First frogmouths now on eggs

A few pairs of Tawny Frogmouths are now incubating their first eggs of the year. The earliest eggs in Canberra were probably laid over last weekend, about the 27th August. This is a little early, the earliest I have seen birds on eggs has been the 12th August several years ago. Most will probably lay in early-mid September which is not much different from the usual dates. Some birds began building their nests over a month ago, possibly in response to the high rainfall in the area during the past few months over winter. However, after a warm spell, there has been some colder weather and this might have halted any early developments. This bird is unusually easy to see as his tail breaks the outline of the branches. Their tails usually lie along the nest branch. (It is the male that incubates during the day, while both sexes take turns at night).

When seen along the nest branch, a predator's view, the bird is less noticeable. Its grey plumage blends well with the colour of the tree's branches.

This nest is quite large and substantially raised up above the branch. This causes the bird's tail to lie high above the branch and hence, reveal the bird's presence.

Meanwhile, the females roost by day, relying on their camouflage for concealment from potential predators. Spots and flecks blend with spots and flecks.

Frogmouths incubating

A pair of Tawny Frogmouths Podargus strigoides at their nest site - can you spot them

September is the month when most tawny frogmouths in the Canberra area lay their eggs and begin their four-week incubation. This year, the earliest birds laid on the 26th August and the last ones have yet to lay, which is typical of the spread that I have found in the past several years. I monitor about fifty pairs in my studies of these birds, and they are rather difficult to find as they are well concealed. Yet every time I do find a pair at their nest site I cannot help but admire their adaptation to their habitat.

The male sitting on the nest set in the fork of a tree - tricky to see in the typical dappled light

The male incubates the eggs during the day while the female sits quietly in a nearby tree. Neither will move when approached apart from shifting their posture, usually to an erect stretched pose by which they blend into the shape of a branch. As their colouring also resembles that of a dead branch, they simply disappear into the wood.

The female sits on a dead branch high in an adjacent tree

The dead branch posture is the one most people are familiar with if they come across a bird, but most of the time they sit fluffed up and bask in the sunshine. Some of the birds I study are familiar with me as I have visited them several times a year over the years, they probably recognize me. And it is probably because the birds have seen me so often that they do not go into their branch pose. I have been right next to birds as they have cocked their head right back and opened their feathers to catch the sun. I always prefer to study undisturbed birds so it is especially pleasing to be accepted as not a threat by a wild animal.

A female basking in sunshine, with loose feathers and head tilted to catch the sun

A female adopts the stick-pose, where she resembles a dead branch in colour and shape

As a little footnote, not all the birds build their nests in a branch fork, some use old nests of other birds. And a favourite old nest is that of the white-winged chough. These are mud nests, set half-way along a lateral branch and the frogmouths add just a few sprigs of leaves and twigs to the cup of the mud nest. This might give the birds a more secure nest site than the usual flimsy loose platform balanced in a fork, but they are more obvious to predators. Over the years, I'll gather information on whether the birds that use old chough nests are more or less successful at rearing young than those that use conventional nests.

A Tawny Frogmouth sitting on his nest in an old White-winged chough Corcorax melanorhamphos nest

Snuggled up

It's late winter in Canberra with frosty nights and sunny days, and the birds are beginning to show springtime behaviour. The Tawny Frogmouths are drawing closer to their breeding sites, moving in from more distant perches to be close to their nest sites. They will be building their nests soon. Although none have started to do so yet, I have seen birds with well-built nests by this date in previous years, with the earliest eggs laid on the 12th August. Meanwhile, they are making the best use of the sunshine as they roost during the day.

A pair of Tawny Frogmouths Podargus strigoides roost by day in a gum tree
the smaller female sits closer to the trunk as is usually the case - for protection by her mate?

They are medium-sized birds, about the size of a Tawny Owl, and live mostly on invertebrates. However, they have a slow metabolism and as insects and such creatures are not abundant during winter, they move as little as possible, slow down their metabolism even further and sit in sunny situations, all to conserve energy. And to do so while daytime predators are about, they have evolved excellent camouflage for protection.

A pair of frogmouths sit high on a sunny branch

Yet, they don't stay completely motionless all day. This pair mostly roost farther along the branch towards the trunk, but as the sun has crossed the sky, they have shuffled along the branch to stay in the sunshine. Today was cold.

The spot where these birds usually sit is farther to the right, as can be seen by the worn red bark on the branch and a fluff of cast down below where they normally sit.

The frogmouths sit fluffed up and huddled into a rounded shape to keep warm, and by snuggling up close to one another the pair gain extra warmth.

Last chicks fledged

A family of Tawny Frogmouths sitting quietly in a tree. As they are nocturnal, they roost by day, relying on their cryptic plumage and minimal movement for concealment from potential predators such as Brown Goshawks. 

The last broods of Tawny Frogmouth Podargus strigoides chicks have finally fledged almost three months after the first broods to do so on 25th October 2014. These final broods fledged on the 16th and 17th January; a brood of one and the other of two, both were from relaid clutches after the adults had lost their first clutches. The pair who finally reared the single chick lost two previous clutches in separate nests to predators unknown (likely Brush-tailed Possum Trichosurus vulpecula). They built a new nest in another tree after each time the eggs were taken, while the pair who reared the twins lost their first brood of chicks after they had left the nest too early. That was possibly after the nesting birds were attacked by a predator, but as these birds are not under constant monitoring, and there was no evidence, we'll never know. They re-used the same nest for their second clutch.

The adult female is on the far left (she has reddish markings on her wings), then the male and two still partially fluffy chicks. Frogmouths usually adopt a 'stick pose' if a potential predator approaches such as a human, but these birds have seen me so often, they know me and here have only partially adopted that pose.

Now that the final results are in I have calculated the breeding success of the sample of Tawny Frogmouth pairs that I study here in Canberra, Australia. I monitored 48 territories this year, similar to most recent years, and most successful pairs (23) reared two chicks, 7 reared three, 8 reared one, another 8 reared none and there were 2 single birds; one male and one female - pity they never met up.

This chick, like so many young fledgling frogmouths, has yet to learn to adopt a protective pose like its parent, in this case mum. Her plumage colouring and posture conceal her well, but I have seen better (see some older posts).

The figure of 17% of pairs not rearing any chicks might seem a high failure rate, but I have recorded almost twice that one year. Overall the breeding success of the population (and that is what matters as all animals must eat to live, including predators) was above average with 1.6 chicks fledged per pair (avg. 1.4), or 1.9 per successful pair (avg. 1.8).

The adults close their eyes and watch one's approach through narrow slitted eyelids. That conceals their bright yellow irides which would betray their camouflage. This chick however, just cannot resist peeping around the branch to watch me with partially open eyes. It will soon learn how to behave safely.

So that ends my study season of Tawny Frogmouths for 2014. It seems a long time since the birds first began building their nests in late July, and it won't be long before July comes around again. For further details of the frogmouths over the season and in previous years click on the links to the right of the page.

What wonderful days and nights I have had with them - great birds.

The male was perched in an adjacent tree, unobtrusive and inconspicuous.

Tawny Frogmouth Trio

A Tawny Frogmouth flies onto her nest with a large spider to feed to her chicks

During my study of Tawny Frogmouths Podargus strigoides I have collected 342 nest records and most of those have been by pairs of birds. However, four have been by trios of birds, one of which from this year is shown here.

The two females have roosted together all breeding season, about fifty metres from the male on the nest

Two females have been together with a male since the beginning of the nesting season and they are readily identifiable from one another as one bird is grey and the other has much more rufous in her plumage, especially on her wing coverts and scapulars. I didn't know whether these extra birds in breeding groups take part in rearing the young, so I watched this group over a few nights to see if all three birds fed the chicks. Under a quarter moon, there was enough light to see the three birds fly in and feed the chicks and I recorded the incidents with flash photography for confirmation.

The male sits on the nest all day - note his bold markings on a pale grey background plumage colour 

The male was easy to identify as his markings are very bold on his overall light grey body plumage, especially on his breast. At night, under flash, these contrasting markings are even more boldly emphasised. He, like all other male frogmouths which I have recorded at nests, regularly took his turn at feeding the chicks.

The male is readily identifiable by his large size, strongly contrasting plumage and well-speckled breast

When the birds landed with their backs to the camera, they could be identified by the colour of their wing coverts and tail feather patterns. The females were noticeably smaller than the male and they could be seen to bring in prey and feed the chicks which gave soft begging calls as they took the food from the adults.

The red female feeds the chicks 

Here the red female can be seen feeding the chicks, then nine seconds later, the grey female flew in and the red bird took off to the right over the camera. The incoming female can be seen carrying a beetle in her bill.

The red female leaves the nest as the grey female flies in with food

One feature that could only be detected with the photography was the difference in wing feather moult between the two females. The red bird had complete, fully grown primaries, secondaries and tail feathers. The grey bird was moulting three inner primary feathers, with moult scores of 4, 3 and 3, all the rest were complete, more likely old rather than newly-grown as most birds moult post-breeding.

The grey female leaves the nest, showing that her inner primary wing feathers are in moult

These differences in the birds moult were best captured in shots of the birds leaving the nest when they had opened their wings fully on take-off, compared with when they closed their wings on landing.

The red female leaves the nest, showing all primary, secondary wing feathers are fully grown and her tail is complete 

Other data which I collect when watching these birds at night are the frequency at which the chicks are fed, over the whole night, by the different sexes of adult, under various weather conditions etc. It will be a while before I collect all that data though.

Another shot of the red female leaving the nest and showing her complete wing feathering

Double-pink

Double-pink sitting quietly in her roost 

Double-pink, a female Tawny Frogmouth that has been breeding within my frogmouth study area in Canberra now for three years. She was released by the RSPCA after a road accident and subsequent treatment, and it was they who put the two pink colour-rings/bands on her legs. These are obviously not having any effect on her as she and her partner reared two chicks two years ago, then another last year.

Now she is back in the same home range and the pair again have eggs in their nest.

One of her pink rings - she has one on each leg

The eggs were probably laid last week, and incubation takes about a month. So it might be a while before I post any updates on their progress, but keep in touch. Last time I posted on their breeding there were lots of viewers.

Her partner sits on the nest all day

Brood of three

The male Tawny Frogmouth covers the chicks during the day

The pair of  Tawny Frogmouths which nested earliest in my study area in Canberra now have three well-grown chicks, about three weeks old.

I recorded their activity remotely last night on a Bushnell trap-camera set on an adjacent branch, and they seem to be bringing in moths to the chicks. Certainly small wingless tubular bodies and one very small frog. There are lots of Bogong moths Agrostis infusa in Canberra at the moment as they migrate from their breeding grounds to the hills south of the area. So there is plenty food for all five birds.

Click on this link if you would like to see footage of the three chicks jiggling for space on the nest.

Tawny Frogmouths building their nest

A female Tawny Frogmouth adds material to her nest

Spring is approaching fast in Canberra, where although the nights are still cold, the days are warming and lengthening. And in response, the Tawny Frogmouths are building their nests more industrially. Two weeks ago, only a few pairs had even began to build, now I know several pairs which have well-built nests.

I set up a camera at a nest to record which of the sexes does most of the building, and from the limited sample of only one pair so far, it looks like the female does more. In one night, she spent about six and a half hours at the nest, bringing in twigs, shuffling them into place and sitting on the nest for long periods of time - I don't think there were any eggs yet, but the camera did not look down into the cup. The male spent about two and a half hours doing the same, although he was also on the nest all day before, plus for about an hour post dusk and pre dawn. They don't build large elaborate nests, just a simple platform which is enough to form base to lay their eggs on, so they don't bring in much material. The female brought in twenty-seven twigs and the male thirteen. Last week, only the male attended the nest, and he brought in just one twig, a short time before dawn.

To watch a few minutes of their edited nest building click here

I plan to set the camera up at other nests to record the effort of  a larger sample of birds.

Autumn Frogmouths

Tawny Frogmouths can be very difficult to see when roosting quietly up in the branches

We are well into autumn in Canberra now and the Tawny Frogmouths are even more tricky to find than in spring or summer. They can be anywhere in their home ranges, but this adult male and juvenile were still within a hundred metres of last year's nest. I couldn't find the adult female. I had expected the youngsters to have left their family groups by now, as this is often the time of year when resident birds establish or confirm their pair-bonds and territories. I thought I would find the birds in their favourite winter roost by now, the ones which are better exposed to morning sun and out of the cold south-west wind. This branch was in the sun, but higher up, about 15 m,  and more hidden than the winter roost.

The adult male, on the left, sits comfortably, partially fluffed up as he basks in the sun, while the young bird is a bit more secretive, taking on a partial branch-pose for camouflage. The adult bird has seen me many times before, so is probably less afraid of me.


The young bird is identified as such by her scruffy moustache and eyebrows, and her nasal bristles are not as finely developed as those of a bird in full adult plumage. She is definitely a  female as she has taken on a rusty colouring to her wing coverts. Males are more uniform grey.

Tawny Frogmouth breeding success

An average brood size of two Tawny Frogmouth chicks

I have been monitoring the breeding success of Tawny Frogmouths Podargus strigoides in Canberra, Australia, for several years and have found that the pattern is fairly constant. About half the breeding pairs rear two young to fledging; a few rear three in any year and about a quarter rear one chick. The proportion of pairs which fail to rear any chicks is about 24% on average over the years, ranging from 17 – 34% (Figure 1). I do not disturb the birds to record clutch size, but it is known to range from 1-3.

Figure 1: The number of young reared per breeding pair of Tawny Frogmouths in 2006 - 2012.

In recent years I had thought that more birds were failing to rear young, but this is just the impression gained as I have added more pairs to the study in the past few years. Although I have been recording more failures, this has been in proportion with larger sample sizes, there is no statistical difference (χ² = 3.8, df = 6, P = 0.43). The main causes of failure, which are usually the loss of whole clutches or broods, are predation by unknown species, but likely Brush-tailed Possum or Brown Goshawk. One male was taken off the nest by a feral cat. A few nests have been blown out of their trees by strong winds.

Figure 2: The number of Tawny Frogmouth pairs which failed to rear any young in any year is proportional  c24%, to the number studied (r = 0.899, P = 0.003).

Further study will aim to determine whether there are any differences between the breeding success of frogmouths in grassy woodland, dry sclerophyll forest or suburban remnant woodland; or if there is any difference between years of drought and high rainfall. Fortunately the study has already covered these criteria.

A male Tawny Frogmouth protects his chick

Tawny Frogmouths feeding two-week old chicks

The tawny Frogmouths which were featured in the previous film, now have three chicks over two weeks old. And they take a lot of feeding.

Here the female, the smaller and less boldly -marked bird, offers a small prey item to the chicks.

The oldest frogmouth chick is now eighteen days old, the other two one and two days less as they do not all hatch in one day. In the attached film, they can be seen to be very hungry at the beginning of the night when the female first brings in some food. They call very quietly in a hoarse whisper, and they compete for the food she brings by stretching up to her bill. In the early part of the night, when still lively, the chicks spend much of the time wriggling and shuffling, wing flapping and stretching. And during the first part of the night the adults were mostly away from the nest, although perhaps close by, but they never brooded the chicks during the main feeding period. 

All the food items were the same, unidentified, but long, thin and with tiny legs - centipedes?

The adult birds were totally silent all night. The background sounds are magpies and currawongs calling at dusk, then several species of frog calling during the night.

When the male first left the nest after his day-long stint, he brought in a sprig of vegetation to add to the nest, the chicks dismissed that as no use for food.

There were 129 food items brought in over the whole night, about 43 for each chick. Most were brought in during the first three hours at a rate of one every two minutes on average, but at times the birds brought in prey three times in a minute. Eventually, about one-o-clock, the chicks began to look sleepy and feebly lifted their heads for food. Then the female shuffled over and brooded them. From then on, the birds only brought six or seven items per hour, and they brooded the chicks for longer sessions as dawn approached. 

Click here to watch the film

(approx. 4 minutes and 10Mb)

The female settles to brood the chicks after a long three hours 

of almost continual supply of food to the chicks.