Lyrebird nest - raided

While surveying singing lyrebirds in the forest on the Brindabella Range near Canberra, which included recording the displaying male described in the previous post, I also checked the progress of the lyrebird nest shown above. The nest was set on a small ledge about three metres up a small crag, which is about five metres high. The rock wall is not easy to climb up as it is slightly overhanging below the nest. As soon as I saw the nest I knew something was wrong. The top of the domed nest had been ripped off and lyrebird feathers, which the female uses to line the nest to keep the single egg warm, had been scattered across the ledge and below the crag. 

The damage can be clearly seen in this second photograph. The nest is typical, formed of a large ball of sticks, larger than a basketball. This is lined with moss and then feathers, the smoky grey body feathers, which the female plucks from her belly. All three components can be seen to have been ripped open and in the third photograph, below, the single egg can be seen lying in the depths of the nest cup which once had a warm sheltered dome over it. Lyrebirds typically lay only one egg, incubation takes seven weeks, and the chick remains in the nest for a further six weeks. 

This was clearly the work of a predator that had probably managed to climb or jump down from the top of the crag onto the top of the nest. The potential predators of lyrebird nests in the area include fox, wild dog or feral pig when a nest is on the ground, and suger glider, greater glider, possum or feral cat if the nest is off the ground. A fox could climb to some nests, but I don't think they could reach this one. Footage from a trail camera set at a lyrebird nest by Matthew Higgins has revealed that a sugar glider can take an egg from a lyrebird nest, so a greater glider or possum could likely take one too. This suggests that a native climbing predator would have taken the egg if it had opened this nest. But it would have taken considerable strength to rip the nest open and the egg was left behind. There was a tiny needle point hole in the egg, possibly made by a claw. A fox would have taken the egg. So, that leaves the likely suspect to be a feral cat, as a cat would be more likely to have been after a young or adult bird on the nest. As obligate carnivores, they prefer to eat meat. Fortunately, there was no evidence of the adult lyrebird having been killed, but this breeding attempt had failed. 

Feral cats have done so much damage to Australian wildlife.  

 Song and Dance

I set a camera trap at a Superb Lyrebird display mound over two weeks in July (13-31^st) and was successful in recording some wonderful song and dancing displays. Male lyrebirds display from a number of display mounds within their territory and females are attracted to them by the song first and then song and dance once they are visible as females approach through the thick undergrowth. The repertoire of the bird’s mimicry of other birds’ calls is, as its name suggests, superb, and enthralling. And how he holds and spreads his elaborate tail feathers is just as mesmerising. Follow this Video link to see a compilation of some of the sequences.

The females lay their eggs in winter, so these displays are performed during the cold months and I have watched them display in the snow. The males play no part in the nest building, incubation or tending of the young. The sexes only meet up for the purpose of mating.

Superb Lyrebirds are famous for their mimicry and although there are well-known film clips of birds imitating cameras and chainsaws, most of the sounds that wild lyrebirds copy are of other local birds that live in the same tall forests. I have only heard one bird imitate a knocking sound that resembled someone hammering on wood, which the bird could easily have heard in the forest. That bird was in the forest of the Brindabella Range near Canberra, the same area where this footage was recorded. It is always a pleasant walk along the tracks in the forest, where the lyrebirds can be frequently heard, but seldom seen as they place their display mounds in dense overgrowth. Hence the reason I deployed the camera, to see what was going on in there…

Male superb lyrebirds sing four different song types with unique associated sets of dance moves, but the individual birds vary their songs and steps and they don’t always dance when they sing (Dalziell et al. 2013, below). As can be seen in this video, they also sing without even raising their tail. The whole sequence of the different songs and dances is very elaborate, but purposeful. As these displays form part of the sexual behaviour, there is probably a strong impulse for the males to sing and dance their best to attract a female.   

Lyrebirds can sing with mimicry away from the mound, such as up on tree branches or logs, but they don’t give mimicry segments of their song while dancing. When singing his full repertoire of mimicry the male in the video stood quite still, and it was once he pulled his tail right over his back and head that he began to dance. This was induced by the presence of a female off camera, and he held that pose and dance sequence all the while a female was with him on or near the mound. In one sequence, he backs off the mound, followed by a female, perhaps, the birds copulated on another mound not far from the one where the camera was set. Each male hase several mounds where they display.

I have not yet worked out the complete list of the bird calls that the lyrebird mimicked, but the main song, mixed with the lyrebird’s own specific song, includes: Yellow-tailed Cockatoo, Laughing Kookaburra, Pied Currawong, Crimson Rosella, Red Wattlebird, Satin Bowerbird and Grey Shrike-thrush. During the intense dances when his tail is fully pulled over, the bird does not mimic these calls, but gives a frantic array of buzzing alarm calls, mimics of the alarm calls of the smaller ground dwelling birds such as White-browed Scrubwren, Brown Thornbill and Eastern Yellow Robin. He even mimics the burring of bird wings, such as when birds mob a predator.

For a more full explanation of  Superb Lyrebird display see these papers by Anastasia Dalziell et al. upon which I have relied heavily in describing the details of the bird’s behaviour in this video. 

Dalziell, A.H., Ppeters, R.A., Cockburn,A. Dorland, A.D., Maisey, A.C., & Magrath, R.D. (2013). Dance choreography is coordinated with song repertoire in a complex avian display. Current Biology 23: 1132-1135. https://www.cell.com/current-biology/pdf/S0960-9822(13)00581-2.pdf 

Dalziell, A.H., Maisey, A.C., Magrath, R.D., & Welbergen, J.A. (2021). Male lyrebirds create a complex acoustic illusion of a mobbing flock during courtship and copulation. Current Biology 31: 1970-1976. https://www.cell.com/current-biology/pdf/S0960-9822(21)00210-4.pdf

Dalziell, A.H., Welbergen, J.A., & Magrath, R.D. (2022). Male superb lyrebirds mimic functionally distinct heterospecific vocalisations during different modes of sexual display. Animal Behaviour 188: 181-196.   https://www.sciencedirect.com/science/article/am/pii/S000334722200094X

 

 The Three Capes

 Tasmania

A four day, three night trip around the Three Capes Walk on the Tasman Peninsular. 

Cape Raoul lies behind Mount Brown at sunset on the first night.

The sand dunes of Crescent Bay by Mount Brown seen from Arthur's Peak on the morning of day two.

Tasman Island off the tip of Cape Pillar, with the jagged rib of the Blade rising towards the island.

The lighthouse on Tasman Island is picked out by sunshine. The rocky pillars on the right form the Blade, a spectacular highpoint above the sound. The island is mostly bare of tall vegetation since its forest was cleared for firewood by the lighthouse keepers and eaten by their stocks of sheep, goats, cattle and pigs. The light was first lit in 1906 and automated in 1977. Shrubs and small trees are slowly reclaiming the land, and the island's breeding populations of Short-tailed Shearwaters and Fairy Prions are recovering after near eradication by feral cats, which were descendants of the lighthouse keepers pets.

A single block of rock lies on the tip of the Blade, with wrap-around views of the peninsular and the ocean beyond. The main rock in much of the Tasman Peninsular is dolerite, which fractures along straight vertical lines to form crude hexagonal pillars. Hence the name Cape Pillar, although all three capes have these rock formsations.

Day four began with a view of Cape Hauy from the Cape Pillar. The trees are much taller on this eatsern, leeward side of the peninsular.

The view back south to Cape Pillar from Cape Hauy, with Tamsan Island peeping over the ridge. The rock stack is Cathedral Rock.

The view from the end  of the third Cape, Cape Hauy with the pencil thin stack of the Totem Pole, the thicker and taller Candlestick, and the Lanterns. The lanterns are two tall rocky islands off the tip of the cape, one is behind the other.

The Totem Pole is a remarkable 65m tall rock stack. It can be climbed at trad grade 24, although timing access is critical as can be seen by the tide swirling around its base. 

Most people simply enjoy the view. A magnificent view of a wonderful wild place. 

 Black Mountain Peregrines

This is the Telstra Tower which stands on top of Black Mountain, a hill, about 1km from the city centre of Canberra. It is surrounded by Red Stringybark/Scribbly Gum forest which holds lots of nest holes for various animals including Galahs, Crimson and Eastern Roselas.

Two days ago, I was walking through the woodland at the base of the mountain, when I saw an adult female preregrine soaring low over the canopy, obviously hunting. It is usually Brown Goshawks that I see hunting there, so I was a bit surprised.

The woodland canopy was busy with migrating Silvereyes and Yellow-faced Honeyeaters on migration down from the higher Brindabella Mountains several kilometres away. And there were numerous rosellas sitting outside their nest holes, staking claim prior to the next breeding season. So there was abundant food for the peregrine.

Then, the next day, I was walking around the summit of Black Mountain when I heard the distinctive harsh calls of a peregrine coming from the tower. Sure enough, there were two adult birds perched on the second top section, on the supporting struts for telecoms antenae. Yes they are in the picture above, but it is not the best of shots, taken with a phone.

The tower is 195 m tall (640 ft) and an obvious man-made feature to attract peregrines. Yet, this is the first time I have seen them there, or heard any. The tower has been closed to the public for a few years, so perhaps the quietness has helped to attract the peregrines. Although the visitor pviewing platform is a long way below where the birds were.

Now, the question is, will the peregrines stay to breed on the tower next breeding season?

Frogmouth chick rescue 

Following on from the last post on how frogmouth fledglings are vulnerable to becoming grounded and dying in tall grass, I found such a bird yesterday. I was monitoring the progress of some of my study birds and was expecting them to have fledged the night before. When I went to the nest site, I saw that they had indeed fledged. The nest was empty and the parents were perched on a branch in a neighbouring tree with one chick beside them. That raised alarm in me as I knew there had been two chicks ready to fledge only a few days prior. Usually, when there are two fledglings and they have split up, mum will sit beside one chick and dad with the other. But, there were both parents with only one chick. Where was the other. Unlike in the previous post, when one chick had probably grounded in wet tall grass and succumbed to hypothermia, in this case the grass was tall, but dry, so I reckoned that if a chick had grounded in the tall grass in the previous night, it could still be alive. So I searched for it, very, very slowly, and careful to look down into the grass before I moved my feet. I didn't want to step on it.

As the adults tend to sit with a chick each if they are separated, I thought the missing chick might be directly below where the rest of the family were perched. And yes, it was, and it was alive.

The grass was more than knee deep and thick, so the bird could not climb up, fly up on its weak wings, or even struggle through the dense growth. It would have died if I had not found it.

The fledgling had fluttered about twenty metres before grounding, not far from the nest branch which can be seen in the background.

And yes the chick was not only alive but perky, giving a ferocious sounding growl as I bent down to pick it up. It opened its big mouth wide and flashed its wings to appear powerful and more fearsome than it really was. 

Of course, once the fledgling began to react, its parenst both reacted to my interference. They both hooted aggressively and swooped over me. That is a big commitment for frogmouths as they only fly in daylight under extreme circumstances of danger. Here dad sits above me, watching my every move as I carefully picked up his still-dependent offspring.

The fledgling looked bigger than it actually was. Most of its growth so far had been in bone and feather development. There were only weak muscles beneath all that fluff.

I popped the bird onto a dead branch in the shade below where the family were perched. This is the best thing to do if anyone finds a frogmouth chick on the ground. The adults will be close by watching. Just because we might not see any adults, that does not mean there are none there. These are frogmouths, masters of disguise and they can be very difficult to see when perched motionless in a tree, which is what they do most the day.

The fledgling soon settled on its new perch and as I walked away it faded deeper and deeper into the mix of branches. I reckon it would have been safe and a parent would soon fly down to perch next to it for the rest of the day to defend it.

But how many other fledglings have died this year in the wet and windy we have had.