Professor's comment on the survival of waterbirds.
Australian ducks and waterbirds are extraordinary, relying on water not just on the driest continent on earth but one that deigns to change its watery spots and capriciously supplies or withholds water as it pleases, subjecting large stretches of land to years, sometime decades, of drought.
Ducks have to be smart to go where water is and, like the pink-eared duck, have to be dispersive and nomadic to identify and secure another swamp or wetland. In search of another temporary home, they often fly in flocks for safety. But we are fooled by flocks and begin to think that they exist in large numbers. Congregating in such ways does not indicate this at all, other than to say that they come from far and wide.
Even the most endangered species, such as the blue-billed duck in Victoria, may look plentiful when they congregate. They are all struggling to survive in a potentially lethal and hostile environment and over the millions of years that they have graced the Australian continent, they have adapted to the ever-changing climatic conditions and survived. But since humans arrived on this continent, and especially in the last 200 years, we have caused their chances of survival to rapidly decrease.
We are fooled into thinking that a species is plentiful also because of their life-expectancy. Grey teals may live to over 30 years and black swan for at least 25 years. We may not readily notice that their numbers are dwindling if the same birds stay in an area and live for a long time.
We know, however, that the graceful brolgas are slipping away from all southern states (South Australia, Victoria and New South Wales). The blue-billed duck is now endangered in Victoria, the freckled duck declared vulnerable in New South Wales and we cannot even be sure of the conservation status of black swans. We know, however, that many other ducks are dropping in population numbers because of human interventions.
And there is a further important point; when a duck gets shot or otherwise killed, we may disrupt the species life cycle permanently and cause harm that may reverberate over many years and even aid in the decline of a species.
Many birds are monogamous and form life-long pairs. Imagine that one parent is killed- almost certainly any offspring won’t survive; kill one parent and a lifelong bond may be broken from which the surviving partner might never fully recover. We now know that partner faithfulness may lead some to not seek another partner. We also have evidence that birds, particularly those with long-term bonds, are capable of deep emotional responses to loss of a partner and may even grieve in a way humans do. There is also ample evidence that fear and sorrow shorten life-spans of the survivors.
For example, in a bonded pair of Alexandrine parrots I watched a goshawk kill the male and the onlooking female (who was not attacked) first cried out in ear-piercing screams, then started panting with half-open beak. Within a few hours after her partner’s death she succumbed and died herself, presumably of shock. We have underestimated birds in the past in thinking that they are just fluttering little automatons guided merely by instinct.
We now know that they experience emotions, probably even the same range of them, as humans do and that their bonds may be based on long-term loyalty and affection. The idea that, say, taking 100 out of a crowd of a 1000 does no harm overall, is sadly mistaken because the effects ripple through the entire group. In nature, usually the least experienced and yet un-bonded, and the sick are taken- we now have changed the rules by often, even if inadvertently, causing the death of the healthiest and that alone will have long-term consequences unless we find ways to minimise the growing and unsustainable death rate we have instigated.
Prof. em. Gisela Kaplan, School of Science & Technology, University of New England, Armidale, NSW- 2351, Australia. (Author of: Bird Minds. Cognition and behaviour of Australian native birds. CSIRO Publishing. Whitley Award Winner 2016-behav. zoology; The Australian Magpie and other bird book titles)
Brolga Picture courtesy of Dorith Callander
Dusky Moorhen Picture courtesy of Eleanor Dilley