Nature in a Warming World

Last week there was great excitement in our part of the world when a pair of Tawny Grassbirds Megalurus timoriensis turned up at Jerrabomberra Wetlands, our prime suburban wetland in a city which is now very well-provided with such habitats.

Tawny Grassbird, Jerrabomberra Wetlands, Canberra; a newcomer moving south.

This is a notable southern and inland extension of their range from that in the field guides, which is normally regarded as coming to just south of Sydney, some 200km from here and on the coast. Individuals of any species can pop up out of range, especially following unusual weather conditions, but I’m not sure that this is the case here. In the last couple of years (but never before that) there have been at least three reports from Melbourne, on the south coast of Victoria some 600km further south again from here; I would expect that this species, if it were expanding its range, would be more likely to follow the coast rather than move inland. Moreover it is unlikely that they only selected Melbourne and Canberra over all the possible non-urban sites in areas between – it is simply that these are places with lots of bird watchers and I am sure that the bird could, and will, be found in many other places where they used not to be. The Tawny Grassbird is a skulker in dense undergrowth, and I expect (with no expertise) that outside of breeding season it is fairly quiet.

No, I am surmising that this is a response to climate change, pushing or encouraging warmer climate birds further south (as is happening in reverse in the Northern Hemisphere). 

Less than 20 years ago the Pacific Koel Eudynamys orientalis, a big dimorphic parasitic cuckoo which overwinters in Indonesia and New Guinea and breeds in northern and eastern Australia, was a very rare phenomenon indeed in Canberra, though the odd one would occasionally overshoot and lob up here for a while. Within the space of a few years it became a more and more common occurrence, until now it is a part of our urban soundscape (one is calling outside as I write). People have almost even given up writing to the paper to complain about its 24 hour a day strident serenade! They now breed here annually. There is no plausible explanation for this other than climate change. 

Pacific Koel; male (above) and female (below).

Another large cuckoo, the Channel-billed Cuckoo Scythrops novaehollandiae, has a very similar distribution and annual movements. It is still rare in the ACT (ie I’ve never seen one here yet! though a couple of weeks ago I heard one fly raucously by outside) but it too is getting commoner each year, and I judge that they will also be breeding here in years to come. 

Channel-billed Cuckoo, Karumba, north Queensland.

White-headed Pigeons Columba leucomela have steadily extended their range south from the mid-south coast of New South Wales well into Victoria in the past decade or so, though there is no doubt that part of their enablement has been the spread of exotic food trees like Camphor Laurel Cinnamomum camphora and Privet Ligustrum spp. However, the Camphor Laurel in particular is probably also being assisted to move south by the warming – nature is infinitely subtle.

White-headed Pigeon, Nowra, New South Wales south coast.

As we well know however birds are not the only organisms known to be moving in response to a warming world. A wide-ranging CSIRO study in 2010, utilising a broad array of published and unpublished data, showed that at least 45 species of south-east Australian marine fish have exhibited “major distributional shifts” which were almost certainly climate-related. Warmer water fish from both further north and west have moved into formerly cooler Tasmanian waters, inevitably displacing local species. 

Nor is it even just animals. In a remarkable study begun in 2003 in the Manu Biosphere Reserve in the Peruvian Andes east of Cusco US ecologists Miles Silman and Ken Freeley banded and measured 14,000 trees of 1,000 species in 14 plots covering 2,400 metres of altitude. After repeat measurements they discovered that an astonishing 85% of tree genera were moving upslope in response to warming at a rate of 2.5 to 3.5 metres per year. Perhaps the most pertinent aspect of this however is that the authors estimate that this rate would need to double for the trees to keep pace with the observed warming. (The link above will take you only to an abstract unless you're a subscriber; see here for an overview.)

Cloud forest, Manu Biosphere Reserve, in the area that Silman and Freeley are monitoring.

Studies of 175 plant species in six French mountain ranges similarly showed that 118 of them – nearly 70% – had moved at least 18.5 metres (ie 60 feet) up the slope per decade over the twentieth century.

And here of course is the rub; once the Tasmanian cool water fish reach the southern limits of that island (these are coastal waters fish, they can’t just swim out to sea), and the Manu trees reach the treeless puna, the high cold treeless mountain steppes, there is nowhere further to go. It is the same dilemma facing Polar Bears in the Arctic and Mountain Pygmy-Possums on the top of the south-east Australian Alps.

But this isn’t the only observed forced reactions of species; there are numerous data sets concerning changes in phenology characters – that is cyclical, especially annual, events such as breeding and migration. As far back as 2003 a wide-ranging review in the prestigious journal Nature revealed “significant mean advancement of spring events” by 2.3 days per decade. Five years later the Intergovernmental Panel on Climate Change’s 2007 report reported that the arrival of spring had been advanced by up to 5.2 days per decade over the past 30 years. Examples cited ranged from first and last appearance of leaves on Gingkos (G. biloba) in Japan, to butterfly emergence in Britain, to bird migration in Australia. 

Gingko leaves, Canberra.

A wide-ranging Australian review, published in 2013, of 89 studies of 347 plant and animal species showed even stronger responses for plants here than in the Northern Hemisphere; the mean rate of advance across all plant responses (leaf set, fruiting, flowering etc) was 11.3 days per decade! Spring migration departure of birds moved forward by 2.2 days per decade (slower than for the Northern Hemisphere, where it was 3.7 days per decade). I mentioned in a recent post how peak flowering of a dominant sub-alpine shrub in the Brindabella Ranges above Canberra has shifted over the 30 years I’ve been taking people up there from about a week into December to late November.

Leafy Bossiaea B. foliosa, Mount Ginini, Namadgi National Park, near Canberra.
Over the past 30 years I have seen the average peak flowering of this pea shrub advance by nearly two weeks.

One of the problems with this is that, naturally enough, each species has a slightly different response to the changes, so that finely-tuned systems are no longer functioning as they evolved to do. Bird chicks are hatching before their key caterpillar food supply does, migratory birds including hummingbirds are arriving before or after the flowers they pollinate are open. In the high alps of south-eastern Australia the already Endangered Mountain Pygmy-Possum Burramys parvus emerges from its hibernation with the snow melt – which is getting earlier each year. Unfortunately the great Bogong Moth migration to the high cool granite crevices of the alps is not getting earlier, which leaves the hungry emerging possums without a key food source.

There are thousands of such phenological studies available, in full or in abstract, or in third-party reports, out there if you’re interested.

In recent times a third general response has been suggested, and demonstrated. While obviously there are always multiple factors acting on the life and evolution of any given organism, we know that in general body size of a given species is likely to be smaller in populations further from the poles – ie in warmer climes. This is known as Bergmann’s Rule and the basis of it is that a smaller object (be it bird, or ball or human baby) has a proportionately greater surface area than a larger one, and thus loses heat faster. We know this for populations of the same species at different latitudes, but what about the same species at the same latitude as climate changes – ie the environment gets steadily warmer? A treasure trove of such data is held in museum specimens throughout the world.

Janet Gardner of the Australian National University, and colleagues, measured 517 museum skins of eight insect-eating birds, collected over 140 years from 1869 to 2001. Six of the species showed a decrease in size since 1950, four of them being statistically significant. The overall impact for those four bird species is that individuals living now at the latitude of Canberra are the size that members of their species were pre-1950 at the latitude of Brisbane (ie 7 degrees of latitude). This I find very striking. Nor is it simply academic - a change in size of even just 4% (as measured in wing lengths by the study) can affect what a bird eats, and thus what it it competing with and must thus further adapt to.

Birds that are getting smaller as temperatures rise.
Brown Treecreeper Climacteris picumnus, Canberra (above);
White-browed Babbler Pomatostomus superciliosus Shark Bay, Western Australia (below).

Nature, as I have observed before, is never as straightforward as our little brains might like. More recently apparently conflicting results from those of Gardner’s team were obtained from south-west Western Australia for wing-lengths of Ringneck Parrots Barnardius zonarius (‘Twenty-eights’, for their call, as the sub-species is known over there), which had increased by 4-5mm over the past 45 years. Tellingly, birds from further north in the state, and from the Western Australian eastern deserts, where temperatures haven’t risen as much, show no such increase. The change is as significant as those of Gardner’s were, but in the opposite direction. There is no reason to suppose however that all species in all situations will respond identically to similar situations, and the author suggests that the parrots might be growing longer wings to assist in heat dispersal, in accord with Allen’s Rule.  

Twenty-eight Parrot, Cervantes, Western Australia.
Longer wings to stay cool?

Only ten years ago such responses to climate change were only guessed at, and there will be more surprises to come. One such, which has no obvious explanation for now, is the case of the Eurasian Scops Owl Otus scops, which comes in two colour forms, dark-reddish and pale-reddish (and intermediates). Italian museum studies showed that the proportion of dark-red forms increased significantly over the last century. Some of that was due to unknown causes (perhaps an increase in Italian forests over that time, where being darker could be advantageous, suggest the authors) but the rest is apparently down to climate change. At this stage the best explanation is that the gene for dark-red is linked to one that confers an advantage in a warmer world, but so far we can only speculate.

Eurasian Scops Owl, pale-reddish and dark-reddish forms.
Illustration taken from Handbook of the Birds of the World, which refers to them as
grey-brown and rufous-brown morphs.

I am no more interested in arguing about the reality of climate change than I am in debating whether gravity exists or if the sky is blue. It does occur to me though that it would be interesting to hear from someone who has chosen to believe in a fabulous world-wide conspiracy of thousands of scientists, to explain how thousands of species of plants and animals were also persuaded to participate in the deception.

BACK ON THURSDAY
(today I posted a day early, as I'll be away tomorrow)

 (And remember that you can get a reminder when the next post appears by putting your email address in the Follow by Email box in the top right of this screen.)

"I Love a Sunburnt Country"

While my overseas readers will probably have no reaction to that line, I'm sure my Australian ones will recognise it immediately. It is the first line of the second verse of a poem called My Country, written in the first decade of the 20th Century by a young Australian called Dorothea Mackellar who was travelling in Britain and Europe. It is in the form of one side of a conversation with someone who loves the misty European countrysides, acknowledging that love while expressing her own passion for the harsh extremes of Australia. She was from a wealthy Sydney family, but spent formative time on family property in the mid-west of New South Wales. The poem caught the Australian imagination and was widely printed in newspapers. It has been put to music more than once  - most recently, and somewhat mind-bogglingly, by eminent Australian composer Elena Kats-Chernin for the Vienna Boys Choir! I recall  singing a version at primary school, though I can't determine what the origin of that tune was. To many of us it's still an unofficial national anthem. (To many of us too, that's no bad thing as the official one could plausibly be described as a dirge-like tune accompanied by words that range from archaic-weird to not-quite-as-good-as-banal. That's a subjective view of course...)

Superb Lyrebird Menura novaehollandiae, Fitzroy Falls, New South Wales.
Presumably singing his own anthem.

This is a week which began with Australia Day, commemorating the day in 1788 that a small armada arrived in Sydney harbour to found a convict colony and claim the entire country for Britain, regardless of the fact that it had already been fully occupied for some 50,000 years. For obvious reasons this a pretty divisive day here. As I have implied numerous times in this blog's postings, I never cease being profoundly grateful for my ridiculously undeserved luck at being born in this remarkable land. 'Pride' however would suggest taking credit for things I'm only the beneficiary of, not responsible for. And that good fortune carries, for me, an obligation of stewardship, and my periodic criticisms of actions which damage the land and our society stem directly from my passion for it. You can't claim to love someone or something if you stand back while it's being assaulted.

Anyway, enough of that. I thought it might be fun to illustrate, line by line, at least the second and third verses of My Country, from my own perspective. (The whole thing is worth reading and some of it is surprisingly modern.) The first verse is her acknowledgement of her imaginary English conversation companion's love of softer climes, the last three talk about the recovery of the land from drought when the rains come. The "droughts and flooding rain" reference is a perfect summary of the El Niño nature of our climate.

I love a sunburnt country,

West MacDonnell Ranges, central Australia

 A land of sweeping plains,

Theldarpa Station, far north-western New South Wales

Of ragged mountain ranges,

Musgrave Ranges, Northern Territory-South Australian border

Of droughts

Droughted Mitchell Grass plains, west of Boulia, far western Queensland

                       and flooding rains.

Kalbarri National Park, Western Australia

I love her far horizons,

Lake Eyre South, South Australia

I love her jewel-sea,

Head of Bight, South Australia

Her beauty and her terror - 

burning spinifex at night, Uluru National Park, Northern Territory.

 The wide brown land for me!

Castle Hill and Chambers Pillar on the horizon, Northern Territory.

A stark white ring-barked forest

All tragic to the moon,

            (Well, like all of us she was a person of her time - I don't need to illustrate this bit though!)    

The sapphire-misted mountains,

View from Mount Kosciuszko, New South Wales.

The hot gold hush of noon.

Illyarrie Eucalyptus erythrocorys woodland, South Beekeepers Nature Reserve, Western Australia.

Green tangle of the brushes,

Monsoon forest, Litchfield National Park, near Darwin, Northern Territory.

Where lithe lianas coil,

Chichester State Forest, New South Wales.

And orchids deck the tree-tops

Bulbophyllum (or Oxysepala) shepherdii, Nowra, New South Wales.

And ferns the warm dark soil.

Tree Ferns Dicksonia antarctica, Monga National Park, New South Wales.

And there I shall leave Dorothea - and you - and come back to a more conventional posting next time. Thanks for bearing with me!

BACK ON TUESDAY

On This Day, 5 January; the big wet

As I write this, it's 38 degrees C outside (and in my study!), about 10 degrees above our long-term average maximum for January. In many places in south-eastern Australia it's well over 40 at present. There's not much rain around, and numerous fires are burning. From down here it's hard to imagine that on this day in 1979 Mount Bellenden Ker, behind Cairns in tropical Queensland, received 1140mm of rain in 24 hours! That month they got 5387mm (ie over 5 metres); their annual average is 8500mm. (Across Australia the average is 165mm...) Mind you, parts of the western slopes of the Andes in north-west Ecuador and south-west Colombia get double that each year.

The mountain was named by Phillip Parker King, for a curious character called John Bellenden Ker, editor of the Botanical Register in London. He was born John Gawler, but at the age of 40 sought and received royal permission to change his name to John Ker Bellenden; having achieved his odd aim, he proceeded to call himself Bellenden Ker... Please don't ask me. He did however get this rather nice Tasmanian shrub named for him.

Bellendena montana, family Proteaceae, Ben Lomond NP, Tasmania.
These are the fruit.

Meantime we await a bit of rain - not a metre preferably! - down here.

Spotted Catbird, (near!) Mt Bellenden Ker.

Back Monday.

Spring Wildflowers 1

One of the things that makes the Canberra region a joy for natural historians is its seasonality; of course all of Australia has seasons of varying contrast, but not much of the continent has such a sharply defined winter-spring changeover. In this it has somewhat more in common (though of course less harshly) with northern Europe, Asia and North America than even with the nearby NSW coastal habitats. As to when spring starts, that can spark a surprising intensity of debate. For reasons I don't have at my fingertips, Australia uses the agreed Meteorological definition of the seasons, which sets the change of season at the first of September (and December, March and June), while Europe and North America use the Astronomical definition, which uses the equinoxes and solstices to mark the season kick-off. I have heard people assert quite strongly that these are the 'real' seasons, but I don't really get that - they're both human conceits. There are good reasons to define the seasons by what's actually happening, as many societies have done, and as some Australian indigenous communities (such as in the Top End) still do. This would of course mean that the dates would change from year to year, and while that seems perfectly reasonable to me, I doubt that we could cope easily with it. 

For me however, spring in Canberra is defined by the first finger orchids and that has happened! For the rest of this post I'll let the flowers do most of the talking. All photos were taken on Black Mountain, a unit of Canberra Nature Park on the edge of the city centre (our Civic), dominated by dry eucalyptus forest.

Blue Fingers, Cyanicula caerulea above,
and Dusky Fingers, Petalostylis fuscatus (often still known as Caladenia fuscata)

Blue or mauve peas dominate their family in terms of flowering at present; the sprawling climber False Sarparilla Hardenbergia violacea, at the top of the post, has been shining for a couple of weeks now, but the small erect Purple Hovea Hovea heterophylla, is another good end-of-winter indicator.

White is currently popular (I generally think of such flowers as being likely to be pollinated by night-flying moths), and the beard-heaths stand out (for more on heaths currently flowering, see the recent post in The House of Fran_mart, under Blogs I Regularly Read, opposite). It is likely that the densely hairy throats deter ants, notorious nectar thieves.

Leucopogon fletcheri, millions of individually tiny flowers
can light up a forest floor!

Another contributor to the white theme are the multi-flowered Rice Flowers; they were originally described as Banksia, for the great Sir Joseph, but it was realised then that the name had already been taken.

Pimelea linifolia; the bark fibres were valued by
Aboriginal people.

And of course wattles are prominent, as they are everywhere and always it seems. With Wattle Day only two days away (when I'll be away) it seems appropriate to showcase them here, starting with a controversial one. Cootamundra Wattle, Acacia baileyana, is native to the western slopes, a couple of hundred kilometres west of here. It is a vigorous invader of native forests, and in parts of the Adelaide Hills has become a serious pest, as it is threatening to do in parts of Canberra Nature Park. On the other hand the seeds are favoured by Superb Parrots, a threatened species.

Acacia baileyana; the name commemorates a veritable
dynasty of 19th and early 20th century Australian
government botanists.

Early Wattle, Acacia genistifolia, which having flowered through much of winter
is about to hand over the baton to less hardy wattles; the name means 'gorse-leafed'.

Lastly for today, the modest little Box-leaf Wattle is starting to play its role in the understorey.

Acacia buxifolia - the name means just 'box-leafed', with no reference
to containers. Buxus was the Latin name for an unrelated European tree;
from a resemblance to its hard timber came the name 'box' for
a group of Australian eucalypts.

And I did warn yesterday about digressions, so maybe time to leave it there, but I'll continue to offer spring flowering updates over the next couple of months. Now stop sitting inside reading this, and get out there and enjoy it!

Silly Drongo?

Fork-tailed Drongo
Etosha National Park, Namibia
2003

It may not be the only drongo in my suburb of Duffy, but it's the one that interests me the most at present! Drongos, despite most Autralians' perceptions, are actually a group of pretty spiffy medium-sized glossy-sheened long-tailed aerial show-offs, which do so in order to catch flying insects. Most of the world's 25 or so species (these things are dependent on your preferred taxonomy) are found in southern Asia and Africa, but one, the chatty, flashy Spangled Drongo, is found commonly in tropical and sub-tropical near-coastal Australia from the Top End to about Sydney. South of that it gets pretty scarce; inland it's scarcer still, so an appearance in Canberra is a rare treat for those of us who appreciate such things. There have probably been less than 10 individuals reported here, and this bird would be only the fourth or fifth in a decade (it can be hard to know if multiple sightings in a short time refer to one or more birds). In my 30+ years in Canberra it's only the second I've seen here. It's difficult to say what drives such unexpected appearances; we can be pretty confident that overall rising temperatures are pushing warmth-loving species further south, but what made this one decide to leave the relatively balmy coast and head up to Canberra, currently very frosty indeed? It's not saying, as it hangs around the same clump of planted acacias on the western edge of Duffy, on the border of Narrabundah Hill, dashing out to catch insects, sometimes taking a sojourn in the yards across the road. Its brown (not glowing red) eyes tell us that it's not a full adult; maybe its inexperience simply led to it getting disoriented, perhaps accompanying a band of migrating honeyeaters returning from their winter break up north.

Spangled Drongo, Duffy. August 2012.
Note bee in beak!

And before we leave this engaging chap to get on with things and presumably eventually go back to where it might find others of its ilk, I should point out that our derogatory use of the word drongo to suggest someone who's not intellectually the full quid is not taken directly from any attribute of the bird (despite what you might read on Wikipedia!). In the 1920s the owners of an Australian racehorse named it Drongo, presumably in the hope that it might prove as dashing as the bird; it didn't quite, though it managed a few gallant second places. In time the word has come to mean someone pretty hopeless, rather than a trier who just fell short, as was the original connotation.