Monday, 24 September 2007

#29 Spotted Pardolates are nesting

Bird-watching in the Hunter Valley has been an absorbing and rewarding lifelong pastime for me, as it has also been throughout Australia on my travels. Springtime is a particularly exciting period to observe our feathered natives, with a flurry of nest-building, courting and family activities in full swing.

A male Spotted Pardalote checks out the photographer
[This photograph by my husband, Grahame]

My bird-watching persuits have always been a relaxing, though engaging, affair where I have rarely attempted to capture photographs, content to just enjoy their company. My husband, Grahame, has recently decided to delve into the frustrating, but stimulating hobby of bird photography in preparation for a satisfying retirement hobby. I will occasionally use his photographs in my Nature Blog to highlight the beauty and diversity of Hunter Valley birdlife.

The brightly plumed Spotted Pardalote is a captivating subject. Werakata National Park in the lower Hunter Valley was our hunting ground, an area of Leptospermum scrub and regenerating Eucalyptus forest.

One of the distinguishing features between the sexes that is sometimes overlooked, is the colouration of the spots on top of the head. The female (top) has pale yellow spots on the crown, whereas the male (bottom) has white. [These photographs by my husband, Grahame]

Nest building

Spotted Pardalotes, Pardalotus punctatus, most commonly excavate a nesting cavity at the end of a tunnel dug in earthen banks or sloping ground. Roadside cuttings can provide appropriate sites for nesting, making fleeting encounters possible. For detailed observation purposes, however, it will be necessary to search out a nest in a situation with more room and less distraction.

The tunnel opening is 4 to 5cm wide, with the burrow reportedly about 50cm long and opening into a breeding chamber lined with bark and other vegetation. These tiny birds with legs about 2mm thick hardly look like efficient earth moving machines, with feet designed for perching and beaks suited to scraping insects from leaf surfaces. As I have not viewed their construction technique, I will always be left wondering what the difficulty factor is in this project, and how long it takes to complete.

Although the earthen tunnel nest offers protection from adverse weather conditions and predatory birds, a lot of energy is obviously expended, and still there is the threat of predation from snakes, lizards and foxes. According to my Michael Morcome Field Guide, 3 to 5 white eggs are laid, incubation takes about 14 days and there are often two broods in a season.

This nest looks to be still under construction. Notice the dampness at the tunnel entrance which appears to be purposefully deposited moisture. I observed this site for quite some time after seeing the female exit, but ran out of patience before the builders returned.

Spotted Pardalotes are also known to nest in small tree hollows and even artificial cavities, but earthen burrows are more common. Male and female are both involved in nest building and parenting duties.

Diet of Spotted Pardalotes

Upon consulting my bird field guide, I found that 'Lerps' featured high on the menu of Spotted Pardalotes. I was unsure exactly what lerps were, so I set out to find out, and then to find some to inspect and photograph.

Lerps are protective covers constructed by the nymphs of jumping plant lice (Order Homoptera/Hemiptera, Family Psyllidae). Lerps are formed from the honeydew excreted by the nymphs on the leaf surface. The honeydew consists of sugars and amino acids which crystallises on contact with air. Psyllids are tiny sap-sucking winged insects that feed on native trees and shrubs, especially eucalypts.

This lerp is about 5mm wide and protects a psyllid nymph as it feeds by sucking sap from leaves. Click on photos to view an enlargement.

Psyllids are Australian native insects. They produce a sticky substance (excrement) called honeydew, which drops to the ground, often splattering cars parked under eucalypts. A dark sooty mould grows on honeydew-covered surfaces, including the lerps.

Each nymph lives under its own white semi-conical waxy lerp feeding on plant juices. Adults are not as readily observed because they are active and tend to hide amongst leaves. Adult psyllids are about 4mm long and winged. Eggs are tiny and laid in rows or clusters on leaf surfaces.

Following a 10-20 day incubation period, the newly hatched nymphs (or ‘crawlers’) emerge and move over the leaf surface in search of food. They then construct a protective shell or cone-shaped cover (more commonly known as a ‘lerp’) from starchy material derived from the host plant.

Growth to adulthood occurs mostly within the confines of the original lerp, with maturation from egg to adult taking between 8 weeks and 6 months, depending on temperature. Warm temperatures create optimum growth conditions.

An overturned lerp with psyllid nymph

A close-up of the psyllid nymph that is less than 2mm long. Notice the unformed wings, and the leg configuration with front leg facing forward and two pairs of hind legs facing backwards.

Physical features of the Spotted Pardalote

Both male and female Spotted Pardalote, are between 8 and 10cm long and profusely spotted. The female has pale yellow or buff spots on the crown, while the male has white. Wings of both sexes are marked with clean white spots.

The male has a bright yellow throat, while the female's yellow throat is dull and patchy. Both have deep red and yellow on the rump, but the male's colour is more pronounced. Both also have a white eyebrow defined by the black spotted crown, but again, the male's markings are more defined. A sound file of the Spotted Pardalote is linked to entry 35 on this Birds in Backyard page.

The male bird's bright yellow throat and white eyebrow [This photograph by my husband, Grahame]

Distribution of the Spotted Pardalote, Pardalotus punctatus, includes the east of eastern Australia from Atherton Tableland in north Queensland through NSW, Victoria and Tasmania, and into the south eastern corner of South Australia. It also occurs naturally in the south west of Western Australia from about Jurien Bay to Esperance.

The female bird with a less bold throat, head and face [This photograph by my husband, Grahame]

And the bright red and yellow rump of the male as it enters its nesting burrow

Out of breeding season, Spotted Pardalotes form small flocks and are rarely seen as they feed high in the eucalypt canopy. But as they pair off to breed, they can be seen entering and leaving their nesting tunnel, and if you are prepared to initially wait for these busy little birds to become comfortable with your presence, they will go about their activities, making observation easy.

Their bright flashy colour and intricately patterned plumage make them stunning subjects to watch, and now is the time to see them.


Esperance Blog said...

Hi Gaye, looks like you and hubby might be competing for photographic excellence. I thought Grahame's lower male bird and your lerps were particularly good. I look forward to the outcome of this new relationship.

Peter ( Woollybutt) said...

Nice work as usual Gaye and you chose one of my favourite birds as your subject. I had an encounter with an SP about a week ago when I stepped on a pile of dirt on the side of a forestry track. The Spotted Pardalotes had excavated their nest in the side of this mound which was part of a roadside drainage culvert. Suprised me somewhat to have a little bird fly up suddenly from under my feet. I only managed a couple of pics because I didn't want to disturb the birds too much by hanging about too long. I have this nest marked now and plan on getting back in the next few days to see if I can get some more pics. I'd love to be able to get some shots of the young birds once they fledge and make their way out from the nest.


Denis Wilson said...

A great posting on the Spotted Pardalotes. One of my favourite birds. You and/or Grahame must be very patient in order to have captured those wonderful photos.

Great report on the full life cycle of the birds, and their favourite food. I have actually nibbled on some of the sugary coatings the Lerps make (as a scientific experiment), but I have never seen the actual insects, so that was a bonus for me.

Wonderful posting. Pls congratulate Grahame for the photos.


Gaye from the Hunter said...

hello Jack,

"I look forward to the outcome of this new relationship."

This should be a pleasant and productive partnership, as we have always enjoyed the bush together. And thankfully, there will be no fighting over lenses - I am not keen to use a lens that requires the restriction of a tripod, and Grahame has no wish to use a lens that requires him to crawl around the ground :)


Gaye from the Hunter said...

hi Peter,

one can't help but be delighted to observe these colourful, busy little birds go about their lives - it is a privilege that they allow us access to their space.

I will be most interested to see pictures of the young if you are able to capture them. The nesting sites that we have visited are a half hour away, and I feel we have missed the fledglings.


Gaye from the Hunter said...

hi Denis,

thank you, and it is Grahame who has the patience to sit and observe the nesting hollow. I prefer to wander in search of little hidden natural treasures. I have the persistence required to search out a subject, but not the patience to sit and wait for something to happen.

I found the Pardalote nesting hollows while I was orchid hunting, along with two extraordinarily well-camouflaged grasshopper nymphs and a wolf spider with a perfectly constructed lid for her tunnel - beaut discoveries :)


Lola said...

Hi Gaye,
You have touched on my favourite subject this time - birds - and what a great blog with a wealth of interesting data, accompanied once again with superb photographs. Well done both Grahame and Gaye on those.
Spotted Pardalotes really are jewels of the bush and a joy to watch as they go about their feeding activities. There is a difference in their calls between those in the eastern states and those in the the south of WA. When encountering flocks feeding, their calls sound just like bells.
Excellent work and commentary on the psyllids and their lerps.

Gaye from the Hunter said...

hi Lola, it's interesting to know that there is a difference in calls of the eastern and western Spotted Pardalotes.

I have pleasant memories of sitting around camp in Western Australia listening to and watching the birdlife.

Thank you for your comment and feedback.


Charlotte Le Clerc said...

What an invaluable information sheet! Fabulous photos as well.

A pair of pardies must be nesting somewhere close by or even in my garden (Rivett, ACT) as today I have witnessed very territorial behaviour between a pair, continually attacking the mirror in my walled courtyard (now covered), plus reflections in the windows, regardless of the fact that I am sitting at the table under the pergola, mere inches away. Managed some great photos, as the pair are not intimidated by my presence at all.

oh - that was hard - it took five or more goes to get past the character bit for posting.... really fuzzy and difficult to use :(