Over the weekend I and a bunch of friends and colleagues (representing the Southampton Natural History Society) went to Salisbury Plain, Wiltshire, in search of Great bustards Otis tarda.
The Great bustard (one of 26 or so bustard species found throughout the Old World and Australasia) is a British native, but excessive hunting and (probably) changing agricultural practises, increasing human disturbance and perhaps other factors led to its extinction as a breeding species round about 1832, though some eggs were apparently discovered in 1838 and it is suspected that some native birds were still living in Norfolk as late as 1845. If you've no idea what a Great bustard is like, imagine a long-legged, long-necked omnivorous bird something like a cross between a crane and a small ratite... or, look at the picture here. The loss of this remarkable bird is a real shame given its size, remarkable appearance and ecological role [adjacent image of Great bustard male, photographed at Beijing Zoo, from wikipedia].
Its loss from the breeding avifauna of the British Isles is hardly unique of course: most of our larger birds were made extinct within recent centuries. Some later recolonised the country naturally, while others are only here thanks to reintroduction efforts. Capercaillie Tetrao urogallus, Eurasian bittern Botaurus stellaris, Eurasian spoonbill Platalea leucorodia, Northern goshawk Accipiter gentilis, Osprey Pandion haliaeetus, White-tailed eagle Haliaeetus albicilla, and Common crane Grus grus are among the list of the lost species that have returned (Whitlock 1953).
Opinions differ as to how numerous the Great bustard was in Britain prior to its decline. Some authors say that huge numbers of the birds were present in large droves during the 1700s, while others say that it was scarce even in the 1600s. By the late 1700s and early 1800s it had definitely become rare, and the last British breeding bird (from 1832) was found in Suffolk. The species didn't disappear entirely at this date, however, as many migrant Great bustards arrived from continental Europe during the 1870s, 80s and 90s. Stragglers (such as the Fair Isle bird shown here) also arrived from the continent throughout the 20th century. As a bird of open, treeless habitats, Great bustards may have become unusually abundant in Britain (and elsewhere) as forests were removed and arable grassland increased in size [adjacent image shows the Fair Isle Great bustard. She arrived on the island in Jan' 1970 and, after failing to thrive in the wild, was tranported to the Porton Down captive group in April (read on). She died in captivity. Quite how and why she got to the Shetlands in the first place is a bit of a mystery].
The Great bustard also occurs in Spain and Portugal, Austria, Germany, Hungary, Romania, Slovakia, Russia, China and Mongolia. The remaining populations of central Europe are highly fragmented and thought in danger of extinction: there are less than 100 birds in Germany, for example, and Poland, the Czech Republic, Slovakia, Moldova and other European countries have lost, or virtually lost, their Great bustards. They disappeared from Switzerland some time after 1553, from Denmark by 1860, from France in 1863, and from Serbia in about 1949. A relict population (perhaps of less than 50 birds) seems to persist in northern Morocco near Tangiers. This population has sometimes been thought extinct but a small group was seen in 1995 (Waters & Waters 2006). Spain is home to the largest European population, and to an active field research programme on the birds.
The Great bustard is migratory across part of its range but, overall, seems flexible in terms of this behaviour. Birds from Russia move to Ukraine, Iraq and Iran during the winter; those in Germany may move to England or France; and bustards from Hungary might fly to Italy or Greece. Many of these movements seem to be responses to extreme weather conditions and are not definitely traditionally 'ingrained' within the birds (Streich et al. 2006). The British birds were apparently non-migratory, though they did move away from the higher, more exposed upland areas during cold, snowy winters.
The biggest bustards: the biggest flying birds?
The Great bustard is a huge bird: males have a wingspan of 2.1-2.5 m and can weigh as much as 18 kg, with 21 kg and 24 kg even claimed for some specimens [the adjacent image shows the life-sized silhouette of a male Great bustard in flight the Great Bustard Trust have in one of their hides]. If you're familiar with the literature on 'maximum sizes' of flying birds, you'll know that there's always been some debate as to whether the Great bustard or Kori bustard Ardeotis kori is larger. Most people say Kori because of 19 kg specimens, but (as just mentioned), the Great bustard is claimed to reach similar or even larger sizes. Incidentally, a particularly large 21-kg Manchurian Great bustard was apparently unable to fly: most authors have assumed that it was 'too heavy to fly', but this has always bothered me and I'd like to know more about the individual concerned - how do we know that it was definitely flightless, and why should 21 kg be 'too heavy'? There's also a claimed record of 34 kg for a Kori, and note that some fossil bustards - I'm thinking of Ioriotis gabunii from the Late Pliocene of Kvabebi in Georgia - might have been about a third larger than a male Great bustard (Boev 1999) (arm bone anatomy suggests that Ioriotis was flighted, and not a unique flightless species). The Mute swan Cygnus olor is also sometimes mentioned as 'heaviest flying bird' (e.g., Carwardine 1995) as there's a male from Poland who apparently weighed 22.5 kg. Again, he had - supposedly - temporarily lost the power of flight.
Contests like this never really mean anything: few weight measurements are really accurate - I suppose they're anywhere between 60% and 90% accurate (due to dodgy equipment, different techniques used in measuring, rounding-up and rounding-down, errors made in conversions and so on) - and individual birds can fluctuate so much according to condition, time of year, and even stuff like amount of exercise and diet that a 19 kg bird might weigh 21 kg a year (or less) later, and vice versa. Pigeons are known to change their mass by as much as 30% across the seasons (Sargisson et al. 2007): any fluctuation won't be that marked in a 20-kg bird, of course, but we know that individual birds can change in mass quite markedly according to their life history. It should also be emphasised that all of these 'record' weights are exceptional. An 'average' male Great bustard weighs 10-16 kg [image below shows the author with Hercule, a stuffed male Great bustard, kept in a private collection prior to his unfortunate death (he was killed when thieves broke into the collection)].
Incidentally, 20-something kg is far from the upper limit for flying birds given that the largest extinct teratorns exceeded 70 kg. The biggest pterosaurs exceeded 200 kg.
Reintroducing Great bustards to England
Throughout the 20th century, people decided that they really should try to get the Great bustard reintroduced to England. Efforts were made as early as 1900 when Spanish birds were released onto an estate at Elveden in Suffolk, but far better known is the Porton Down (Wiltshire) project of the 1970s and 80s, led by the Great Bustard Trust (GBT). Birds from Portugal and Hungary were reared in captivity on Porton Down, and their release on Salisbury Plain was planned. Unfortunately, no chicks were ever fledged (despite successful laying) and the GBT ceased operation in 1997. The remaining captive birds were transferred to Whipsnade Animal Park (Bedfordshire). I grew up hearing and reading about the successes and failures of the GBT and was disappointed that it never succeeded.
However, inspired by these efforts, David Waters set up the Great Bustard Group (GBG) in 1998. By working closely with the A. N. Severtsov Institute of Ecology and Evolution (a branch of the Russian National Academy of Science), and with colleagues in Spain, the GBG has been able to import 'surplus' eggs from Russia, and to then rear the chicks with a minimum of human contact (Waters & Waters 2006). Russian birds have proved closely related to the extinct British ones, so their use for the reintroduction is more appropriate than of Iberian birds. Concentrating on Ministry of Defence land on Salisbury Plain, the GBG reintroduction effort resulted in wild breeding in 2009, so things are looking good [GBG emblem on a land-rover shown in adjacent image. In pic below, we look at very distant bustards. Hopefully this photo provides some idea of the habitat].
Despite their size, the birds (which are allowed to wander where they like, and have flown far and wide across the country) are incredibly hard to find and to spot. They excel at concealing themselves in open areas, and their mostly grey and brown plumage makes them very hard to see on plains and fields. Males are more obvious than females because of their large white wing and tail feathers, and when performing their incredible 'balloon' displays they must stand out for miles, literally. In this display, the males inflate their necks, lower and partially evert their wings, raise their tails, and erect the whisker-like feathers on their throats. Anyway, we saw two at extreme distance - they could be observed sufficiently through a telescope but were really at the limits of binocular range and there was no possibility of photography. Two additional birds were seen at closer range, but I didn't have any luck with those.
I wanted to say sooo much more about bustards in general - they're very neat birds. But it'll have to wait to another time. I'm very happy to have finally seen Great bustards in the wild in the UK, and I hope to see them again.
Bustards have previously been mentioned at Tet Zoo following my viewing of a wild Houbara Chlamydotis undulata in Morocco back in late 2008. And you can read more about the Great Bustard Group here. Teratorns were mentioned in passing, so if interested see Life-size two-dimensional condors and teratorns.
Refs - -
Boev, Z. 1999. Late Pliocene bustards (Aves: Otitidae) from western Bulgaria. Historia naturalis bulgarica 10, 97-108.
Carwardine, M. 1995. The Guinness Book of Animal Records. Guinness Publishing, Enfield, Middlesex.
Sargisson RJ, McLean IG, Brown GS, & White KG (2007). Seasonal variation in pigeon body weight and delayed matching-to-sample performance. Journal of the experimental analysis of behavior, 88 (3), 395-404 PMID: 18047229.
Streich, W. J., Litzbarski, H., Ludwig, B. & Ludwig, S. 2006. What triggers facultative migration of Great bustard (Otis tarda) in central Europe? European Journal of Wildlife Research 52, 48-53.
Waters, E. & Waters, D. 2006. The Great Bustard. The Great Bustard Group, Salisbury.
Whitlock, R. 1953. Rare and Extinct Birds of Britain. Phoenix House, London.
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'Manchurian' kori bustard???
Oops - an error, thanks for flagging. This was a mistaken reference to a Manchurian Great bustard, allegedly 21 kg and 'too heavy to fly'.
That's a rather fitting description. Generally speaking, it's interesting to note how relatively unfamiliar birds bustards are to many/most non-biologists. As you say, a couple of species do get regularly mentioned in 'What is the biggest flying bird?' discussions, but that's pretty much all the popular attention they tend to get, at least as far as most non-specialists are concerned. Do bustards lack the charisma of, say, cranes?
My parents and friends always scolded me when I was a kid for bringing up bustards. They thought I was swearing...
Is this a typo (perhaps meant to say "third as large again)? It doesn't currently seem quite right in context.
Yeah, I meant 'a third larger'... if that makes sense. As in = it's as big as a male Great bustard, plus c. 33% of another male Great bustard.
In The Letter of Marque by Patrick O'Brian, Dr. Stephen Maturin is on his way to a very important meeting. He is distracted on his way there by someone who tells him that he can show him a bustard. Maturin is unable to resist the temptation. The book is set somewhere around 1813, and Stephen is astonished to know that bustards can still be see. He almost makes his ship miss its tide, which would have been a very great problem indeed. He apologized to Jack (the Captain) for his "gross self-indulgence in bustards".
I tried to spot them on Salisbury plain and failed. I will try again.
Red Kites by the way were not extirpated in Britain, they continued to exist in parts of mid-Wales, and their current greatly extended range has partly been due to deliberate reintroductions, partly due to expansion of the mid-Wales population.
Also while the extinction in the UK of the Northern Goshawk is generally accepted, (with its current situation being partly due to recolonisation from the continent and partly due to escapes from falconers) there are some who believe it was never totally wiped out here. I have heard accounts that it continued to breed at a few locations in South Wales during the period when it was officially extinct.
"Two additional birds were seen at closer range, but I lucked out on those."
If you lucked out, that means that you were lucky enough to see them, not that you were unlucky enough to miss them, as the text seems to imply. Just saying.
Ooooh, bustards!!! I have never seen one in the wild in Europe and was only vaguely aware they existed (they just don't get the same tv coverage as elephants or tigers, do they?), until I had the fortune to see lots and lots of bustards in Australia (those were Australian bustards though, obviously). I have been a fan ever since, and I'd love for bustards to become more common in these parts again.
Imagine standing next to a bustard... only possible with a stuffed one! Birds of the distance, or surprise at close quarters.
I once (driving at night) almost hit a mob of at least ten Kori bustards as I came round a bend on the hill road inland from Borroloola. Mostly-white explosion of feathers blocking my view of the road was not hit birds, but huge wingspans of all those birds in sudden take-off away from me - it was a relief not to have hit any, but also to have made the curve without going over the edge.
Anyway, what were they doing hanging out at one spot? - what's their breeding system - do they lek? At night?
Great Bustards, great birds!
Strange, and rather worrying is, that millions of pounds spend on bird conservation in Britain are on birds which are internationally less in danger. Great Bustard is currently the only breeding bird in Briatin which is officially internationally threatened. Still, its
reintroduction in Britain is entirely work of a small group of people who self financed it and received just lots of criticism from more "official" conservation NGOs.
I was lucky to see displaying Great Bustard in Spain and Germany, and are totally awesome. Curiously, the displaying male lays tail flat on the back and turns half-opened wings so that underside is visible. For you anatomy freaks - bones and muscles must undergo some very strange concortion there!
@John (#11): Around Borroloola, shouldn't that have been Australian rather than Kori bustards as well? I think they are pretty social and like hanging out in groups (although I am not sure what they would be doing in a road).
I have seen Great Bustards in Spain and they are truly magnificent - they are surprisingly fast and strong fliers as well. To find them in the fields the advice was "look for a boulder that moves" - they are certainly the size of one.
One thing that always strikes me about bustards is that their feet look far too small for such large birds.
It's too bad humanity missed the 70+ kg teratorns - Argentavis magnificens would have been absolutely incredible to see.
I once read of a famous group of great bustards in Germany. Although bustards usually nest out in open country so they can readily see predators approaching, these particular birds nested in a sheltered valley, in a large nook or hollow at the base of steep cliffs. As is generally the case with bustards, these wary birds were extremely difficult to approach while nesting. A large handsome male, nick-named "Rommel" by the locals, was especially alert as he patrolled the area each day.
The ornithologist Clarence G. Patton was keen to grab a few fertilized eggs from the nests of these birds for use in an international breeding program. (He figured this was the best way to establish a breeding group at a zoo without disrupting this group of wild birds.) However, Dr. Patton found it horrendously difficult to get past the watchful eye of Rommel, whose alarm cries disturbed and upset the entire breeding group -- something Dr. Patton was anxious to avoid.
After many weeks in the field spent studying the foraging habits of the birds, and much, much patience, Dr. Patton was able to dash in and grab a few eggs from a momentarily unguarded nest. A few moments later, the male Rommel returned to the nesting area, completely unaware of the ornithologist's intrusion.
As he carefully packed the eggs away and prepared to leave the area, Patton felt so proud of himself that he could not help shouting in triumph:
"Rommel, you magnificent bustard! I raid your nook!"
They must be -- in order not to stall.
ROTFL!
A beautiful bird. It's a real shame that humans have led to its downfall across so much of its range.
"Incidentally, 20-something kg is far from the upper limit for flying birds given that the largest extinct teratorns exceeded 70 kg. The biggest pterosaurs exceeded 200 kg." I know you are not insinuating that pterosaurs are birds, but it is implied by the "upper limit for (...) birds". An unsuspecting reader may start wondering...
There is a very good reason why some particular weight is going to be "too heavy" for sustained powered flight. The power required for flight scales to body mass with a higher exponent (7/6 from physical first principles) than maximum metabolic rate (power output, which empirically scales at less than 1, around 0.75). There must be a particular weight at which the lines cross, above which birds (with cardiovascular, respiratory, and muscular systems as we know them) cannot sustain powered flight. And when you map empirical maximum metabolic rates onto the physical constraints, they cross at 15 - 20 kg, just the size of modern bustards and swans.
Anything larger cannot fly, if you define 'fly' as sustained powered flight instead of extensive soaring and cheating on takeoff. Huge extinct birds were soarers, not flyers.
As for pterosaurs, who knows? Different muscular/cardiovascular constraints on maximum power? Higher atmospheric pressure?
It's a real puzzle, and not one to be blown off by simply asserting that these things could fly. How?
Yeah, Pennycuick (1986) and so on... but does the term 'flying' specifically mean 'sustained powered flight'? Well... not really, so is there really anything wrong with saying that giant teratorns and pterosaurs were capable of flight? But your general point is well taken :)
Of course, "flight" can be as general as you want it to be, Humpty [insert smiley thing].
But so the model ought to apply as well to individual birds of a size already pushing the limits for powered takeoff; why couldn't an individual swan or bustard get too fat to fly?
A TV show says it'll screen a report on the Great Bustard reintroduction to Britain next week. Tuesday 9th August, ITV1, 19:30 to 20:00 (unless their schedule gets changed that night 4 some unexpected reason). It is called Wildlife Patrol. (P.S. I really appreciate the work that goes into this blog. It's a great source of both information and entertainment.)