Spinebills: a Pin-sharp Probe

Western Australia is home to a huge variety of amazing wildlife. In our unique south-west region, we are lucky enough to have 14 species of birds that are endemic - that is, they are found nowhere else on the planet. Recently, one of these species, perhaps one of the most beautiful of all Australian birds, has been visiting my garden regularly, and I've had the pleasure of being able to photograph it at close quarters.

The female Booldjit has a stunning rufous collar and red iris.

'Booldjit' (Noongar for what most people know as the Western Spinebill, Acanthorhynchus superciliosus), is truly a gem of a bird. Both sexes have a stunning buff-coloured belly, a rufous collar and a striking red eye. And the male's black mask, white eyebrow (hence the species name superciliosus - 'supercilium' refers to a line above the eye), black cheek and black-and-white bib make him an especially eye-catching decoration in any garden. Their colour difference is the result of a phenomenon called 'sexual selection', where evolutionary pressures have caused males to develop striking feather patterns that attract females, and allow the brightest individuals the right to pass on their genes. By contrast, duller individuals are less attractive and as a consequence do not get the right to contribute to the next generation, so over time the sexes become more and more different. Sexual colour dimorphism, the result of sexual selection, is a common feature of many Australian songbirds, especially those in the wren and honeyeater families, the latter being the group to which spinebills belong.

On the topic of evolution, another feature of this brilliant bird is its aptly named bill, which has the very fine, curved shape of a spine on a plant. This bill is itself the result of millions of years of constant competition between bird and plant - the bird has evolved a longer, finer beak, the same shape as those belonging to kangaroo paws, grevilleas and other local native flora on which it feeds. Here are two successive photos of a male Booldjit probing his delicate beak into the flowers of a Tall Kangaroo Paw (Anigozanthos flavidus):

While drinking his fill of nectar, the spinebill is also performing an important pollination task, which is the benefit the 'roo paw is seeking for offering a sugar-rich reward. Carefully positioned anthers, which bear the plant's pollen, probe from the front of the flower and with every feed, give the spinebill a fine dusting of pollen on its forehead. These images showing the yellow pollen grains, like a tiny dusting of talcum powder, being passed to the spinebill's forehead, with some falling along the length of its bill as it withdraws from the first flower.

Once sugar-tube is empty, the Booldjit then flutters rapidly to the next flower, and to the next, carrying out more probing and pollinating, as it clutches the stems delicately with intricate feet. What is fascinating about observing this activity is the rapidity with which the bird forages. In less than 90 seconds it can have visited all of the 20+ flower heads on the two kangaroo paw clumps outside my kitchen window, and with several individual flower tubes on each arrangement, that's less than 2 seconds per forage!

Probing for nectar: A few pollen grans can be seen floating away to the top left of the bird's head as it forages.

I've noticed the male spinebill is in to feed at least 3-4 times each day, whereas the female only comes about twice - once in the morning, and once in the evening. Perhaps this is because the male expends more energy defending its territory and protecting its female(s)? She is noticeably less active than him, and has often perched in a nearby shrub, resting and looking around. The more abundant Brown Honeyeaters are also more dominant, and I've seen them chase off their smaller rivals on several occasions when the two species arrive to feed simultaneously. This might explain why the spinebills are so rapid - drink your fill before someone else does!

It is a thrill to observe the intricacies of the natural world, which are constantly going on around us, on every level whether big or small.

Kookaburra Rescue

Today I received a phonecall from one of my neighbours with news of a Kookaburra chick, which she had discovered in her backyard, apparently fallen from a nest. As her house was literally within a stone's throw of mine, I grabbed my ladder and went to investigate. This chick (pictured above) was about 18 days old, with feathers well developed. Although this species is feral in WA's south-west, I have a soft spot for it because I reared a young kookaburra ('Jack') just like this when I was 16, so I decided the best thing to do was return it to the nest and let nature take its course. The problem was, where was the nest?

The tree above, which is a mature Tasmanian Blue Gum (Eucalyptus globulus), was the only tree from which the chick could have come, but there were no obvious hollows. The neighbour kindly pointed out to me where she thought the birds had a nest - the clump of bark strips, which appeared to be several years of shed bark accumulated on two branches, about three-quarters of the way up the tree. Closer inspection indeed revealed there was a small hole beneath the accumulate bark.

The entrance to the Kookaburras' 'nest hollow' is visible beneath the accumulated bark, just right of centre.

When I climbed my ladder to have a look inside, I was met by a loud squawking noise, and I came face to face with the orphaned chick's sibling! And what was even more interesting was noticing that the nest 'hollow' was not a true tree-hollow at all! The chamber's ceiling was composed of accumulated bark strips, which had formed quite a dense cover, and the nest floor was merely a makeshift platform on top of a bulge in the trunk where a thin limb was protruding (as seen in the centre of the above picture). This was by far the most unusual Kookaburra nest site I had seen, and with such a small and convex floor, and a severe slope and overhang at the nest's entrance, it was no surprise that one chick had fallen out!

Before I reunited the Kookaburra chick with his family, I decided to capitalise on the situation for an educational lesson. You might not realise that this species has a very unusual toe arrangement, with its two inner toes fused together for half their length, a phenomenon known as 'syndactyly'. I'm not sure what the purpose is, but like everything in our wonderful natural world, there must be a reason explicable by the birds role in its environment. Perhaps it helps the bird grip to the front of the arboreal termite mounds in which it traditionally nests? (the Kookaburra's natural range is in south-eastern Australia where such termites are common). If anyone out there knows more on this, I would welcome their feedback :)

The syndactyl toe arrangement is an unusual anatomical feature.

A quick clamber up the ladder saw me replacing the chick inside the nest 'hollow'. While I took a few photos, one of the adults waited patiently with the next morsel for its young: a tasty-looking cricket!

I would be most interested to hear from others who have found Kookaburras nesting in such 'hollows'. Please post your comments below :)

Sibling reunited. The orphaned chick gives a final wink goodbye!

Morning Kaaraks

This morning I woke to the sound of a young Kaarak (Forest Red-tailed Black Cockatoo) calling outside my window. I was half asleep, but the closeness of the characteristic soft wheezing drew me further out of my slumber and urged me to go and investigate. Camera in hand, I ventured outside and saw a juvenile cockatoo perched quite low in a Marri tree just near the house, its parents foraging on 'honkey nuts' just above its head. Normally family groups of this species which visit my bush garden are quite wary and not particularly tolerant of a photographer stalking them! On this occasion, however, this family trio didn't' seem worried, and from my verandah I managed to sneak closer and snap away just as the female descended to her beautiful baby and gave her some breakfast.

An adult female Kaarak feeds her offspring some 'Marri muesli' for breakfast.

Despite a few mouthfuls of 'marri muesli', the young Kaarak still wasn't happy, and she kept wheezing and climbed higher towards her father. Young cockatoos spend several years with their parents, learning the art of foraging, and also gaining practice at navigating their way around the canopy. Even if they aren't giving the unmistakable contact call of a juvenile, observing their climbing method can be a dead giveaway to their age. This young one took a little negotiating to make her way around a clump of new foliage growing out of the Marri limb on which she was clambering - a funny sight! Eventually she reached 'dad' and was given a second helping.

Knowing the cockatoos were outside enjoying the natural habitat this bush block provides was a wonderful feeling, and a brilliant way to start the day. Now time for my breakfast!

The female Kaarak (left) with her offspring, who is busy nibbling her perch!

Colour-ringing Wedgies

Setting off towards a speck in the distance that is a giant Wedge-tailed Eagle nest always evokes a feeling of excitement, especially when you have visited it two months prior and know the chick you saw then will now be fully-grown and nearly ready to fly. With my mum and sister leading the way, I began the descent into the rugged Perth Hills valley, clutching the straps of my backpack to ease the load of heavy climbing gear, ropes, cameras, lenses and eagle-banding equipment on my shoulders.

 

An hour later, the three of us stopped in the shade of the Wandoo nest tree, which was now quite a bit taller than when I first climbed this particular eagle nest 16 years ago. The nest, too, had increased substantially in size, being more than 2 m deep and just as wide, making me look like a midget as I ascended my rope to just below the nest, and peered over the edge. I was delighted to see not one but two eagle chicks, an indicator that food supply in this territory had been ample this season, and that the adult eagles were probably experienced breeders. It was an extra special feeling after making a similar discovery at Matuwa (Lorna Glen) just a few weeks prior – 2015 must be a lucky year for ‘twins’!).

  

Before: The two eaglets aged about 1 week in early September. One chick normally dies in the first few weeks on the nest.

After: The same two eaglets, now large juveniles, 10 weeks later. One is very well camouflaged among the nest cavity.

I managed to capture both juvenile eagles - one female (left) and the other a male (right) - and lower them to the ground in a handling bag, before they were ready for processing.

As part of a long-term study on Wedge-tailed Eagle ecology in the Perth region, I have this year obtained the relevant State and Federal licenses to commence marking individual fledgling (juvenile) eagles with leg-rings (bands). A stainless steel ring from the Australian Bird and Bat Banding Scheme (ABBBS) is placed on the right leg, and a yellow colour-ring (custom made by IO Mekaniska in Sweden) with a 3-digit number is placed on the birds’ left leg. The only other colour rings being used on Wedge-tailed Eagles in Australia are the blue ones at Matuwa in the WA Arid Zone, where I have also been researching wedge-tail movements. The idea is that the colour-rings are highly visible and will allow any marked eagles, if they are re-sighted in the future, to be identified as a juvenile from one of the two study areas: Perth (yellow) or Matuwa (blue). If the number can be read, we can then tell exactly which nest site the eagle came from. And yes, you are right: I have chosen these two colours to match those of the Aussie Rules football team whose mascot is the majestic eagle from the West Coast ;-)

The yellow colour rings are unique to the Perth Region study area and are designed to be easily visible.

While mum held onto one eagle, my sister and I recorded measurements from the other, then we swapped over. Apart from standard morphometrics like weight, wing length, tarsal (lower leg) length and head-bill length, another measurement being taken is the length of the rear talon, and it was amazing to record the female eagle had a rear talon of just over 40mm, quite a weapon! Imagine being a small animal on the receiving end of that one day!

When both eagles had been ringed and processed, I ascended my ropes again to return them to their nest. With such well-developed wings, one has to be careful that eagles do not 'fledge early' and fly from their nest in an escape manoeuvre prompted by a person releasing them. My trick is to hang from my climbing rope just below the rim of the eagle nest, remove each bird, one at a time, from the handling bag, then release them upwards onto their nest. I find as soon as the birds' wings are out, they hold them up and flap slightly, and when their legs are released, the birds basically flap themselves back onto the eyrie. By hanging below the nest one is effectively out of sight, and not causing the looming threat that a person would if they were hanging level with or above the nest and towering over the eaglets.

It was wonderful to look back across the valley and see both juvenile eagles standing on their eyrie, exercising their very well-developed wings and peering out across the valley, and probably watching my every footstep, just as they had been earlier in the afternoon. The adult birds, highly alert to every movement in the vicinity of their nest site, were also watching with piercing eyes as three small specks of human ascended the opposite hill and climbed into their car. What an exciting afternoon - for all seven of us.

Kite Family

It is that time of year when I visit a certain gully in the Perth hills to check the breeding progress of the family of Square-tailed Kites I've been monitoring for the past few years. This species, known as Mararl or Djedurnmalak in the Noongar language, is one of my favourite raptors, so I was very excited to reach the nest and find a female kite sitting, a good sign it was active again! When I ascended the nest tree, I found the female had something to be very proud of...

The first thing that went through my mind was the voice of my good friend Ewan, a raptor biologist from Scotland, saying "It's a Red Kite chick you little bloody ripper!!" (This came from our visit to the nest of a Red Kite, a species very similar to the Australian Square-tailed Kite but one in a different genus, during my time in Scotland last year). The second thing I thought was - "W-O-W!!". These two exceptionally beautiful and well-grown kite chicks are about a month old, their wing feathers well emerged and body feathers gradually covering up their natal down. It will take about a three more weeks before they are ready to fledge.

The younger kite chick has slightly more natal down still showing.

The older kite chick with its very flash 'mohawk'!

As I was about to leave the tree, the female kite's behaviour changed, as though she seemed to want to tell me something. I sat for a few more minutes, and the goosebumps spread across me as she walked to the edge of the nest, flapped towards me and landed on a perch less than a metre away! She then proceeded to perch and look at me, as gentle and placid as ever, as though jogging her memories of previous time we've spent in the canopy together, and scan around the bush, perhaps in anticipation of her mate returning with food.

It was wonderful to find the kites have nested again, and that everything is on track for successful fledging. They still remain one of my most favourite birds.