Too hot to handle?

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Although echidnas are pretty common, I’ve rarely seen seen them in Berowra.  So when I saw this one flopped out in the neighbours’ front yard on my sweaty walk home from work yesterday – ambient temperature in the mid 20s even at 7pm – I was worried.  Were echidnas, like fruit bats and stingless bees, troubled by temperature extremes?  Had this one been driven from its usual secluded haunts by this horrid heat wave?  Should I be on the blower to WIRES?

A cursory google did not inspire confidence.  Wikipedia notes that echidnas don’t sweat (in fact, they don’t pant, lick, or even wee on themselves and flap their wings to cool off either) and suggests that they “cannot deal with heat well“.  WIRES agrees that echidnas “cannot tolerate temperatures above 30 degrees“.

Notwithstanding, this seemed to be a very sprightly monotreme.  Most of the echidnas I’ve met have more or less fixed this position:

This beastie, however, was very busy, ignoring me and rummaging around in the flowerbeds.  Could it really be in trouble?  I decided, for the moment, that human intervention wasn’t necessary and then went home to check whether I’d just made a stupid decision.  Should I trust Wikipedia or my instincts?

I hit pay dirt when I found “Thermoregulation by Monotremes” by Queensland’s “Mr Hot Echidna”, Peter Brice.  As a researcher who has devoted time to  inserting “calibrated temperature sensitive radio-transmitters … coated with a smooth layer of inert wax… into the abdominal cavities of echidnas” (Brice et al 2002), he’s your go-to guy on this topic.

Niche subject as it might seem, the way echidnas and platypuses manage their body temperature has played an interesting role in propping up a hierarchical, human-centred view of evolution.  You’ve heard the story before, I’m sure. From this viewpoint, animals whose bodies are set up differently to us fancy-pants “classic mammals” are viewed as “primitive”.  Early twentieth century researchers decided that, for instance, that playpus had “an inadequate regulating mechanism” when after only 17 minutes at 35 degree temperatures, their research subject  “turned onto its back and fainted” (Brice, 2009, 260).  A poignant tale and the sort of thing that led one early twentieth century researcher to conclude that monotremes were “‘the lowest in the scale of warm-blooded animals’” (Brice, 2009, 256)

Don’t get me wrong, echidnas are very weird animals.  And that’s leaving aside the egg laying mammal business and the once-venomous spurs in their backwards facing hind legs.

Echidnas are cool. 31 degrees counts as a “normal” body temperature for them, though only females incubating eggs really keep their temperatures steady for long.  They seem to occupy a half-way house between warm blooded and “cold blooded” animals.  Echidnas don’t entirely rely on their surrounding environment to warm themselves as reptiles – ectotherms – do.  But unlike us humans – homeothermic endotherms – with our tedious need for a stable and predictable body temperature – echidnas can run hot or cold.

Just when you thought we were all “thermed”-out, you find that echidnas are also constitutional eurytherms – they can handle wide range of temperatures – and facultative endotherms – they warm their bodies up, in part, by doing stuff.

Echidnas also hibernate – well, some of them do, if they’ve eaten enough by the time the cold weather rolls in. But their hibernation, or its timing at least is, according to Brice (2009, 257) “distinctly odd”.  They often kip out during the late summer and then wake up to mate at coldest part of the year.  And they can deal with fluctuating temperatures in a way I can only envy – for instance, after a chilly night, they can dig their way out of shelter with their blood temperature of only twenty degrees.  With no bedsocks.

And they can also deal with a day spent in a hollow log at 40 degrees C without expiring from the heat, though no one knows exactly how.

We shouldn’t seeing echidnas and their wildly fluctuating temperatures as primitive, I reckon. Instead we should admire the way these critters harbour resources with their furry but weirdly chilly bodies, helping them live above the snowline in the Alps, in the desert and even on the sizzling streets of deepest surburbia.

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Echidna, close up and personal

References

Brice, Peter H. (2009) “Thermoregulation in monotremes: riddles in a mosaic” Australian Journal of Zoology, 2009, 57, 255–263

Brice, Peter H., Gordon C. Grigg, Lyn A. Beard, Janette A. Donovan (2002) “Heat tolerance of short-beaked echidnas (Tachyglossus aculeatus) in the field” Journal of Thermal Biology 27(6), 449-57

Happy Easter from Morgan the syncretic leghorn

We have pommie chooks!  Or from somewhere north of the equator, anyway.  I’m not sure how they managed to make the perilous transcontinental journey before their cute fluffy butts made it to our place at a week old, but somehow they must have dodged border control.

4 fluffy butts horizontal crop

How do I know our feathered friends come from the far north?

Well, here in Sydney, we’re past the equinox and the nights are drawing in.  We may have had a February that smashed heat records, 1.3 degrees C above the longterm averages.   But it’s hours of daylight that tells chickens when to get laying (thanks to that sort-of-third eye) and the days are getting shorter.  Even as the world goes to hell in a handbasket, it is, nonetheless, autumn.

And yet my chooks have decided to start laying.  Just in time for spring with its baby bunnies, and peeping chicks, and Easter eggs, and its celebration of rebirth and renewal.  In the northern hemisphere, that is.

I love Easter.  Most religious festivals are a delicious mish-mash of stuff from the Big Book and whatever else people were into at the time.  But with Easter the syncretism is really out there, bouncing around with its ears pricked up, laying  coloured eggs in the spring greenery.  After witnessing the pre-Good Friday panic by shoppers terrified by the prospect of a day without ready access to a new packet of Cocopops, the nice young guy at the checkout reckoned  we might add a zombie apocalypse to the usual combo of vernal equinox, Passover, and frenzied confectionary consumption.  As he pointed out delicately, Jesus did after all, come back from the dead.

In the midst of this cultural mash-up, it seems appropriate that it’s Morgan the flighty leghorn, named after a Welsh enchantress in an Arthurian legend, who has marked the occasion of the (deeply seasonally inappropriate) Christian festival of rebirth with the gift of her first lovely white eggs.

A muddled pagan blessing to egg eaters, one and all.

 

Autumn in terminal decline?

In amongst the nasty consequences of global warming – sea-level-rise-ocean-acidification-violent-storms-heat-waves-large-scale-extinctions (if you say it quickly and rock back and forth at the same time it doesn’t seem quite so bad) – a decline in the intensity of autumn leaf colour really doesn’t draw the eye.  Bar a few unusual plants like the red-fruited kurrajong and the Antarctic beech, most deciduous plants around here aren’t even natives.  So who cares, eh?

But as I huddle in my chilly house on its shady south-facing hillside, waiting for the leaves on the neighbour’s looming liquidambar to fall, the impact of climate change on deciduous trees seems like a tremendously pressing question.

I’m not the only one gripped by this crucial topic.  The latest  Trends in Ecology and Evolution has roundly denounced the scandalous neglect of autumn. Spring gets its own live feed on BBC TV, but even scientists get depressed by extended discussions of leaf senescence, it seems.   Garnering less than half as many articles as its greener sibling, autumn, according to the indignant authors, is a “neglected season in climate change research”.

Well, neglected no longer!  Not here in the backyards of Berowra.  Right here, right now we bring you…. in the prophetic words of Gallinat and her outraged colleagues… “the future of autumn research”.

As we march boldly into fall’s future, I’m cling to the hope that photoperiod (that’s the day-length to you and me) will rescue me from climate change, sending that winter-sun-blocking foliage promptly into the compost bin regardless of how roasting hot it is. And it’s not a vain hope – the amount of light a deciduous plant receives does seem to help many decide whether it’s time to shed their leaves or not.

In the case of liquidambar, long days or lots of light delay dormancy, as you can see from these nifty pictures of a specimen down the street, well illuminated day and night so as to minimise deaths on a local pedestrian crossing, clinging to its leaves long after its neighbours have shrugged their own.

Depressingly, it does seem that sweetgums need cooler weather to finally ditch their leaves, even in the short days of midwinter.   Photoperiod matters most near the poles – but for trees at the lower latitudes (like Sydney, curse it) temperature is the clincher.

This raises interesting questions about the future of the veggie garden. Around the winter solstice it lurks in the shade of our dawn redwood, a living fossil that grew across the temperate Arctic when dinosaurs stomped the earth, and was dramatically rediscovered in the 1940s in a single isolated valley in China.  Will its gorgeous copper needles still fall in time to give my broadbeans a decent run-up to spring when we’re wearing shorts all winter?

In the words of a Facebook status update, “it’s complicated”.  Could this be why climate scientists, like nervous singles, are staying well clear?

For instance, warmer springs lead to earlier bud burst, which can sometimes mean earlier leaf-fall.  And deciduous trees in general tend to lose their leaves more readily in dry weather.  “On average”, according to Estiarte and Peñuelas (2015) “climatic warming will delay and drought will advance leaf senescence”.  Work that one out.

And that’s not even throwing nutrient availability into the mix.  For instance, what if trees start going ballistic with all that carbon dioxide in the atmosphere?  This vision of a greenhouse planet jungle awash with joyful plants growing at breakneck speed sounds like something out of a climate denialist fantasy, doesn’t it?  “More open cut mines, pretty please!” beg the earth’s desperate forests “my future is coal!”

Sadly for the wind-farm haters, it mostly doesn’t work like that.  Carbon dioxide can give trees a flying start but eventually the nitrogen supply conks out, or drought and too much CO2 do the leaves in.  Even with the help of globe-trotting survivors like sweet gums and dawn redwoods, coal (and copious quantities of greenhouse gases) won’t make the world greener.  Let’s just hope, even gardening in our bikinis, we can still find gold.

References

  1. Estiarte, M and Peñuelas, J (2015) “Alteration of the phenology of leaf senescence and fall in winter deciduous species by climate change: effects on nutrient proficiency” from Global Change Biology 21(2) 1005-17
  2. Flexas, J, Loreto, F and Medrano, H. (2012) Terrestrial photosynthesis in a changing environment: a molecular, physiological and ecological approach, Cambridge, Cambridge University Press
  3. Gallinat, AS, Primack, RB, Wagner, DL (2015) “Autumn, the neglected season in climate change research” from Trends in ecology and evolution 30(3)
  4. Warren JM, Jensen AM, Medlyn BE, Norby RJ, Tissue DT, (2015) ‘Carbon dioxide stimulation of photosynthesis in Liquidambar styraciflua is not sustained during a 12-year field experiment’, AOB Plants, vol.7, Article no.plu074
  5. Warren, JM, Norby, RJ, Wullschleger SD (2011) ‘Elevated CO2 enhances leaf senescence during extreme drought in a temperate forest”.  Tree Physiology 31, 117-30
  6. Worrall, J (1993) “Temperature effects on bud-burst and leaf-fall in subalpine larch” Journal of Sustainable Forestry 1(2)

Timber!

We’ve had a mob of at least fifteen yellow tailed black cockatoos hanging around in the last few days, mewing like strangled cats and being chased around by magpies and (I think) even noisy minors.  We get the yellow tails quite often around these parts, especially in the winter-time, thanks to the large and sickly but apparently tasty radiata pines that loom over our place.

The rule in Hornsby Shire is you can cut down a tree that’s within three metres of the foundations of your house.  If only there was some special by-law where the council chops down the tree for you for free if you can’t slip a paperback book between a towering pine and your bathroom.  One of these days I’ll be communing with nature and the nearest treebole will swell just that tiny bit further and burst straight through into the shower cubicle. That fresh piney smell with not a cent spent on disinfectant.

It’s been very very very windy in Sydney lately, and quite a few people have been unfortunate enough to experience that piney odour, quickly followed by plenty of refreshing indoor rain. We’ve been pretty lucky, but we’ve spent a lot of time staring anxiously out the window at various ominously swaying monumental specimens.  When I lived in Brisbane I used to be a bit judgey about the lawn to tree ratio in most peoples’ yards.  But if cyclones start creeping their way down the coast I may have to reconsider.

Yellow tailed black cockatoos are doing pretty well on the east coast, including urban areas, no doubt thanks to their penchant for pines.  But apparently they often struggle to find nesting sites, preferring hollows in trees a century or more old.  They seem to like our senescent radiatas, and spend time perched high on the various dead branches voguing.  I hope, when we finally save enough shekels to pull down the extensive array of dangerous trees in our yard, we still see them.

Flowers of the Frozen North

Something new in the garden today: hazelnut flowers.  Our filberts have been in for about three years, and have produced a few catkins, but I’ve never seen these before.  They are very very tiny, though, so maybe they were there last year and I never noticed.

The miniscule red blooms are all on one tree – Ennis, “preferred variety for all markets”, Daleys boldly asserts.  Lucky Ennis.   “Hall’s Giant” sounds so much more magically productive but it’s mainly a pollinator, dangling those catkins.

Will we get some nuts this year?  It seems unlikely.  The raspberries, our little Stella cherry, three neglected high-chill apples, the Hayward kiwis, and the hazelnuts, all planted with foolish optimism. Okay, Sydney is subtropical and all these plants require a hundred plus chilling hours … that’s a hundred or maybe a hundred and fifty hours below 7 degrees C while in Sydney’s chilliest month, July, the average minimum is 8.1 degrees…. but we are at 200 metres elevation!  maybe we’re in a frost pocket! What about those chilly south-westerlies?

Our mighty leader, Anthony Abbott MP, confidently claims that “climate change is crap” so perhaps we are, as my hirsute medallion-wearing neighbour asserts, heading towards a Snowball Earth scenario: the Pacific Highway to Hornsby will be lined with snowpoles  and we will be skating, not taking the ferry, across Berowra Creek.  All my eccentric plant selections will be vindicated.

While I’m waiting for a glacier to form in the Sydney Basin, or at the very least for a small crop of hazelnuts, at the bottom of the garden the winter veggies are flowering.

The daikon is too tough to eat now, but the flowers are lovely and I’m planning to save the seeds.  The winter’s chinese greens are also in bloom.  The leaves are getting smaller, stringier and slightly bitter though I’ve still been picking them.  I’ve got a feeling these may be the mutant offspring of my favourite – red bok choi, an F1 hybrid.

The process of creating the F1s is like something from “Game of Thrones” – ten generations of in-breeding to produce a pure-blooded weaking, that is then matched with an inbred of a different tribe, to produce children with renewed vigour, sharing little with their spindly parents. These muscular cross-breeds are frustratingly incapable of passing on their all-conquering qualities to the next generation (an appropriately Machiavellian outcome that keeps gardeners in the thrall of the Plant Wizards of Monsanto). It’s kind of cool to save the seeds of the F1 hybrids not just to give the multinationals a crinkly mouth but also to see what sport comes up in the next generation.  And the next.  Who knows, perhaps eventually some robust throwback will thrive in the endless Winter?

Bok choi flowers

Bee-ing positive

Tropic snow and bee

It’s dry as a chip in the garden: less than 20% the average amount of July rainfall in Sydney and bushfires have already starting in the north of NSW, months ahead of the official fire season.  Warm too – a record 24 days of 18 degrees C and above.  It’s been 2.7 degrees C above the historical average for July.  Climate change – it’s here, suckers.

But on the bright side, gorgeous blooms on the Tropic Snow peach, and plenty of bees.  Touch wood, the varroa mite hasn’t arrived in Australia (yet) and our honeybees seem to be doing better than the rest of the world. I’m thinking about getting a hive or two, either of native stingless bees (though you can’t collect their honey here in Sydney) or just your everyday honeybees.  So far I haven’t had any flowers from my kiwifruit vines (notoriously hard to pollinate), but you have to plan ahead.

In the mean time… welcome, visiting bees!  Please help yourselves to our beautiful if precipitate peach-blossom.

Winners and weeds

A sighting in the garden today: brown cuckoo doves.  I’ve seen them here before, startlingly portly long-tailed pigeons, hanging out in the neighbours’ tangle of tall trees.  I spotted at least three today, one futilely hopping from branch to branch, doggedly followed by a stouter fella: I guess it’s breeding season.

I felt tremendously smug when I first saw this rainforest bird above my washing line.  I should have known better, having read Tim Low’s New Nature not so long ago. This is one bird doing alright out in the Anthropocene.  It’s a winner.

Brown cuckoo doves are spreading south from their usual stomping grounds.  I’m not surprised.  If I were a tropical bird, I wouldn’t mind it round Sydney at the moment: third warmest June on record, more than 2 degrees warmer than the longterm average – balmy!

And they don’t mind weeds either.  Apparently they relish regrowth around roads and logged forest, and lantana and wild tobacco suit them down to the ground.  Witness this shot of a cuckoo dove snaffling fruit from our embarrassingly giant large-leafed privet.  Privet tree.  Yes, yes, we are going to kill it off and chop it down – the Round-Up is in the cupboard… But reading Low has given me pause.  When we poison our oversized weed tree, will we lose our nifty rainforest critters too?