Geoffrey
This is an interesting point. I presume that what is/was done is that the man-made dams are closed but natural waterholes/billabongs etc are allowed to remain. This would seem to lead
to a few further questions:
- Did the presence of the extra water led to increased numbers of birds, as well as larger animals, in the areas around the closed water resource? This is relative to the "carrying capacity" of the area before the water resource was created.
- Does closing the water resource lead to a decrease in the number (and/or diversity) of birds (and/or other native biota ) in the area around the resource?
- Before the now-closed resource existed, did a high proportion of birds in the area die in a drought or period of great heat stress, but as no-one was here to see it this wasn't realised?
On Fri, 15 Mar 2019 at 14:12, Geoffrey Dabb <> wrote:
Thanks Janet. I’ll pass on. Geoffrey
Hi Geoffrey
You raise an important point about access to free water for arid zone birds in the face of exposure to extreme temperatures but not one we have addressed in our research. Birds can die in heatwaves even when they have access to free water,
and the underlying causes of mortality in such conditions are complex. Some birds, like jacky winters, extract water from their food while others like honeyeaters regularly drink free water. This influences the potential for heat stroke versus dehydration,
the two underlying causes of heat-related mortality, and understanding these processes is the subject of current research by physiologists e.g.
https://www.forbes.com/sites/grrlscientist/2017/02/28/extreme-heat-threatens-desert-songbirds-with-death-by-dehydration/#13733eec2d26
Identifying thermal refugia used by animals in extreme conditions is also an important goal for current research, and documenting the characteristics of thermal refugia can help to guide regeneration efforts, and prioritize areas of habitat
that are critical for survival. De-watering is considered essential to de-stocking and de-stocking is considered the best way of restoring pastoral country; it is a blunt instrument but aims to allow habitat to recover to the benefit of all species including
birds, with minimal active management input (a consideration given minimal funding).
PS Feel free to post this if you think people would be interested in the article I highlight.
On 15 Mar 2019, at 9:59 AM, Geoffrey Dabb <> wrote:
Janet - I sent this to the local chatline. Thanks for the talk. I expect they now know about this issue in the mallee parks, but I can’t find anything about recent concern, and any action. Geoffrey
Many members heard Janet Gardner’s disturbing talk on Wednesday evening about the effect of climate change on birds, in particular the probability of some birds dying in temperatures in the high 40s. This recalled for
me 29 November 2012 when I abandoned a camp at Hattah-Kulkyne in the face of predicted temperatures in the high 40s that could be about to set an all-time record in Mildura. I spent the next night at Hay and posted myself at Wattle Dam, near Cocoparra NP
early the next morning. The small dam was visited by many bird species, panting and obviously stressed. Without the water it seemed to me many could not have survived. A selection below –
Surely such man-made water sources, necessarily set among or near sheltering trees will be important for survival of local birds in many dry areas. However in the mallee area where Janet is conducting research there
has been a policy of deliberately closing dams in the interest of improving bird habitat. The reasoning is that dams allow goats to survive. All (?) open dams at Gluepot have been closed as well as many at other mallee parks. Elevated drinking troughs have
been erected at some bird observation points. If appropriately constructed and located these might provide survival
watering places for birds in severe conditions. However, they would need to be able to be kept filled in extreme conditions. Moreover, they would need to have regard to the needs of a wide range of bird species. It was once thought that ‘Black-eared Miners
do not need artificial water sources ….’
--
Dr Janet Gardner
Australian Research Council Future Fellow
Research School of Biology
The Australian National University
Canberra, ACT 0200
Ph: +61 2 6125 3611
|
