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It’s a … thornbill!

January 17, 2022

Thornbills are one of the most difficult bird groups to distinguish. I knew one birder who gave up birdwatching because she “got sick of staring at thornbills trying to guess what kind they were” and took up botany instead – plants don’t fly away.

We have five species of Acanthiza – the thornbill family – in the district: Brown, Striated, Yellow, Yellow-rumped and Buff-rumped. Plus there is the weebill (Smicrornis brevirostris) which is like a thornbill except that it has a ‘wee’ bill instead of a ‘thorn’, that is, its beak is shorter and fatter – it is also Australia’s smallest bird.

All thornbills build dome nests with a side entrance and are insect-eaters primarily.

Learning thornbills is indeed too complicated and exacting to interest many people, so I will suggest one simple distinction: two of them forage on the ground; the rest never leave the trees.
The Yellow-rumped and Buff-rumped are ground foragers. Although they use trees for nesting and sleeping and refuge, they feed in busy little flocks on the ground.

All you have to decide then is whether the yellow colour on the rump (only visible when they open their wings usually) is bright yellow or dull yellow (=buff), which sounds easy, right?
Also the Yellow-rumped has brown eyes and the Buff-rumped has white eyes, which is another distinction hard to make from a distance.

Perhaps it would be sufficient to say “Thornbill!” and be glad that these delightful little creatures share our glorious planet.

Leave the identification to pedants.

Buff-rumped thornbil – A. reguloides. The buff on the rump is just visible
Yellow-rumped thornbill A. chrysorrhhoa

Skewered!

January 11, 2022

This blog site has featured many articles about Hemipterans, an order of insects that includes cicadas, psyllids and various other types of ‘bugs’. Amongst other things these insects are characterised by having sucking mouthparts known as rostrums. The rostrum is capable of piercing and consists of two tubes. One facilitates the injection of saliva into a food source. The saliva contains enzymes that dissolve cellular material. The second tube allows the insect to suck out the pre-digested liquid.

Whereas psyllids, gum-leaf hoppers, spittlebugs and the like suck sap from plants there is a group of Hemipterans that are predatory and feed on other invertebrates. The Orange Assassin Bug (Gminatus australis) is one such creature. When ‘at rest’ the rostrum is tucked underneath the body (see picture above).  

The Assassin Bug is an ambush predator that grabs passing prey with its front legs before stabbing it with its rostrum, injecting enzymes and sucking out the liquid food. The legs are haired to help grip the prey. The unlucky victim pictured above is a Horned Treehopper (Ceraon sp.).

Interestingly both predator and prey are Hemipterans. I guess ‘Who lives by the rostrum, dies by the rostrum’.

Hidden in plain sight

January 1, 2022

The fly family Syrphidae comprises insects commonly known as Hover Flies. Adult hover flies feed on nectar and pollen and are often found ‘hovering’ around flowers, hence the name. They are an important pollinating group of insects.

Hover flies are harmless to humans having no biting or stinging capability. This harmlessness makes them susceptible to predation. To mitigate this hover flies exhibit Batesian mimicry to different extents. Batesian mimicry is a form of biological resemblance whereby a harmless organism e.g. a hover fly, mimics an organism with warning capability i.e. sting or colouration, with the hope that it is mistaken for something dangerous and left alone. At the minimum this mimicry in hoverflies consists of black and yellow colouring so as to resemble bees. The previous insect blog described the mimicking characteristics of a harmless drone fly, a species of hover fly.

At the moment Sweet Bursaria (Bursaria spinosa) is flowering attracting many species of insects (and insect photographers!). Yesterday’s ‘find’ was a black and yellow wasp, pictured above. Trying to identify it proved more difficult than photographing it. After several hours of unsuccessful research I noticed the antennae of the insect were short and stubby, pictured below, much more fly-like than long, bent wasp antennae. Another hour of trawling the web revealed the creature to be a Wasp-mimic Hover Fly (Ceriana (Sphiximorpha) breviscapa). Unless you are close enough to note it only has one pair of wings and those antennae, it looks for all intents and purposes like a more dangerous Potter Wasp.

Batesian mimicry to the max!

Gosh – a super swooper!

December 28, 2021

It’s commonplace to get swooped by a magpie during the nesting season, but I was taken by surprise when I stepped into a clearing and got swooped by a large screaming dark bird of prey. It kept swooping low over my head and perching on various branches on either side. After a few good looks, I recognised it as a Brown Goshawk (Accipiter fasciatus) and the fact that it was so large meant that it was a female – the female is almost a third larger than the male in goshawks and sparrowhawks. It got harassed in turn by first one, then two, then three Leaden Flycatchers – a noteworthy bird to observe in itself.

I had seen this same bird perched and calling on a tree a month or so ago a short distance from this spot and then it flew off in this direction when irritated by some nervous Grey Fantails.

Goshawk nest

I asked the Victorian Birders facebook page if anyone had encountered swooping Goshawks before, and someone shared a story of one that drew blood from a passing jogger in Langwarrin defending its nest. I knew there must be a nest nearby.

On a subsequent day, Ron Litjens and I returned to the area and saw both male and female birds flying around and sure enough, we soon spotted the nest at the top of a tall Red Gum.

It is impossible to tell as yet how successful the nesting season has been, but we will keep monitoring from time to time and hope to see some chicks emerge before too long.

Goshawks are stealth hunters. They do not soar around on thermals and drop like kites or eagles. They sit quietly until they see a prey bird – honeyeater or blackbird, for example, then launch suddenly with powerful feet extended to grab the victim out of the tree they are in. I was once noticing a honeyeater feeding on blossom in a small bush on a street in a rural town, when a great whoosh passed my ear and a goshawk hit the bush like an explosion and flew off with the hapless honeyeater held at a cruel angle.

The power of this bird makes being swooped by it a good deal more terrifying than a pedestrian-buzzing magpie.

Two bees or not two bees

December 21, 2021

That is the question. And the answer is NOT two bees.

In the picture below there are two insects that superficially appear to be the same. The one on the left is a European Honeybee (Apis mellifera). The insect on the right is a Drone Fly (Eristalis sp.), seen in much greater detail in the photo at the bottom left. Both are active pollinators and when buzzing around a flower look much the same. The Drone Fly spends more time hovering when feeding on pollen whereas the Honey Bee has a more direct approach. The Drone Fly has short stubby antennae and only one pair of wings, the Honey Bee has bent antennae and two pairs of wings, not that either characteristic is obvious in the frenzy of feeding.

The similarity between the two insects is a classic case of Batesian mimicry where a creature that is harmless against a predator i.e. the Drone Fly takes on the visual characteristics of a creature that is harmful or dangerous to the same predator i.e. the Honey Bee. In this case the harmless Drone Fly has taken on the characteristics of the Honey Bee that has stinging capability. The Drone Fly is relying on the fact that its shared predator such as a Robber Fly can’t distinguish between the two and it will leave it alone fearing being stung. Drone Flies are not the only insect to demonstrate this type of antipredator adaption. Many species of moths and beetles also mimic the Honey Bee in appearance.

If I were to adopt Batesian mimicry I’d probably have to start taking steroids and speak with a guttural German accent.

Scratchy Songbird

December 13, 2021

One of the great sounds of Spring and Summer that catches my ear every year is the scratchy call of the Rufous Songlark (Megalurus mathewsi). The books describe it as witcher-weedle witcher-weedle as well as other trills and phrases. The call of the male heralds the onset of the breeding season and it is so loud it can be heard from a great distance. In the non-breeding season, both sexes are fairly quiet and unobtrusive but, anyway, they migrate North or inland for Autumn and Winter.

Twice this year, I have come across two males having a ‘Battle of the Band’ duel. One pair was at Mangalore, and the other on the Rail Trail near Cheviot Tunnel. One would fly to an exposed perch belting out his song, then the other would appear and chase him away before choosing another perch to stage a reprise. In neither case, did I spot a female, so I’m not sure who they were trying to impress, but they sure impressed me.

Rufous Songlark, at Mangalore

Occasionally in our district I have come across the related Brown Songlark (Cincloramphus cruralis), which is a bigger bird, more often found on the ground or perched on a fence-post to sing and display.

The Rufous prefers a few trees and is often found on farms that have retained some paddock trees. As my photo suggests, they don’t mind a fence-post either.

The path to enlightenment is never smooth.

December 8, 2021

Several years ago the answer to the simple question about a discovery found in the vegie garden, ‘What eggs are these?’ resulted in much angst (click HERE). Using book and web resources to identify adult insects is hard enough. Identifying insects by their larvae is even harder and by their eggs, nigh on impossible unless you’re an expert. To answer the question the eggs were placed in a jar until they hatched. This resulted in the positive identification of the larvae but their subsequent release back into the garden was not a great success. They grew into bugs that decimated the tomato crop that year.

So when the same question was asked of a similar vegie patch discovery this year, caution was observed. The eggs in question, pictured left, were yellow and clustered on the underside of a vegetable leaf. The eggs were again placed in a jar and did not hatch until the leaf to which they were attached was a dried scrap.

The resultant larvae, pictured right, looked more like tiny iguanas than anything else but easily identifiable – ladybird beetle babies. Adult beetles and their larvae are highly beneficial in the vegie patch as they voracious consumers of aphids. No dramas in reintroducing these into the wild.

Occasionally the path to enlightenment is smooth.

Frogmouth squats in Chough’s Nest

November 28, 2021

The craft that goes into the construction of a White-winged Chough’s nest (Corcorax melanorhamphos) is extraordinary. The family work together to sculpt a beautiful mud bowl. ANU researcher Dr Connie Leon was fascinated by the complex family dynamics and noticed that they practised a type of slavery – young birds from neighbouring clans are coerced into the work gang, building the nest, taking a turn on the nest for brooding, and then helping to feed the very demanding chicks. In other words, the clan is augmented by additional young workers lured from other clans and kept there by vigilance.

Chough families are often seen on roadsides in our area and can grow to as large as 20 birds, although I have seen super flocks in Autumn at times of many more than that.  It seems a waste of energy to build a beautiful mud bowl nest each year. This family of choughs left an excellent nest behind and built a new one for the season on the other side of the same tree.

White-winged chough at new mud nest

So in moved a Tawny Frogmouth pair (Podargus strigoides) to occupy a perfectly-good choughs’ nest from the previous year. Frogmouths normally build a very flimsy nest on a fork on a horizontal branch where they train up a couple of lugubrious fluffy chicks to sit as still and stiff as their parents.

It must have been an irresistible opportunity to squat in this elaborate nest that no frogmouth could ever construct and bring up the family in security and comfort.

Tawny Frogmouth using an abandoned Choughs’ Nest

The slogan they follow seems to be: reduce (work), reuse, recycle.

It’s a Breeding Frenzy

November 12, 2021

It’s a lively breeding season in this lush Spring after generous rain over the year thus far. One of the easiest birds to observe, to wonder at, and to photograph is the Eastern Yellow Robin (Eopsaltria australis) because they are bold, they forage at eye-level or lower, and they tend to settle calmly when they land, not be restless like a thornbill.

Though I always try to keep my distance from a nesting bird, this Eastern Yellow Robin in the Yea Wetlands makes little effort to hide itself or its nest. There seem to be several pairs nesting at the moment and although the one pictured at the nest has very young chicks, some parents have got ahead in the race. I found one very young individual with rich brown plumage moving alone through the trees by the river. It will probably still get occasional feeding from its parents, like a teenager still likes to go home for Sunday lunch, but I saw no adult while I was watching, making me unsure of its identification till I checked up later.

It’s a good year for birds, a good year for breeding, a good year for learning more about birds.

The Greeblies are here

November 8, 2021

After three anxious weeks of watching them on the nest – a floating structure built way to close to the shore by my way of thinking and in the vicinity of a big ol’ Red-bellied Black (Snake), mum and dad Australasian Grebes (Tachybaptus novaehollandiae) hatched what can only be described a three cotton balls with paddles.

Although the three Greeblies (not the official term for a Grebe chicks!) are quite capable of swimming at birth when danger threatens they clamber aboard the back of one of the parents and hide under their wings (see picture above and below). If the parents are concerned then they do the usual grebe-thing of diving under the water only to reappear metres away. The young ones are taken along for the ride.

This form of chick transportation only takes place in the first few weeks after hatching. By then the greeblies are too big to fit on their parents’ backs and have themselves learned the art of diving when danger approaches. Daily life now appears to consist of the adults diving down and picking up food that is voraciously eaten by the chicks as soon as they surface.

After a couple of months the parents will leave the young to fend for themselves. In good seasons they may reuse the nest to lay a second clutch of eggs.

I don’t think I could stand the stress of waiting again.