Sunday 21 December 2008

#58 Christmas beetles get busy

Christmas Beetles are busy passing on their genes at this time of the year, and I am particularly pleased with the series of images I captured of one species in action.

Over two days in mid December, I found Black Nail Beetles (Repsimus manicatus) in numbers on a couple of my Callistemon shrubs. With a ladder, and a good dose of patience and a healthy sense of discovery and humour, I searched for mating pairs, and was rewarded with good views of the entire act.

Black Nail Beetles (Repsimus manicatus) are so called
because the elytra (wing covers) resemble long black
polished fingernails

Adult beetles emerge during the early to mid summer period from the soil, hence the common name of "Christmas Beetles". From Family Scarabaeidae, there are approximately 34 species of Christmas Beetles distributed throughout Australia, most commonly in the high-rainfall coastal areas of eastern states.

Life Cycle of the Christmas Beetle

The life cycle extends over one or two years, depending on species. Eggs are laid into soil or compost in the spring and early summer. Females are capable of laying between 20 and 40 eggs each. Newly hatched larvae feed on organic matter in the soil, and older larvae feed on organic matter and/or roots. Ref: Dept Primary Industries, Queensland.

The larvae have a distinctive 'C' shape and are often called curl grubs. In late winter/early spring fully-grown larvae move close to the surface and hollow out a chamber in which they pupate. Pupation lasts several weeks.

After pupation the new adults must wait in the soil for suitable conditions, usually when the soil is softened by rain, allowing them to dig their way to the surface. In very dry conditions the beetles cannot burrow to the surface, and die in the soil. In flooded conditions they will drown. Ref: Dept Primary Industries, Qld.

The underside of a Black Nail Christmas Beetle as it eats

After emerging, beetles fly a short distance to food plants to feed and mate. The females then return to the soil and lay eggs, although some lay eggs before feeding. Feeding and egg-laying may continue for several days. Adults may live for some weeks. Ref: Dept Primary Industries, Qld.

Adults are voracious feeders and large swarms can rapidly defoliate trees. Although the damage to my Bottlebrush shrubs is evident, it is not extreme, and a light prune will be all that is needed to tidy them up.

Black Nail Beetles ( Repsimus manicatus) copulating.
- notice the distinctive difference in size and
shape of the hind legs of male and female.

The Black Nail Beetle has immensely developed hind legs, with the male having thicker legs than the female. When I disturbed the beetles, they raised back legs in a horizontal posture, presumably to assume a more threatening size as a defense strategy.

It was interesting to note that the Black Nail Christmas Beetles were not attracted to the porch light of a night.

The large hooked back claws are not used in mating,
but for moving about the foliage

This image shows a thick white fluid oozing from
the female's reproductive canal

. . . . . and this image illustrates the shape of the male's
reproductive organ just withdrawn from the female

It might sound like a rather odd pastime, spying on the mating practices of beetles, but what fascinating up-close observations! And all in my garden! This is the first time I have noticed this species of beetle in my yard, so it was a beaut find.

***** ***** *****

Christmas is different things to different people. I hope everyone stays safe over the festive season, and has reason to smile. I'd like to send a special "cheerio" to those who might be lonely, alone, unwell, low in spirit, or down on luck.

Seasons greetings from Gaye from the Hunter

Wednesday 10 December 2008

#57 A Bird-dropping spider breeds and dies

Spiders appear in numbers overnight, almost magically, as summer approaches. I am always keen to discover new spiders in my backyard, and to further observe habits of the regulars.

The Bird Dropping Spider is not exactly a regular in my garden; I have only seen two specimens. Last summer I was lucky enough to be able to keep tabs on a mature breeding female.

A Bird Dropping Spider in my garden

I believe the species of Bird Dropping Spider I have found in my Hunter Valley rural garden is probably Calaenia excavata (formerly C. kinbergi) from family Araneidae.

It is no puzzle as to how this odd little spider got its common name; it is a master of camouflage as it rests with legs folded against its body throughout daylight hours looking remarkably like a blob of bird excrement, therefore escaping the attention of predators like wasps and birds.

"The Bird-dropping Spider also uses mimicry of a quite different sort to capture its prey, which consist almost exclusively of male moths. At night the Bird-dropping Spider hangs from the edge of a leaf or twig on a short silk thread, its forelegs outstretched. While doing this it releases a chemical scent (pheromone) that mimics the airborne sex pheromone released by female moths to attract their mates. The unfortunate male moths that are attracted by the spider's deceiving pheromone eventually flutter close enough to the spider to be grabbed by its strong front legs." Ref: Australian Museum Online.

White and brown colouring mimics a bird's dropping

Underside of Calaenia excavata (Bird Dropping Spider)

The female Calaenia excavata's body grows up to 12mm, while the tiny male is only 3mm. Unfortunately, I did not find the male (it is possible he became a meal after mating), but of course it could be easily overlooked.

Egg sacs that I observed were from 8 to 10mm, spherical in shape, brown with black markings, and paper-like in texture. Six egg sacs were constructed over a period of about 4 weeks, and were suspended in a Leptospermum shrub, loosely connected by silk. The female remained with her unhatched egg sacs until she died.

I did not take the effort to observe the nocturnal hunting techniques of this clever spider, so the only time I saw her outstretched legs was when she was at the end of her life. Shortly after I took the following image, the spider dropped from her position to the ground, and was lifeless.

Female Bird Dropping Spider close to the end of her life

Despite checking the egg sacs most days, I did not see the spiderlings emerge and disperse. I did, however, break open an empty egg sac to inspect the interior. A tiny escape hole was evident.

Bird Dropping Spider Calaenia excavata empty egg sacs

These odd, yet remarkable little spiders are not considered dangerous. I look forward to finding more living and breeding in my garden. They are apparently commonly found in citrus orchards, so if you have a couple of citrus trees in your backyard, you have more chance of finding the Bird Dropping Spider than I have.

Esperance Blog has an excellent entry on the Bird Dropping Spider, Calaenia excavata, over the other side of the country.

Spider identification links

Thursday 4 December 2008

#56 Backyard predators

When we refer to predators in Australia, creatures like raptors, dingoes, foxes and feral cats are first to come to mind, but we will all have predators of a less conspicuous nature in our immediate outdoor living space - birds, lizards, snakes, frogs, spiders and other invertebrates.

Magpies are amongst the most endearing predators to regularly visit my backyard. The Australian Magpie (Gymnorhina tibicen) has several races. It is my understanding, (I am happy to be corrected here), that there are 8 variable races in Australia in two major groups (black-backed and white-backed), with wide hybrid zones between them.

As far as I am aware, the only Magpie in the Hunter Valley is the black-backed G tibicen (race terraereginae). With its delightful chortle and playful nature, the magpie is a very welcome visitor to my yard. Not only are they entertaining, but they also play an important role in keeping the invertebrate population under control. With keen hearing, they are excellent predators.

Our backyard Magpie collects grubs
and Wolf Spider for its young in the nest

Other common feathered predators to visit my backyard are Masked Lapwings, Willie Wagtails, Silver-eyes.

During the warmer weather, my backyard is home to many species of spiders. Most are web-builders who wait for their meals to come to them, but there are some predators amongst my local spiders. Most obvious is the Garden Wolf Spider (Lycosa godeffroyi).

Up close, Wolfies can be a scary sight, but they are relatively harmless unless provoked. At night, and on grey days, these fearless hunters can be spotted moving about their environment looking for a meal. I have seen them catch spiders, beetles, and various unidentified invertebrates. They are an awesome predator!

A Garden Wolf Spider tackles a large beetle

I have had the opportunity to watch a few species of lizard hunt in my backyard. Having an Eastern Water Dragon (Physignathus lesueurii) choose to live in my garden for nearly two years, I was privileged to observe his life in detail.

Bearded Dragons (Pogona barbata) and Southern Rainbow Skinks (Carlia tetradactyla) have also spent time living in my backyard. All three lizard species have different hunting techniques.

A Water Dragon catches more than he can handle.
The lizard was not able to dismember the frog,
and can not eat it whole.

Although I have photographed and identified nine species of frogs in my backyard, I have unfortunately not seen a frog actually in the act of catching its prey.

Wasps are efficient predators. Mud Dauber Wasps (Sceliphron laetum) and Potter Wasps (Eumenes latreilli) breed in my backyard most summers. Although they feed on nectar, they prey on spiders and caterpillars to stock their breeding chambers for their developing young.

A Potter Wasp stuffs a caterpillar into a breeding cell

Some ants prey on living creatures. I have observed Green-head Ants (Rhytidoponera metallica) preying on living caterpillars in my garden, but the following picture of one of the "Inch Ants" carting off a live bee was taken in coastal sandy heath in the lower Hunter Valley.

An ant carts off a live, pollen-laden bee

Although I have not observed snakes hunting in my immediate vicinity, I was very fortunate to witness the following scene where a Stephen's Banded Snake (Hoplocephalus stephensii) had just killed a large Peron's Tree Frog (Litoria peronii) in the rainforest of Barrington Tops National Park in the east of the Hunter Valley.

Snake catches frog

So, lurking in your backyard, there could be a variety of predators acting out spectacular hunting and killing scenes. Predators will even prey on predators. The secret lives of our backyard native creatures are fascinating.

Wednesday 26 November 2008

#55 The Grey Butcherbird - from hatchling to fledgling

Taking the opportunity to observe the habits of a pair of Grey Butcherbirds raise their young in the Hunter Valley, NSW, was a fascinating and entertaining experience. I wish to share a series of images by my husband, Grahame, from hatchling to fledgling.

Female Grey Butcherbird settles on her chicks

The Grey Butcherbird (Cracticus torquatus) appears to be a year-round resident of the Hunter Valley. I delight in hearing its joyous cackle, sometimes competing with the glorious tune of its cousin, the Pied Butcherbird.

I considered their nest site an odd choice, resting precariously on a dead sapling that was teetering at 45 degrees. It was totally exposed to the elements, and to aerial predators, without the protection of foliage.

Male offers female a morsel of food
(chicks in nest - 14 Oct 2008)

Male supplies one of 4 youngsters with food -22 Oct 08

Distribution of the Grey Butcherbird is woodland and open forest throughout Australia, excluding hotter deserts and Cape York Peninsular. (ref: Readers Digest Complete Book of Australian Birds). It is a reasonably common bird in rural Hunter Valley where I live.

Both parents feed the young - 14 Oct 2008

The female incubates 3 to 5 eggs for 24 to 26 days. She is fed on the nest by the male, but both parents feed the young. Young fledge in about 4 weeks. (ref: Readers Digest)

The 4 chicks - 28 Oct 2008

The habits of the birds were very interesting to observe at length. Both parents collected and carried away faeces sacs. Following is a series of three images illustrating the collection process:

The young offers his rear-end . . . . .

. . . . a bulge appears as the chick pushes out waste . . . .

. . . . . and the parent collects the sac for removal.

We watched both birds return to the nest with frogs, moths, worms, grasshoppers, other invertebrates, and a dismembered bird or animal. At one stage, the adult male successfully fed a piece of meat and bone, as big as the chick, to one of his brood.

I was amazed at the rate at which both parents returned to the nest with offerings for their young. They are very efficient hunters, perching on a branch, watching the ground, and pouncing.

A frog for one of the four gaping mouths (28 Oct 2008)

1st Nov the 4 chicks are exercising their wings

4 Nov, only 2 chicks remain - the missing two chicks may have fledged, fallen, or been predated

According to some of my reference books, Butcherbirds are likely to nest in the same territory year after year, so we will check out this area again next year in the hope of making further observations.

Note: I recently had the opportunity to observe a bird-banding project in Western Australia. Interested people can read about this rewarding experience on my journal blog, Snippets and Sentiments.

Monday 20 October 2008

#54 Eastern Brown Snakes in the Hunter Valley

The highly venomous Eastern Brown Snake is not my favourite creature of the bush, but I feel these misunderstood reptiles deserve a bit of support. In my part of the Hunter Valley, they are dispatched with shovels, roles of hose, moving vehicles, and goodness knows by what other means.

I saw my first living snake of the season last week -
a fine specimen of Eastern Brown sunning itself

Yes, the Eastern Brown Snake (Pseudonaja textilis) is venomous; potentially fatal - but only if a person is bitten. Most bites occur as a result of a person threatening the snake. A snake will generally go out of its way to avoid humans, but humans have created habitat that is to the liking of the snake, hence, humans and snakes will occasional cross paths.

A Brown Snake finds refuge in a roadside
telecommunications pit

The Common or Eastern Brown Snake (Pseudonaja textilis) varies in colour from yellowish brown, brown, reddish brown, greyish brown to almost black. Juveniles bear a black blotch on the head and a black band on the nape of the neck, (and in some areas, prominent narrow black bands on the body).

Habitat: This snake is widespread through subhumid to arid eastern Australia, occupying almost all habitats except rainforests or wet sclerophyll forests and alpine areas.

Land clearing has apparently proven beneficial, as brown snakes seem to be most abundant in agricultural regions. The Eastern Brown Snake is the snake I encounter most (although, still rarely) in the rural area of the Hunter Valley where I live.

The Eastern Brown Snake well camouflaged . . . . .

. . . . . and another well hidden Eastern Brown Snake
eyes off the photographer (me)

Breeding: Clutches of 10 to 30 eggs have been recorded; laid in late spring. A litter may contain both banded and unbanded individuals. Eggs hatch after about eighty days, and hatchlings measure about 27cm. When nesting, this snake utilises any available cover, but is particularly fond of man-made cover such as sheets of metal.

Habits: The Eastern Brown Snake is diurnal (although sometimes nocturnal in hot weather). It relies on keen vision to locate prey which can consist of mammals, birds, lizards, and occasionally other snakes.

The abundance in rural areas is probably due to the presence of numerous introduced mice and rats which provide a valuable food source.

Eastern Brown Snakes are extremely swift, alert and nervous; quick to retaliate if provoked, readily adopting a defensive stance raising its forebody in an S-shape, hissing loudly and striking repeatedly. I have never observed this defensive behaviour, but I have seen it remain motionless in an effort to remain hidden, and flee swiftly.

Ref: "Australian Reptiles - A Photographic Reference to the Terrestrial Reptiles of Australia" by Stephen K. Wilson and David G. Knowles.

Ref: "Australian Reptiles and Frogs" by Raymond T. Hoser.

An unusual sight: an Eastern Brown and a Red-bellied Black (Pseudechis porphyriacus) sharing living space after being washed from winter shelters during the June 2007 Hunter River flood.

A dead juvenile Eastern Brown Snake with
distinctive head markings

I don't normally feature images of dead animals, but many of the snake road-kills in my area are deliberate killings - unnecessary, and often cruel.

I encounter very few snakes during my normal day to day activities in rural Hunter Valley, but following the June 2007 flood, Eastern Brown Snakes and Red-bellied Black Snakes were washed from their winter hides on the river bank opposite my home. I had a fabulous opportunity to observe them.

I also witnessed unnecessary cruelty from humans. Sections of a previous post, I feel, are worth repeating:

If people find a snake inside their home or workplace, wildlife aid people or NPWS should be able to offer advice as to who to contact to have the snake removed and relocated safely. Rural people who encounter snakes would be wise to give the snake space to move on.

Regardless of size or venom toxicity, all species avoid confrontations with humans whenever possible and must be trodden on or otherwise harassed before they resort to biting in self-defense. The primary function of venom is to subdue prey, not to attack animals too large to be consumed.

An Eastern Brown Snake basking in the sun

It is not only unnecessarily violent and heartless to kill snakes, but it is illegal. Snakes are protected. If we hold a healthy respect for these animals, along with a commonsense approach, we can live in the same locality without incident. After all, it is we humans who are invading and changing the snakes' environment, not vice versa.

Note: My journal blog Snippets and Sentiments has evolved into mainly entries telling of my daily rambles amongst nature, which might be of interest to those who visit this nature blog.