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Q: Why do birds have down?

January 3, 2019
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Birds are very well insulated. They have fluffy down feathers to trap body heat in when it is cold. One has just got to think about the warmth of a real down jacket or sleeping bag. But what happens to birds when it is hot? Last Christmas Day was very hot and the birds around the birdbath (pictured) were behaving in some peculiar ways.

Animals like humans have sweat glands in the skin. These glands produce moisture on the skin surface which evaporates, producing an evaporative cooling effect. Birds however do not have sweat glands and resort to a number of other methods to stay cool.

When it is hot birds, like dogs (which only have sweat glands in select parts of the body e.g. nose & feet), cool themselves by panting. An open mouth combined with an increase in the breathing frequency allows evaporative cooling to take place on the moist surfaces of the lungs and air sacs. The more rapid the breathing rate the greater the heat transfer. Through this process heat is lost from the body but so is moisture. Birds need to drink need to replace this moisture. Pictured above left is a Common Blackbird (Turdus merula) in a typical panting stance.

Birds can also shed heat by spreading their wings and promoting airflow in less feathered parts of their bodies such as this Willie Wagtail (Rhipidura leucophrys) pictured right . Anybody who has owned chickens will be familiar with this pose in hot weather.

And internally birds can control heat by redirecting blood flow away from areas such as the gut which produces metabolic heat (stopping eating has the same effect) to areas wear heat transfer to the surrounding air is easier e.g legs or combs in the case of chickens.

So the answer to the question posed in the title…

A: So they don’t fly too high…obviously.

Strike up the band…

January 1, 2019

…the fiddlers are in town. Fiddler Beetles (Eupoecila australasiae), pictured left, are so-called because of the violin-styled motif on the hard outer wing cases, and are also known as the Rose Chafers. They are members of the Scarab family of beetles of which there are over 2000 species in Australia. Scarabs are probably better known as one of the sacred symbols in Ancient Egypt.

Flower Chafers, of which the Fiddler Beetle is one species, are a sub-group of the scarab family. The word chafer comes from the Old High German word chevar meaning gnawer and beetles such as cockchafers are notorious for eating the roots of grasses, thus destroying lawns.

Most scarabs are nocturnal insects but the flower chafer group are daytime nectar feeders particularly on the flowers of Eucalyptus and Angophora and therefore are important pollinating species. They are also distinguished by flying with their outer wing-cases closed (most beetles open their outer wing-cases when flying). The pupae feed on decayed wood and emerge as adults in early summer.

At this time of the year a number of flower chafers are active including Punctate or Spotted Flower Chafer (Neorrhina punctatum), pictured right, and the Grey-furrowed Rose Chafer (Trichaulax philipsii), pictured below left, most notable because the grey furrows are actually densely packed hairs on the wing-case.


 
And this time of year would not be complete without a mention of the Christmas Scarab (Anoplognathus sp.) pictured below. Not a flower chafer, it is a nocturnal feeder causing the characteristic shredding of Eucalyptus leaves, a serious problem when beetle numbers get out of control.

It is so representative of my Christmases as a kid, it should wear a red cap with a white pom-pom.

Call of the Wild

December 27, 2018

When I was young I used to watch wildlife shows, particularly those set in Africa. I can still see the cheetah hiding in the long grass with nothing but its eyes and ears visible. And then with a burst of speed it would leap out and bring down some hapless eland.

The picture left depicts the same scene, but in the insect world. The labybird beetle, in this case a Transverse Ladybird (Coccinella transversalis) is eyeing off lunch (and probably dinner as well) in the form of aphids.

Aphids (pictured right) like cicadas and gumtree hoppers are sap-sucking insects. Many species feed on one type of plant only. Aphids are detrimental to plants in a number of ways – they suck the sap, they can transfer diseases between plants and they also produce a honeydew on which mold species grows.

For a number of reasons aphid numbers can increase rapidly. Sexual reproduction is not necessary for propagation. Females can produce live female nymphs in certain seasons thereby producing large numbers of aphids quickly. In other seasons the females mate with males to produce eggs and thus either male or female offspring. In addition, like gumtree hoppers some ants ‘farm’ the aphids offering them protection from predators in exchange for the energy-rich honeydew (pictured below left).

Luckily there are a number of natural predators to control aphid numbers. Adult ladybirds consume hundreds of aphids a week. Both ladybird and hoverfly larvae are voracious predators of aphids.

Unlike the cheetah you won’t see the ladybird pictured above hurtling towards its prey at 70+mph (even though it has two more legs). It will be more a casual stroll and then CHOMP.

A Piece of Aussie History

December 23, 2018

The Botany Bay Weevil (Chrysolopus spectabilis) pictured below, also known as the Diamond Beetle, is the first Australian insect to be described from the Cook expedition of 1770 (the species that is, not this particular insect). Only four other insects were collected on that trip.

 

Botany Bay Weevils live exclusively on a few select wattles, several of which are found in the King Parrot Creek valley. The adults feed on the young leaves and the grubs live in the root system of the same plant.

As with other weevils I have photographed the response of this weevil when disturbed is to either drop off the plant and disappear into the long grass or cling onto something for grim death. Lucky it chose the latter…it’s easier to photograph.

Living in an original muddie

December 20, 2018

An expedition with Sue to locate a White-faced Heron’s nest in the Strath Creek Pioneer Reserve yielded nothing, but on the way back we observed what looked like a mud nest of a White-winged Chough (Corcorax melanorhamphos) high up in one of the eucalypts. From our limited vantage point it was difficult to tell if it was from a previous season or this one. This week the tell-tale head of an adult looking over the nest rim (see picture left) confirmed an active nest site.

Choughs are ground-foraging birds that live in social groups of up to 20 individuals. Their diet mainly consists of seeds and invertebrates such as termites and beetles. At rest choughs are essentially black. The reason for the white-winged descriptor is obvious when the bird is flying or landing (see picture right). Choughs often get mistaken for the larger raven or currawong. Unmistakeable though are the red eyes of the adult which bulge when the bird is excited.

The nest is built of grass and mud or sometimes manure. From 3 to 5 eggs are usually laid by a single female in the group. Nest building is a shared group activity as is nest guarding and rearing the young. This is necessary as chick predation by birds such as currawongs is a major danger. The last time we documented a chough’s nest, three chicks survived in the nest.

We will update you as things progress this season.

Spare the fuzzy ones

December 15, 2018

During the warmer months of the year the bite from the Australian Common (AC) March Fly (Tabanus australicus) can take the shine off a BBQ and in my experience many of these flies are pre-emptively despatched during the course of a lazy summer’s afternoon outdoors. In reality it is only the female fly that bites. She requires blood with which to develop eggs and obtains it by biting warm-blooded creatures, including us. The male is a nectar feeder.

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Flower-feeding March Fly

Being a March Fly is doubly tough if you are Flower-feeding (FF) March Fly (Scaptia auriflua), pictured above and right, because both male and female are strictly nectar feeders and do not bite at all (unless perhaps you are coated in honey). They are one of the beneficial pollinators in the garden and should be spared the wrath of the rolled up newspaper so that they can continue to do their good work.

 

Australian Common March Fly

Telling the difference between the AC and the FF March Fly can be difficult.  The FF March Fly is ‘fuzzy’ being covered with dense hair to mimic a bee. The abdomen has large distinctive cream circles on a black background (pictured above). The AC March Fly (pictured left) has stripes on the abdomen. In close up the differences are obvious but when walking through the bush it’s still hard to tell.

Ultimately, to tell the difference you may have to wait until the fly decides to suck on a flower or on your leg.

FoF Entertainment Review

December 13, 2018

Event:  Ecdysis – the musical

Genre:   Drama

Classification:  G – General exhibition, suitable for the whole family

Director:   Mother Nature

Cast:   Members of the Aeshnidae, Cordulegastroidea and Libelluliodea families (i.e. dragonflies)

Soundtrack:   Various frogs, crickets & cicadas

Year:   2018

Plot summary:  Ecdysis (the musical) is the coming of age story of a dragonfly as it transitions from nymph to adult. This process as the title suggests is called ecdysis. Dragonflies can spend between months and years of their lifecycle underwater as nymphs, depending on the species.  During ecdysis the nymph leaves the water on a piece of vegetation. The adult emerges through a split in the back of the nymphal exoskeleton (see picture below).  The wings are very small. Over the course of several hours internal hydraulics pump up both the body and the wings. I won’t give away the ending.

Rating:   Five stars

Showing:  NOW. On warm nights after dark, at a dam or wetland near you

Reviews:  “By far and away the best couple of hours I have spent in a long time and the backing track was great”   R. Litjens

Truly the greatest show on earth”  O. Donata