Week 20: Large Birds Part II

Marabou stork – Leptoptilos crumenifer

The marabou stork is not the most attractive bird and it would make a terrible dinner guest as carrion forms a large part of its diet. Marabous will follow vultures to carcasses, allowing them to do the difficult work of ripping open the skin, before plunging their own huge bills into the flesh. As with vultures, the lack of facial feathers prevents blood and gore from building up around the head. In addition to scavenging, marabous are generally opportunistic, taking small vertebrates, eggs and invertebrates. This generalism has facilitated an increase in the use of rubbish dumps as sources of food in the burgeoning urban areas of Africa.

The marabou stork is a member of the stork family, Ciconiidae, and order, Ciconiiformes. This is small order of about 19 species which used to include ibises and spoonbills until their move to the Pelecaniformes.

Australian pelican – Pelecanus conspicillatus

Speaking of the Pelecaniformes, the Australian pelican is a handsome example of the eight species of pelican. It is notable for having the longest beak of any living bird! It was also one of the first species I spotted on my trip to Queensland. Unfortunately I did not see it eat. The foraging ecology of pelicans is famous (or perhaps infamous) for the utilisation of the huge gular pouch to catch fish. Whilst small and large fish form the majority of the diet, pelicans will also eat amphibians and crustaceans and some observations from Regent’s Park even show them to eat pigeons! Pelicans can also use the skin of their pouches to regulate their temperature, fluttering the skin to promote cooling in the same way that elephants flap their ears.

The habitat of pelicans is generally, and unsurprisingly, based particularly around wetlands (although I have seen brown pelicans [Pelecanus occidentalis] off the beaches of Miami and the Caribbean). There they join a wider assemblage of pelecaniform species. The Pelecaniformes have evolved various ways of plying the waterways for food with much emphasis on beak morphology. The statuesque herons come in a range of sizes but most are expert anglers. The ibises (or, more correctly, ibides) take a more relaxed view, probing the substrate for invertebrates whilst the spoonbills sweep the water with their huge utensils. Perhaps the oddest members of the order are the hamerkop (Scopus umbretta) and shoebill (Balaeniceps rex), two monotypic species related to pelicans. The former is a small, hammer-headed wading bird which build huge nests whilst the latter is a large, stork-like bird with an even larger, whale shaped bill (hence the Latin 'king whale-head'). The shoebill also has a dastardly stare which could strike fear into anyone.

Andean condor – Vultur gryphus

The Andean condor means playing the superlative game again. I had thought that this condor had the second largest wingspan of any living bird but apparently the two largest pelicans are also bigger. Moreover, the splitting of the wandering albatross species complex into many species throws a few more, longer winged species into the mix. The Andean condor does, however, have the largest wing area of any living bird species which is not surprising as the barn doors of the condor are far wider than the tapered wings of the albatrosses.

As the name suggests, the Andean condor hails from the Andes mountain range which forms the spine of South America. Without a sternum, the condor is not designed for flapping, instead it relies heavily on thermals to keep it aloft, keeping to high places and using the topography of the land to soar about. Seeing these birds in their element must surely be an amazing sight and its unsurprising that the ancient Native Americans worshipped them as sun deities. Their legendary appearance lives on in the coats of arms of no fewer than five South American countries.

Soaring around, looking for carrion is what traditionally makes the Andean condor a vulture, one of the seven species in the New World vulture family Cathartidae. In the second half of the 20^th century, some ornithologists began to realise that the similarity between the Old and New World vultures might only be skin deep. Morphological and karyotypic (number and shape of chromosomes) data were used to support the grouping of New World vultures with the storks with the apparent similarity with Old World vultures resulting from convergent evolution. Whilst this convergence in morphology and ecology still stands, the evolutionary relationships have been better resolved with the placement of New World vultures as a sister clade to the rest of the birds of prey (excluding falcons), either sharing the order Accipitriformes or being elevated to their own order Cathartiformes.   

Lammergeier – Gypaetus barbatus

The lammergeier (or bearded vulture) is a true vulture in the sense of being a member of the Aegypiinae Old World vultures however it is atypical in its appearance and ecology. It has orangey-yellow head plumage to match its torso and the face is completed with a stiff, black beard (barbatus = ‘bearded’). Although lammergeiers are scavengers, their diet is unique for being based largely on bone marrow. Obviously bone marrow can be pretty difficult to access. For smaller bones, lammergeiers can crack the bone open but for bigger bones, they have a rather clever technique. Lammergeiers have learnt to carry bones up to 150 m into the air, dropping them from a height so that they fall and crack open on the ground. Adult birds can carry bones weighing nearly as much as they do! Sometimes this method is even extended to crack open tortoises. Bone cracking is a classic example of a learned technique and immature birds can spend years honing their skills. Once ingested the bones need industrial strength acid dissolve. As such, lammergeiers have stomach acid at pH 1 which dissolves the calcium rich bone in a day.

Lammergeiers cling to high altitude regions across Southern Europe, Central Asia and Africa. The mountainous habitat is a harsh environment but living off bones means that food can often be found. Furthermore, when carcasses are all but stripped of flesh, the marrow can live on, desiccated within the bones.

Great bustard – Otis tarda

The great bustard is generally cited as the heaviest flying bird, weighing up to 18 kg. It is also, arguably, the most sexually dimorphic bird species in terms of size as males can weigh up to four times the weight of females. Great bustards have a patchy distribution across the grassland and steppes of Iberia, Central Europe and Asia. They were once part of the British countryside too but they were hunted to extinction by the 1840s. Now the Great Bustard Project is working to establish a new breeding population in the rolling fields of Wessex. Since 2004, birds reared from Russian and then Spanish eggs have been introduced annually. Bustards bread for the first time in nearly 200 years in 2009 and the population is slowly growing.

In the UK, great bustards have much in common with the common crane as both were almost absent from our countryside and now programmes are tirelessly working to bring them back with the Great Crane Project experiencing much success. Evidence of these two species in our heritage is subtle but present. Most noticeably, bustards, cranes and other species are found in the heraldic emblems of the past. Bustards are found on the coats of arms of Wiltshire and Cambridgeshire. Peregrine falcons are found on the arms of Surrey, Bagshot and the University of Lincoln whilst Lincolnshire’s is capped by a lapwing. Northamptonshire even has a white falcon that looks a bit like a gyrfalcon (unlikely that gyrs have ever visited Northants). Finally, in Cornwall, red-billed choughs used to be a common sight, flying on broad wings along the cliffs, and as such they grace the coat of arms of Cornwall. Another word for chough is beckit and the 12^th Century Bishop Thomas Beckit had three choughs on his coat of arms, as did the seat of his power, Canterbury. During the reign of the Tudors, Cardinal Thomas Wolsey took the choughs of his namesake for his own crest and bestowed that crest on his new college of Christchurch in Oxford.

Red-crowned crane – Grus japonensis

Cranes are members of the Gruidae family which sits in the Gruiformes order with the rails, crakes and gallinules. This relationship might seem surprising but when measuring both the rails and cranes I could see the similarity in bill morphology. Cranes are essentially rails on steroids. 

The red-crowned crane is one of the largest and (in my opinion) most beautiful of the 15 crane species. Cranes are characterised by the long legs and necks which are stretched out in flight. They have a generally omnivorous diet, although a degree of niche segregation can occur when multiple crane species live in sympatry. China is the hotspot of crane diversity, containing, at various points, eight species. Many are migratory so may either only winter or breed in China. The red-crowned crane exhibits different migration strategies between the two disjunct populations. In Japan, the cranes barely move at all, hopping just 150 km whilst the mainland race breeds in Northern China and Siberia then splits up and migrates around 1,500 km to Korea and Jiangsu, China.

The red-crowned crane is one of the most endangered crane species. It is possible that the risk to cranes is somehow linked to diet as it has been noted that the most common species are largely herbivorous within the scale of omnivory whilst the red-crowned and (rarer) whooping cranes feature more animals in their diet including invertebrates, fish, amphibians, reptiles and birds. A carnivorous diet results in a degree of dispersal whilst foraging as opposed to the gregarious nature of more herbivorous cranes. Red-crowned cranes do, however, breed in groups, taking advantage of safety in numbers. Cranes are typically monogamous, keeping the same partner for many years. Couples maintain their bonds via the rhythmic, synchronised dancing as well as duetting with loud, trumpeting calls.

The red-crowned crane has important symbolism for both the Chinese and the Japanese. In China, and particularly Taoism, the crane symbolises longevity and immortality. In Japan, red-crowned cranes were said to live for 1,000 years whilst they are also recognised for their loyalty in monogamy and their strength in migration. I think they are impressive birds and should rightly be respected and cherished.

Week 19: Large Birds Part I

Now for some of the species that were too large for the normal collection and they are large in every sense of the word. Beware there will be a lot of superlatives!

Ostrich – Struthio camelus

Behold, the largest species of bird in the world! Well that was obviously no surprise but even though ostriches are well known they are still very impressive beasts. Males can stand up to 2.8 m high and weigh in at 145 kg plus they also hold the land-speed record for birds, running at speeds of 70 km/h. Ostriches also lay the largest eggs of any birds, 20 times the weight of a chicken's, yet the eggs are the smallest in relation to body size of any bird.

The two ostriches (S. camelus and the Somali ostrich S. molybdophanes) are ratites, a term generally reserved for flightless birds of the order Struthioniformes including emus, rheas, cassowaries and kiwis. With the flux of modern taxonomy, the validity of this clade is in question as the volant tinamous should be nested within the flightless birds suggesting independent routes to flightlessness. As well as the extant ratites, there were larger and more bizarre members of the group. On New Zealand the moas reigned supreme until the relatively recent immigration of Mouris whilst on Madagascar, the huge elephant birds stalked the forest.

Together the ratites have a Gondwanan distribution. This refers to a geographical distribution of organisms contingent on the past arrangement of continents. During the evolution of birds in the Cretaceous, ancestors of the ratites were distributed over the southern continent of Gondwana (South America, Africa, India, Australasia and Antarctica). Once Gondwana began to break up during this period, each new continent took its own ratites. Emus, cassowaries, kiwis and moas evolved in Australasia, South America evolved rheas and Africa took the ostriches. Well at least that was the traditional view; more recent genetic work places the separation of these lineages as more recent than the continental splits. This implies that volant ancestors colonised the different continents and independently became flightless, probably in lieu of the lack of large terrestrial vertebrates following the extinction of the dinosaurs.

Southern Cassowary – Casuarius casuarius

Speaking of dinosaurs, the southern cassowary could be lifted straight from the Cretaceous! Of the three Australasian cassowaries, the southern cassowary is the largest and its bright blue neck with pink wattles stands out against the black, ‘furry’ body. It is the species of most relevance to me as I was lucky enough to see several individuals of this vulnerable, enigmatic species in the wild whilst undertaking fieldwork in the rainforests of Far North Queensland. One encounter stands out in particular.

My friend, Emily, and I were stepping along one of our paths into the rainforest when Emily froze and back-tracked suddenly, cursing as she went! I then spotted the issue when I noticed a cassowary standing about 15 m ahead. My first thought was ‘photo opportunity’, so I whipped out my phone and took terrible snaps. But then it turned to face us. We did nothing at first until it started walking towards us. Suddenly, through my mind flashed the stories of people being head-butted with their huge casques or lacerated with their elongated claws. We started walking back down the track but the cassowary began to pick up the pace. The more we sped up, the more it did, until soon we were running as fast as we could which was difficult due to the suddenly claustrophobic foliage and lianas. Finally (after what was probably just seconds) we emerged into the sun light and the cassowary did not follow. Our hearts thumping, we regained our composure but the fear of that encounter remained for the duration of our work!

Green peafowl – Pavo muticus

I have to admit I did not know what this species looked like beforehand but being a congener of the familiar peacock (Indian peafowl, Pavo cristatus) I surmised correctly that it would be impressive. Moreover, the unfamiliarity gives it an exotic feel where we might take peacocks for granted. This denizen of Southeast Asian forests shares many of the traits that make the peacock famous including the huge ‘tail’ of many eyes which is actually formed from upper tail coverts rather than the rectrices. The tail of the peacock is famous in biology as the pin-up for sexual selection. That such an elaborate ornament should evolve under natural selection troubled Charles Darwin greatly who said that ‘the sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick!’ In time, Darwin, and the generations of biologists to follow, have expounded theories of sexual selection which explain the ornaments of peacocks and other animals. Whether choosing ornamented males for their sexy sons are their good genes, it seems that beauty is the way to go.

Emperor penguin – Aptenodytes forsteri

Of the 19 penguin species, the emperor is the largest, as the name might suggest. It is also the only bird species to breed in the Antarctic winter. The emperor penguins are famous for their annual 100 km trek into the Antarctic desert whereupon they breed, the female laying a single egg. The first duty of the male is incubation so that the female might return to the sea to breed. The egg is passed carefully between the feet of the male to the female, avoiding the lethally cold ground at all costs. With the female departed the male must while away the winter months, burning precious fat reserves until the female returns. During this time, huddling is imperative to conserve heat as are the suite of hypothermic adaptations including blubber, down and the most densely packed feathers of any bird which can be erected to trap additional air.

Soon after the chick hatches it is fed its first protein rich regurgitation.Then, the female returns with her own supply, locating the male through vocal recognition and relieving him of his duties so that he can travel back to the sea. Thereafter, rearing the chick is taken in turn. The free parent must run a gauntlet of leopard seals and orcas to reach open water whereupon they may fly through the water, diving up to 500 m deep, feasting upon Antarctic fish, squid and krill. 

A month and a half into life and the chicks are big enough to be left alone whilst the parent both feed at sea. This is not really ‘alone’, however, as the chicks form large crèches, avoiding the bitter wind and the predatory Southern giant petrels. As summer approaches, the chicks begin to moult into juvenile plumage and make to join their parents in the booming summer seas which, by this point, are considerably closer owing to the melting sea ice.

 Wandering albatross – Diomedia exulans

The wandering albatross has the largest wingspan of any living bird at up to 3.5 m (11 ft 6 in) which is slightly absurd if you think about it. Most of their life is spent at sea with monogamous adults only returning to land to dance and breed on rocky islands in the Southern Ocean. They are at the slowest end of the life-history continuum. The life-history continuum represents the trade-off that all organisms have to face: whether to live longer or reproduce more. Large organisms tend to be at the slow end and wandering albatrosses can live beyond 50 and reach sexual maturity in their teens, thereafter only rearing one chick every two years. 

Whilst the generic name Diomedia references the Ancient Greek hero of the Trojan War. Diomedes, who’s companions transformed into birds, the specific epithet exulans means ‘exile’ or ‘wanderer’ noting the vast areas this albatross covers. One impressive individual was observed to travel 6,000 km in just 12 days.

The albatross is famous for its role in the Rime of the Ancient Mariner, the epic poem by Samuel Taylor Coleridge, where the ‘bird of good omen’ was a welcome companion to the sailors and where the killing of one is a terrible crime resulting in the burden of an albatross around the neck. Today, it is humans that are the harbingers of doom for the albatrosses as plastic pollution threatens colonies around the world.

Week 18: Woodpeckers

Day 71: White-browed piculet – Sasia ochracea

Bamboo bambino

This pretty little bird is a close relative of the woodpeckers, being in the same family Picidae but the piculet subfamily Picuminae. As, essentially, miniature woodpeckers, the piculets (literally ‘small woodpecker’) have many of the adaptations of their larger cousins which I will discuss later. One thing all woodpeckers do is nest in holes which they drill into trees. In the case of the white-browed piculet, it is not trees that house the nests but bamboo stems. They prove that pandas are not the only bamboo specialists although this piculet is not found in Southwest Asia rather than China. 

Day 72: White-naped woodpecker – Chrysocolaptes festivus

Pack a hard hat

The white-naped woodpecker is a member of the vibrant flamebacks (Chrysocolaptes spp.) As well as the gold and orange colouration that characterises this genus, the male white-naped woodpecker also sports a splendid, crimson crest. The red crest is actually common to many woodpeckers species including the pileated woodpecker which probably inspired the cartoon Woody Woodpecker. In fact the red in the male’s crest is something I want to pick up on as, across the woodpeckers, I found that the amount of the red on the head was diagnostic of the sex of the individuals. I accept that there are exceptions but, by-and-large, all that was required to sex a specimen was to check the extent of red on the head with males generally having more. Although the dimorphism of pheasants, ducks etc was obvious, it varied greatly from species to species yet with woodpeckers I do not think I have encountered such consistent dichromatism.

The white-naped woodpecker is a very typical woodpecker and thus exhibits the adaptations that define the clade. Woodpeckers obviously peck wood. This is generally an activity undertaken to procure insects hidden beneath the bark of trees but woodpeckers also use their chisel-like bills to excavate holes and to drum in spring courtship. Drumming is a physically challenging act with woodpeckers experiencing deceleration rates of 1,000 g! To cope with this, they have relatively small brains orientated within their reinforced skulls in such a way as to maximise contact (minimising pressure) and minimise contact time. The strenuous activity of pecking up to 12,000 times a day is supported by strong neck muscles, gripping, zygodactylic feet and a thick, rigid tail which braces the whole bird. Additionally woodpeckers protect themselves from flying debris with feathered, closable nostrils and translucent nictitating membranes which flick across the eyes.

Once suitable excavations are made into bark, woodpeckers insert their extremely long, barbed tongues into crevices to wheedle out ants and larvae. Extending up to three times the length of the bill, these incredible tongues are retracted back into the head, coiling up behind the brain where they aid the cushioning tissue encasing the brain. Woodpeckers are biological machines.

Day 73: Lesser spotted woodpecker – Dendrocopos minor

The wish list

Lesser spotted woodpeckers are one of four woodpecker species found in the UK, the others being the enigmatic wryneck (Jynx torquilla), the ubiquitous great spotted woodpecker (Dendocopos major) and the laughing, ant-eating, weasel-sporting green woodpecker (Picus viridis). The lessser spotted woodpecker is of significance for its placement on two special lists. Firstly, it is the last species that I shall discuss from the main collection at Tring. After five months in the Natural History Musuem’s bird collection we have reached the bottom of our list of non-passerines. However, this is not quite the end as we have yet to measure the very large bird species (ratites, storks, cranes etc) housed in the Large Collection as well as the endangered and extinct species and species known only from type specimens. These remaining species will be discussed next week but for now, the majority of the job is done!

The second list upon which the lesser spotted woodpecker finds itself is my wish list. As a birder (and part-time twitcher) I keep a list of all the bird species I have observed in the UK (224 and growing). Whilst recent additions have been rare birds twitched in the West Country (black-winged stilt, penduline tits and Bonaparte’s gull) I am inclined to spend some time finding the less rare but less twitchable birds of this country. The sparrow-sized lesser spotted woodpecker is far less common than its larger counterpart. Pairs keep large territories and signal to each other with high-pitched, staccato drumming a noise which, coupled with calling, can give them away. Otherwise, their unobtrusive habits and sparse distribution make them difficult to see and the closest I have come is hearing a call or two in the New Forest. The season for drumming is dwindling so I may have to wait until next year to see one but hope to discover for myself this species, and others, in the years to come.

And thus, whilst one ornithological adventure draws to an end, the lesser spotted woodpecker is one of many I hope to come.