming of domestic sheep (Ovis aries):

The domestic sheep prefers grass as its staple diet, and cannot thrive in succulent karoo - in which the small shrubs virtually exclude grass - year-round.

Therefore, the pastoral practice in this region is for the livestock to be moved to Bushmanland (https://www.researchgate.net/figure/Northwestern-part-of-Northern-Cape-showing-the-area-that-we-consider-to-fall-within_fig1_336835392 and https://en.wikipedia.org/wiki/Bushmanland,_Northern_Cape), with its relatively grassy semi-desert vegetation (https://www.inaturalist.org/observations/150480278), for the summer, and then returned to Little Namaqualand for the winter.

It is noteworthy that the herbivorous termite in Bushmanland is not M. viator but instead Hodotermes mossambicus (https://www.inaturalist.org/taxa/558312-Hodotermes-mossambicus), which eats grass rather than shrubs.

Thus, the livestock spend winter in the habitat of M. viator, sharing a mainly dicotyledonous diet with one harvesting termite (https://www.inaturalist.org/observations/132288477 and https://www.inaturalist.org/observations/138127670), and spend summer in the habitat of H. mossambicus, sharing a mainly monocotyledonous diet with another harvesting termite (https://www.inaturalist.org/observations/150534825 and https://www.inaturalist.org/observations/139114838).

In Kleinzee:

At the time of our visit, Kleinzee was a mining town run by De Beers (https://en.wikipedia.org/wiki/De_Beers) - which subsequently abandoned the enterprise hereabouts.

Our official guide, Paul Kruger, told me that, at the stable on his property, M. viator had a noteworthy pattern of behaviour. This termite suddenly emerged from holes in the ground, just before rain, fervently cutting and burying the hay provided for Equus caballus.

I found it puzzling that M. viator was so eager to harvest grass, given that

  • this species has a staple diet of small shrubs, and
  • grasses are so uncommon in succulent karoo as to be hardly noticeable, even in good seasons.

Unusually wet season:

The normally dry Buffels River, which runs through Kleinzee, was in spate during our visit.

I was told that this river had flowed strongly three times in 2005, most recently in October; the current event brought that total to four times in one year.

Indeed, I was told that

  • it had been drizzling about every 10 days in Kleinzee, since April 2006, and
  • only a few days before we arrived, there had been a truly exceptional rain event in Little Namaqualand, with 130 mm recorded at Springbok (https://en.wikipedia.org/wiki/Springbok,_South_Africa), and 12 mm recorded at Kleinzee.

For comparison:
Mean annual precipitation is 16.7 cm at Springbok (part of the watershed for the Buffels River), and only 1.8 cm (plus frequent fog) at Kleinzee (https://tcktcktck.org/south-africa/northern-cape/kleinsee#:~:text=The%20district's%20yearly%20temperature%20is,%25%20of%20the%20time)%20annually.).

The situation at the time of our visit was exceptional, because drainage lines generally flow strongly only about once every 7-10 years in Little Namaqualand.

Based on a rule-of-thumb that depth of penetration is about tenfold the precipitation, 130 mm of rain can be expected to percolate >1 m deep in the substrate, but 12 mm cannot be expected to percolate much deeper than 10 cm.

The dominant small, succulent shrubs in succulent karoo have shallow roots, adapted to precipitation so light that the subsoil remains dry for years on end. It is by virtue of the fact that the precipitation, although minimal, occurs fairly frequently (on average, 36.5 days per year excluding the advection fog from the shore that occurs mainly in autumn and early winter), that perennial plants occur here, with enough density to seem to carpet an arid landscape.

Publicado el 29 de mayo de 2023 por milewski milewski | 3 comentarios | Deja un comentario

27 de mayo de 2023

Adaptive colouration in the hard-ground barasingha (Rucervus duvaucelii branderi)

@paradoxornithidae @matthewinabinett @tandala @michalsloviak

The hard-ground barasingha (Rucervus duvaucelii branderi) has remarkably plain colouration for a large, gregarious ruminant (https://www.inaturalist.org/observations/41060671 and https://www.inaturalist.org/observations/135787270 and https://www.inaturalist.org/observations/123326209 and https://www.gettyimages.com.au/detail/photo/hard-ground-swamp-deer-barasingha-royalty-free-image/178208647?phrase=swamp+deer&adppopup=true and https://www.gettyimages.com.au/detail/photo/barasingha-stags-royalty-free-image/495063657?phrase=swamp+deer&adppopup=true and https://www.alamy.com/stock-photo-barasingha-12-tined-deer-also-known-as-swamp-deer-71617444.html?imageid=7FF4EC5B-7908-48DE-AAD0-B26E6C3A92D2&p=215720&pn=1&searchId=276985531ee281cf572c89f88e85bd3d&searchtype=0 and https://www.flickr.com/photos/reflections-nmp/5685437727 and https://www.flickr.com/photos/cirdan-travels/25759806461).

However, it shows the following:

  • sexual dimorphism, in which mature males are darker than adult females and lack countershading on the torso,
  • a possible caudal flag,
  • anterior and posterior auricular flags, and
  • a buccal semet.

In interpreting the photos of the hard-ground barasingha on the Web, please remember that Kanha National Park is closed to visitors during the rainy season in summer, which lasts 4.5 months (https://www.kanha-national-park.com/best_time_to_visit.html#:~:text=Kanha%20National%20Park%20in%20Madhya,weather%20becomes%20pleasant%20this%20time and https://www.thewildlifeindia.com/2022/09/Monsoon-Magic-of-Kanha-National-Park-Meadows.html).

Although the antlers are shed in the dry season, I have yet to see a photo of any mature male in the antlerless condition or in young velvet.


The following shows that, during the rutting season, mature males have shaggy pelage while adult females retain summer pelage (https://www.alamy.com/stock-photo-barasingha-deer-or-swamp-deer-cervus-duvauceli-male-and-female-india-111494883.html?imageid=CBF16B70-FEA4-4F8C-8CE3-B0ADAD81EC0A&p=329545&pn=1&searchId=276985531ee281cf572c89f88e85bd3d&searchtype=0).

The following show that adult males lack countershading on the torso, enhancing their conspicuousness (https://www.flickr.com/photos/hmadan/4205687133 and https://www.inaturalist.org/observations/123287742 and https://www.inaturalist.org/observations/72271929 and https://www.inaturalist.org/observations/41095389 and https://www.alamy.com/buck-barasingha-recurvus-duvaucelii-in-kanha-national-park-india-image361790523.html?imageid=368FF456-4A1B-42FA-9DE7-8CC82FF8FA27&p=143932&pn=2&searchId=9457f45e1535e0baeab1d072e9f2dbd7&searchtype=0 and https://www.alamy.com/barasingha-swamp-deer-in-india-image217155284.html?imageid=9C92EA35-0044-4A0D-AC43-A22A4B7C18C3&p=149431&pn=1&searchId=276985531ee281cf572c89f88e85bd3d&searchtype=0).

The following shows that adult but not fully mature males have not necessarily developed this feature yet (https://www.inaturalist.org/observations/123284736).

Adult males possess a poorly-developed and individually variable muzzle-ring (https://www.inaturalist.org/posts/55779-the-muzzle-ring-as-a-deep-ancestral-marker-in-deer-part-1).

This is shown in https://www.alamy.com/stock-photo-barasingha-12-tined-deer-72093014.html and https://www.alamy.com/stock-photo-swamp-deer-barasingha-kanha-national-park-103926875.html?imageid=736E7E6C-7E36-4689-B53E-9A618B953BD0&p=300848&pn=1&searchId=276985531ee281cf572c89f88e85bd3d&searchtype=0 and https://www.alamy.com/close-up-of-a-swamp-deer-rucervus-duvaucelii-kanha-national-park-madhya-pradesh-india-image376770510.html and https://www.shutterstock.com/image-photo/male-barasingha-swamp-deer-rucervus-duvaucelii-686501974 and https://www.alamy.com/hard-ground-swamp-deer-or-barasingha-cervus-duvauceliithreatened-kanha-image6941233.html and https://www.agefotostock.com/age/en/details-photo/barasingha-central-hardground-or-swamp-deer-cervus-duvaucelii-branderi-in-kanha-national-park-madhya-pradesh-india/X1B-904819 and https://www.agefotostock.com/age/en/details-photo/barasingha-swamp-deer-rucervus-duvaucelii-male-grazing-kanha-national-park-madhya-pradesh-india-asia/AAM-AAES111859 and https://nickgarbutt.photoshelter.com/image/I0000nl2DBDcw4UE and https://www.alamy.com/stock-photo-a-hard-ground-barahsinga-rucervus-duvauceli-branderi-grazing-at-kanha-35435038.html?imageid=37304E47-F115-47B3-9321-47F798B2EA43&p=12384&pn=2&searchId=9457f45e1535e0baeab1d072e9f2dbd7&searchtype=0 and https://www.ardeaprints.com/jr-745-1304405.html and https://www.gettyimages.com.au/detail/photo/barasingha-deer-and-mynas-royalty-free-image/521358970?phrase=swamp+deer&adppopup=true and https://www.facebook.com/amanwilsonphotography/photos/hard-ground-swamp-deer/1225524230870187/).

The following (https://www.inaturalist.org/observations/48644048 and https://www.alamy.com/stock-photo-barasingha-deer-or-swamp-deer-cervus-duvauceli-male-111494839.html?imageid=9D42A777-F780-49CC-A47C-1DAB3977E1A2&p=329545&pn=1&searchId=276985531ee281cf572c89f88e85bd3d&searchtype=0) show that adult males may possess pale

  • at the crook-of-throat, and
  • at the tips of the tines of the antlers (at least in some individuals).

The following shows that the spotting on the body fades early in juveniles, but is retained along the dorsal line in adult females in summer pelage (https://www.alamy.com/stock-photo-stah-does-barasingha-aka-swamp-deer-cervus-duvauceli-kanha-tiger-reserve-24557302.html?imageid=36B59956-4568-48E0-9348-D7CA71FC7D73&p=135160&pn=1&searchId=276985531ee281cf572c89f88e85bd3d&searchtype=0).

In 'winter' pelage, the dark dorsal stripe is somewhat retained, but the accompanying pale spots become faint (https://www.naturepl.com/stock-photo/hard-ground-barasingha--upland-barasingha--swamp-deer-%28cervus-duvauceli/search/detail-0_01345300.html).


The following show that there is a considerable pattern on the hindquarters (https://www.gettyimages.com.au/detail/news-photo/barasingha-or-swamp-deer-cervidae-news-photo/492765651?adppopup=true and https://www.inaturalist.org/observations/157012022 and https://www.alamy.com/india-barasingha-southern-swamp-deer-rucervus-duvaucelii-branderi-at-kanha-tiger-reserve-image226010798.html?imageid=6CAC9BD2-38D4-4478-B311-33562A557B7E&p=158464&pn=2&searchId=9457f45e1535e0baeab1d072e9f2dbd7&searchtype=0 and https://www.inaturalist.org/observations/56530542).

The ventral surface of the tail is white (https://www.kanha.co.in/kanha-wildlife/kanha-barasingha.html).

However, the tail is small. Furthermore, in most views, the pattern on and near the tail is so subtle as to be hardly noticeable (https://www.alamy.com/stock-photo-stah-does-barasingha-aka-swamp-deer-cervus-duvauceli-kanha-tiger-reserve-26521418.html?imageid=8362A2B4-A2CF-4065-97AF-533B49F54364&p=135160&pn=3&searchId=7cd4c73a247af679b402df2f61bcb554&searchtype=0 and https://www.gettyimages.com.au/detail/photo/swamp-deer-or-barasingha-royalty-free-image/981724418?phrase=swamp+deer&adppopup=true and https://www.alamy.com/swamp-deer-also-known-as-baraginga-rucervus-duvaucelii-male-from-kanha-national-park-madhya-pradesh-india-image473715869.html?imageid=D03B6D4F-3C7D-44B1-AD4A-8805A87AFEF9&p=1910266&pn=3&searchId=7cd4c73a247af679b402df2f61bcb554&searchtype=0 and https://www.superstock.com/asset/hard-ground-swamp-deer-pond-cervus-duvauceli-branderi-kanha-national/4220-20145884).

The following shows that adult males do not display the tail when fleeing (https://www.flickr.com/photos/girlslens/42013764681 and https://www.agefotostock.com/age/en/details-photo/hard-ground-swamp-deer-leaping-cervus-duvauceli-branderi/MEV-10788396).

The possibility remains that the hard-ground barasingha possesses a caudal flag in a social/sexual context. However, the photographic evidence has yet to emerge.


The following show that the anterior surface of the ear pinna, which is extremely hairy in the hard-ground barasingha, is conspicuously pale (https://www.alamy.com/stock-photo-female-barasingha-aka-swamp-deer-cervus-duvauceli-kanha-tiger-reserve-24557283.html?imageid=A9389520-61FB-49BC-A345-D584F311F213&p=135160&pn=3&searchId=7cd4c73a247af679b402df2f61bcb554&searchtype=0 and https://www.gettyimages.com.au/detail/photo/barasingha-royalty-free-image/495374407?phrase=swamp+deer&adppopup=true).

The following shows that this persists somewhat in mature males, despite the overall darkening of the pelage (https://nickgarbutt.photoshelter.com/image/I0000IfnSIMigzrw and https://www.gettyimages.com.au/detail/news-photo/barasingha-or-swamp-deer-cervidae-news-photo/492765653?adppopup=true and https://www.gettyimages.com.au/detail/photo/swamp-deer-or-barasingha-stags-royalty-free-image/114571486?phrase=swamp+deer&adppopup=true).

The following show that the posterior of the ear is pale at its base and on the ventral surface of the pinna (https://www.shutterstock.com/image-photo/two-female-barasingha-swamp-deer-rucervus-2303161159 and https://www.alamy.com/two-female-barasingha-or-swamp-deer-rucervus-duvaucelii-kanha-national-park-india-image551808559.html?imageid=D270AC8A-B237-4F0F-86EC-F573C241279D&p=70019&pn=1&searchId=276985531ee281cf572c89f88e85bd3d&searchtype=0).

The following hints that this feature may be reduced or absent in mature males (https://3.bp.blogspot.com/-T-LSDuDf67E/S5I5vDt4v_I/AAAAAAAAAsM/Lac7IzM2CBAbXjnWpxfje4VpDuo_Vl6fACPcBGAYYCw/s1600/Barasingha%2Bin%2BFlight.jpg).

However, as for the loss of countershading on the torso, this may apply only to fully mature males (https://www.istockphoto.com/photo/barasingha-or-swamp-deer-crossing-the-road-at-kanha-national-park-madhya-pradesh-gm1143848337-307332227 and https://www.shutterstock.com/image-photo/barasinga-popularly-known-swamp-deer-found-1212245020 and https://www.alamy.com/stock-photo-swamp-deer-cervus-duvauceli-india-34384520.html?imageid=1D376CF4-2092-47DC-B616-E11D3E488747&p=5264&pn=2&searchId=9457f45e1535e0baeab1d072e9f2dbd7&searchtype=0 and https://www.alamy.com/stock-photo-barasingha-deer-or-swamp-deer-cervus-duvauceli-males-india-111494877.html?imageid=D4AEB073-F7C3-44EE-B4F2-5843F7EE009B&p=329545&pn=2&searchId=9457f45e1535e0baeab1d072e9f2dbd7&searchtype=0 and https://www.alamy.com/swamp-deer-also-known-as-barasinga-rucervus-duvaucelii-feeding-in-kanha-national-park-madhya-pradesh-india-image473710698.html?imageid=4C52A322-53E0-46DD-A04F-D8D9588A99F5&p=1910266&pn=3&searchId=7cd4c73a247af679b402df2f61bcb554&searchtype=0).


The following show the sexual difference in the pattern of dark and pale at the mouth (https://www.alamy.com/stock-photo-barashingha-deer-or-swamp-deer-cervus-duvauceli-males-fighting-111494576.html?imageid=AFAFB591-BE9D-4EA0-A8D8-33F1D79C4C68&p=329545&pn=2&searchId=9457f45e1535e0baeab1d072e9f2dbd7&searchtype=0 and https://www.shutterstock.com/image-photo/female-barasingha-swamp-deer-rucervus-duvaucelii-1476784394).

The buccal semet in females conforms to what I have previously called a gape-spot (https://www.inaturalist.org/journal/milewski/55804-the-muzzle-ring-as-a-deep-ancestral-marker-in-deer-part-2-the-gape-spot).


From one perspective, the hard-ground barasingha is simply a dull version of various patterns of colouration widespread in cervids, particularly on the tail and buttocks, and on the muzzle.

However, this hardly does justice to the topic.

From another perspective, what is most remarkable about this colouration is the anterior auricular flag, which is better-developed than in most cervids.

However, this, too, needs qualification. The main reason for the conspicuousness of the white hairs on the front-of-ear may be the sheer hairiness of this surface - possibly explained by protection from blood-sucking insects in marshes.

From a different perspective again, what is most noteworthy about the adaptive colouration of the hard-ground barasingha is the seasonal change in the length of the pelage, which is also involved in sexual dimorphism.

What is odd about this seasonal change is that the habitat of this subspecies lies in the tropics, where the climate in 'winter' is mild. Comparable bovids under similar climates in Africa, such as Kobus (https://www.inaturalist.org/observations?place_id=any&taxon_id=42325&view=species), show no seasonal changes in pelage.

At the same time, this makes little difference to the adaptive colouration, because the relatively bright hue of the summer pelage (https://www.inaturalist.org/observations/157012025 and https://3.bp.blogspot.com/-nXWgDhRaP-8/SBq1CvQ0A1I/AAAAAAAAAOE/nflIUIX3-UA/s1600/Swampdeer.jpgv and https://4.bp.blogspot.com/-GAns8sSDDwQ/SBq1HfQ0A2I/AAAAAAAAAOM/G28tNH_0lZA/s1600/swamp-deer.jpg) is not necessarily visible to ungulates and carnivores.

Overall, my finding is that the most important pattern in the colouration of the hard-ground barasingha is the auricular flags in females (https://www.natureinstock.com/search/preview/hard-ground-barasingha-upland-barasingha-swamp-deer-cervus-duvauceli/0_12200926.html and https://www.shutterstock.com/editorial/image-editorial/nature-4907890a).

The colouration on the front-of-ear differs only slightly from that of comparable reduncin bovids (https://www.edwardselfephotosafaris.com/know-your-african-wildlife-puku). However, the ears are noticeable in the hard-ground barasingha because the rest of its figure is relatively featureless.













Publicado el 27 de mayo de 2023 por milewski milewski | 15 comentarios | Deja un comentario

Aposematic colouration in snakes

Various snakes show extreme tones inside the mouth in defensive display, e.g.

This is one of the least ambivalent aspects of aposematic colouration in snakes. However, it

  • is only a minor feature of the body as a whole,
  • occurs in only a few taxa of snakes, and
  • does not provoke deep theoretical discussion, other than to comment on how odd it is that Trachydosaurus and Tiliqua also use this tactic, despite lacking venom.

How many harmless spp. of snakes open the mouth to display striking colours in self-defence? Which hues are used, and which are the predators targeted?

Various snakes rattle the tail as part of defensive display, and some display colouration while doing so.

Whereas an open mouth clearly warns of venom (or just bite), warning colouration on the tail is ambiguous, because it could refer to the mouth (particularly where the posture of threat display brings the tail close to the mouth, as in certain Crotalus, https://www.outsideonline.com/outdoor-adventure/exploration-survival/snake-bite-dog-rattlesnake-avoidance-training/), or it could warn of the danger from the cloacal gland (and faeces).

Tail-rattling and hissing/puffing are analogous 'aposematic' sounds, produced by opposite ends of the body. Therefore, it seems logical enough that both can be accentuated by aposematic colouration.

However, the tail has the complication that the snake could be trying to distract the predator away from the head, not to threaten the predator with its hind end. If so, the term 'aposematic' seems inappropriate. Calabaria reinhardtii (https://www.inaturalist.org/taxa/32123-Calabaria-reinhardtii) hides its head in a ball while displaying the tail, with dark-pale contrast on the tail (https://www.inaturalist.org/observations/136487375 and http://www.kingsnake.com/sandboa/calball2.jpg and http://www.kingsnake.com/sandboa/cal_ball.jpg).

So, unless this species releases cloacal defence, it would seem to be a case of non-aposematic colouration, for distraction, or perhaps startling.

Some snakes seem to have an aposematically-coloured tongue, e.g. pink and black in Thelotornis (https://www.inaturalist.org/observations?place_id=any&taxon_id=28332&view=species and https://www.inaturalist.org/observations/87692641 and https://www.inaturalist.org/observations/142618345).

I see this as only a minor aspect of aposematism in snakes. However, it is significant because it announces the animal to be a snake. Apart from snakes, the only herps with forked tongues are varanid lizards.

It is possible that the relatively few types of snake that are whole-body aposematic (mainly dark and pale banded, as epitomised by Bungarus spp., https://www.inaturalist.org/observations?place_id=any&taxon_id=30436&view=species) are uncomplicated, announcing their venomousness much as a skunk announces its noxiousness.

However, what the literature on snakes does not seem to have considered are the possibilities that

  • whole-body aposematism is more about cloacal secretion than venom, or
  • banded snakes may be noxious/poisonous in the sense of their flesh being poisonous for predators to eat, regardless of the question of venom in the head.

This might perhaps help to explain why most of the 'coral snakes' are both reluctant to display their heads and unlikely to bite effectively, having small mouths.

Micrurus (https://www.inaturalist.org/observations?place_id=any&taxon_id=30493&view=species) displays its tail (https://www.canstockphoto.com/eastern-ribbon-coral-snake-micrurus-2377871.html and https://www.reptilesofecuador.com/micrurus_melanotus.html and https://animalia.bio/micrurus-mipartitus and https://www.reptilesofecuador.com/micrurus_scutiventris.html and https://www.alamy.com/andean-redtail-coral-snake-micrurus-mipartitus-esmeraldas-province-western-ecuador-image432368979.html?imageid=B0195DA4-6EFE-4F94-B9F1-1E07317E38A4&p=54509&pn=1&searchId=b5bd9b6231731e6c7664badf55235e49&searchtype=0), and this may be to warn of cloacal secretions, or possibly to allow a predator to taste it without injuring the head ().

Is so, then snakes may be partly analogous to poison frogs (https://www.agefotostock.com/age/en/details-photo/orange-and-black-poison-dart-frog-golfodulcean-poison-frog-golfodulcean-poison-frog-phyllobates-vittatus-morph-with-red-stripe-cutout-costa-rica/BWI-BS445984) rather than Black widow spiders (https://www.smithsonianmag.com/science-nature/eight-fun-facts-about-black-widows-180978098/), in the function of aposematic colouration.

To complicate the matter, of course the cloacal sacs would add to the unpalatability/indigestibility of the whole snake.

It is too easy to jump to the conclusion that if a snake has warning colours or a display of its tail, it is the venom (or pretension to venom in the case of bluffing/mimicking snakes) that is being advertised.

Publicado el 27 de mayo de 2023 por milewski milewski | 2 comentarios | Deja un comentario

26 de mayo de 2023

Microchaetus, the largest earthworms on Earth?

(writing in progress)

The large-bodied earthworms of the southern hemisphere belong to four families, containing many genera.

Present in Madagascar (distinctive family).








Large earthworms in North America and Australia belong to the family Megascolecidae.

In the USA:

Driloleirus macelfreshi (Oregon giant earthworm), up to 1.3 m long, has a habitat of riparian forest


Driloleirus americanus (giant palouse earthworm), occurs in Washington state (probably the Columbia River basalt area?). It has a length of up to 3 m, and a width of up to 2.5 cm. Its habitat is indigenous shrublands in eastern Washington state and western Idaho.


In Australia:

The largest-bodied of the approximately 1000 spp. of earthworms in Australia is the giant Gippsland earthworm (Megascolides australis, https://en.wikipedia.org/wiki/Giant_Gippsland_earthworm and scroll in https://www.gardenmyths.com/earthworm-myths/ and https://www.sciencedirect.com/science/article/abs/pii/003807179290119I), which has a mean length of 80 cm (in the largest individuals, up to 4 m when stretched), a width of 2 cm, and a body mass of about 200 g (up to 400 g). The body is fragile (https://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=64420).

Megascolides australis is long-lived and slow-growing. Hatchlings have a length of 20 cm, and take up to 5 years to reach maturity. The castings are left underground. The distribution of this species is limited to less than 50,000 hectares, in the Bass River valley, east of Melbourne. The habitat is riparian grassland.


One megascolecid, Amynthas corticis (up to 17 cm long, https://www.inaturalist.org/taxa/196395-Amynthas-corticis), is parthenogenetic. It is capable of autotomy, shedding the posterior of the body in order to escape from predators.

Amynthas https://www.inaturalist.org/observations?place_id=any&taxon_id=196397&view=species

The largest earthworms on Earth apparently belong to the genus Microchaetus, in the family Glossoscolecidae (or Microchaetidae). Their bodies are up to about 7 m long. They penetrate the soils to depths of 30-70 cm.











The giant golden mole (Chrysospalax trevelyani, https://en.wikipedia.org/wiki/Giant_golden_mole and https://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL8110060554 and https://www.tandfonline.com/doi/abs/10.1080/02541858.1985.11447950) is the largest-bodied chrysochlorid in southern Africa.

It is up to 23 cm long. Its distribution is in the Eastern Cape, from East London to southern Pondoland. Its main diet is said to be Microchaetus (https://www.cambridge.org/core/journals/oryx/article/giant-golden-mole/918E35A64B0631A18128B57621FC4B8F).

(writing in progress)

Publicado el 26 de mayo de 2023 por milewski milewski | 10 comentarios | Deja un comentario

25 de mayo de 2023

Scarcity of termitaria of the grass-harvesting termite Trinervitermes in Namibia, and implications for the aardwolf (Proteles cristatus)

@hamishrobertson @tonyrebelo @jeremygilmore @botswanabugs

In May 2006, a colleague and I traversed Namibia from the southern border to the eastern Caprivi Strip.

One of my search-images at the time was for the termitaria of Trinervitermes (https://www.inaturalist.org/observations?taxon_id=567388).

Trinervitermes trinervoides is widespread and common in South Africa. It is one of the main foods of Proteles cristatus, which is remarkably widespread in southern Africa (https://www.inaturalist.org/taxa/1306005-Proteles-cristatus).

There is at least one record of a termitarium of Trinervitermes in Namibia (https://www.inaturalist.org/observations/154573786). This is in the pro-Namib, viz. the eastern border of the Namib desert (https://www.landscapesnamibia.org/sossusvlei-namib/landscape-members/689 and https://www.sciencedirect.com/science/article/abs/pii/S0140196396902037 and https://www.sciencedirect.com/science/article/abs/pii/S0140196318302155).

Another record is pertinent. The incidence of termitaria of Trinervitermes in the Kgalagadi Transfrontier Park (https://www.inaturalist.org/observations/32915349) indicates that there may be a similar incidence in the adjacent part of Namibia, where the relevant environment straddles the international border.

However, in my own transect of Namibia, I did not spot even a single termitarium of this genus.

This raises a puzzle.

Proteles cristatus is widespread in Namibia (https://www.inaturalist.org/observations?place_id=7140&taxon_id=1306005).

Since its diet in southern Africa is said to consist mainly of Hodotermes and Trinervitermes (in that order of preference), three possible explanations are:

On 11 May 2006, we excavated an abandoned mound of Macrotermes michaelseni, near Okahandja (https://en.wikipedia.org/wiki/Okahandja). This fungus-culturing termite is absent from the southern half of Namibia.

Trinervitermes - and its stores of cut grass-stems - was present inside this mound. I tasted the nasutes to confirm the taste of turpentine. It seems that Trinervitermes exploits old mounds of Macrotermes, without changing their external appearance.

Elsewhere in northern Namibia, I found Hodotermes in the mounds of M. michaelseni.

This observation raises the following question:
Where Trinervitermes and Macrotermes coexist, is it true to say that the former refrains from building its own above-ground structures?

Publicado el 25 de mayo de 2023 por milewski milewski | 5 comentarios | Deja un comentario

24 de mayo de 2023

Anomalously tall vegetation, on anomalously nutrient-rich soils, in an arid climate in southern Namibia

Near Keetmanshoop in southern Namibia (https://en.wikipedia.org/wiki/Keetmanshoop and https://en.wikipedia.org/wiki/Gr%C3%BCnau,_Namibia), there is a limited but considerable incidence of trees that is unexplained by deep groundwater in seasonal drainage lines.

Open savanna, about 5 m high, of Vachellia erioloba (https://www.inaturalist.org/observations/133078127), occurs under mean annual rainfall of about 125 mm (https://maps-namibia.com/namibia-rainfall-map).

At Gellap Ost (http://the-eis.com/elibrary/search/6553 and https://www.nbri.org.na/gellap-ost-research-station and https://www.mindat.org/feature-3357334.html), the substrate on the broadscale plain is a rather sandy-looking dark loam, free of stones, derived from dolerite bedrock.

The upper stratum consists of trees of V. erioloba, up to 6 m high and 6 m wide (https://www.inaturalist.org/observations/133078122 and https://www.inaturalist.org/observations/133078123). The individual trees are, on average, about 50 m apart.

Some of the trees bear the nest-complexes of Philetairus socius (https://www.inaturalist.org/observations/32789834).

Karoid shrubs are scarce, and consist mainly of Rhigozum trichotomum (https://www.inaturalist.org/taxa/355852-Rhigozum-trichotomum).

The main stratum here consists mainly of a short tussock-grass, Stipagrostis obtusa (https://www.inaturalist.org/taxa/594826-Stipagrostis-obtusa). This is grassier than on the shale-derived substrate nearby, which supports Catophractes (https://www.inaturalist.org/taxa/70059-Catophractes-alexandri) and other shrubs, rather than grasses and trees.

In the Keetmanshoop area, V. erioloba is not associated with Kalahari sand, which does not extend this far to the west (https://www.researchgate.net/figure/Geographic-location-black-dot-and-vegetation-structure-of-each-study-site-along-the_fig1_241520991). Instead, it is associated with dolerite (https://www.inaturalist.org/observations/133078121).

In the same general area, Aloidendron dichotomum (https://www.inaturalist.org/taxa/527446-Aloidendron-dichotomum) is unusually tall for an aloe. It occurs on outcrops of dolerite (https://www.inaturalist.org/observations/142126920 and https://www.inaturalist.org/observations/148037408 and https://www.inaturalist.org/observations/109356346 and https://www.inaturalist.org/observations/122831811 and https://www.inaturalist.org/observations/37025903 and https://www.inaturalist.org/observations/160059615 and https://www.inaturalist.org/observations/11046247 and https://www.inaturalist.org/observations/41560387).

Aloidendron dichotomum is arborescent enough to be used for nesting by P. socius (https://www.inaturalist.org/observations/25798893).


In general, vegetation can be expected to be tallest in rainy climates, and on moderately nutrient-poor soils.

The climate near Keetmanshoop is arid, and dolerite is a relatively nutrient-rich parent material. Therefore, the incidence of trees hereabouts seems anomalous.

The nutrient-richness of vegetation dominated by V. erioloba and S. obtusa is evident in the great palatability of both species to ungulates.

It is well-known that V. erioloba occurs in Kgalagadi Transfrontier Park (https://en.wikipedia.org/wiki/Kgalagadi_Transfrontier_Park), where mean annual rainfall is about 200 mm. However, the landforms here consist of seasonal drainage lines among dunes of deep sand (https://www.inaturalist.org/observations/40959605), allowing roots to draw water tens of metres deep during drought.

The habitats of V. erioloba and A. dichotomum near Keetmanshoop and Grunau lie immediately adjacent to the Nama Karoo biome (https://en.wikipedia.org/wiki/Nama_Karoo). It is understandable that the vegetation is grassier than in the Nama Karoo, because the proportion of rainfall in summer increases as one proceeds northwards from the southern border of Namibia. However, the incidence of trees on plains and rocky outcrops of dolerite seems incongruous relative to the Nama Karoo, and cannot be explained by the seasonal shift in the rainfall.

Publicado el 24 de mayo de 2023 por milewski milewski | 3 comentarios | Deja un comentario

23 de mayo de 2023

The ecological significance of forested mounds of the termite Macrotermes in the Caprivi Strip

@tonyrebelo @jeremygilmore @hamishrobertson @joshua_tx @s_k_johnsgard @botswanabugs @bartwursten @troos

In May 2006, a colleague and I visited the eastern Caprivi Strip (http://www.eyesonafrica.net/african-safari-namibia/caprivi.htm and https://en.wikipedia.org/wiki/Caprivi_Strip) to do the fieldwork for https://agris.fao.org/agris-search/search.do?recordID=US201301621709 and https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-7998.2008.00544.x.

On the early morning of 19 May 2006, I studied an example of a large mound built - and still occupied - by Macrotermes (https://en.wikipedia.org/wiki/Macrotermes). We had slept at this location the previous night.

The height of this mound was >3.5 m above general ground level, and probably as much as 4.5 m. Its width (diameter, including the broad apron of the mound) was 25 m, measured from the general level of the floodplain that formed the matrix for the scattered mounds.

The scene in https://www.inaturalist.org/observations/149034602 is indicative. However, the sheer area of the mound - nearly 500 square metres - makes the situation difficult to photograph.

The species of Macrotermes could not be identified at the time, and - surprisingly - this seems still to be true today. The most likely candidates are Macrotermes natalensis and Macrotermes falciger, both of which are greatly underrepresented in iNaturalist.


The plant community on the mound contained a total of about 20 spp., visible at the time of my visit.

Eight individual trees occurred on this mound, consisting of

Peripheral plants of M. mochisia, 1.5 m high, had been so heavily browsed by large folivores that their growth-form was bonsai/topiary-like (https://www.inaturalist.org/observations/67387378 and https://www.inaturalist.org/observations/116415537).

This was reminiscent of Gardenia (please see https://www.inaturalist.org/journal/milewski/60060-explaining-the-extreme-growth-form-of-gardenia-in-the-serengeti#), but with the crown less rounded.

The understorey on the mound consisted mainly of Euclea divinorum (https://www.inaturalist.org/taxa/343032-Euclea-divinorum) and Ximenia americana (https://www.inaturalist.org/taxa/83832-Ximenia-americana), the latter superficially resembling Gymnosporia senegalensis (which may itself have been present as a scarce species).

Carissa spinarum (https://www.inaturalist.org/taxa/369502-Carissa-spinarum) was common on this mound, but Diospyros lycioides (https://www.inaturalist.org/taxa/469308-Diospyros-lycioides) seemed absent.

Salvadora persica (https://www.inaturalist.org/taxa/197082-Salvadora-persica) was present on this mound. Dichrostachys cinerea (https://www.inaturalist.org/taxa/129706-Dichrostachys-cinerea) occurred only where the mound joined the surrounding ground level.

The main liane on the mound was Capparis tomentosa (https://www.inaturalist.org/taxa/342724-Capparis-tomentosa), festooning not only the periphery of the mound, but also the trees. There were also two lines of Cucurbitaceae, one with small fleshy fruits (possibly https://www.inaturalist.org/taxa/165503-Momordica-balsamina), and the other bearing large, knobbly melons, lying on the ground and ripening at the time (possibly https://www.inaturalist.org/taxa/1245066-Citrullus-naudinianus). Asparagus africanus? (https://www.inaturalist.org/taxa/505798-Asparagus-africanus) was present only as small individuals.

Setaria verticillata (https://www.inaturalist.org/taxa/79069-Setaria-verticillata) was sparsely present on the mound, brown and collapsed at the time, with the burr-like seed-heads evident (https://www.minnesotawildflowers.info/grass-sedge-rush/bristly-foxtail#lboxg-10). A lawn-type grass occurred immediately adjacent to the mound, but did not encroach even on to the apron of the mound.

?Kalanchoe lanceolata? (a fragile-looking ?annual succulent) was present, and in flower at the time.

I estimated the contributions to the total vertically-projected cover of the vegetation on this mound, as follows:

Diospyros mespiliformis (tall trees): 55%
Manilkara mochisia (shorter trees): 25%
Capparis tomentosa (robust liane): 10%
Ximenia americana (common spinescent shrub): 5%
Euclea divinorum: 2%
Salvadora persica (partly liane-like): 1%
Cucurbitaceous liane (large fruits): trace
Cucurbitaceous liane (small fruits): trace
Unidentified shrub with dentate leaves: trace
Setaria verticillata: trace
?Phyllanthus reticulatus: trace
Acanthaceae, unidentified perennial: trace
Asparagus africanus?: trace
Malvaceae, unidentified: trace
Crassulaceae, unidentified: trace
Grewia sp. with no apparent fruits (different from the sp. in nearby woodland of T. sericea): trace
Sundry unidentified (five spp.): trace each


In this general environment, the matrix (the surrounding plain) was a floodplain, bearing open savanna with a main stratum of short, coarse (plastic-like) grass (dry and brown at the time).

On the clayey flats (with a grey sandy surface over most of the area) of the matrix, there was a sparse stratum of trees and shrubs.

This consisted of Combretum imberbe and congeners, Senegalia nigrescens, Piliostigma thonningii (https://www.inaturalist.org/taxa/592162-Piliostigma-thonningii), Dichrostachys cinerea, and Ziziphus mucronata (https://www.inaturalist.org/taxa/340228-Ziziphus-mucronata), with a few individuals of Gardenia.

In the case of C. imberbe, most of the individuals on the floodplain were about 1-1.5 m high.

All of these spp. were absent from the mound itself.

Patches of cracking clay in the matrix supported only sapling-size/stunted Combretum imberbe (https://www.inaturalist.org/observations/133825301), and shrubs of Dichrostachys cinerea (https://www.inaturalist.org/observations/133105517).

However, the large mounds were not the only situation in which trees were concentrated. Terminalia sericea (including large trees) dominated on a sandy patch about 75 m away, slightly elevated above the level of the matrix of short grassland. This sand was fine-grained and pale grey, and at most 0.5 m deep over a hard layer, as we discovered when our van became temporarily stuck.

Accompanying T. sericea on the sandy patch were Grewia sp. (in ripe fruit, the edible layer of which was naturally completely dry), Gymnosporia senegalensis (https://www.inaturalist.org/taxa/340106-Gymnosporia-senegalensis), Philenoptera violacea (https://www.inaturalist.org/taxa/340211-Philenoptera-violacea), and Vachellia erioloba (uncommon) - all of which were absent from the mound described above.


The area was well-grazed, albeit only by Bos taurus X indicus. Despite this substitution of domestic livestock for the original wild grazers, the ecosystem looked natural and healthy. The nearest village or kraal was at least several km distant.

There was abundant evidence of current foraging by termites throughout this area. The faeces of B. taurus X indicus were being promptly consumed by Macrotermes.

There was much evidence (in the form of mud-runnels) that Macrotermes was foraging for litter on the mound itself. This included grass (also covered by mud-runnels) being consumed by Macrotermes on the apron of the mound. However, my impression was that only trampled grass was suitable for Macrotermes.

The mud-runnels made for foraging by Macrotermes were present on the surface in the matrix, even where the surface was cracking clay. This was often on the faeces of B. taurus X indicus.

Hodotermes mossambicus (https://www.inaturalist.org/taxa/558312-Hodotermes-mossambicus) was abundant hereabouts, particularly on the floodplain. However, I did not see it at this location, perhaps because of the time of day.

The soil-heaps of mole-rats were absent from this whole area, despite the occurrence elsewhere in the Caprivi Strip of Fukomys damarensis (https://www.inaturalist.org/taxa/446619-Fukomys-damarensis).

Birds heard on/near this mound:

Vanellus coronatus (https://www.inaturalist.org/taxa/4877-Vanellus-coronatus), common on the short grassland of the matrix
Ptilopsis granti (https://www.inaturalist.org/taxa/144592-Ptilopsis-granti), heard repeatedly the previous night
Corythaixoides concolor (https://www.inaturalist.org/taxa/7238-Corythaixoides-concolor)
Streptopelia semitorquata (https://www.inaturalist.org/taxa/2988-Streptopelia-semitorquata)
Streptopelia capicola (https://www.inaturalist.org/taxa/2959-Streptopelia-capicola)
Streptopelia decipiens (https://www.inaturalist.org/taxa/2951-Streptopelia-decipiens)
Oriolus auratus (https://www.inaturalist.org/taxa/7868-Oriolus-auratus)
Pycnonotus barbatus (https://www.inaturalist.org/taxa/14588-Pycnonotus-barbatus)


In Africa more broadly, it is well-known that mounds of Macrotermes tend to support plant spp. absent from the matrix.

However, what is remarkable in this case is that the plant communities on and off this particularly large mound (comparable in area to a typical suburban residential plot) shared virtually no species of plants.

The mound supported a considerable patch of forest, which was

  • exempt from wildfire,
  • composed of plants dispersed and sown by vertebrates, mostly via fleshy fruits and endozoochory, and
  • surrounded by open savanna, itself probably exempt from wildfire when heavily grazed.

The presence of S. persica indicates that the soils on this mound, even at its apex, were rich in cations, particularly sodium (https://scialert.net/fulltext/?doi=ajpp.2020.14.22#:~:text=Salvadora%20persica%20(Arak%20or%20Miswak,often%20mucronate%20at%20the%20apex.).

The complete lack of caesalpinioid legumes, and indeed legumes in general, on the mound is noteworthy.

All of the trees, and most of the shrubs and lianes, on this mound possess fleshy fruits - many of them edible to humans (https://www.inaturalist.org/observations/69198499 and https://www.inaturalist.org/observations/156933406 and https://www.inaturalist.org/observations/68367756).

The protection of the whole mound from wildfire was owing to

  • the lack of a flammable lower stratum on the mound itself, and
  • the shortness of the grass in the surrounding matrix, partly owing to grazing.

The presence of faeces indicated that the vegetation on the mound was probably attractive to B. taurus X indicus, despite the scarcity of grass on the mound.

My impression was that three main consumers of grass interact in an important way in the complex of vegetation. In the matrix and probably also on the mound, grass is eaten mainly by ungulates and Hodotermes; the faeces (derived mainly from grass) of the ungulates are consumed by Macrotermes, which also consumes woody material of various plants; and the faeces of Hodotermes fertilise the whole ecosystem, particularly in the matrix.

What makes this situation, in the Caprivi Strip, remarkable is the combination of Macrotermes and Hodotermes. Extensive, forested mounds of Macrotermes are mainly a feature of tropical African woodlands, beyond the distribution of Hodotermes. The Caprivi Strip is at, or near, the northern limit of the distribution of Hodotermes. This unusual overlap in distribution seems to have produced a regime of thorough consumption of grass and litter, tending to exclude wildfire, and promoting palatable plants - including fruits edible for humans.

Publicado el 23 de mayo de 2023 por milewski milewski | 12 comentarios | Deja un comentario

22 de mayo de 2023

The anterior auricular flag of the greater kudu (Strepsiceros)

There is no doubt that the overall colouration of the greater kudu (Strepsiceros) is adapted for inconspicuousness, via disruption of the figure (https://www.inaturalist.org/observations/153426937).

Even the ear pinnae, which are remarkably large (https://www.inaturalist.org/observations/130293311), have a pattern intricate enough to contribute to this disruption colouration (https://www.inaturalist.org/observations/159543578 and https://www.inaturalist.org/observations/122202839).

However, it is equally true that, in many views, the ear pinnae are conspicuous enough to draw attention to the figure (https://www.shutterstock.com/image-photo/female-greater-kudu-kruger-national-park-1072876346 and https://www.inaturalist.org/observations/155867431 and https://www.inaturalist.org/observations/161363460 and https://www.inaturalist.org/observations/146211806 and https://www.inaturalist.org/observations/143955834 and https://www.inaturalist.org/observations/137962439 and https://www.inaturalist.org/observations/103146864 and https://www.inaturalist.org/observations/63566582 and https://www.inaturalist.org/observations/53711503 and https://www.inaturalist.org/observations/368626).

Furthermore, the greater kudu seems not to have been recorded folding its ear out of sight, in the way familiar in the steenbok.

Publicado el 22 de mayo de 2023 por milewski milewski | 3 comentarios | Deja un comentario

21 de mayo de 2023

An apparent case of fright-moult (autotomy of feathers) in the laughing dove (Spilopelia senegalensis)

@felix_riegel @tonyrebelo @jeremygilmore @baldcoot @aguilita @ldacosta @jimsinclair @lsueza @adamwelz @colin25 @karimhaddad @lukedowney @thebeachcomber @botswanabugs

Autotomy (https://en.wikipedia.org/wiki/Autotomy) is known in various animals. However, its incidence in birds is poorly-documented.

There are intriguing hints, on the Web, of autotomy of the feathers in the small-bodied columbids

Please see:
https://www.birds-online.de/wp/en/birds-online-english/health-and-diseases/plumage-disorders-and-molt/moult/fright-moult/ and https://www.sarveywildlife.org/blog.aspx?post=3023&title=Mourning-Dove-attacked-by-cat and https://feederwatch.org/unusual-bird/mourning-dove-without-tail-feathers/

The term used has been 'fright moult' or 'fright molt'.

Also please see https://www.youtube.com/watch?v=mLJ0m5gEEf0 and https://www.facebook.com/watch/?v=600613034506485 and https://www.birdnote.org/listen/shows/having-your-tail-scared and https://wrenandsparrow.com/blog/f/fright-molt and https://folkwaysnotebook.blogspot.com/2015/08/fight-or-flight.html.

If certain species of birds, particularly Columbidae, use autotomy of feathers as a way of escaping from predators, this seems analogous to the shedding of tails by lizards when attacked.

I have, at various times in my life, found piles of the feathers of doves, in both the Perth metropolitan area of Western Australia, and in Cape Town, South Africa. I did not record all these occasions, which may possibly total as many as 20 over my lifetime so far, in which feathers were present in quantity but there was no trace of other body-parts.

I paid too little attention at the start, because I was naive about the possibility of 'fright moult' in birds. I had simply presumed that the feathers were the refuse of a kill, not considering that the bird might instead have escaped.

Once I realised the possibilities, I recorded the following.

On 5 July 2006, in the suburbs of Fremantle, Western Australia, I encountered particular evidence of this kind of autotomy. This was during a spell of calm weather, when there was no wind to remove the feathers.

On the lawn of a wide road-verge, I found what looked like the results of a 'feather-explosion'. I cannot be sure of the identities involved, but I suspect that the bird was an individual of Spilopelia senegalensis (https://www.inaturalist.org/taxa/1455922-Spilopelia-senegalensis), and the attacker was an individual of Felis catus, pouncing in vain by day, on the ground.

The road-verge here was wide, and the feathers were far (at least 3 m) from the tarmac. This means that the dove was probably not hit by a motor vehicle.

I collected most of the feathers, which totalled about 370 of various types and sizes (from one individual bird). If these feathers were shed on 4 or 5 July 2006, I found them one day after the attack, or on the same day.

The smallest were merely down feathers. The largest, which were >5 cm long, were probably secondaries.

I do not know if the attacker (probably F. catus) caught this dove, but I suspect that it did not.

I do not know whether the feathers were detached in reaction to pressure exerted by the predator, or shed spontaneously before contact was made. On this occasion, some of the secondaries seemed to be aggregated at their bases, suggesting that they were detached in the clutches of the attacker.

However, the sheer number of feathers indicates that many or most of them were shed without being pulled off in any way by the attacker.

Has any Reader observed any similar evidence of fright-moult, referring to S. senegalensis, G. cuneata, Z. macroura, any other species of columbid, or any other species of bird?

Also please see https://www.inaturalist.org/journal/milewski/68965-the-difference-between-commensalism-and-habituation-exemplified-by-spilopelia-chinensis-in-australian-suburbs#.

Publicado el 21 de mayo de 2023 por milewski milewski | 22 comentarios | Deja un comentario