Saturday, September 3, 2011

WET but not so WILD

It rained. It rained. Now I know that is simply repeating the same short sentence twice but I felt the point needed emphasising. It rained. And then it rained some more. By day’s end the rain gauge registered 41.5mm of rain. To put this figure in perspective, August comes in as Nanango’s driest month with an average of 32.2mm. An overnight fall in excess of 40mm is, in anyone’s experience of an austral winter, a substantial amount of the wet stuff from the Heavens.

A number of possibilities immediately spring to mind when one arises on a Saturday morning to dark, threatening, clouds blanketing the world around you. As a birder you instinctively appreciate that any plans to go birding around the ridges is out of the question. No right-minded bird would risk a thorough drenching simply to oblige a passing human with the opportunity to focus a pair of binoculars on the finer points of its plumage. Both avian subject and human observer would return to base camp all the worse for the inclemency of the morning.

A second thought occurred almost as quickly: the Utility Room cupboard remains incomplete; indeed, has remained incomplete since originally blueprinted back in 2001! It could have been attended to during the recent January floods when Fay and I became isolated on our property but I was literally up to my neck, well, okay, up to my knees, in muck, mud, water and occasional enemy sniper fire. I sporadically drift into realms of fantasy.

Not that the persistent rainfall eliminated all possibilities of birding. When your accustomed hour of arising is somewhere between 0330 and 0400 hours - don’t ask, it’s a long tale of general lifestyle, diabetes and our continuing research into the local early birds - there is always time to listen out for, if not actually see, birds. The Tawny Frogmouth Podargus strigoides obliged. The Bush Stone-curlews Burhinus grallarius, crepuscular creatures, were howling by 0526 hours from somewhere east of the house.

Heavy overnight downpours have lead to an untested theory Fay and I are developing.

As a preamble I should point out that we are both unashamedly feeders of birds. We have been since our days in the U.K. My first introduction to serious birding was back in the days of my mid-teens, when Fay was merely my girlfriend [yes, we can be classed as childhood sweethearts even though we didn’t actually attend the same school- Fay was clever and went to the local grammar school; I was thick and went to the nearby secondary modern, although thereafter it seems to have become a comprehensive].

Boreal readers may well wonder why the above point is stressed. In the U.K. almost everyone we know feeds birds in one form or another. Our good friends, Keith & Jen of Albrighton, Shropshire, have established a rather elaborate feeder system in their back yard which can be observed at leisure from their conservatory. Les and Sandy of Tewkesbury, Gloustershire, have a simpler but very effective backyard feeder. In the USA feeding birds has become a multi-million dollar business. It is encouraged by birding authorities.

That is not the case here in Australia. Birds Australia, soon to be merged with Bird Observation & Conservation of Australia [formerly Bird Observers Club of Australia], more commonly referred to as BOCA, to form Birdlife Australia, actively discourages the feeding of wild birds. Or at least the organization does not encourage the feeding of wild birds. That same message is oft repeated at gatherings of Australian birders all around the country. The exponents of this particular “anti-ism” range from scientists with genuine but untested concerns to the ranters who could just as easily protest the universal acceptance that the Earth is an oblate sphere when in reality it is flat and all archival evidence from Outer Space to the contrary is a diabolical fabrication instigated by a perverse American government, hell-bent on the de-Christianization of the world.

We smile, we ignore and we continue to feed our local backyard birds. We are aware of the work by Brittingham et al. [1985] as we are aware of the work by Bromley & Geis [1998].

We note that no more than a few hours after gorging itself on titbits of cheese from our verandah, the male Grey Butcherbird Cracticus torquatus honoured us with a magnificent display of hawking. It perched on the east side of the tall angophora [the site of one feeder] and launched itself out into the open sky between tree and grapevine fence to catch small black insects that were visible to the naked human eye. At one point it landed atop the newel post of the front steps before swallowing its prey. The Noisy Miners Manorina melanocephala and Magpie-larks Grallina cyanoleuca, also regular visitors to Café Avian, joined in on the action. The humble juvenile Australian Magpie Cracticus tibicen, seemingly lacking the required aerial acrobatics, simply jumped into the air in an attempt to catch its share of black insects. We cannot comment on its success rate as it had its back turned to us.

I drift. Back to the developing, if as yet untested, theory.

Wild birds become more desperate for food supplements following a heavy overnight downpour.

We have no empirical evidence, no quantitative measures of seed, cheese or biscuit crumb mixture consumed during a post overnight rain session as compared to a “normal” [no overnight rain] feeding session. Currently it is no more than conjecture based on the evidence of our own eyes and the number of birds visiting our feeders.

Allen Road data date back to 2001. As well as species present we record climatic conditions; minimum and maximum temperatures along with rainfall figures and almost invariable the data indicates an escalation of the feeding frenzy on mornings following heavy overnight rainfall. Apostlebird Struthidea cinerea numbers explode. Rainbow Lorikeet Trichoglossus haematodus numbers fulminate. Crested Pigeon Ocyphaps lophotes and Bar-shouldered Dove Geopelia humeralis numbers increase dramatically. White-winged Choughs Corcorax melanorhamphos numbers can double. Galahs Eolophus roseicapillus seemingly emerge from out of the woodwork to engorge themselves on the proffered feast.

If not merely a climatic coincidence, why the sudden increase in numbers following heavy overnight rainfall? Are the birds simply hungrier? Does the amount of rainfall impact deleteriously on their normal food sources? Is it that the wet condition demand greater energy reserves and these are easiest procured from Café Avian than from out in the wild?

Or is it that heavy overnight falls of rain deleteriously effect insects, a major food source of many birds in our area?

Whatever, it seems a simple equation: the heavier the overnight rain the more frenzied the ensuing scramble for food at Café Avian. When we are presented with incontrovertible evidence to the contrary [that it is better for our backyard birds to starve than be provided with a supplementary food source] we may consider demolishing the feeders.

On the other hand, their presence around the place, amid the grevilleas and banksias, makes for a more pleasant life in general.