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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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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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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The Pollination Story; part 2, getting noticed

This series started recently here, with the beginnings of the great pollination partnership between flowering plants and animals. From early on in the development of the partnership, competition was strong between neighbouring plant species for the services of the insects that were already being trained to associate the flowers' scents and 'flags' - petals and sepals - with an energy reward. How to be more noticeable? A very simple one is for flowers to be held high over a low-growing plant.

Silky Swainson-Pea Swainsona sericea Fabaceae, south of Canberra, a threatened species.
The flowers are waved high above the ground-clinging foliage.

Another way of course is to have huge flowers, but that's pretty risky - a single flower can be damaged by weather or by animals interested in eating it rather than seeking its nectar. A better solution is to have lots of little flowers clustered; such a cluster can last a long time by having successive flowers open over a period of time, and the loss of individual flowers is of no moment. Here are some common Australian examples, but you'll know of plenty of equivalents, wherever you live.

Firewood Banksia Banksia menziesii, Badgingarra NP, Western Australia.
As with many flower spikes, the hundreds of flowers here are opening from the base - the top half
of the spike presently comprises buds.

Rose Banjine Pimelea rosea, Cape le Grande NP, Western Australia.

Raspberry Jam Tree Acacia acuminata, Christmas Rock Nature Reserve, Western Australia.
In wattles the true nature of the flower balls or spikes is best seen in the buds, before the
numerous stamens hide the individual tiny flowers.
(The common name is from the astonishing scent of the cut wood.)

Candles Stackhousia monogyna Stackhousiaceae, Canberra.
A very common spring flower round here; the spikes are far more obvious than the individual small flowers.

The most familiar such clusters of flowers however are found in the daisies. The 'basic' daisy flower is a cluster of hundreds of tiny florets growing from a common base.

Billy Button Craspedia sp., Namadgi National Park, above Canberra.

However many other daisies have taken this sleight of hand a step further by adding 'petals', often in contrasting colours, around the head of florets. These 'petals' are in fact sterile florets whose sole purpose is to draw attention to the fertile disc florets.

Olearia tenuifolia, Mount Tennent, south of Canberra.
The purple sterile ray florets contrast dramatically with the fertile yellow disc florets.

Yet other daisies utilise colourful papery bracts - modified leaves - instead of ray florets to make the tiny disc florets more conspicuous.

Alpine Paper Daisy Xerochrysum subundulatum, Kosciuszko National Park, New South Wales.
The bracts are stiff and shiny (hence the common name).

Other unrelated plant groups have arrived independently at the same solution, with often dramatic results.

Flannel Flower Actinotus helianthus Apiaceae, Pilliga NP, New South Wales.
Here the tiny flowers can be clearly made out if the picture is enlarged, surrounded by
soft 'flannel-like' bracts.

Waratah Telopea speciosissima Proteaceae, Budderoo NP, New South Wales.
Like the related banksias, waratahs have numerous clustered flowers (though seated on a flat
disc rather a spike), but have gone further, with the big red leafy bracts to make them even more obvious.
(This is the state flower of New South Wales.)

Royal Hakea Hakea victoriae Proteaceae, Fitzgerald River NP, Western Australia.
This is an amazing plant, growing metres high in the heathland (see below); the small white flowers (here
represented by the woody fruits) are hidden down among the leathery cabbage-sized leaves,
whose bright colours draw attention to them.

Royal Hakeas in the landscape, Fitzgerald River NP.
The species only grows in this park, one of the most botanically diverse places on earth.

So far we've looked at multiple flowers - inflorescences - but I'll end today with a couple of examples of single flowers which have taken unusual evolutionary steps to become more visible.

Pigface Carpabrotus sp., Kalbarri NP, Western Australia.
The fertile stamens are in the centre of the flowers. There are no true petals - the numerous 'false petals'
are staminodes, sterile structures derived from stamens which are playing the part of petals to increase visibility.
(The fruiting structure, not seen here, is alleged to resemble a pig's head...)

And lastly, perhaps if we wanted to draw attention to plane flying overhead, we might flash a mirror. It seems that the familiar buttercups, members of an ancient flowering plant group, are doing just that!

Buttercup Ranunculus sp. Tallong, New South Wales.
The shiny petals are due to a layer of reflective subsurface cells.

Next time, we'll explore how individual flowers became more complex, to distinguish themselves from their neighbours of other species.

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