About Me

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Canberra-based naturalist, conservationist, educator since 1980. I’m passionate about the natural world (especially the southern hemisphere), and trying to understand it and to share such understandings. To that aim I’ve written several books (most recently 'Birds in Their Habitats' and 'Australian Bird Names; origins and meanings'), run tours all over Australia, and for the last decade to South America, done a lot of ABC radio work, chaired a government environmental advisory committee and taught many adult education classes – and of course presented this blog, since 2012. I am the recipient of the Australian Natural History Medallion, the Australian Plants Award and most recently a Medal of the Order of Australia for ‘services to conservation and the environment’. I live happily in suburban Duffy with my partner Louise surrounded by a dense native garden and lots of birds.

Thursday, 31 March 2016

A Perusal of Pigeons. Part 3, Australia.

This is the third (and finally the final!) part of a series looking at the world's pigeons and doves. If you missed earlier episodes, they began here with an overview. The second part looked at the five (or six) generally-recognised sub-families, three of which comprise only five species between them. We perused the sub-family of fruit-eating pigeons and doves (including some Australian ones) and began to look at the biggest sub-family of 'typical' primarily seed-eaters. This in the end proved too large a task for one posting, so I left the Australian members of the group to their own posting - many specifically Australian genera have arisen during the continent's long isolation, and I know a bit more about them than about some of the others.

However as I worked through this posting I found that a lot has happened recently with regard to our understanding of the relationships - the taxonomy - of Australian pigeons, so I hoped it might be useful to provide an updated overview as I went of where things stand with the latest thinking. In doing so I trust that I haven't obscured the more interesting topic, the birds themselves. Understandably, most of our field guides can't keep up with all this new thinking, so some of the names I use will not be in your favourite guide (though hopefully the next edition will have them). If at least two of the major authoritative international bird lists have adopted a name recently, I have too.
Spinifex Pigeons Geophaps plumifera with Euro Macropus robustus, Bladensburg National Park, central Queensland.
As with virtually everything else about Australia's biota, an understanding about our pigeons lies in the long period of isolation - from about 50 million years ago when we separated from Antarctica and South America, to the last few million years when we approached closely enough to Asia for an interchange of animals and plants to occur. The Australian fruit doves and imperial pigeons are recent arrivals - their ancestors came aboard as we (with New Guinea as the bowsprit) crashed into Indonesia. The seed-eating group in Australia (some of which do actually also eat some fruit) are old Australians and are for the most part quite different from equivalent pigeons in other lands.

Central to the the old Australian pigeons are the bronzewings, a group of nine fairly large species in four genera, which between them are found across the entire continent except for the extremely arid Great Victoria Desert and adjacent Nullarbor Plain in the central south. The longest-known of these (and the reason for the group name) is the Common Bronzewing - its familiarity is such that 'Pigeon' is deemed an unnecessary addition - Phaps chalcoptera, found across the virtually the entire continent. It was by far the first Australian pigeon to be named (aside from a couple occurring further afield and named from specimens collected elsewhere), in 1790, just two years after the founding of the first English colony at Botany Bay. Phaps, unoriginally but unarguably, just means 'pigeon'... The other bronzewing genera names are variations of this.
Common Bronzewing, Merimbula, New South Wales.
The glorious iridescent wing bars (see also below, in Canberra) are a feature.

The closely related and similar Brush Bronzewing P. elegans is a much less common bird of southern coastal scrubs and heathlands. 

The third member of the genus is a very different bird in all ways, including appearance and habitat. The Flock Bronzewing is a nomad of the vast plains of the arid inland, a true child of El Niño, appearing in vast numbers in good years and strewing the ground with their eggs (there are tales of sheep stained yellow by them, through lying on them at night) then vanishing again. Flocks of up to a million were reported from the 19th century but by start of the 20th it seemed that they may have gone for good due to relentless habitat alteration, especially over-grazing by sheep and rabbits, shooting and cat and fox predation on nesting birds and eggs. By mid-20th century they were making a recovery – perhaps related to rabbit control by the Myxomatosis virus? – and I’ve driven through big scattered flocks, though nowhere near what they were.
Flock Bronzewing Phaps histrionica, west of Windora, south-west Queensland.
The apparently odd species name actually comes from Latin for a mime performer, for the strange face mask.
Another three-species genus is Geophaps ('ground pigeon', though all the group fits this description), all birds of the semi-arid tropics and sub-tropics. The most colourful - and I have to shamefacedly confess, utterly endearing - is the little Spinifex Pigeon G. plumifera from the central and western deserts. Spinifex refers to a large genus (Triodia) of grasses, forming large spiny hummocks, which dominates some 20% of Australia; Spinifex Pigeons (along with many other animals) are almost always associated with them.
Spinifex Pigeon (above Bladensburg NP, central Queensland,
and below Kings Canyon, central Australia).

Spinifex Pigeons have an always-surprising habit of materialising from the landscape; one moment you are alone,
the next there are up to a dozen scuttling about on whirring little legs.
Squatter Pigeons G. scripta (here at Cobbold Gorge, north-central Queensland) are found in the dry east coast
hinterland from far northern New South Wales to near the tip of Queensland.
Squatter Pigeons from further north (such as this one from Mareeba) have a red eye ring.
The third Geophaps, the Partridge Pigeon (named for their habit of running along the ground in jinking flocks, then flying up in a burst from the ground when disturbed) G. smithii, has a much smaller range across the Top End of the Northern Territory and the adjacent Kimberley district of far northern Western Australia. It has a very striking visage!
Partridge Pigeon, Kakadu National Park, east of Darwin, where they can be quite
confiding around visitor centres and picnic areas.
There are two species of the unusual-looking rock-pigeons, which are limited to the sandstone escarpment country of Kakadu (for the Chestnut-quilled Rock-Pigeon Petrophassa rufipennis) and the Kimberley to the west (for White-quilled Rock-Pigeon P. albipennis). They can only be seen by climbing into their rugged stony fastnesses, though they are not uncommon in their limited range. However it seems that feral cats could be a real threat, given their small distributions.
Chestnut-quilled Rock-Pigeon, Burrunggui (formerly known as Nourlangie Rock), Kakadu NP.
Both species are often seen out on bare rock, like this. They are most striking birds.
Last of the bronzewing group is the now extremely familiar Crested Pigeon Ocyphaps lophota, the only one of the genus. I say 'now' because they have expanded dramatically to the south and east in recent decades, to the point that they are now abundant and ubiquitous throughout much of the country and in all mainland capital cities except Melbourne (where they are making inroads). In Canberra for instance they regularly appeared as drought refugees from the west, then disappeared again. In the drought of the early 1980s however they came again - and for reasons uncertain, became established. Now it is pretty much impossible to walk or drive anywhere in Canberra without encountering them; a pair come daily to our bird bath. And I have to add that I find them a delight.
Crested Pigeon bathing in the sprinkler in our Canberra back yard.
(The cage is actually to keep green vegetables in and possums out!)
I have another reason for using this photo too. Below is a (very grainy) close-up of the opened wing; look at the narrowing of the third feather from the outside. This is the origin of the very distinctive whistling whirr that Cresties make when they take off - it is an automatic warning to others feeding on the ground that there may be danger approaching.

Another familiar and widespread genus is Geopelia, whose three small long-tailed ground-feeders cover most of Australia except for the south-west. They superficially resemble the turtle-doves (see the last posting) but it seems they are old Australians which branched off from the bronzewings. Diamond Doves have a huge range across virtually all of Australia except for the south and south-east coasts (where most of the human population lives). They can be seen at any watering spot in the deserts and semi-arid lands, and are limited to Australia.
Diamond Dove G. cuneata at the Diamantina River (perhaps appropriately!),
far west Queensland. This is a tiny dove, only 20cm long.
Equally tiny is the Peaceful Dove G. placida (though often called G. striata in Australia - see below), more familiar as it occurs more often in populated areas than does the Diamond Dove. I think it of as integral to the riverine River Red Gum forests (Eucalyptus camaldulensis) of the inland, where its incessant 'toodle-OO' reminds me of soporific warm afternoons, though it is found more widely than that. However there are strong signs that the introduced and aggressive Spotted Dove Streptopelia chinensis is displacing it in urban situations.
Peaceful Dove, Longreach, central Queensland.
It is also found in New Guinea, and closely related doves are found in Indonesia and south-east Asia. There has been a tendency in the past to regard all of these as one species (G. striata) but most authoritative lists, including the IOC (International Ornithological Congress) and Handbook of the Birds of the World, now recognise three species. In addition to the Peaceful Dove, these are the Zebra Dove G. striata of much of south-east Asia and Indonesia (though it's unclear which are native birds and which have been introduced), and the Barred Dove G. maugei of the Lesser Sunda Islands (which included Timor and Flores). Irrespective of their status, it would seem that these derived from Peaceful Doves which crossed the ocean straits northward in relatively recent times.
Zebra Dove, Kota Kinabalu, Sabah.
The third Geopelia is the Bar-shouldered Dove G. humeralis, whose musical but insistent 'let's go to school!' can be heard throughout woodlands of the east and north coast and hinterlands. It is half as big again as the two smaller species.
Bar-shouldered Dove, suburban Darwin.
That leaves us with four species, each in a separate genus, whose relationships are uncertain, not least because at least three of them are members of the seed-eating sub-family which eat a lot of fruit.  

Chalcophaps comprises three species, one of which is confined to New Guinea, Sulawesi and the Solomons, while another, the Common Emerald Dove C. indica, extends from India to Indonesia. (Note that this is a recent understanding - until then the Australian Emerald Dove was included in this species.) Now emerald doves in Australia, New Guinea and associated islands are known as Pacific Emerald Dove C. longirostris (though this is not of course universally accepted). More vexed a question is what they actually are - the Handbook of the Birds of the World helpfully tells us that they "appear to be intermediate between the African spotwings and the Australian bronzewings", so their origin is anyone's guess! Irrespective they are lovely birds, found in Australia in rainforests and vine forests of the east and north coasts. Given their evident island-hopping skills it is unsurprising that they've found their way to Lord Howe Island.
Emerald Dove, Lord Howe Island.
The cuckoo-doves, genus Macropygia, are about 10 species of large long-tailed fruit-eating rainforest pigeons found widely from China and India to Australia, where there is just one species - a pretty good indication that they didn't arise here but arrived fairly recently. Until recently the cuckoo-doves from eastern Australia were in fact known as M. amboinensis, a species found from New Guinea to Sulawesi and islands between, but are now given full species status as Brown Cuckoo-dove M. phasianella.
Brown Cuckoo-Dove, Nowra. These are active and acrobatic pigeons whose long tails help them balance
as they scramble through branches, especially in rainforests, for fruit (though their primary purpose is
doubtless as a rudder when flying through dense vegetation).
The final two Australian species are undoubtedly home grown, though their relationships have long been debated. Perhaps this contributes, albeit subconsciously, to them being among my favourite pigeons, though you may observe, with some justification, that I have rather a lot of those.

Wonga Pigeons Leucosarcia melanoleuca are big striking blue-grey and white pigeons of dense understorey, especially rainforest, along most of the east coast. Their incessant 'woo woo woo' (they have a very high boredom threshold) is a familiar sound of the wet forests, often emitted from a perch above the ground, though they generally forage on the forest floor where they take more insects, worms and snails than most pigeons. Some believe it to be of ancient Australian pigeon stock with no close relations, others that it was an early side-branch of the bronzewing lineage. Clearly more DNA work is required.
Wonga Pigeons, Nowra, New South Wales.
The name is presumably onomatopoeic, from an Aboriginal language, but as is so shamefully often the case
we don't know with certainty which one, though we can deduce that it was likely to have been
one of the Sydney area tongues. It was originally recorded as Wonga Wonga or Wanga Wanga.
Finally, the Topknot Pigeon Lopholaimus antarcticus. There is no consensus as to which of the sub-families it even belongs (though if it is of the fruit pigeon sub-family, all other Australian members of which arrived here recently, its origins require some interesting explanation). It is a big (45cm long), strange-looking pigeon with a unique double crest and very seldom-used voice (when it is used it utters either a low grunt or screech) which lives in highly mobile flocks in rainforests of the east coast, following the fruits.
Topknot Pigeons, Bunya Mountains, southern Queesnland.
So, pigeons, in many more words and pictures than I'd expected. I've learnt a lot in putting these postings together, and I hope you've found it worth while. At the least I hope it contributes in a small way to your enjoyment of these delightful and fascinating birds.


Thursday, 24 March 2016

A Perusal of Pigeons. Part 2.

Last time I talked a bit about the overall family characteristics of Columbidae - better known to their friends as pigeons and doves. Today I want to complete the story by going though the major groups, illustrating where possible (though we don't always achieve what we want - it turns out I won't actually finish until next week!). As ever my photos are almost exclusively from the southern hemisphere (except where I've strayed slightly north of the equator in places like Ecuador, Borneo and central Africa). 

Most authorities recognise five or six sub-families within the overall pigeon family; as these authorities tend to be human, they don't always agree with each other and there is more to be said on this before the dust (which could well be pigeon powder down) settles. In addition the precise position is still unclear of the tragically extinct Dodo and Rodriguez Solitaire, exterminated by sailors on their remote Indian Ocean islands within decades of being discovered - in the early 17th century for the Dodo, a century later for the solitaire. They have widely been regarded as a sub-family of giant flightless pigeons, but some would put them in their own, related, family. Of living pigeons, the Pheasant Pigeon of New Guinea and the Tooth-billed Pigeon of Samoa each form their own sub-family, and the three magnificent crowned pigeons of New Guinea and islands form another.
Western Crowned Pigeon Goura cristata, courtesy Wikipedia.
The other sub-families are much larger and ubiquitous, and in fact are fairly intuitive. One comprises the fruit-eating pigeons and doves (roughly a third of the species), the other is made up of 'the rest', mostly seed-eaters. Some would go further and separate out the fruit pigeons and imperial pigeons (of Oceania and south-east Asia) from the blue and green pigeons which are also found across southern Asia and Africa.

The fruit pigeons are mostly arboreal (fair enough, as that's where fruit tends to be found!), in contrast with many of the mostly seed-eating 'typical' pigeons. My photos of them are relatively limited, due to this habit of hanging out in rainforest foliage (and my photographic limitations of course), but I have enough to illustrate the major groups.

The imperial pigeons of the genus Ducula comprise some 35 species of large often colourful fruit pigeons found from southern Asia to northern Australia and the Pacific.
Green Imperial Pigeon Ducula aenea, Kota Kinabalu, Sabah.
This handsome bird is found from India to Indonesia.

Pied (or Torresian) Imperial Pigeon Ducula bicolor, Darwin, Northern Territory.
This is one of a group of black and white imperial pigeons. It occurs coastally from
south-east Asia to tropical Australia (though some would divide it into four or five species).
In the western part of its Australian range it is sedentary, but from the Top End and north Queensland
it migrates to Indonesia and New Guinea after breeding, although increasing numbers now over-winter
in Darwin, perhaps as Carpentaria Palms, their favoured fruit tree, have become popular garden plants.
Formerly vastly abundant, numbers were shattered by 19th plundering of island breeding colonies;
fortunately they are now recovering.
The closely related genus of fruit pigeons (or doves) Ptilinopus is even larger than Ducula, with around 50 species centred in the area between New Guinea and the Philippines, but extending to Taiwan, Australia and Polynesia. I find them particularly hard to photograph!
Wompoo Fruit-Dove Ptilinopus magnificus, Cairns. This bird is every bit as magnificent as its name
suggests, despite this photo not doing it justice. The strange vernacular name is from its call,
a bubbling, guttural call that rolls through the rainforest, and is one of its characteristic sounds.
It is found in rainforest in New Guinea and the east coast of tropical and sub-tropical Australia.
Rose-crowned Fruit-Dove Ptilinopus regina, Kakadu NP.
A glorious little fruit-dove, found in east coast rainforests, Top End monsoon forest (as here)
and into Indonesia.
Finally in this sub-family, the green pigeons, genus Treron, comprise 30 species found across Africa and Asia. They are all green, a pigment they derive from carotenoids in their fruit diet. Unlike most other pigeons, males and females have different plumages (ie they are dimorphic). They differ in other ways too - instead of cooing, they whistle or even quack! And unlike the Ptilinopus fruit doves, their narrow gut and gizzard have evolved to grind up the seeds of the figs they eat.
A beautiful softly-plumaged male Pink-necked Green Pigeon Treron vernans, Kota Kinabalu, Sabah.
(Females are mostly greenish-yellow.)
A very widespread little pigeon, found throughout much of south-east Asia, Indonesia and the Philippines.
Which brings us to all the rest... The type genus, as one would expect from the family name, is Columba, and it is no surprise that the type species is the perhaps over-familiar Feral Pigeon (or Rock Dove if you'd rather).
Feral Pigeons C. livia, Canberra.
As mentioned last time, this species was originally a cliff dweller around the Mediterranean,
and was first domesticated - for food - in the eastern Mediterranean perhaps 10, 000 year ago.
Since then of course it has spread around the world.
There are some 35 other species of Columba through Africa, Asia and Europe, with one having reached Australia.
White-headed Pigeon Columba leucomela, Nowra, New South Wales.
Associated with rainforest along the east coast of Australia, this handsome species is extending its range,
apparently in association with - both as cause and effect - invasive exotic fruit-bearing trees
such as Camphor Laurel and Privet.
Speckled (or Rock) Pigeons C. guineae, Bontebok NP, South Africa, but common across much of Africa.
(Scan of an old slide, sorry.)
Apparently similar American pigeons were formerly placed in Columba too, but DNA work has now separated them out as 17 species of Patagioenas, which actually diverged from the main pigeon line about 8 million years ago, so is much older than Columba.
The Picazuro Pigeon P. picazuro, here in Buenos Aires, is widespread in eastern South America.
Pale-vented Pigeon P, cayennensis, Puerto Maldonado, Peruvian Amazonia.
Another widespread South American species, this one throughout the northern lowlands and up to Mexico.
The Chilean Pigeon P. araucana, here near Puerto Varas, southern Chile,
is a pigeon of the temperate rainforests of the south of the continent.
Ruddy Pigeon P. subvinacea, Rio Silanche Reserve, in the cloud forests north-west of Quito, Ecuador.
This is another of the genus found across northern South America.
Spot-winged Pigeon P. maculosa, Putre, high in the Andes in northern Chile. (In a eucalpyt!)
Generally found east of the Andes in the centre-south of the continent.
Let's stay for now in South America, where there are also quite a number of smaller ground-dwelling doves. Zenaida is a small genus of just seven species, but includes some of the commonest and most familiar American doves, including the extraordinarily abundant Mourning Dove Z. macroura of North America, where close to 50 million birds are shot annually for entertainment and meat, with little apparent impact on the population.
Eared Dove Z. auriculata, Lima, Peru.
This dove is almost equally abundant throughout South America.

West Peruvian Dove Z. meloda, Lima.
Another common dove, but in a more limited range centred on the coastal plains of Peru.

Galápagos Dove Z. galapagoensis, Santa Fe.
A Galápagos endemic whose ancestor made the hazardous sea crossing - probably involuntarily - from the mainland.
Found throughout the arid lowlands of the archipelago.
There are just four species of the Metriopela ground-doves, limited to the high arid Andes, but at least a couple are common and conspicuous, including in towns.
Bare-faced Ground Dove Metriopelia ceciliae, Socorama, northern Chile,
a bird of high altitude scrubby vegetation.

Black-winged Ground Dove M. melanoptera in cactus, Colca Canyon, southern Peru.
It shares this high dry habitat with the Bare-faced Ground Dove, up to 4,400 metres above sea level.
Like it, the Black-winged also frequents Andean villages.
Another genus of small and widespread American ground doves is Columbina ('little dove', appropriately enough). Like the green pigeons they are unusual among their family in having slightly different male and female plumages, males being somewhat brighter.
Croaking Ground Dove Columbina cruziana, Cuenca, southern Ecuadorian Andes.
This is a male, from its pale grey head. The two-tone bill is distinctive, as is
the remarkably undove-like squelchy call. It is mostly a bird of the arid Pacific coast from
southern Colombia to northern Chile, but also climbs into the west slopes of the Andes, as here.
Leptotila comprises another eleven species of ground doves, some of which enter rainforests.
White-tipped Dove Leptotila verreauxi, Aguas Verdes, northern Peru.
Back in the Old World the turtle-doves Streptopelia are widespread in Africa and Eurasia, with some species widely transported across the world. (The odd 'turtle' of the name is onomatopoeic for the call; you may remember the apparently weird line in the Song of Solomon "the voice of the turtle is heard in the land".) The most familiar of these in Australia is the introduced Spotted Dove S. chinensis (for some strange reason the habit today is to drop the 'turtle' from the name), where it has become a serious invasive pest in cities and towns. Official apathy has been a good friend of this dove here, and there is good evidence that small native doves disappear when it arrives.
Spotted Dove, Rottnest Island, Western Australia.
Another exotic member of the genus has hitherto not left Western Australia, though since its deliberate release in Perth in 1899 it has spread north almost to the tropics, into the arid goldfields and south-east to Albany and Esperance. This species, the Laughing Turtle-Dove S. senegalensis, also has a vast natural range, throughout much of Africa, the middle east and central and southern Asia.
Laughing Turtle-Dove, Shark Bay, 700km north of the original release site in Perth.
Some other turtle-doves are not so easy to find. The Adamawa Turtle-Dove S. hypopyrrha is scattered across the arid inland of west Africa, but the Nigerian and Cameroonian populations are now deep within Boko Haram territory, though there is another population further west towards Senegal.
Adamawa Turtle-Dove, Bénoué National Perk, Cameroon.
Turtur (reprising the 'turtle' theme) is a small genus of similarly long-tailed African doves, some of which are very common and widespread.
Blue-spotted Wood Dove (the name refers to two small blue spots on each wing) T. afer, Entebbe, Uganda.
And with that I am going, unexpectedly, to leave it until next week. It has already become more of an epic than I anticipated, so I'll leave the not inconsiderable topic of Australian pigeons and doves - many of which are very different from those of other continents - until next week.

I hope you'll think it's worth coming back then.


Thursday, 17 March 2016

A Perusal of Pigeons. Part 1.

As any regular reader of this blog will have noticed, I tend to alternate between featuring a place or area, and then specific animals or plants. This is the turn of the latter, and it feels like time for some birds again. Sometimes the most apparently obvious candidates are the ones overlooked, and pigeons and doves are familiar animals to just about anyone in the world, in one form or another. There are over 300 species in the family Columbidae (now generally regarded as having no close relatives), found across every inhabited continent, from rainforests to high mountains to woodlands to deserts. Their greatest diversity is in Australia and southern and south-eastern Asia.
Feral Pigeons Columbia livia Cusco, southern Peru.
This ubiquitous species was originally a cliff dweller, the Rock Dove, around the Mediterranean, before being
domesticated for food and more recently spread throughout the world.

The distinction between pigeons and doves is completely arbitrary (the familiar Feral Pigeon is widely known as Rock Dove, remember), though 'dove' is often retained for smaller, longer-tailed species. 

The word 'pigeon' came from the Old French pijon, written variously and first recorded in its current form in England in the late 15th century. Originally it apparently referred to a young dove, though was also used for any young bird. It did not become the generally first-choice term until early 19th century however, gradually replacing terms such as queece, culver and cushat, and in part replacing the older 'dove', which by contrast was of Old English origin. It was apparently from an onomatopoeic word since lost, but presumed to resemble dufe.

Characteristics include a relatively small head on a short neck, compact body, short legs, bare skin around the eyes, and a short slender bill with a constriction in the middle, the pinched shape exacerbated by a cere, soft swollen skin at the base. 
This Bare-faced Ground-Dove Metriopelia ceciliae, in Socomora in the high Atacama Desert of northern Chile,
illustrates well the essential elements of the family.
This Galápagos Dove Zenaida galapagoensis, in the port of Puerto Ayora,
is modelling the standard pigeon feet, with three toes forward and one back, like a passerine.
This is an excellent - though not the only - form for perching.
Pigeons have a couple of tricks only shared by a couple of other bird groups. One is in drinking; most birds can only take in water a tiny billful at a time, dipping the lower mandible in and tipping back the head repeatedly. This prolongs the time spent at risk from predators, in the open on the water's edge. Pigeons however have learnt to suck, so they can keep the bill down in the water and take their fill quickly. They do it by creating a sort of peristaltic pump by sending waves of muscular contractions along the oesophagus to pull the water back. (The other group of bird 'suckers' is that of the grass finches, many of which achieve the same result by a quite different mechanism, using their tongues as a double-action scoop, at up to twenty times a second.)
Bar-shouldered Doves Geopelia humeralis, Idalia NP, central Queensland;
the bill can be, as here, submerged to the eyes.

Peaceful Dove Geopelia placida (barred wings and blueish eye-ring) and Diamond Doves G. cuneata, (spotted wings and red eye-ring) near Mount Isa, north-west Queensland.
In addition to its time efficiency, this drinking method enables pigeons to access tiny water sources like shallow puddles and water in crevices not readily available to suck-drinkers.
Bar-shouldered Doves drinking from a film of surface water, Batchelor, Northern Territory.
The other area where pigeons really distinguish themselves is in the production of pigeon 'milk'; of course it's not really milk - that's a mammalian prerogative - but it is a liquid protein food for young animals. Unlike mammalian milk it's produced from the lining of the crop, and it's produced by both sexes. (Flamingos do the same thing, though theirs comes from glands throughout the entire upper digestive tract; it has more fat and less protein than pigeon milk. In emergencies male - and only male - Emperor Penguins can also produce it for a short time, from the oesophagus.)

Pigeon nests tend to be flimsy - from beneath one can often see the egg through the lattice of sticks. Clutch sizes tend to be small, varying from one to three. Fruit-eating pigeons have smaller clutches - obligate fructivores have only one (fruit being low energy food). Green-pigeons eat seed as well as fruit, and lay two eggs.

Common Bronzewing Phaps chalcoptera nest on tree ledge, near Forbes, New South Wales.

Crested Pigeon Ocyphaps lophota nest, Canberra.
Courtship methods vary widely. Many use dramatic display flights, including clapping the wings loudly in the air, and exaggerated rocking, gliding descents with wings angled upwards, sometimes followed by elaborate ground displays. Others however, including many Australian species, stick to the ground displays. The 'bow coo' display is common to many pigeons, which sums up the male's performance - deep courteous bows, each one followed by an equivalently deep 'COO'.
Crested Pigeons displaying (above and below), in a carpark, Erldunda, Northern Territory.

Spinifex Pigeon Geophaps plumifera displaying, West MacDonnell Ranges, central Australia.
The object of his desire is out of our sight behind the spinifex grass clump.
These two are the only Australian species with an erect crest, though some species
elsewhere in the world are likewise ornamented.
A pigeon's flight tends to be fast and direct, aided by a generally large wing area. The wing shape however varies with the lifestyle of the bird. A pigeon which conforms to the 'fast and far' generalisation is likely to have longer and slenderer wings, while a ground-dweller which relies on an explosive take-off in emergencies is likely to have shorter rounder ones.

Spot-winged Pigeon Patagioenas maculosa, Socorama, northern Chile.
This bird flies powerfully between feeding sites in its open scrubby habitat.
Diamond Dove, West MaccDonnell Ranges, central Australia.
A small ground-feeding dove which needs to be able to take off fast when raptors appear.
It doesn't always work of course; this Australian Hobby Falco longipennis, was too fast or too cunning for this unfortunate Diamond Dove, Karumba, tropical Queensland.
A pigeon has very large breast muscles - up to 45% of body weight in some species, well above that of most other birds (mostly in the 15-25% range). Fast flyers will not necessarily need a long tail as a rudder; this need increases for birds making rapid changes of direction, such as a bird likely to be pursued in a forest. The cuckoo-doves of Asia and Australia are a good case in point.
Brown Cuckoo-Dove Macropygia amboinensis, north Queensland.
Pigeons overall have not fared very well from humans (though some generalists have benefitted greatly from our alteration of habitats). The extraordinary destruction of every last Passenger Pigeon Ectopistes migratorius, a species measured in the many billions in the United States and Canada into the late 19th century, is well-known to most readers of this blog I imagine. Migrating flocks in the 1860s were reported to be close to 500km long and up to 1.5km wide; I'll pause and try to consider that with you. Severe habitat loss threatened them along with enormous shooting expeditions. By 1914 every single one had been slaughtered, mostly for fun. However at least seven other species have also fallen into the black hole of extinction, in addition to the closely related giant flightless Dodo and two Solitaire species, from remote Indian Ocean islands. Moreover another 24 species are Endangered, 9 of them Critically. Overall 61 pigeon species are listed in some category of Threatened; frighteningly, another 40 are listed as Near Threatened - ie in danger of being threatened with extinction if remedial action is not taken. That is 20% of all pigeon and dove species are at very real risk of slipping from the world, and a third overall are at some risk.

It is hard to conceive that this beautiful bird, not much more than a hundred years ago was one
of the most abundant birds on earth.
Mounted male Passenger Pigeon, Field Museum of Natural History, Chicago. Courtesy Wikipedia.

That's a grim note to end on, but there's far too much to say about this fascinating and attractive group of birds in one posting, so I'll be back next time for a journey through the world of pigeons, introducing groups and species from four continents. I'm tempted to call it a Cook's Tour, but that would be too insensitive...