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I've been a Canberran since moving here from Adelaide on the first day of 1980. I now live in suburban Duffy with my partner Louise Maher, ABC 666 radio and on-line journalist. Among my early memories is following Sleepy Lizards (Shinglebacks) around the paddocks north of Adelaide, guarded by the faithful bull terrier. I have always been passionate about the natural world, trying to understand how it works, how the nature of Australia came to be, and sharing those understandings. My especial passions are birds, orchids and mammals. I am now a full-time naturalist, running bush tours, writing books etc, doing consultancies, presenting a regular radio slot on local ABC, chairing a government environment advisory committee and running adult education classes. I was awarded the Australian Plants Society Award in 2001 and the Australian Natural History Medallion in 2006, both for services to education and conservation. As part of my fascination with our Gondwanan origins I've been running tours to South America for the past few years.

Friday, 1 August 2014

The Pollination Story, Part 4; the birds arrive, dream customers

If you've just arrived in this story, here's the most recent episode; you can follow back from there if you like.

Undoubtedly birds had long taken sporadic advantage of the nectar and pollen on offer from insect-attracting flowers, though the quantities available would scarcely have made it worth their while. However given their advantages over insects as potential pollen couriers - the ability to cover much greater distances carrying much more pollen, and bigger brains to recognise more complex cues and differences in flowers - it was inevitable that some plants would adapt their strategies and make bigger investments to employ them.
Brown Honeyeater Lichmera indistincta on Melaleuca viridifloris, Barkly Tableland, Northern Territory
(above and below).
 

The development of bilateral symmetry (see the link above) could progress further, to produce flowers that only a bird could probe.
Eastern Spinebill females Acanthorhynchus tenuisostris  on Pityrodia sp.,
National Botanic Gardens, Canberra.
The characters of a bird-pollinated flower will be different from those of an insect-specialising one. They are likely to be red, pink or orange - this is more to hide them from insects, which see best at the yellow-blue (and beyond) end of the spectrum, as birds can see these colours perfectly well too. They will be tube-shaped or have large protruding stamens, and must have strong stems and flower stalks. The corolla - the collective petals - must be strong enough to bear their weight, but without offering a landing platform that insects can use. Anthers and stigmas must be distant from the nectary, so that the bird's forehead is contacting them while the tongue is collecting nectar. And because birds need bigger rewards, the flowers not only produce more nectar,  but are often clumped or in spikes to increase their attractiveness.
Dusky Honeyeater Myzomela obscura, on Grevillea sp., Darwin.
Such flowers tick all the boxes to attract bird pollinators.

It would of course be no good for the plant to give a bird all the nectar it wants - the whole point is to send it off, with a pollen shipment, to another flower. In fact most bird-pollinated plants seem to produce approximately 5-20% of a bird's daily needs. A bird can dip into over 50 eucalypt flowers per minute, compared with a bee's maximum of about six. 

Important work done by David Paton of Adelaide University back in the 1970s, on New Holland Honeyeaters Phylidonyris novaehollandiae in the heathlands of central Victoria, showed the importance of nectar to such species.
New Holland Honeyeater with Calothamnus sp., Cape le Grande NP, Western Australia.
Note the pollen on its forehead.
Paton discovered that the birds relied on nectar as their key energy source; their abundance, breeding success and physical condition all depended on nectar abundance and distribution. They needed small flying insects as a protein source, but could get all they needed in ten minutes, even if at an energy loss. Their energy requirements however demanded several hours of foraging a day. Very good news for the plants!

Australia seems to have an inordinately large number of bird-pollinated plans compared with other areas. Over a thousand Australian plant species are known to be visited by over 100 bird species; in Europe and North Africa there appear to be none at all, and in North America just a handful. The honeyeaters, the largest Australian bird family with some 70 species (some 10% of the bird fauna), are predominant.
Eastern Little (or Brush) Wattlebird Anthochaera chrysoptera, on Banksia serrata,
south coast New South Wales.
Western Little Wattlebird Anthochaera lunulata on Banksia speciosa,Esperance, Western Australia.

Scarlet Honeyeater Myzomela sanguinolenta on bottlebrush, Callistemon sp.
Cape Hillsborough NP, Queensland.
Other groups are also significant however, notably the lorikeets, small brightly coloured nomadic parrots which often descend in flocks.
Musk Lorikeet Glossopsitta concinna, on Eucalyptus leucoxylon, Coles Bay, Tasmania.
Rainbow Lorikeet Trichoglossus haematodus, Rosedale, New South Wales.
Many other Australian groups take nectar to a significant degree, though are not as single-minded as honeyeaters and lorikeets; they include silvereyes, woodswallows, other parrots, thornbills and pardalotes. 
Silvereye Zosterops lateralis on Callistemon, Canberra.
(From the balcony outside my study window in fact!)
In Africa the obvious nectar specialists are the glittering sunbirds, 130 species of nectar-lovers (some of which are Asian, with one in northern Australia). They resemble some of the smaller long-billed Australian honeyeaters to a surprising degree - but we ought not to be surprised, given their very similar lifestyles.
Scarlet-chested Sunbird Chalcomitra senegalensis, Entebbe Botanic Gardens, Uganda.
This species ranges across most of Africa.
And of course in the Americas, especially the Neotropics, are the superb hummingbirds, nearly 350 species of superb aerialists, the ultimate hoverers. Some of them are specialists in just one plant species, or a few closely-related ones, to a degree not found elsewhere. This of course is a plant's dream.
Sapphire-vented Puffleg Eriocnemis luciani, El Cajas NP, high Andes, southern Ecuador.
This one is almost cheating by perching to feed! I can (after many attempts) offer you
a couple of examples of hummers feeding more typically, hanging implausibly in the air in front of the flower.
Green Violetear Colibri thalassinus on Nicotiana flowers, near Cusco, Peruvian Andes.

Bearded Mountaineer Oreonympha nobilis, also near Cusco, and also on Nicotiana.
This one is much less common, being limited to the southern Peruvian Andes above about 3000 metres.
While less bird species than insects are involved in pollination on the part of both plants and animals, in the southern hemisphere in particular they are a key part of the fabric. Keep an eye out for them - it really is a great story!

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Monday, 28 July 2014

On This Day, 28 July; Peruvian Independence Day, Cocha Salvador

On this day in 1821 the Argentine General José de San Martín, having led the Army of the Andes (comprising Chileans and Argentinians) to victory in Lima over the last significant Spanish stronghold in South America, declared Peru to be independent. True independence actually took a little longer, but this is the day of national celebration every year. I'm not going to attempt an overview posting on Peru here - apart from anything else there is so much of the country that I've not yet seen. 

Instead I'd like to draw your attention to this wonderful country today by introducing you to just one magnificent and remarkable lake, deep in the Amazon basin. Cocha Salvador is a very large oxbow lake, a former great bend of the Manu River cut off by floods and now forming a deep still backwater with rainforest down to the shores.
Primary rainforest on the shores of Cocha Salvador.
The Manu Reserved Zone is a vast wilderness within the Manu Biosphere Reserve, inhabited by indigenous people and only otherwise accessible to researchers and visitors accompanied by authorised and environmentally trained guides. Cocha Salvador is in this reserve, not in Manu National Park as often claimed in web sites of companies who go there - the park itself is closed to all visitors except authorised researchers. It is near to Machiguenga Lodge, owned and operated by the Machiguenga people. I have to say that last time I was there the project was not thriving, but I'd love to be told that things have improved since then.

The lake is accessible by boat along the river, then a short walk through the forest before embarking on simple heavy rafts, poled along; only one group at a time may be on the water, by booking through the Parks Service. 

We arrived at dawn for a highly memorable excursion.

Sunrise over Cocha Salvador.
The key aim of any visit to Cocha Salvador is to encounter one of the most impressive, and rarest, big mammals in South America. The big oxbow lakes - and they are few - are key habitats for Giant Otters Pteronura brasiliensis, an endangered species across their northern Amazon Basin range. Heavy hunting for skins has reduced its numbers to no more than 5,000; it is listed as Endangered. Even in remote Manu it is estimated that only a dozen families survive. One of these is in Cocha Salvador.
Giant Otters really are big - up to 1.8 metres long and weighing 30kg, though in pre-hunting days much larger individuals were reported. They are highly social, unlike most other members of the weasel family, and each animal may eat up to 3kg of fish a day, so large rich hunting grounds are needed.


They are also highly vocal, and their squeals, whistles and whining calls help to locate them.

They are far from the only large animals in the water though, and there is an ongoing struggle with the Black Caimans Melanosuchus niger, the largest member of the alligator family, which can grow to five metres long. Both otters and caiman prey on each others youngsters; the otters will also team up to attack larger caiman.
Big Black Caiman, Cocha Salvador.
Waterbirds are also abundant, especially in the forest fringes.
Amazon Kingfishers Chloroceryle amazona hunt from perches. These are
large kingfishers, up to 30cm long. This is a male.
Tiger-Herons are a secretive group of herons, sometimes regarded as the most primitive of living herons.
Fasciated Tiger-Herons Tigrisoma fasciatum are widespread in northern South America and Central America,
but are most readily seen in quiet backwaters such as Cocha Salvador.
This is a young bird.
Unlike the tiger-herons, Great Egrets Egretta (or Ardea) alba - or perhaps a complex of closely related species - can be found throughout the world. They are always a delight, even in remote places where rarer birds are also on offer.
Limpkins Aramus guarauna are always exciting to see, as the sole member of their family. They live on
big water snails, and gained largely unrecognised exposure by providing the call of the
Hippogriph in the Harry Potter movies.
And it's not often you can see two single-member families in one morning's outing (bird-nerds value
such things!), but we managed it on Cocha Salvador. Sunbitterns Eurypyga helias are not bitterns at all; their
closest relative seems to be the enigmatic Kagu of New Caledonia.
Muscovy Duck descendants can be seen in farmyards throughout the world, but their
wild ancestors Cairina moschata can generally only be encountered now in remote Amazon waters.
(Their odd name incidentally has nothing to do with Moscow, but was a reference to the supposed
musky smell of the meat.)
Dead trees in the water support big colonies of hanging nests, belonging to Yellow-rumped Caciques Cacicus cela, common members of the icterid family - the 'North American blackbirds' whose ancestors crossed south on the Isthmus of Panama a few million years ago.
Yellow-rumped Cacique colony (above) and an owner-builder (below).
 

And on the way back to the basic wharf, don't forget to keep an eye into the tree-tops - monkeys are a highlight of the Amazon.
Colombian Red Howler Monkey male Alouatta seniculus; their pulsing roar, like a great wind,
is one of the sounds of the Amazon for me.
So, Happy National Day to my Peruvian friends - and thank you for sharing Cocha Salvador with me!
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Thursday, 24 July 2014

The Pollination Story; part 3, specialising

This is chapter 3 in the fascinating - to me anyway! - story of pollination; see here for the previous episode. It didn't take plants long, in evolutionary terms, to devise numerous ways, visual and chemical, to be more obvious to compete with their neighbours for the essential insect pollinators. We looked at some of these strategies last time.

Another is to put out advertising hoardings - "get your lovely fresh energy-enhanced nectar HERE!" - in the form of nectar guides on the petals, to direct their customers straight to the source. They weren't the last advertisers to assume that their clients weren't bright enough to work things out for themselves!
Alpine Gentian Gentianella muelleriana, Kosciuzko National Park, New South Wales.
Pelargonium rodneyanum.
Lilac Lily Schelhammera undulata, Family Colchicaceae, Budderoo NP, New South Wales.
We see these as contrasting colours, and it's likely the insects do too, but it's not safe to assume that a butterfly sees the same colours that we do - it probably doesn't in fact. For instance many, perhaps most, insects can see much shorter wavelengths than we can - once they get shorter than what we interpret as violet, we just lump them all as 'ultraviolet', but if a butterfly could speak it would probably have names for another half dozen or so colours that we could never imagine. By viewing flowers under ultraviolet light we can see nectar-guide streaks otherwise invisible to us - but we still have no way of seeing what a butterfly or wasp sees. 

But all this was but a prelude to more and more sophisticated specialisation - after all the point is not just to have the pollen taken from you, but to be reliably delivered to another flower of the same species. Colour is one way of narrowing the field of overlap with competitors; insects see best at the yellow-blue end of the spectrum. Another is petal number (and for current purposes I'm using 'petal' loosely to include both petals and sepals). Some insects can in fact 'count' to some degree, so a major direction was towards reducing the number of petals and keeping them constant; insects learnt to associate these petal numbers – 'iconic numerals' – with a favoured food source. This was a big step forward from earlier flowers with no regular shape, and varying numbers of petals clustered randomly. It led to flat flowers with set petal numbers.

The next major move was into three dimensions - ie a tubular flower like a Daffodil or Correa. It not only excludes most pollinators - ie assisting the goal of specialising - but more accurately guides the pollinator past the flower's sexual organs. 
Brachyotum quinquenerve Melastomaceae, Manu NP, Peru.
So far, all the flower shapes I've considered have been radially symmetrical ('actinomorphic') - ie any line drawn across the flower will divide it in half. This limits the potential for variation.
Correa barkeriana Rutaceae, Barren Grounds NR, New South Wales.
The next stage of complexity was to a flower that is bilaterally symmetrical - only one line, down the middle, can divide it in half.
Wedge Pea Gompholobium huegelii, Canberra, is relatively simple.
Carousel Spider Orchid Caladenia (Arachnorchis) arenicola Perth, (below) is more complex.
In each case only one pair of mirror images can be obtained, by running a line down the
centre of the front of the flower.
The advantage of this may not be immediately obvious, but it removes the limitations on flower shape variations imposed by the requirement that the flower has to be uniformly shaped. Evolution can now tweak infinitely by altering the top or bottom of the flower without changing the other, or by changing each differently.

So, why not free yourself entirely of restrictions on variation by having no symmetry? It is intriguingly rare, but apparently some tropical bird- and bat-pollinated flowers have indeed taken this path. Unfortunately I can't offer you any examples, and any help with finding some would be greatly appreciated! 

Next time, a whole new suite of bigger and better customers!

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Monday, 21 July 2014

As You Lake It

Having a couple of other matters demanding attention at the moment (ones more related to earning a living than is writing a blog post!), I thought to take the easy way out and just offer you some hopefully attractive pictures of some lakes. Inevitably I soon starting thinking more about lakes, and what they are, so my offering has become a bit more than just a series of images, and hopefully is more interesting for that.

A lake is of course a body of water, though there is no consensus as to just how big (ie how large it has to be to graduate from being a mere pond or pool); different suggestions range from a couple of hectares to 40 hectares. It can't be connected to the sea (so is usually, but not necessarily, fresh water), and is land-locked except for an inflow and outflow channel, though these are optional. However, there are several kinds of lake, based on origins and flow characteristics.

While less obvious in Australia (where we tend to be a bit light on with regard to water anyway), lakes originating with glacial activity, past or ongoing, form a substantial portion of the world's lakes, so let's start there. Glaciers can gouge out hollows which later fill with water, or dam valleys with moraine material left behind as melting glaciers retreat.
Dove Lake and Cradle Mountain, Tasmania.
Tasmania underwent major glaciation during the last glacial period, far more than did the mainland.
Lake Cootapatamba, Kosciuszko National Park, New South Wales.
These southern alps also had minor glaciation until 10,000 years ago, and Cootapatamba
derives from that. It is Australia's highest lake.
El Cajas National Park, in the high Andes above Cuenca, central Ecuador, is studded with glacial lakes,
above and below. The altitude here is over 4000 metres above sea level.

Further south, glaciers are still very much a part of the Andean landscape, and glacial lakes abound.
Lago Todos de los Santos near the Argentinian border with Chile,
east of Puerto Varas.

Lake in the high pampas, Andes east of Coyaique, Chilean northern Patagonia.
Further south still, the mighty peaks of Torres del Paine National Park in far southern Chile are not part of the Andean chain, but are actively glacial and at their feet are some superb lakes.
Lago Nordenskjold, Torres del Paine National Park.
In front of the towers (above) and with wind ripping the surface from the water (below).


In Australia, in the arid inland, many lake are endorheic - that is the flow is only into the them, and they are dry much more often than not, though they are based on vast ancient rich lake systems, with flamingoes, fresh water dolphins and crocodiles not so long ago. Mostly they are salty, because of ongoing evaporation.
Lake Amadeus, near Uluru, central Australia.
Part of a vast 'fossil' lake system, 500km long and covering 1750 square kilometres.
Lake Gilles, South Australia, in its normal state (above)
and as much more rarely seen (below, in September 2013).
Waterholes, often called oxbows, or billabongs in Australia, form when a river changes course - as often happens during floods especially - and the old bed is cut off from the main stream and fills during times of overflow from the new bed. In arid Australia such waterholes can also form in the main bed which very rarely flows, but deep holes retain water for considerable time; they are critically important to life in desert landscapes, and can have their own endemic fish and invertebrate species.
Combo Waterhole near Winton, north-western Queensland.
(It was here that the great Australian bush poet and journalist A.B. ('Banjo') Paterson was inspired
to write Waltzing Matilda, sometimes thought of Australia's 'other national anthem'.)
Cocha Salvador, Manu National Park, Amazonian Peru, at dawn.
A large oxbow lake.
Volcanic craters can fill with water to form sometimes large lakes.
Crater Lake near Kibale, Uganda.
Larger crater lake, Queen Elizabeth National Park, Uganda.
And while in that part of the world, many of the great east African lakes are formed on the great rift which is splitting Africa. Such lakes are unusual in that they are getting deeper faster than siltation can fill them up.
Lake Edward, Queen Elizabeth NP, Uganda (above)
and Lake Victoria, Entebbe, Uganda (below).
Two mighty rift lakes.

Fresh-water lakes can form in the dips behind sea dunes.
Meroo Lake, south coast New South Wales.
And unlikely as it seems, sand can support lakes well above sea level, though it is unusual. Some famous examples, 40 or so of them, are on Fraser Island, off the southern Queensland coast.
Lake Mackenzie, Fraser Island, a perched lake on sand.
So, a brief review of some lakes I have known... I hope you enjoyed the journey too.

PS I've just realised that this is the first posting ever by me without a named plant or animal, so I should rectify that.
Chilean Flamingoes in glacial lake in front of the Towers, Torres del Paine NP.

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