Wet and windy weather

As of today, 15th, there has been 104 mm of rain in the Canberra area in November. 48 mm fell in the previous four days with 30 mm on the wettest day, the 11th. And it has been very windy, with gusts of over 40 km/h each day, peaking at 65 km/h on the 14th. So these have been testing times for birds with chicks, like this Tawny Frogmouth who was covering two chicks during the rain. 

This other frogmouth had his chicks tight beneath him. One is right beneath his belly, its tail and wing tips are protruding towards the camera, and its sibling is tucked under his breast feathers, face to the camera. The chicks are at a difficult age to protect from the rain. Their flight feathers are well formed, but their bodies are still mostly downy. If the down becomes wet they can become chilled and die.

This chick's body was lying below another nest, where the adult was still brooding two chicks. It must have been too difficult to cover three large chicks adequately. This chick died when about 18 days old. They fledge at about 28 days.

And at another nest, this chick died while trying to hatch. Perhaps the adults were intent on covering its siblings and so sat tight through the rain and wind, possibly too tight, and the chick could not push the shell open. It had opened the shell, as can be seen by the crack line around the top, but never left the egg. So close. The chicks bill can be seen above the slug - whose presence is an indicator of how wet the weather was.

I found this Brown Goshawk chick lying freshly dead below a nest in the same wood as the last frogmouth nest. It was not yet stiff with rigor mortis, nor found by ants, and it had been very windy earlier in the morning. The chick had a partially filled crop, as can be seen by the bulge in its throat, so the adults had been providing enough food. Wind blow was the most likely cause of death. There was still at least one other chick in the nest and the adult female was in attendance, looking after it.

The goshawk nest was set at the end of a slim high branch and it was bouncing about in the still brisk wind. The female was quick to return and protect any chicks in the nest as soon as I left the area.

I found two hatched goshawk eggshells below a tree where the adults frequently perch. There were lots of droppings below, that indicated this. And the adult female would have taken the eggshells from the nest and dropped them there. In the above shot, the cup-shaped membrane of the bottom half of a shell indicates where the chick had cut its way around the egg, then lifted the lid and popped out.

This lid of a goshawk eggshell shows the chip marks where the chick had pecked with its egg-tooth to prise open the shell. The pattern is similar to that around the frogmouth eggshell.

Young birds are so vulnerable to the weather.

Mist-netting birds

Owlet Nightjar Aegotheles cristatus

I was out mist-netting birds last weekend at The Charcoal Tank Nature Reserve, New South Wales, on a trip organised by Mark Clayton. The aim is to catch a sample of birds several times a year as part of a long-term study of the changes in the numbers and species in the bird population. The nets were set the evening before and opened at first light, hence we caught this nocturnal bird, an Owlet Nightjar. This is the first I have seen caught in almost-daylight. Perhaps it had been feeding late because it was a cold night at the end of winter and there were few insects about.

Small, quiet, with big dark brown eyes, a long tail, and dark grey plumage
- all ideal for a nocturnal woodland bird

Owlet Nightjars are neither owls nor nightjars, they are classed in a family of their own, Aegothelidae. They roost by day in tree hollows and hunt at night, feeding on invertebrates, mostly insects, which they can catch in flight although they spend much time foraging on the ground. They are small dainty birds, only about 50g in weight, and they have a soft plumage similar to owls and frogmouths, for quiet flight.

Horsfield's Bronze-Cuckoo Chalcites basalis
  - the broad dark stripe over its ear coverts and the scalloped,
 buff tips to the wing coverts are diagnostic markings of the species. 

As the day opened up we heard four species of cuckoo calling: Pallid Cacomantis pallidus, Fan-tailed C. flabelliformis, Shining Bronze-Cuckoo Chalcites lucidus and this one, Horsfield's Bronze-cuckoo. We caught four of this last species and all were males, indicative of how male cuckoos, and many other species of birds, tend to migrate to their breeding grounds ahead of the females. The tail patterns, both topside and underneath, are diagnostic of the species' sex - the females have russet colouring on the outer tail feathers, the males, like this one, have black and white outer feathers.

     Top-side of Horsfield's Bronze-Cuckoo's tail     

    Underside of tail

We caught a good number of regular breeding birds of the area especially White-plumed Honeyeater Ptilotula penicillata and White-eared Honeyeaters Nesoptilotis leucotis for comparisons of biometrics. Our sample included a good mix of species; some resident, some returning to breed and some migrants passing through. There were examples of two races of Silvereye, Zosterops lateralis; the local Z.l. westernensis and the migrant Z.l. ochrochorous which breeds on King Island in the Bass Strait. We also caught fifteen Striated Pardalotes Pardalotus striatus at once in one net and there were three races in that flock; P.s. striatus which breeds in Tasmania, P.s. substriatus which breeds in the interior of the continent and P.s. ornatus which breeds in the south-east.

Z.l.ochrochrous

Z.l. westernensis 

                       

Z.l.w. Rufous flanks

Z.l.o. Tawny flanks

Z.l.w. Yellow throat

Z.l.o. White throat with yellow flecks

Perhaps, the most spectacular bird we caught was a male Brown Goshawk Accipiter fasciatus in full breeding plumage. Accipiters are aggressive and can inflict cuts with their bills and talons, so great care is necessary when handling them. This powerful predatory bird was such a contrast from the docile Owlet Nightjar we began the day with.

The talons are grasped firmly and the head held up away from our hands.
The whole bird is kept well away from our faces.

The bird had clean, slate-blue upper coverts and head. Its breast and underwing coverts were solidly barred.
All its flight feathers were complete, no moult.

The rounded tail is one of the better features to look out for if in doubt whether a bird seen is a
Brown Goshawk or a Collared Sparrowhawk Accipiter cirrocephalus, which has a square-ended tail.

The bright yellow eyes of an Accipiter - a determined hunter.

Note the heavy eyebrows, these shield the eyes, not only from sunshine, but against twigs and leaves when a goshawk crashes through thick vegetation in pursuit of its prey. The brows are unfeathered and the skin shows signs of abrasion. One of the honeyeaters we caught had a 4mm long thorn stuck in the skin on its crown, an example of what birds have to contend with when flying through woodland. I pulled the thorn out cleanly and the honeyeater flew off happily.

All the birds we caught flew off back into the bush. No animals were harmed in the making of this blog. 

A close call

The colour-banded Tawny Frogmouth has two chicks, not one as first thought when they hatched. It is always difficult to see just how many there are when they are small and covered by an adult. But now they are more than two weeks old, beginning to fidget and are ever inquisitive - peering over the edge of the nest to what is going on down below and all around.

Which is just as well, for while I was watching them today, there was a chorus of alarm calls, mostly from Noisy Miners, screeching nearer and nearer. When I looked around at what the frogmouths were watching I saw a Brown Goshawk flit through the trees, around the frogmouths' nest tree, and then gone. It was hot today, about 33 degrees, so the frogmouths had been sitting quietly with their bills open to catch a breeze and cool down. Then as the alarms went off, they clipped their bills shut, half closed their eyes, and gently eased into their broken-branch pose. Once the danger was passed they gently relaxed and opened their bills again. The adult never heeded me much, but the chicks seemed to think I was fascinating, staring at me continuously.

GoshawksA female Brown Goshawk sits on a branch near her nest and young screaming sharp alarm calls.

Many of the Tawny Frogmouths have failed at their breeding attempts this year and some have disappeared from their nest areas. I suspect that in territories where no further nests were built the missing birds might have been killed and eaten by the Brown Goshawks. So I have been noting the distances between goshawk and frogmouth nests. The vacant frogmouth territories are about 100-200m from the nearest goshawk nests and there are wider distances between frogmouth nests in areas where there are goshawks.

One frogmouth pair have failed twice this year and I noticed a Collared Sparrowhawk nest in the tree next to the second nest. Sparrowhawks are smaller than frogmouths, but aggressive, so perhaps they disturbed the frogmouths enough for them to fail at their nesting attempts. That pair of frogmouths are now on a third clutch of eggs about 150m away from the previous nests.

While I was measuring the distances between these nests the goshawks were very defensive of their nests and young. They repeatedly swooped at me. Their speed is astonishing and it was interesting to be in the situation of a small bird being attacked. These birds are efficient killers.

The female goshawk launches off to attack me.

Her flight is straight and deliberate.

Her eye contact was fixed, determined and focused on me.

It was only in the last metre or so that she pulled out and skimmed over my head. Thankfully they did not attack me with open talons as they would a small bird, her feet are dropping into partial attack position, but the sharp claws are turned in. She was too close and quick for the camera to focus.

Goshawks fledging

The brown goshawks which nest in the same woods as the tawny frogmouths are busy feeding fledglings now. They have had mixed fortune in their success, with one pair rearing three chicks, one with two, another with one and one pair failed to rear any. Prey remains below the nests included several young rabbits, two magpie fledglings and a galah.


An adult male brown goshawk calls in alarm as I approached his nest with young.

A female brown goshawk flies past me screaming in alarm. She is larger than the male and can be seen to be moulting tail and primary feathers.

Two fledglings stand on branches next to their nest while another has stayed in the nest.

The nest is typically set in a clump of mistletoe high in a tall yellow box tree.