We saw over 200 species of birds on our trip to Namibia: some just once or twice, some almost every day, some as single individuals hidden in brush, some in large groups out in the open. Since I can’t show you everything we saw, I’m going to summarize some highlights of our bird watching by representing them in a Christmas song.
With apologies to Frederick Austin, the composer of “The Twelve Days of Christmas”…
On our trip to Southern Africa, we were very pleased to see… (are you singing the opening line?)
12 Rosy-faced Lovebirds
Lovebirds make cute noises and like to huddle together for warmth.
11 Ostrich chicks
Mother Ostrich casts a big shadow by fluffing out her feathers, and the chicks find the shade.
10 Red-billed Quelea
The MOST numerous non-domesticated bird in the world, and Africa’s biggest agricultural (grain) pest. This species holds the record for the highest body temperature tolerated by warm-blooded animals (up to 49 C or 120 F)!
9 Sacred Ibis
Sacred Ibis are known for their role in Egyptian religion (the earthly form of the god Thoth), but they are now extinct there.
8 (Greater) Flamingos flying
Greater Flamingos are the largest and most widespread of all flamingos, but are also the palest, with bright pink coloration only on the wings and legs.
7 Helmeted Guineafowl
Helmeted Guineafowl wander around in huge flocks, often in single file. They have been domesticated and are excellent watchdogs, sounding loud alarm calls when disturbed.
6 Hartlaub Gulls
Hartlaub’s Gull is endemic to Southern Africa and is the most common gull seen on the coast. It forms large, noisy breeding colonies and has adapted well to human presence along the coast.
5 Bare-faced Babblers (be sure to drag out the “five”)
Their name gives it away; these birds chatter continuously. They are highly social, live in tight family groups, and practice cooperative breeding with helpers from previous years tending the new chicks.
4 Blue Cranes
Blue Cranes are the national bird of South Africa. Their elegant, long tail feathers, stately appearance, and courtly dancing made them a favorite of indigenous people in South Africa.
3 Pied Avocets
They look like Black-necked Stilts, but they have upturned beaks that they use to sweep back and forth in the water to trap small invertebrate prey.
2 Namaqua Sandgrouse
They are so well camouflaged that you can’t see them unless they move. These birds can saturate their innermost breast feathers with water to carry it long distances back to their nestlings.
And a bevy of some brightly colored birds! (final line of the song OR substitute one of the brightly colored birds below into your song for the “partridge in a pear tree” part).
Green-winged Patillia in Acacia melliferaMarico Sunbird looking for some nectar (Photo by Debbie Reynolds)Swallow-tailed Bee-eater on a branch (Photo by Debbie Reynolds)Cape Starling walking in the grassCrimson-breasted Shrike upon a twig
The Secretarybird is unusual-looking for a raptor, but in fact, its closest relatives are the Accipiter hawks, those long-tailed, bird-eating avian predators often found in your backyard. Secretarybirds are widespread in sub-Saharan Africa, but not very common due to habitat loss. They prefer the grassy savannahs and semi-desert scrub to hunt for snakes, rodents, birds or bird eggs, insects, etc.
Secretarybirds have the head and body of an eagle and the long legs of a crane, which make them about 4 feet in height. They stalk their prey, rather than soar or perch looking for them, and those long legs are useful to see into the surrounding vegetation, as well as protect them from the bites of the snakes they love to eat. Long legs are also useful to enable them to walk long distances each day searching for their next meal.Walking near a Springbok antelope illustrates the unusual height of the Secretarybird a little better. But why is it called a Secretarybird? The answer lies in the strange set of head feathers that stick out like the pencils that secretaries supposedly stored behind their ears or in their hair, in case they broke the one they were using. (This is a folk tale, I’m sure.)The frontal view is imposing with all the head feathers erected. Image by an unknown photographer.The typical posture of a Secretarybird hunting for a meal. Once they find a prey item, they attack it by stomping it to death. This is especially useful in immobilizing snakes before they can bite.
Although they spend most of the day walking and hunting, Secretarybirds are able flyers with 7-foot wingspans to propel their 8-9 pound bodies through the air. They roost at night and nest in trees, especially thorny acacias. They are not migratory, but may be nomadic, moving location when food becomes scarce.
A beautiful bird in flight that might resemble a crane with its long wings and legs. But the raptorial beak and long tail distinguish Secretarybirds from cranes. From Wikipedia, photo by Stephen Temple.
When looking for new birds in the foreign countries we visit, we sometimes come across entire families of birds we have not seen before. We discovered that Namibia is a great place to see several species of the Bustard family. The name Bustard translates from Latin to Old French to Anglo-Saxon French as “slow bird”, which really doesn’t describe these fast-running, ground-foraging birds at all well.
To give some context to this discussion, think of Bustards as the European/African ecological counterparts of North American grouse, or chickens, or turkeys.
The male Kori Bustard (left) is about the same weight as the male American Turkey (right). In both species, males attract females by erecting their tail and breast feathers in an ostentatious display. Turkeys gobble and Kori Bustards emit a deep booming call to attract females.
The Kori Bustard is the largest flying bird native to Africa, and male Kori Bustards may be the heaviest living animal capable of flight at an average of 30 pounds (maximum recorded weight of 40 pounds), ahead of other large-bodied avian species like American Turkeys, Whooper and Mute Swans, Andean Condors, and Wandering Albatross.
Kori Bustards are found throughout southern Africa, except dense woodlands, but they especially favor the open plains and savanna grasslands, where they walk slowly while looking for insects, small vertebrates (lizards and snakes), small mammals, bird eggs, seeds, berries, and roots.
In size and behavior, Kori Bustards are similar to North American turkeys in their ground-feeding habits, the male displays of raised tail feathers for females, and polygamous breeding behavior, in which the male attracts and inseminates females, but does nothing else to rear the chicks.
The Bustard family also includes smaller ground-feeding and fast-running species called Korhaans, a name derived from the Afrikaans language to describe the grunting sound these birds make.
Ruppell’s Korhaan is a much smaller bustard than the Kori Bustard, only measuring about two feet in length. These birds prefer the more arid grasslands and savannahs, where their camouflaged plumage and quick darting escape actions help them survive predation. Unlike the Kori Bustard, this species is monogamous and can often be found in small family groups.The Northern Black Korhaan is about the same size as Ruppell’s Korhaan, and is also found in open plains, semi-desert scrub, and grasslands. The male is a boldly patterned black and white bird, while the female is well camouflaged with gray-brown plumage that blends so well into the yellow-brown grasses that she is rarely seen. Males run when chased, but then burst into flight to escape, much like the Sage Grouse of the American plains do.
We happened to drive by a male Red-crested Korhaan in pursuit of a female. These quick-darting birds are a little smaller than the other two Korhaan species and weigh just over a pound. Unfortunately, this male’s many attempts to show off his red crest and pursue her through thick brush were unsuccessful, but highly entertaining.
The male poked his head up from the dense grasses to check on the female’s location. When he is at rest and not actively displaying, his red crest is well hidden at the nape of his neck.Sexual advances include a stooped posture and fluffing the salmon-colored feathers at the back of his head, which unfurl like a collar around his head.The male in the lower part of the image is giving her his best display, but she (upper part of the image) was not overly interested, and the chase ultimately ended with both birds running off.
As if the display of a ruffled neck feather collar weren’t enough, Male Red-crested Korhaans also engage in what is called a “suicide flight”, in which they fly up over the female and then drop to the ground, catching themselves just before they hit. Obviously, the males that don’t survive this reproductive display don’t reproduce!
Such interesting bird life histories in the dry Namib savannah environment!
This year I’m especially thankful for great doctors as I’m recovering from knee replacement surgery, my tolerant husband, and a wonderful family that brings me such delight every time we get together.
I’m re-posting something from 2015, as a reminder that I am thankful for more than just the people in my life.
And I’m thankful to you, dear blog readers, for your dedication to reading my nerdy musings and for your insightful, interesting comments. Blessings to all!
Cheetahs are one of the most amazing animals on the planet (in my opinion). The Namibian savannah is an ideal environment for them to live because of its open, grassy areas and the relative lack of other, larger, and more dominant competitors that might steal their kills (e.g., lions and leopards). To appreciate just how unique and well-suited they are as hunters of the savannah’s antelope, watch the video below. You won’t be able to view the video in your email unless you click on the bolded title of the post to go directly to the blog URL (https://bybio.wordpress.com) .
Smithsonian Channel, 2012.
We were fortunate to see Cheetahs on two occasions in Etosha National Park, which has a large cheetah population. In both cases, the cheetahs were resting under trees in the shade in midday. Although they are primarily diurnal hunters, their high-intensity chases leave them both breathless and overheated, and they must rest for a while to recover.
Our guide spotted a group of White-backed and Lappet-faced Vultures sitting out in the open and knew there was probably a recent kill near them.And then, he spotted this Cheetah sitting in the shade under a Mopane tree, panting.Panting and salivation are one of the ways Cheetahs can cool off after the chase. You can see the slightly blood-tinged fur on its right cheek that indicates it has recently fed. Cheetahs eat immediately after they kill their prey and gulp food quickly before other predators find the kill. They eat an average of 6 pounds of meat a day but can consume as much as 22 pounds of meat at one time, if left undisturbed.We may have bothered the Cheetah enough that it finally got up and walked back to its kill, offering us a wonderful view of its spectacular anatomy: barrel chest with big lungs and heart, very large forelimb and hindlimb musculature, elongated back, and long legs, and a long, muscular tail used as a rudder for quick turns during a full-out sprint. These anatomical gifts are what give the cheetah its incredibly long stride and its ability to rapidly recycle its limb flexion and extension so that it can get up to maximal speed in just three seconds!Making its way back to its kill for another snack. Spots on the cheetah’s body really make its form stand out as it walks through the sea of dead grass stems. But look at the next image below.But those same spots ensure that cheetahs are hidden in the long grass and shade, and may be difficult for prey to spot when the cheetahs are low down in the vegetation, waiting for the opportunity to attack.
On another occasion, we found these two cheetahs lying in the shade of an acacia tree right next to the gravel road we were driving. Our guide guessed these were probably two brothers who were hunting together. It is common among male littermates to form this hunting bond, and occasionally also between two unrelated males. Females are usually solitary, except when they have youngsters in tow, who may participate in the hunt and the kill as they get older and stronger.
If the spots are for camouflage while hunting, what is the purpose of those black teardrop streaks alongside their nose? Since cheetahs are diurnal hunters that use their keen eyesight to spot and track prey, some people speculate that the teardrops function like the black cream that football players put beneath their eyes to reduce sun glare.
At home in the Namibian savannah — what an incredible experience seeing these magnificent animals!
[An unrelated note about Cheetahs: have you ever wondered why American Pronghorn can run so fast (up to 60 mph) when there is no American predator that can match that speed?
The top speed of American wolves is about 35 mph; the maximum speed of American pumas (cougars) is about 50 mph. Neither would be able to catch Pronghorn in an open field chase. But, after the last Ice Age and up until about 10-15,000 years ago, there was a diverse ecosystem of herbivores and carnivores in the American grasslands that rivalled those in Africa, and the chief predator of the Pronghorn in that ecosystem was the American Cheetah. If only time machines were a real thing…sigh.]
What do you think about when you see something like this?
Large herbivores coming to a waterhole in the arid savannah of Namibia
The first thing that strikes me about this scene is: how can all these different herbivores coexist in the same place in the Namibian savannah, especially in the dry season?
The Etosha Savannah, with its mixture of open grassy fields and woody shrubs and trees, supports a variety of grass-eating grazers and leaf and fruit-eating browsers. That diversity is essential to the maintenance of the savannah habitat. In fact, if just one group dominates (grazers or browsers), the Savannah ecosystem collapses into a different system with far less species diversity.
Grazers like zebra, wildebeest, and white rhino specialize in consuming the grasses and have unique adaptations for harvesting and digesting their cellulose-rich diet.
The front incisor teeth of zebras are specialized for cropping the grass from its stem, and their back molars are specialized for grinding the grass into smaller pieces. The molars are high-crowned and continue to grow, so they resist wear from continual grinding.Zebras prefer the short, nutritious grass that appears during the rainy season, but they will eat and can digest the dried stems of tall grasses during the dry season, and in this way, prepare the savannah for other grazers that prefer shorter grasses.White Rhinos act like mowing machines when they graze the savannah and are especially good at cropping short grasses. Although these rhinos lack incisors, they grab grasses with their broad, square-shaped upper lip and pull them into their mouth. Large, serrated molars grind the grass before swallowing. Blue Wildebeest occur in large herds, occasionally with zebras, and are most often found in short grass areas of the savannah. They are mobile grazers and are quick to move to new areas when there is insufficient grass.
Browsers like Giraffe, Greater Kudu, and Steenbok feed primarily on the leaves, seeds, fruits, shoots, and roots of shrubs and trees year-round, but they divide the browsing niche by height.
Giraffes are browsers that eat the seeds, pods, flowers, leaves, and bark of more than 100 different plant species. They can extract the most nutritious leaves from the tallest vegetation by using their muscular and highly flexible tongue. You can read more about giraffes in the savannah by clicking here.Greater Kudu are large, majestic-looking antelope with spiral horns that can reach 6 feet in length. They are strict browsers, selecting leaves and shoots, fruits and flowers, tubers and seed pods at a middle height in the brushy vegetation of the savannah, lower than where giraffes browse, but not usually at ground level.Steenbok are small antelopes that can be found in a variety of desert to savannah habitats, where they look for low-lying herbaceous flowering plants, seedling trees, tubers, and roots. They are typically solitary or occur in pairs of female and young, or male and female, during the breeding season. Steenbok are so small, they can often just lie low in the vegetation to avoid predators. But they are adept jumpers as well, bounding away in a zig-zag pattern to elude the predator. This image is a composite of the evasive action taken by the young steenbok in the previous photo.
A few mammalian species, like the Gemsbok (oryx), Springbok, and Impala, switch between grazing and browsing in the savannah depending on the time of year (wet vs dry season).
Gemsbok are grazers during the wet season when there is ample, nutritious grass, and depend more on browsing leaves and shoots during the dry season.Springbok feed on a mix of grass, herbaceous vegetation, succulents, tubers, and roots, but vary their diet by season.Black-faced Impalas are a subspecies of Impala found in more arid savannahs, and were introduced to Etosha National Park 50 years ago. They possess incredible speed and jumping ability, and can run more than 50 mph, leap more than 30 feet, and jump more than 10 feet. Even with all that agility, impalas are a favorite target of lions.Impalas have a narrow muzzle, which helps them reach into thorny bushes to extract leaves, and a split upper lip that helps them pick up leafy vegetation from the ground. They prefer to feed in the border of woodlands and savannah, which gives them access to both grass and leaves, but also some physical protection from predation.
Savannahs need a variety of both grazers and browsers to remain a savannah. Heavy grazing of grassy rangeland by herbivores like cattle usually results in dominance of unpalatable shrubs and increases in woody plants, which the cattle avoid. It also favors the production of annual grasses at the expense of perennial species.
A savannah needs more than just grazers to maintain its integrity.
A variety of browsers can control the encroachment of woody plants into the savannah by preventing the establishment of their seedlings and limiting the growth of young trees with the removal of their leaves. Thus, browsers greatly reduce the likelihood that seedlings will develop into mature trees in the savannah.
Browsers like the Greater Kudu and Steenbok that feed at the border of woodland and savannah keep those woody species in check and prevent them from colonizing the savannah grasses.
Thus, a combination of both grazing and browsing herbivores is the key to maintaining the diverse structure and vegetation composition of the savannah ecosystem, which in turn answers my question posed above: how can all these different herbivores coexist in the same place in the Namibian savannah, especially in the dry season?
Etosha National Park in Namibia is one of the largest parks in Africa. It has been a game reserve since the early 1900s and has an astounding variety and abundance of mammals, including elephants, rhinos, lions, cheetahs, kudu, impala, springbok, eland, zebra, dik-dik, etc, within its 8600 square mile park boundaries. The arid-adapted elephants of Etosha are the largest land mammals in the world, and the largest of all the elephants in the world.
It’s an intimidating sight when four bull elephants come marching right at you (on their way to a waterhole).
Etosha has a distinct dry season from May to October when animals can only find water at specific waterholes (which coincidentally is the best time for tourists to see Namibian wildlife). The arid-adapted elephants of Etosha are larger-bodied than other elephants, lose less water because of their advantageous surface to volume ratio, can travel longer distances to find food and water with their long legs, and can withstand some dehydration so that they only have to find water about every three days. In addition, they can even utilize brackish water if necessary.
African elephants have larger ears than Asian elephants, and Etosha elephants wave their ears back and forth to radiate and dissipate heat carried to their ears by large blood vessels.Blood vessels in the back of the elephant’s ears are dilated and engorged with blood when the animal needs to unload heat.This looks like a really bad solution to seeking shade from midday heat. Not only are the elephants too big and too many, but the tree has no leaves to cast any shade. Oh well, good try, as a behavioral solution to staying cool.No, the best solution to cool off is to trot? to the nearest water hole and take a plunge.Ah….cool water definitely feels good in midday heat.If it’s not deep enough for whole body immersion, then elephants throw cool watery mud on their heads and backs.And the bathing experience is capped off with a dusting to coat their slick skin. Dust and mud are a kind of sunscreen for elephants.Elephant herds are primarily made up of females and their youngsters of varying ages. The maternal-child bond is so strong, the mother will support and protect her offspring throughout their life (or her life). Youngsters are taught where waterholes are, how to protect themselves with mud, what food to eat and where to find it, and defense against predators when they need it.Young elephants nurse for about two years, but start consuming vegetation at six months.Newborn and younger elephants will also consume their mother’s feces in order to get the right gut bacteria to digest vegetation and to obtain vitamins produced by bacteria in the mother’s large intestine (colon).Elephants browse vegetation or graze grasses 18 hours a day, traveling 40-90 miles as they move around in the savannah. Their prodigious appetite cannot be satisfied on just leaves alone, and so they also consume fruit, seeds, bark, roots, dead grass, etc. But unlike ruminant animals like cows, elephants only utilize about 25 % of the food energy they consume.
Elephants in Etosha are considered to be “ecosystem engineers” of their desert/savannah environment, in the same way that beavers engineer their wetland ecosystem by building dams. Because they require so much food daily, they often have to push over trees to get at the top vegetation which has not been browsed.
This seems like destructive behavior, but it keeps the savannah environment open and grassy, rather than letting acacia trees, for example, turn the savannah into a thorn forest. Felling trees for vegetation allows other animals to harvest leaves, fruits, seeds, bark, roots, etc., and provides additional food for other herbivores, and it increases seed dispersal of the trees.
Because their ecosystem engineering makes it possible for more animals to coexist in Etosha National Park, elephants indirectly benefit the economy of Namibia by increasing tourism, and attracting wildlife lovers like all of you that read this blog!
There are many examples of the evolutionary arms race between plants and animals, in which an adaptation in one of the players leads to a counter-adaptation in the other. The interaction of giraffes and acacia trees in Africa is one of these examples.
Acacia shrubs and trees are native to tropical and subtropical regions of South America, Africa, and Australasia, and are not only ecologically important to animals for food and nesting sites, but for human uses as well. They provide timber, seed pods, tannins, gum Arabic, and other products, and in addition, they increase soil fertility by fixing nitrogen.
A typical scene in the African savannah, with umbrella-shaped acacia trees providing shade for antelopes in the middle of the day. The shape of the tree is most likely a result of browsing by giraffes that pluck the leaves from the new shoots at the very top of the tree, resulting in its flattened top.
Acacias are also known as “thorn plants” for the ubiquitous spiny projections along their leafy branches, which are meant to deter herbivores. Ant colonies that have taken up residence in the swollen bases of thorns provide additional defense against browsers when they rush out to bite whatever has disturbed the leaves or branches.
Gray Go-away birds are sitting in one type of acacia that has short, curved thorns at intervals along the branches. That curvature ensures that whatever brushes past the branches will get snagged, and painfully. I know this from experience!Some acacias have paired spines that project in opposite directions, placed at intervals along the branches. Somehow, this Red-necked Falcon landed between the spines, or perhaps its toes are just too tough for the spine to penetrate.A Short-toed Rock Thrush (it’s not actually a thrush) is sitting in yet another type of acacia, which has both thorns and spines, and the spines are of different lengths. If the spine doesn’t snag you, the thorn probably will. The difference in spine length can be a response to browsing.
Giraffes are the tallest living land animals, a feat achieved by their extremely long legs and their extremely long necks. They are browsers that eat the seeds, pods, flowers, leaves, and bark of more than 100 different plant species, but acacia trees and shrubs are their preferred food because of their high protein, water, and calcium content.
Competition with other plant-browsing species no doubt contributed to selection for height during giraffe evolution. As the winners of that competition, they have sole access to the new shoots that appear on tree tops during the wet season. Note that just a few leaves are remaining on the spiny acacia shrub in front of this giraffe, but a whole treeful of leaves are on the tree it is standing next to.That long neck is not flexible, i.e., it doesn’t bend in the middle, so giraffes must stretch out horizontally to reach low bushes, and they must bend their legs to lower their heads to drink.
In addition to their height, which allows giraffes to feed from the tops of the tallest trees, they have perfected a means of extracting tender, juicy leaves from the thorny plants.
Giraffes have prehensile lips, especially the upper one, which can grasp and manipulate branches and leaves. A fine layer of hairs helps protect the lips from thorns. In addition, giraffes have exceptionally long tongues, up to 20 inches in some individuals, and the tongue is very muscular and flexible, which helps the animal pull leaves away from the branch.
[Side note: I took one of my classes for a behind-the-scenes visit to the giraffe pen at the zoo once, and a giraffe manipulated my jacket right off my shoulders with its tongue.]
The inside of the giraffe’s mouth and its tongue are covered with hardened, bumpy skin, which protects them from being punctured by thorns. Giraffe saliva is thick and sticky, which also helps coat the mouth and the digestive tract from accidental puncture by thorns. (Photo in unsplash.com)
So, it would seem that giraffes have successfully countered the acacia trees’ spiny defense against herbivory by their anatomical modifications. What else could acacias do to prevent being eaten?
Plants can respond to herbivore damage by increasing the amount of tannins in their leaves. Tannins are complex, polyphenolic molecules that bind to proteins and make them unavailable for digestion, and their astringent, puckery taste makes the plant material unpalatable. Young acacia shoots lack tannins when they are growing, but once browsed, they increase the tannin production in the remaining leaves on the tree, thus making the whole tree less attractive to the giraffes.
Back to the Giraffes, how do they counter this chemical defense by acacia trees?
If one giraffe finds an acacia palatable, others may join it, before the plant has time to mount a chemical defense by synthesizing tannins in the leaves. This group of giraffes has done a good job of removing the top leaves from this acacia shrub. The only leaves on the plant are down near its base, and they are probably the old, tough leaves with less moisture and protein content.Plants that have been browsed release a small molecule called ethylene (the same molecule that is released by ripening fruit). Ethylene is carried through the air to neighboring plants and induces the formation of tannins in the leaves of those plants. Thus, acacia trees that are near other trees that have been browsed will mount their own chemical defense.
And what do giraffes do about this chemical signalling between acacias? Somehow, they have learned a particular behavior when feeding on multiple acacia trees in the savannah: they feed downwind from other acacia trees to ensure that new leaves that are produced have less tannin in them and then move upwind through the savannah.
The evolutionary arms race between players is a continuing struggle to dominate. What will the giraffes and acacias evolve next to thwart each other? Whatever it is, it will take generations to develop.
Walvis Bay is Namibia’s primary port and is a paradise for viewing wildlife. Flamingos, gulls, terns, and pelicans gather in the shallow lagoons to forage, cape fur seals rest and breed on the sandy beaches, and several species of whales, dolphins, and seals can be found swimming around boats in the wide harbor.
The Great White Pelican in Namibia takes on a delicate pink hue during the breeding season due to its diet and reproductive hormones. The bill and gular pouch are a rainbow of color with patches of red, blue, and yellow.
Like the American White Pelican, the Old World birds are highly social and hunt in flocks by stirring up the water with wings or feet and reaching down with their enormous bill to grab fish or crustaceans. In Namibia, Pelicans are found primarily along the coast as well as inland in a few places where there are dams and estuaries.
The Pelicans in Walvis Bay are quite bold. Since they are rewarded with fish when they approach fishing boats, they fly right up and land on the railings and decks.And their close presence can be a little intimidating–just watch out for that huge bill. The outer wing covert feathers are incredibly smooth and silky.I happened to be standing at the rail when one Pelican made its approach and just had time to hold my camera up in front of me for the shot — no focus, just point and shoot as the bird flew toward me.Northern Fur Seals also accompanied us on our tour of the harbor, playfully swimming around and under the boat.Occasionally one of the seals would hop up on the stern, sneak under the rails, and come on the deck for a mouthful of fish.
Cape Fur Seals are the largest of all the fur seals, and are only found on the western coast of South Africa and Namibia. Males weigh three times what the females do, and can get as large as 600 pounds (300 kg)
Males return to the harbor beaches in early spring and begin to gather females into their harems. There was a lot of vocalization going on in this large group of several hundred indidivuals, especially among the males as they tried to establish their piece of ground. The much smaller females laid on the beach and watched the contests between aggressive combatants.Males use their teeth to gouge their opponents, and it looks like some of the attacks have done some damage.A lone juvenile African (Jackass) Penguin also swam near our boat. There are breeding colonies of these Penguins on several islands off the coast of South African and Namibia.Humpback Whales surfaced every now and then in the harbor waters, but only showed us their dorsal fin, not their spectacular heads or tails as they breeched. Whales and dolphins migrate to Walvis Bay to feed on the rich marine life that enters the bay from the upwelling of the Benguela current from Antarctica.An unlucky juvenile Humpback Whale washed up on the beach near our hotel. Kelp Gulls tried to feed on it, but couldn’t break through the tough skin.Another first-ever sighting: an Ocean Sunfish approached the surface and swam alongside our boat. These huge, 6 foot by 6 foot, pancake-shaped fish, some of the largest bony fish in the oceans, swim down several hundred feet to feed on jellyfish and crustaceans, and then come up and float on one side to bask in warmer surface water.The Ocean Sunfish is as tall as it is long and can weigh up to one ton. Photo from: https://www.livescience.com/61124-worlds-heaviest-bony-fish-found.html. These fish have phenomenally high growth rates: one fish grew from 26 to 400 kg (880 pounds) in 15 months and measured 6 feet in height. Females lay about 300 million! eggs per year — most of which will end up in the food chain for other marine species.Hartlaub’s Gull is a non-migratory resident along the coast of South Africa and Namibia. In fact, it is endemic (only found) in this region. Half the world’s population of this species lives along the coast of the Greater Cape Town area, including Robben Island. It is common in its limited range, but rare in the world at large.The adult on the left was being continually pestered by one or two youngsters that followed everywhere it went. The fledging period is tough for adult birds…and for humans raising teenagers.Striking black-and-white Pied Avocets foraged for crustaceans or insects in the shallow areas of lagoons. Like the American Avocet, this bird forages by sweeping its bill back and forth in the shallow water, hoping to stir up its food from the muddy bottom.Greater Flamingos are the most widespread and the largest of the six flamingo species. There are resident populations in places throughout Africa and also migratory populations that breed in Europe and Asia and winter along the coast of northern Africa and India.Unlike the American variety of flamingos, the Greater Flamingos are mostly white, but they have bright pink legs and wing feathers that make them stand out when they fly. Juveniles are mostly gray until they molt to the adult plumage.
All flamingos use their oddly-shaped bills in an unusual way, turning it upside down to feed. This is because the upper jaw is the mobile part of the beak in flamingos, unlike in other birds. They suck water into the mouth with the action of the upper beak and tongue, strain out the small animal matter in the water, and then pass the remaining water out through lamellar grooves on the sides of the upper and lower beak. It’s an odd but effective way to filter feed.
GIF from the San Diego Zoo showing how flamingos use their bills to filter small crustaceans from the water.
There are no giant sandworms in the Namib Desert (as in the movie “Dune”), but there are sand dancing lizards and sand geckos and strange flightless beetles, and a myriad of arid-adapted plants that call the shifting sands of Namibia home.
The Sandworm from “Dune” can supposedly “swim” rapidly under the sand toward a rhythmic source of sound. Is this science fiction too far from reality? [Photo from thegamer.com]
Sometimes, the fantastic is, in fact, based on reality. Let me introduce the Shovel-snouted Lizard, also known as Anchieta’s dune lizard, or the Namib sand diver, or the Dancing sand lizard.
They are well-named, for their shovel-snout face that helps them bury themselves in the sand very quickly.
These small-bodied (2-3 inch) dune inhabitants have relatively long legs and long tails for their body size, and extremely long toes, which propel them at high speeds across the dune surface. They are active in the daytime while hunting for beetles or spiders, but will burrow rapidly under the sand when threatened by a predator or when the sand surface gets too hot, even when they minimize contact with it by alternately lifting their legs off the surface (hence, the “dancing sand lizard” appellation).
In contrast, the Sand Gecko or Web-footed Gecko is nocturnal and avoids daytime heat by remaining submerged in the sand, preferably in the shade of a big rock.
Sand Geckos are bigger than the Shovel-shouted lizards (up to four inches in length), and also have long legs and webbed toes with pads that enable them to run rapidly on the surface of the sand. These geckos use their long legs to stand straight up (like a mammal would), reducing their exposure to the hot sand.
Geckos hunt for crickets and spiders at night, and on foggy nights and early mornings, water condenses on their head, especially their very large eyes, and they lick the moisture off with their tongues.
Desert lizards are ideally suited for that environment: they have very low evaporative water loss over their scaly skin; they excrete a uric acid paste, which saves water from their digestive tract; and they have very low metabolism and respiratory water loss when they are not active, or when they are exposed to cold. And most importantly, in the Namib Desert, they have opportunities to capture free water from fog.
One of the most interesting behaviors of animals living in the dunes of the Namib is that of the darkling beetles (members of the Tenebrionid beetle family) on foggy nights when they emerge from the sand, trudge up the crest of the dune to its peak, and stand on their heads with abdomens pointed to the sky to engage in “fog basking”.
Darkling beetles recycle nutrients from decaying vegetation and animal matter. They are the desert’s decomposers.Note the prominent longitudinal grooves and bumpy surface of the elytra of this species of darkling beetle.
These beetles are unusual in that their wing covers (called elytra) are fused, and therefore, the beetles are flightless. However, the fused carapace serves a crucial purpose in providing an almost impermeable barrier to water loss. In addition, the surface of the elytra is waxy and hydrophobic, and water beads up on the surface and runs in longitudinal grooves toward the beetle’s mouth when they “stand on their heads” during fog basking.
In fact, these beetles don’t even use their spiracles (respiratory openings in the abdomen) for breathing since they are covered by the elytra. Instead, they exchange gases through their anus.
BBC Wildlife from the BBC Earth Channel
Fog, in fact, drives the entire dune ecosystem in the Namib Desert, as shown in the diagram below. Fog develops from clouds drifting over the cold Benguela current of the South Atlantic off the coast of Namibia and South Africa. It occurs at unpredictable times over 10 months of the year, but animals, particularly the darkling beetles, sense the change in the wind movement over the sand and use that cue to begin their long climb to the top of the dune to catch the moisture. [So, is thumping the sand to attract sandworms really that unrealistic?]
There are also many plant species whose distribution in the Namid Desert depends on the moisture from the fog, i.e., they are in the “fog zone”.
For example, the prehistoric Welwitschia plants are known from fossils dating back to the Jurassic period, approximately 200 million years ago. These plants are members of the Gymnosperm (e.g, conifers, cycads, and gingkos) group of plants.
Welwitschia plants have just two, ever-growing leaves that sprout from a woody base. The plants produce both male and female cones with pollen that is carried by wind from plant to plant. Individual plants are estimated to be thousands of years old, supported by one long, central taproot, and millions of shallow rootlets just beneath the surface of the sandy gravel. The leaves have a tough, waxy cuticle that is resistant to water loss, but captures fog moisture to be transported inside the leaf.In the Welwitschia plain, where most of these plants are found, the desert surface is almost barren of plant life except for an occasional Welwitschia plant or a hearty bush. It is truly one of the driest environments on the planet.
Many plants in the fog belt of the Namib Desert are succulents that store water in their leaves or stems. Still others have fine hairs or spines that reflect heat but can trap the dewy moisture of the fog. Some plant species have few leaves but carry out photosynthesis in their green stems, which are more resistant to water loss. Desert plants minimize their water loss by keeping their stomata (pores in the leaf for gas transfer) closed during the day and carrying out photosynthetic reactions at night instead.
The leaves of this succulent are oriented vertically to reduce radiation during the hottest part of the day and minimize water loss.The fine hairs of the flowering plant dull its color but protect it from “sunburn” by reflecting a lot of the solar radiation. The smaller succulent in the lower left of the image has tiny, fleshy leaves on its spidery stems.If you look closely at this plant, you see branching, green stems and some flowers, but no leaves.This prostrate plant with spidery stems and small, succulent leaves spreads over the ground and probably traps moisture in the decaying vegetation between its branches. In addition, prostrate plants like this have a wide network of superficial roots that tap the moisture that settles in the top layer of the sand after a foggy night.
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