Siblicide

Another 6-hour stint in my hide overlooking the eagle nest this morning revealed an absolutely incredible event, one I never thought I'd ever see, let alone capture on film. Only one eaglet remained on the nest... and the fate of the other was already sealed. It had been killed by the surviving eaglet, and I watched in amazement as the adult female returned to the nest...


Siblicide from Simon Cherriman on Vimeo.

Spot the Stick

At first glance this picture doesn't appear to have a bird in frame at all, but if you look carefully you can see that the figure in the centre IS a bird - it's a Tawny Frogmouth! This remarkable bird was one of just over 40 avian species recorded at the Bioblitz, held this weekend at Elachbutting Rock in the WA Wheatbelt region, about 300km inland from Perth. This event aims to conduct a '24-hour snapshot' of a patch of native remnant vegetation, determine which plant and animal species live there, and engage local community members through trapping, birdwatching, plant identification, spotlighting and a whole range of other activities. You can read about the great fun and cool critters we found at last year's Bioblitz here.

Here's one more of the frogmouth, looking slightly more like a bird (or maybe not!). Stuart Rae, a research scientist currently studying this species in Canberra, tells me this is the male bird, who takes up incubation duties during the daytime. Even though he is very camouflaged, at least you can see his nest :)

Colossal Marri

A twenty metre nest-box-installing climb into the vibrant crown of this giant, wonderful, incredible, colossal, ancient (200+ yr-old) Marri tree, which glowed in the afternoon sun and tempted me up there like a cave full of glistening jewels, was the highlight of my day. And possibly year. We only met last week but we are now best of friends. Her arms cradled me with all the gentle care in the world, and the view she offered me (I could see Mt Dale 50km away!) was immense. To think that if she could talk, this tree would whisper tales of witnessing countless Nyoongar ceremonies, then one day seeing the first party of white explorers following the Helena River into the Darling Scarp, CHANGES THE GRAIN of the human mind.

 

This was one of eight beautiful Eucalypt trees I had the privilege of climbing today to install nest boxes for Black Cockatoos at Helena College, made by students at the school as part of a community services project. The students were able to salvage demolition timber and plywood to apply our 're-cyc-ology' train of thought to their boxes. My enormous thanks go to Margaret Hogan and Kate Abbott for organising Gill and I to assist with the project, and the school handymen Jason and Jason for their help providing guidance to the students during construction, and helping me with installation too.

Here's a cutting from the local Hills Gazette showing one of the boxes ready to be hoisted up!

Saliva!

Today I had the privilege of spending some time in a hide overlooking a Wedge-tailed Eagle nest in the Perth hills. I wasn't sure how successful I would be with capturing footage when I arrived in darkness around 5 am, but I when I left in daylight nearly 6 hours later, I sure was happy with the result! Both adult eagles attended the nest regularly during my presence and I was able to capture lots of interesting behavioural footage and photos. This will be added to my wildlife footage library and used in future documentaries about eagles and wildlife in the Perth hills (stay tuned!).

Two interesting things happened today that I had never observed before, one I knew about and one I had never heard of. When both adults were at the nest, the male eagle spent much time plucking small portions of prey (the red stuff in the above photo, in this case Western Grey Kangaroo), and passing them to the female (as seen above). She delicately accepted an offering, passed it back to the male, and the pair would exchange the portion back and forth several times, before one of them swallowed it. This happened about half a dozen times and was quite a deliberate gesture between the adults, which ignored the two chicks during these exchanges (they had been well fed earlier). The only explanation I can think of is that this is another ritual which strengthens the pair-bond between these long-lived, monogamous (mate for life) eagles.

During each exchange, the eagles' beaks would start to dribble saliva, which dripped of the tip of their bill before one ate the piece of 'roo. This brings me to the next point. While feeding the chicks, saliva drizzling from the adult female's bill was clearly visible as it ran onto the piece of prey and into the eaglets' mouths. This was (as far as I know) first documented by well-known conservationist David Fleay, who was able to observe such intimate behaviours by breeding Wedge-tails in captivity, and he concluded the saliva helps very young chicks to swallow and digest prey (saliva is no longer used when the eaglets reach a certain age).

Another thought which has been suggested is that by passing on saliva to their offspring, adult eagles expose them to various bacteria, helping build their immune system at a young age. Just like letting our children play in the mud and eat soil! If it helps build a healthier, stronger animal, then why not!? Perhaps this could also explain the adults exchange described above - by passing saliva to each other, both adults may be ensuring they both 'have the same germs' to avoid any unexpected bouts of sickness.

So many occurrences in the natural world we can only guess at, making it all the more wonderful I think. As I often say, such incredibly powerful predators can demonstrate the most gentle, caring behaviour when tending their chicks or nurturing each other. Few things are as fascinating to watch!

To finish with, here is a short, unedited clip of the female feeding her chick and using saliva to lubricate the meal.


Saliva! from Simon Cherriman on Vimeo.

Silent Flight

Finding a beautiful animal killed by a car is never a happy experience but one can take advantage of the situation to observe detail not possible when the animal is still alive. This macro photograph shows the comb-like edge of a Barn Owl's outer primary feather, forming the leading edge of the wing, the specialised adaptation which makes them have silent flight. How? With each flap, this 'softer' edge gently brushes through the air, making no noise, unlike the flat-edge of other diurnal birds' wings (magpies, for example).

Barn Owls also have a large facial disc composed of bristled feathers, like a radar dish which channels the tiniest sound right to the ears. Ear openings in the skull are offset, with one being higher on the head than the other, allowing the owl to calculate the direction and distance of a small rustle in the leaves. Together with a reversible outer toe for getting that grip just right, and a neck which can turn 270˚ to 'pivot the radar dish' in most directions, this specialist equipment makes them perfect nocturnal hunters capable of catching prey in total blackness, without even a glimmer of light needed.

Here is a wider shot of the upper surface of the owl's wing, showing the stunningly beautiful feather patterns. Never pass up the opportunity to learn something new, even from a dead bird!