Birds in Their Habitats

by Ian Fraser

  Bird names in daily English

  Let’s go back to the Sulphur-crested Cockatoos, which have got bored with destroying the street lights and have gathered under the pin oaks in the adjacent parkland to crack open the iron-hard acorns. The power in their bills, with leverage assisted by a hinge where the top mandible meets the skull, is astonishing. Some birds are sitting in the trees above the flock, screeching abuse and flaring their crests as I approach. Whether they are really acting as sentinels is another question, though it seems quite possible, but the term ‘cockatoo’ certainly entered the Australian lexicon in this context, especially being used for someone who watched out for the police while illegal activities proceeded (particularly the coin-tossing gambling game known as two-up). According to the Australian National Dictionary, the term was in use as far back as 1827, recorded by the naval surgeon and social commentator Peter Cunningham. Cockatoo (or more usually just cockie) has yet another Australian meaning too: that of a farmer, based on the behaviour of some cockies, notably corellas, which forage for food by scratching in the dirt. There are subspecies of this particular cockie too, such as cow cockie or fruit cockie, but it was generally used disparagingly for a smallholder, though that has changed to a more neutral implication in recent times.

  With the Canberra cockies among the acorns are a scattering of slightly smaller cockatoos: elegantly pink and grey Galahs, like a soft sunrise through morning clouds. These are relatively recent arrivals in south-eastern Australia, spreading from the north and west with crops and water points, and only arriving in Canberra in the 1950s. For reasons not entirely clear, their name has come to be applied to a foolish person, especially an exhibitionist one. Actually, once you’ve watched a flock of Galahs taking ages to settle down to roost, squabbling and whirling into the air over and again, or hanging upside down on the wires and harassing each other during the day, it’s probably not too hard an idiom to fathom. (Much of the problem is that crop: the oesophageal sac that enables them to carry seed away to digest somewhere secure and comfortable.) Curiously ‘galah’ seems to have only come into written use in that sense in the 1930s, though doubtless it was in oral circulation before that.

  We have form I’m afraid for using bird names as derogatory terms. ‘Coot’ tends to follow ‘silly’, for no overt reason. They’re not bald though – when ‘bald as a coot’ was first applied, at least as far back as the 15th century, the original meaning of bald, or beld, or balled – that of having a white patch – was still in use; and, no, coots aren’t white, but their bills are, at least in Europe and Australia. (The Compact Oxford English Dictionary – surely named with irony! – makes it clear that the origin of bald is somewhat mysterious, but favours this explanation.)

  Even more shameful is our sneering appellation of ‘booby’ (i.e. a foolish fellow) to the nesting birds which were so trusting of sailors that they allowed themselves to be clubbed to death by the thousands. Turkey, goose, cuckoo are all terms for foolish or even slightly demented people. Sir William Hooker of Kew Gardens commented acerbically on 19th-century zoological artist William Swainson’s ill-advised forays into Australian botany ‘of which he is as ignorant as a goose’. A peacock is someone vain and pompous, though it seems to me that not all blokes who dress up and strut to impress females have feathers. Pigeons were also regarded as foolish and the word has a venerable history of describing an easy mark or sucker. A stool pigeon, now an informer, was originally someone used as ‘a decoy to entice criminals into a trap’ (World Wide Words 2001).

  Drongo is used in Australia as a generally affectionate term of derision, implying a no-hoper, and its meaning too has changed with time. Drongos (and, in this case, the Spangled Drongo of northern Australia, New Guinea and associated islands) are in fact very sharp, speedy aerialists indeed, so presumably the owners of the 1920s Australian racehorse named it thus in the hope it would be as nippy. Despite the now reasonable assumption that the poor nag must have been totally hopeless, it wasn’t, and even managed the odd gallant second. However, the horse never actually won, and so the original connotation was more of a trier who just fell short.

  Rooster is an example of a recent political coinage that entered the lexicon, at least for a while. It was used by a prominent member of the Australian Labor Party, then in opposition, to describe a group of senior party members who he accused of undermining the party leader. It has since largely been forgotten, along with the person who coined it.

  Other bird idioms are more benign. I suspect the term ‘emu parade’ may be sinking into history too, though anyone who grew up in Australia more than a couple of decades ago is likely to have been submitted to one, perhaps as an after-school group punishment. It comprised a straggling line of people moving across the ground to pick up rubbish, like a foraging flock of emus. In England, one who collects things, especially bright and shiny ones, is a magpie; in Australia the same person became a bowerbird. If you stretch your neck for a closer look, you’re craning, or taking a gander. (To goose on the other hand refers to other, less savoury, farmyard behaviour, into which we need not delve too closely here.)

  A few such terms are actually positive. ‘Raven-haired’ in the classics always seems to be followed by ‘beauty’. ‘Hawk-eyed’ or ‘eagle-eyed’ are good ways of expressing exceptional visual acuity. Some people seem always to be able to swan along, looking relaxed and graceful. (I’m more apt to be duck-like, paddling furiously beneath the surface while trying to maintain a façade of calm competence above it.) Not that I’ve ever worn a dinner suit, but surely ‘penguin suit’ to describe one can only be positive! Less certain as to its flattery intent is the application of ‘penguin’ to nuns, though both refer to pristine black and white garb.

  Canberra again: the Great Koel debate

  Some 20 years ago, I arrived home in inner suburban Canberra from my regular radio natural history slot, during which I had asked people to keep their ears open for a then unfamiliar call in town – the ringing rising ‘COO-eee’ of the Pacific Koel (as we now know it). I had confessed that I was yet to see one here, but when I got out of the car I immediately heard the clear blast of sound from the backyard. There, in the ornamental plum tree just over the back fence, was the magnificent big glossy black long-tailed cuckoo, his bulging eyes as big and red as the plums around him.

  Those days seem long ago now: as I write, looking into a different backyard, I can hear at least two males yelling at each other, sometimes breaking into their alternative anthem, a manically ascending ‘whoopa whoopa whoopa whoopa!’. It is an indivisible part of Canberra’s summer soundtrack now, with large numbers arriving each spring and returning north to New Guinea and Indonesia in autumn. We have discovered in the process that a significant division of the world around here is now into those like me who revel in the wild calls cutting through the suburban hubbub of traffic (yes, even in the small hours), and those who definitely don’t …

  In addition to controversy, the koels have been responsible for a considerable amount of entertainment here too in recent times. A newly elected opposition member of the Legislative Assembly was rapidly appointed as Shadow Environment Minister (it was then a pretty small assembly), and on behalf of some constituents demanded to know what the Environment Minister intended to do ‘to eradicate or manage’ this ‘imported pest’. Oops!

  Birds in a warming world

  However, the real story is why this species has suddenly become a common migratory visitor where once it was very scarce. I am confident that the answer is largely to do with the warming of the planet; the koel is just a very audible part of a vast diaspora of species into areas previously too cool for them, towards the poles and up mountains, for instance. However, the cards also fell very propitiously for the koel. For one thing, Canberra gardens provide lots of fruit and berries that the big cuckoo relies on. On the coast these are readily available in rainforest pockets and other wet forests, as well as from the widespread and invasive exotic Camphor Laurel (Cinnamomum c
amphora), but in the woodlands, grasslands and dry forests around Canberra they are in short supply. So, having ventured south and inland they found a bounty awaiting them here. But something else was of great value to them too – the abundant breeding Red Wattlebirds, big strong honeyeaters quite capable of raising demanding koel chicks.

  But this too contains an interesting story. During the 20th century, the wattlebirds moved north along the east coast (perhaps assisted by orchards, though this isn’t clear) until they reached Sydney (Blakers et al. 1984) – where the koels met them. Now the koels had hitherto laid their eggs in the nest of another big honeyeater, the Noisy Friarbird, plus Australasian Figbirds and Magpie-larks, all of which probably have at least some evolved defences. However, the Red Wattlebirds, with just the right-sized nest, knew nothing of big cuckoos taking over their brood and were totally defenceless. The koels only cottoned onto this possibility in the 1970s and within a decade the unfortunate wattlebirds had become the main host of the koel in Sydney (Brooker and Brooker 1989). And it seems they still haven’t learned. Australian National University Ph.D. student Virginia Abernathy experimented with artificial eggs in Red Wattlebird nests. Unlike most cuckoo hosts, the wattlebirds had no idea that they could or should eject the eggs, so are totally vulnerable (Professor Naomi Langmore, pers. comm.). A koel’s dream!

  But the ultimate driver of all this was the warming world. In early 2017, a pair of Tawny Grassbirds, a skulking but fairly vocal non-migratory species from considerably north of here, appeared in a major Canberra suburban wetland; this followed records from the coast near Melbourne, well south of here. I recently heard the unmistakably frenetic and slightly wheezy honking trumpet call of a Channel-billed Cuckoo go past outside, but was unable to see it – I wasn’t too worried because I am sure that it is only a matter of time before this one too becomes a regular visitor, with Canberra records increasing by the year. Its annual migratory cycle is very similar to that of the koel.

  All over the world, evidence is piling up of organisms moving their ranges – fish, invertebrates, frogs, mammals and even plants (not individual plants, of course, but whole communities are moving up mountains, from the Andes to the French alps). And if you’re moving up a mountain or towards a pole, there comes a point when there is nowhere else to go.

  It is not just movement, though. Behaviour is also changing, especially in phenology – the annual cycles that determine fundamental behaviour such as breeding and behaviour. As far back as 2003, a wideranging review in the prestigious journal Nature revealed ‘significant mean advancement of spring events’ by 2.3 days per decade (Parmesan and Yohe 2003). Four years later, the Intergovernmental Panel on Climate Change’s 2007 report revealed 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 in Japan, to butterfly emergence in Britain, to bird migration in Australia (IPCC 2007, p. 99). A more recent comprehensive Australian review of 89 studies of 347 plant and animal species concluded that the spring migration departure of birds moved forward by 2.2 days per decade (less than for the Northern Hemisphere, where it was 3.7 days per decade) (Chambers et al. 2013).

  One of the problems with all 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 hatch before or after their key caterpillar food supply is available, migratory birds are arriving before or after the flowers they pollinate are open.

  But wait, there’s more … In recent times, a third general response has been suggested, and demonstrated. Although 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 (i.e. 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. If you live in a cold place, it makes sense to be larger to retain heat better. We know that this is the case for populations of the same species at different latitudes, but what about the same species at the same latitude as climate changes (i.e. 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 Australian insect-eating birds, collected over 130 years from 1869 to 2001. Six of the species (Variegated Fairy-wren, Yellow-rumped Thornbill, Hooded Robin, White-browed Babbler, Brown Treecreeper and Jacky Winter) showed a decrease in size since 1950, with 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 (i.e. 7 degrees of latitude) (Gardner et al. 2009). 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 is competing with and must further adapt to.

  Only 10 years ago this particular response to climate change was only being guessed at, and there will be more surprises to come. An example, whose detailed explanation has yet to emerge, has been revealed by two European owl species, both of which come in two colour forms. In the case of the Eurasian Scops Owl, its colour forms are 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 (Galeotti et al. 2009).

  The same is true of the similar case of the Tawny Owl, which has a grey and a brown morph, in a simple genetic system where brown is dominant to grey. Historically, browns have formed a minority of the population and, for reasons uncertain, are less viable in very snowy winters, such as have historically been the norm in Finland where the study was conducted. In recent times, however, winter snow cover has decreased and the proportion of brown owls has steadily increased (Karell et al. 2011). The reason for grey being better than brown in the snow, but not otherwise, is not clear, and again may well not be directly related to the colours – it could be another character that is driving the success, which happens to be genetically linked to brownness. However, both owl stories are clear cases of climate change directly driving evolution.

  But can we say that a warming world is bad for birds? Unfortunately, in at least some cases, and especially in already hot dry situations, we certainly can. In a discussion of strategies for keeping body temperature to a safe level, while avoiding dehydration (pages 17–20), we saw that, as both frequency and intensity of extreme air temperature events rise, both heat shedding by radiation and convection from the bill, and by evaporation through panting, may become inefficient, and even hazardous. The crucial window of opportunity for keeping cool becomes a dangerously narrowing crack. Albright et al. (2017), in their study of passerines in the deserts of south-western USA (see page 19), concluded that, by the end of the 21st century, the smaller species they looked at will be exposed to at least four times the number of potentially fatal temperature events as they are now.

  Gardner et al. (2016) analysed the data from long-term banding studies in semi-arid woodland in New South Wales, looking at the effect of long-term exposure to higher, but non-lethal, temperatures on White-plumed Honeyeaters (a very common woodland and semi-arid land bird). By comparing the measurements against climatic data, they found that repeated exposure to temperatures in excess of 35°C led to a 3% loss of body mass per day of exposure, especially in the
absence of rain in the previous 30 days. This may be either directly due to dehydration, or because foraging is harder in such conditions, or more likely a combination of both stresses. During the 26 years of the study data, the temperature increased on average by 0.06° per year, the number of days over 35° increased and rainfall decreased. In that same time, summer survival rates (as measured by recaptures in the following winter) fell disproportionately among smaller birds, which tended to be females. So, although smaller individuals of a species seem to be advantaged in a warming world in general, in more extreme situations this is not the case. It comes back to the relatively larger surface area of a small bird, which applies not only to the body surface but to internal surfaces such as the mouth and upper respiratory tract through which birds seek to lose heat via evaporation by panting. Smaller birds in such conditions are constantly water stressed, seek to reduce stress by sitting still, so are not foraging enough, lose more weight and thus are in a deadly spiral.

  Overall, the news is bad for birds living in already physiologically stressful arid lands if they are warming and drying even more.

  Melbourne Cricket Ground: a groggy gull

  January 2015, and a night cricket match was underway (well OK, it shouldn’t really be called a cricket match, since the entire contest was only scheduled to take 40 overs, but it did have some similarities). A ball was swiped through the on-side and was clearly en route to the boundary, but instead was seriously impeded by a Silver Gull loafing without due care and attention. The bird understandably collapsed into a bedraggled heap and was carried to the boundary by a bemused fielder (who mimed to someone on the sideline that a coup de grace per large firearm could be required, but this is Australia, so who did he think would have such a weapon at the cricket?!).