Monday, 20 January 2014

In extreme heat, birdbaths can become bird magnets

Last week southern Australia experienced a heat wave with four consecutive days of peak daily temperatures well above 40 degrees Celsius. For all warm-blooded animals heat stress can be a killer, so as we all know, adopting strategies to keep cool on extreme heat days is essential for survival.
Keeping cool involves a range of measures including reducing physical activity and staying out of the direct sun – that is seeking shade. In addition animal bodies have evolved ways of regulating internal body temperature. We humans do not have a cover of insulating fur or feathers that trap heat but we have sweat glands, which allow us to cool by evaporation. 
Many animals and certainly birds do not have sweat glands so on hot days dogs for example can often be seen panting and most birds are seen breathing through open beaks. This allows for a certain amount of evaporative cooling, however this comes at a cost – loss of moisture from the body with the associated need to keep hydrated. So on very hot days birds tend to reduce physical activity by roosting in the shade and making many visits, at least for some species, to drink at their favorite watering point/s. Of course some bird species seem to be able to survive without drinking water – they obtain all the moisture they need from their food.
Outdoor bird photography on extreme heat days is generally not on for a range of reasons and in any case the birds are generally lying low. However the need for birds to keep hydrated means birdbaths or other fresh water points can be very productive places to spend time observing and photographing birds on very hot days.
So for a couple of hours on two of the extreme heat days I set up in the shade by a long established birdbath to see which birds came in for a drink and or a bath.
Birds obviously have favorite drinking and bathing spots they use on a regular basis. Even with familiar water points most birds still approach them with caution and are often very nervous when drinking and bathing. Clearly predators including predatory birds have learnt that watering points can be productive sources of bird and other animal prey and the prey species know this, hence their nervous behavior.
This behavior raises an important animal/bird welfare issue – our presence at a watering point may keep wary birds away from water critical for their survival. This is particularly important when the water point is small and the only one for miles around. So whether we are simply setting up near a water point to observe or photograph birds or other animals, or perhaps when on holidays or travelling, we may be tempted to camp near a water point, we need to spare a thought for the animals that are using the water and ensure our actions are not keeping them away from water critical to their survival.
The birdbath I observed was located in a house garden and the birds had adapted to the presence of humans so my presence some six to eight metres away on a verandah semi concealed behind some shrubs did not seem to trouble the birds at all. In addition there were other sources of water nearby.
Over the few hours I watched the birdbath, thirteen species of birds came in to drink. The odd bird had a bath, however overwhelmingly they were drinking. I suspect many birds made repeat visits for a drink at short intervals.
Photographs were difficult under the dappled light conditions and in addition the bird’s nervous behavior and behavior towards one another added to the difficulty as they  moved about a lot. There were often two or three species present at the bath together. While there seemed to be plenty of room for all, clearly many birds had a low tolerance for other birds that were too close, so the odd squabble broke out. 
The birds moved about on the rim of the bath making me wait to capture photos of them in the sunny patches. Here are some of the photos I managed to capture (click on the images to enlarge).
Sharing or not sharing?
Spotted Pardalotes were frequent visitors to the birdbath. This may be a family group with one adult female in the foreground and two juvenile females behind - they were happy to share the birdbath.
Three White-naped Honeyeaters and one Brown-headed Honeyeater share
a section of the bath as a Striated Pardalote departs.
With all of the bath to share this Eastern Spinebill has emerged from a bath too close to a Silvereye which has its head feathers ruffled in protest. The Spinebills' head feathers also look to be raised?
 This pair of Honeyeaters, a New Holland on left and a White-naped,
argue over one small section of the birdbath.
The New Holland above has suddenly departed, ending the altercation and leaving
the startled White-naped to scramble back onto the bath.
Birds coming and going were often cause for concern among the nervous birds at the bath.
Here a Spotted Pardalote comes in above a Striated Pardalote.
Nervous birds keeping an eye on the sky?
Nervous birds at the bath often looked up to check the sky for predators.
This is a young Spotted Pardalote.
This Striated Pardalote is checking the sky for danger. Note the yellow spot on wing - this is the Tasmanian sub species striatus which is a winter migrant to mainland Southeast Australia between March and October. With the extreme heat wave this bird may be wishing it had made the trip
south across Bass Strait to spend summer in Tasmania?
This Silvereye is not looking at the camera, it is checking the sky above and behind for danger.
The following shots are more or less arranged in order with the most numerous and frequent visitors to the bath first. 
The White-naped Honeyeaters were numerous and visited the bath often in small groups.
A pair of Brown-headed Honeyeaters, the bird on the left is a juvenile - note the bluish eye ring.
Spotted Pardalotes came in often to drink - this is the very handsome adult male.
A male Striated Pardalote - this is Southeastern Australian mainland sub species ornatus
- note the red spot on wing.
An adult Eastern Spinebill ready for a drink.
When the New Holland Honeyeaters were not at the bath drinking and bossing
the other birds around, they fed on nectar in the Agapanthus beside the bath
- very convenient for them with both food and water in one location.
A juvenile Willie Wagtail - note the brown feathers on the wing.
Dusky Woodswallows came in as singles or in small family groups.
A juvenile Dusky Woodswallow - this bird was raised in a nearby woodland.
There were good numbers of Yellow-faced Honeyeaters around however this
was the only one I observed come into the bath.
I could hear a flock of Silvereyes nearby, however only a few came to this bath to drink.
There are other water sources nearby so there was plenty of choice.
This Grey Shrike-thrush was one of the larger birds to come to the bath.
It is wary and checking above for danger.
A Red-browed Finch catching a small patch of light.
I was surprised that only one Thornbill came in to drink. I have seen up to four species
come in together at our other birdbaths. This is a Striated Thornbill.
The above thirteen species came to the birdbath while I was there. A pair of Common Blackbirds also came by, but were very wary as  they always chose to drink and bath at a nearby bath.
The male Common Blackbird is an introduced species. He and his partner below were busy feeding young still in the nest. In between ferrying food they stopped often to drink and bath to cool down at a nearby birdbath which I could see from where I sat. Note the open bill in the heat.
The female Common Blackbird, mate of the male above. It was hot work for the pair feeding young. I suspect they were also taking water to the young in the nest.

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