My old friend the Australian Kestrel looking over his shoulder to say "farewell" . . .

I’m a pretty sentimental soul, so after putting almost 6 years of weekly surveys behind me – six years of relishing the story of the migratory shorebirds of Boat Harbour and the many wonderful wildlife encounters there . . . six years of amazing observations, such as the most northerly record of a King Penguin in Australian waters or the amazing out of phase Sanderling in full breeding plumage in an Australian high summer – hanging up the data sheets was always going to be hard. Whilst concluding my count today a large pod of dolphins frolicked just off the back of the reef as if to remind me what a wonderful job I was leaving behind. Perhaps they were trying to say “so long and thanks for all the fish” I felt like I was trudging up some steps to a gallows as I walked up the beach and onto the big dune for the last time. As I got a bit of height on the dune, I turned for a last look. I could just see a little further around the beach at this point and then, what should I spy on the shoreline but a beautiful roost of 15 Red-necked Avocets. A stunning first for me at Boat Harbour!

A portion of the Avocet roost on Boat Harbour.

My spirits were lifted considerably as I dashed across the sand in the sunshine, focussed the scope on them and soaked in the beauty and fascinating behaviour of these birds for a good half hour. What a stunning species they are, with their gorgeous deep chestnut plumage on their head and neck which is so brilliantly set off by the black and white plumage on the remainder of their bodies. Their easy, almost floating flight and gentle jostling as they settle again on the shoreline is a vision of pure loveliness. Their foraging behaviour of “mowing” – sweeping their beautifully recurved bill from side to side in the shallows – is not only delightful to behold but a powerful reminder of the almost endless solutions which shorebirds have hit upon in order to secure a niche for themselves among the wetland species. Their long, grey-green legs complete a statement of pure elegance of the sort which defeats even the best works of the Art Deco masters.

Avocet Taxonomy

The elegance and beauty of the Red-necked Avocet.

ALONG WITH the Banded Stilt and Black-winged Stilt, Red-necked Avocets are a member of the Recurvirostridae sub-family which, according to genetic studies, places them in one of the three major shorebird families, the Charadriidae, or plovers. This is interesting, as these birds, with their long legs, necks and bills, all look much more like their distant cousins the sandpipers than their more closely related plovers, who all possess stumpy bills, short necks and relatively shorter legs. It all reflects the system of punishment and reward that is what we see demonstrated in the patterns of diversity and abundance all around us. If any character trait that an individual possess is successful, it will be rewarded with replication. If not, then it’s less likely to become widespread. Successful formulas are hit on again and again as each individual struggles within an ecological community to carve a place for itself amid the competition for limited resources. Thus we see quite unrelated species of life bearing strong similarities when faced with the same or similar circumstances.

A little closure

After this gorgeous encounter, I set off feeling much more reconciled with the past and happier and optimistic about the new chapters of birdy adventures that lie before me. On the last day of almost 6 years of surveys (totaling 428 in all), that I could have a stunning first like this served as a big reminder that the unexpected will always happen when out in nature, so I should look forward to more adventures ahead rather than feeling sad about what’s behind. It’s true to say that if you really love nature, wherever you are there’s going to be something to relish, something to wonder over and something to satisfy that deep need in us all to connect with something much greater.

Until next time . . . happy birding!

Sandpipers demonstrate this wonderfully. When we examine the incredible diversity of bill shapes and lengths and combinations thereof with leg lengths and neck lengths we can see that this principle of exploiting ecological niches through taking advantage of openings and opportunities has been played out in a manner which is at once extreme and very obvious. These combinations of characters among sandpipers indicate massively rampant opportunism which has become available through a wonderful “invention” called “tactile foraging”.

Getting in touch with your prey

Unless it possessed a highly sensitive bill, this Bar-tailed Godwit would be undertaking a rather pointless exercise!

TACTILE FORAGING has freed sandpipers up from relying on merely spotting prey on top of the mud or sand and chasing it down. Tactile foraging has opened up to sandpipers the opportunity to exploit an amazing diversity and abundance of organisms which dwell beneath the mud for all or part of their days or lives. It’s about accessing a world where the game of finding food, shelter, territory and breeding opportunities has been going on in similar extremes of rampant opportunism for many hundreds of millions of years. Such is the diversity and abundance of organisms which dwell beneath the intertidal sand and mudflats of the world that a bird can specialise on one species or even one species in a particular stage of its life cycle as the mainstay of it food resources. For sandpipers, tactile foraging is vastly more than something like you or I sticking our fingers in the mud and sand to feel what is down there. The highly sensitive bills of shorebirds are the result of a process which has taken the sense of touch to extremes which, for many species, amount to virtually seeing beneath the sediment upon which they are foraging.

Red Knots master the muddy medium

A Red Knot in winter plumage on Boat Harbour, NSW.

TO UNDERSTAND this process, let’s examine the bill structures of one of the masters of tactile foraging, the Red Knot. The Red Knot is a medium-large sandpiper which, like all migratory shorebirds, assiduously avoids winters. Therefore, it enjoys the warmth of summer in the northern hemisphere, where it breeds on the tundra of far north Siberia and the island of New Siberia. When it cools down in the north, the Red Knot migrates south, to enjoy the mudflats of bays, estuaries and beaches in an Australian and New Zealand summer. Red Knots are found on other flyways too, but Australia has two races of Red Knot, Calidris canutus rogersi and C. canutus piersmai: the former visiting New Zealand and eastern Australia and the latter occurring in Western Australia. Through mastering tactile foraging, Red Knots have managed to practically specialise on a diet of small bivalves, around the size of the average little fingernail.

Magnified view of a Red Knot bill tip revealing the pits which contain Herbst Corpuscles. Image after "Shorebirds an illustrated behavioural ecology": Theunis Piersma, Bruno Ens, Leo Zwarts ISBN: 9789050111928

The bills of birds are bony structures attached to their skulls and are in many respects analogous to the upper and lower mandibles in a number of other vertebrate species. The bill is covered with a thin but tough layer of keratin (the same structure which comprises our finger nails). This keratin sheath serves enough purposes for birds to require several blog posts! Beneath the keratin sheath on the tip of the bill of the Red Knot, and many other sandpiper species, lies a number of rows of pits. These pits are lined with many tiny highly pressure sensitive cells called Herbst corpuscles. So sensitive are these cells that they can detect the surrounding pressure of the water between the grains of mud and sand when they probe with their bill and displace that sand and water. Here’s how it works . . .

Displaced interstitial water pressure responding to resistance by an object (in this case a small bivalve) in the sediment.

Most of us have walked along the wet sand of a beach and noted how the pressure of our footfall forces the water in the sand to retreat. The water, trapped between each grain of sand – known as “interstitial water” – retreats from the weight of our footfall due to the displacement it causes in the sand. A similar event takes place when a bird presses its bill into the sand: it displaces sand and water. The retreat of the water will take place in a regular fashion if the sediment is even and undisturbed and thus the pressure will be constant. However, if there is an object beneath the sand which impedes the flow of the interstitial water, the pressure will be uneven and the highly sensitive bill of the Red Knot is capable of detecting this. When they determine that the nearby object is a small bivalve, they snap it up whole and swallow it. The shell is crushed in their powerful gizzards and the shellfish moves into the bird’s proventriculus (sort of like our stomach) for digestion.

Seeing beneath the sediment

AND ADULT Red Knot becomes so skilled in the art of tactile foraging that it appears that they are capable of knowing what lies in the sediment up to 5 cms from the tip of their bills. In effect, this amounts to being able to “see” beneath the sediment upon which the bird is foraging. Research has demonstrated that it takes as many as three years for growing Red Knots to master the skills of using these extraordinary tools, but once that mastery is achieved, the Red Knots have a niche for themselves which very few sandpipers are capable of exploiting. They have evolved so that their bills are no longer or shorter than is required to access a particular population demographic of bivalves to suit the body size that they have also evolved. They have evolved the precise tools to ensure that they have a niche which they can so dominate, that other species cannot access it. Their cousin, the Great Knot, has similar tools and capacities, but a slightly longer bill that enables it reach down to different populations of bivalves and other invertebrate groups as well, which further illustrates the principle of “resource partitioning”, which will be a topic for a future post.

Great Knots "sewing" on Cable Beach, Broome WA as the tide falls.

All this explains the foraging patterns which many Calidrid Sandpipers adopt when foraging called “sewing”: walking along the sand or mud systematically probing in a side-to-side manner. This is often partaken of in a somewhat communal fashion, possibly indicating that foraging parties may respond to the success of various individuals in hitting upon clusters of prey (much as pigeons do). It certainly opens up the opportunity for humans to enjoy one of the more engaging sights on those mudflats which are frequented by this species.

It’s magic!

AGAIN WE find that when we peel away the layers of what is taking place around us we are surrounded by an almost never ending complexity. For the nature enthusiast this presents a whole fascinating contemplation of this amazing biosphere which is the outcome of billions of individuals over billions of years simply making the most of what they have right now, of a place where resources and the ability to tap into those resources present both limitations and opportunities, where success multiplies and failure dwindles. It’s a story where the more we know, the more wonderful the contemplation becomes and when we run out of understanding or the capacity to grasp its enormity and complexity we become once again a child and in that child’s ecstasy declare “it’s magic”!

The price of success

SPECIALISATION always comes at a cost. The extent of tactile foraging which the Red Knot enjoys means that it requires sediment to be composed and layered in such a way that it is conducive to large numbers of small bivalves being present. The consistency of the sediment must be such that the passage of interstitial water flows through it in a manner which sends the right pressure waves for the Red Knot to “read” what is taking place. This clearly demonstrates that certain very specific environmental conditions have shaped the Red Knot. When these conditions are no longer available, there will not be any more Red Knots as they are intimately tied to certain habitats. Developers cannot claim that by destroying wetlands that these birds will simply just go elsewhere, as there are very few “elsewheres” and all of those “elsewheres” are generally running at full carrying capacity. As I type this, I am aware that there is a 25 km stretch of beach on the north of the Yellow Sea which has conditions so ideal for Red Knots that the majority of the 220,000 Red Knots which live on the East-Asian Australasian Flyway stop over there during their migration to and from their breeding grounds in Siberia and their wintering grounds in Australia and New Zealand. In early 2010 the Chinese government permitted the “reclamation” of a 5 km stretch of mudflat adjacent to those beaches for industrial purposes, forcing the southern migrating Red Knots this August to be reduced to foraging along only 20 kms. This will create enormous pressure on these birds to recover from their 5 or 6 thousand kilometer flight from Siberia and to be able to refuel adequately to fly up to 9,500 kilometers back to Australia and New Zealand. We can’t expect that there wont be losses. If this is not frightening enough, we now know that the Chinese government plans to “reclaim” the remaining 20 kms of this stretch of beach within the coming 12 months. I leave it to you to consider the likely outcome.

During my time in Sydney, I’ve conducted a number of surveys and studies of everything from bush birds broadly and fairy-wrens particularly to Ospreys and even Little Penguins! However, those projects which I have invested the most of myself in have been the establishment of the Long Reef migratory shorebird monitoring team and my sub-contracted weekly participation in shorebird monitoring which covers all the prime shorebird locations in Sydney, the Central Coast and the Hunter region. This second project having been established to determine if the construction and running of the Port Botany container terminal expansion is impacting on the lives of the shorebirds of the region.

Long Reef . . . a revelation!

THE SHOREBIRD monitoring project at Long Reef was established at the end of 2006 in recognition of the complete lack of regular data collected at a site which was, at the time, not considered worthy of a regular effort and the threats from disturbance which it was clearly subjected to.

Since establishing regular, monthly counts on the reef we have determined that the site is of great importance regionally. The counts have also given further impetus to the recognition of the value of rocky headlands and smaller wetlands as part of a matrix of sites which support the dispersal of migratory shorebirds across the continent post southward migration.

A Sharp-tailed Sandpiper foraging on the reef at low tide. "Sharpies" are irregular visitors to the reef.

The shorebird species list has been impressive:

• Bar-tailed Godwit
• Eastern Curlew
• Whimbrel
• Grey-tailed Tattler
• Wandering Tattler
• Ruddy Turnstone
• Red Knot
• Sanderling
• Red-necked Stint
• Sharp-tailed Sandpiper
• Curlew Sandpiper
• Sooty Oystercatcher (non-migratory)
• Pacific Golden Plover
• Red-capped Plover (non-migratory)
• Double-banded Plover
• Lesser Sand Plover
• Greater Sand Plover

Once common on Long Reef, Greater Sand Plovers are now rare once or twice a year visitors.

On one day alone in November 2009, I encountered:

• Bar-tailed Godwit
• Eastern Curlew
• Grey-tailed Tattler
• Ruddy Turnstone
• Red Knot
• Sanderling
• Red-necked Stint
• Sharp-tailed Sandpiper
• Curlew Sandpiper
• Sooty Oystercatcher (non-migratory)
• Pacific Golden Plover
• Lesser Sand Plover
• Greater Sand Plover

Making the site surely one of the most diverse on the temperate part of the continent for that one day.

Red-necked Stints are one of the mainstay species on Long Reef, with around 230 being present during the summer of 2009/10.

A FEW DAYS later, November 22, I had what might be my oddest encounter on that reef: a Double-banded Plover in non-breeding plumage. Given that the entire population was meant to be in New Zealand breeding I can only say that nothing is ever  a certainty when you’re talking about birds!

We observed some odd fluctuations in the numbers of some species, particularly Red-necked Stints and particularly in the late Autumn – early Winter, which perhaps indicates that when conditions get particularly cool further south, the 1 and 2 year old birds migrate a little northward to sites like Long Reef.

Ultimately, the data collected at Long Reef will contribute to our knowledge on a national and regional scale as it forms part of our broader understanding on the patterns of diversity and abundance in the region. We also hope it will become part of the collective effort to save these birds from the abyss of extinction, which will surely take place if we don’t change our ways and communicate the needs for action in China. In 2010 I moved away from the Northern Beaches and handed this project onto an enthusiastic and knowledgeable colleague, Eduardo Gallo, so the project is in safe hands. Visit the Long Reef Waders site to find out more.

My beloved Boat Harbour

MY ALMOST 6 year stint (no pun intended) of weekly shorebird surveys on Boat Harbour has been become such a part of me that it’s certainly been the hardest thing to let go of as I prepare to move north. Friends and family I can still communicate with, but to lose my weekly rhythm, my weekly journeys to this small rocky headland is like losing an integral part of my identity. I grew up on the adjacent beaches of Bate Bay: Eloura, South Cronulla and Wanda. I still have those visions of lazy Sunday Summer walks on Wanda Beach in the late 1960′s where I’d see  those tiny stints, sanderling and plovers in quite large numbers dashing up and down the beaches as the low tide wavelets would expose the sand worms and other invertebrates which they would be feasting on. Of course, times have changed and their numbers are greatly reduced, with the birds now confined to the mists of my memory and much smaller numbers on the reef at Boat Harbour . . .

Since late 2006, in all kinds of weather – freezing, windy, rainy, hot, humid and all manner of combinations thereof, I have immersed myself in the lives of the birds on this headland and savoured so many moments that only a naturalist whose pulse is quickened at what others may miss or consider unremarkable can do. Every visit has been a joy but now, as it all comes to an end, I can’t let go without relating a few special moments. I could have picked many, but here’s three:

Great Knots on Boat Harbour

GREAT KNOTS are one of the most abundant shorebird species which visit Australia. Like their cousins, the Red Knots, Great Knots not only possess all of the wonderful physiological traits which enable them to fly non-stop for more than a week at speeds up to 110 kph but they possess the extraordinary ability to “see”  with their bills beneath the mud and sand substrates where they forage for their favoured prey – tiny bivalves (more on this in a future post).

A very rare visit from an icon of the East Asian-Australasian Flyway, the Great Knot.

When I was Warden of the Broome Bird Observatory, Great Knots were a big part of my experience of that truly magical place. I had been sorely missing their presence for some years after coming to Sydney until one day on Boat Harbour, there were two of them joining the other regular species at a high tide roost. Rocky headlands are not the sort of sites where you would expect to find this species on a regular basis as their bills are far better equipped for probing mud rather than gleaning off the surface. However, research by Danny Rogers (Scientific Advisor to the Australasian Wader Studies Group) indicates that these birds go through a 3 or 4 year learning curve where they go from surface gleaners to mud probers. I concluded that it was likely therefore, that we had a couple of younger birds who had, for some reason, come across from nearby Botany Bay where a small number of these birds stay each Austral Summer.

It was truly exhilarating to be there for this rare encounter and one which I was to only replicate a week or two later in all 6 years that I have conducted these surveys.

Out of phase Sanderling

SANDERLING ARE KNOWN to science as Calidris alba, meaning that they’re white sandpipers. This is true for anybody who encounters these small shorebirds during the Australian Summer, when they’re sporting their clean white “Winter” plumage. In all my life, this is the only way that I’ve known Sanderling, so it was a great surprise to one day begin a survey on Boat Harbour reef and encounter this odd, small shorebird covered in speckles and flecks of what appeared to be breeding plumage . . . full breeding plumage!

A Sanderling in full breeding plumage is about as odd as it gets in Sydney shorebirding.

I spent some time trying to sort out what this species may be, all the time thinking “What species of shorebird has a bill like a Sanderling?”. Finally the penny dropped . . . “A Sanderling!”. Once I realised that this was a Sanderling in full breeding plumage, I knew that I had something very special in front of me. Fortunately, there was another Sanderling present, in full “Winter” plumage and I was able to take some comparison images to document this extraordinary event. Somehow or other this bird had gone out of phase with its breeding plumage. I believe that this can happen to birds who “overwinter” (resist the urge to migrate) for too many years.

Now, reflecting back on that warm Summer day in 2008 I can still recall how this encounter brought home to me something very powerful in the lives of these amazing birds: that here was a bird dressed in the kind of finery that is only ever witnessed in the High Arctic wilderness and the 14,000 km distant island of New Siberia (which is probably as bleak as it sounds), where these incredible birds make their annual journey to breed. It brought home to me the immensity of their annual journey in a way that nothing else ever had before or since: here was evidence that these birds actually do this, that this bird would be perfectly camouflaged sitting on eggs in the low, windswept vegetation which comprises the tundra of that far distant realm. It brought home the wonder of this world which has shaped these extraordinary creatures and of the incredible good fortune that we find ourselves to be alive to witness and take account of these things.

That “American” Golden Plover

I HAD BEEN observing the odd-looking Pacific Golden Plover among the cohort of plovers on Boat Harbour reef for some months and had on more than one occasion considered that this bird might be part of that transition of the population of the neighbouring Pacific Golden Plover and American Golden Plover populations in north and western Alaska. I’d considered taking this up with Phil Straw, who is overseeing the monitoring project, but then again you do get odd plumages among birds from time to time. I’d let it go until later in the season . . .

The plover which attracted all the attention . . .

As Summer turned to Autumn, the Pacific Golden Plovers began to come into their breeding plumage, ready for departure to far distant Alaska. Now, our odd-looking individual was really starting to stand out: enough so that it attracted the attention of a photographer whose images indicated that the legs of the bird did not extend beyond the tail. This is one of the diagnostic features of comparison that indicates this species may be an American Golden Plover. One post to the email list “Birding-Aus” and the rush was on. On my next visit to Boat Harbour I was greeted by one of the employees of the company which controls the road to reef. He joyously recounted that “Hundreds of twitchers” had been visiting the reef all week: they were making a fortune! As I arrived on the sand I encountered at least ten birders all bristling with long camera lenses. Some had even erected beach tents, to set up camp for the day. I was accompanied by American Golden Plover aficionado, Alan McBride.

After some hour of study of this bird we concluded that it didn’t have all the features of an American Golden Plover. However, this didn’t stop everybody joyfully ticking off the bird and its addition to the Australian records for visitations by this species in the annals of the Birds Australia database. I went with Alan’s more sober judgement and concluded as per my original thoughts, that this bird was either a hybrid or part of that transitional population which surely must exist between two species which have only in recent years been split. Either way, it was thought provoking yet again to witness yet another part of the story of these wonderful creatures on this generally quiet little rocky headland.

The thick and the thin

A Double-banded Plover sporting beautiful breeding plumage on Boat Harbour reef. Let's preserve this!

I CAN’T GO without saying that there’s been some very sad moments for me on Boat Harbour too, such as having to put down a Silver Gull with a broken wing or arriving one morning in 2010 to find more than 500 dead and dying, beach washed Short-tailed Shearwaters on the sands surrounding the reef. Regularly in the Summer, I’ve witnessed the increasing patterns of human disturbance which has caused the great drop in the shorebird population of this area and looks set to continue to do so. It’s both exasperating and depressing in the extreme to be helpless in the face of the selfishness that pervades the local community in this respect. Despite these times, through it all, the thick and the thin, has been the exhilaration and privilege of contemplating and observing the forces which drive the patterns of diversity and abundance of these species, what has shaped them and will continue to shape them in the eons ahead of us. It’s been a marvelous thing to have observed in such a manner the lives of the birds which live on and around the reef and to hitch a ride on their experiences of life for a few short years. For now, however, it’s time to say farewell and hopefully move on to other wonderful experiences in another part of Australia as I continue my journey through this fascinating thing I call a life.

For many in the Sydney region, however, there is a dark side to these colourful little birds, a source of deep and enduring frustration that leaves bird watchers with a sense of worthlessness in their trade and embarrassed downward glances as they describe circles in the dust of trails with their feet every time they encounter these birds . . . for the uninitiated, the females are simply very difficult to identify, as are the males when not in breeding plumage.

Fairy-wrens are small, insectivorous birds which carry their tails “cocked”, or erect and are generally found in small matriarchal family groups. Although restricted to Australia and New Guinea, there isn’t one part of the Australian continent which doesn’t have at least one species present. Genetic studies have revealed that they’re distant relations of the corvids, the crow group, as are all old, endemic Australian passerines. Some species are among our most heavily studied birds and whilst some have adapted well to the presence of humans others are on the back foot and some are headed for the back door unless better management practices are put in place. In terms of the latter, I refer mostly to the Purple-crowned Fairy-wren, which is seeing its range shrunk considerably by the activities of the “pastoral” industry and thoughtless 4 wheel drive enthusiasts (more on this in a future post).

The Superb Fairy-wren is a universal favourite.

Two species can be found in the Sydney region and, whilst we all celebrate their presence, many birders struggle with identifying the species of the female birds year round and the males during winter when they’re in eclipse (non-breeding) plumage. The two species in question are the Variegated Fairy-wren Malurus lamberti and the Superb Fairy-wren M. cyaneus.

A simple diagnosis

The key to understanding the differences between these two species is actually very easy and that is that if you were to remove the tail of any fairy-wren in locations where these birds both occur and lie it along the bird’s back, if it appears to be barely longer than the bird’s body, it’s a Superb Fairy-wren and if it is significantly longer, it’s a Variegated Fairy-wren.

Now, because we don’t always get a good look at the whole bird, it’s often a good idea to have more than one diagnostic tool handy so tail colour can help us too. If the tail is brown, you have a Superb Fairy-wren but we need to be cautious here, as some male Superb Fairy-wrens can show a considerable amount of blue in their tail even in eclipse plumage, especially in certain qualities of light, so we have to return to the tail length in those cases to make the call.

Determining the sexes

Separating the sexes is simple enough, the females have rufous lores, a rufous eye ring and pinkish bills, the males during summer are in their very festive breeding plumage. In the winter, the males have no eye rings, but black bills. The male Variegated Fairy-wren has a thick, black “moustache” (see image) whilst the male Superb Fairy-wren has a smaller and thinner black “moustache”.

Printable ID Guides for download

I have created printable A4 guides to identifying these birds, which are available here:

• Breeding plumage fairy-wren ID [1.7 MB]
• Non-breeding plumage fairy-wren ID [1.7 MB]

You should now feel confident that next time you get out into the bush that you’re going to be a new birder: one who can make those strident fairy-wren ID calls that will no doubt impress all your birding buddies who are looking at their feet whilst drawing circles with them in the dirt.

Until next time . . . Happy birding!

Spoon-billed Sandpiper. Image © 2011 Chris Collins.

ONE OF THE WORLD’S great iconic shorebird species, the Spoon-billed Sandpiper, is also the most threatened. There are perhaps only dozens of pairs of this species remaining and captive breeding programs under way. How successful this can be for a tiny migratory shorebird is yet to be ascertained, so it is encouraging to hear that a survey conducted by Heritage Expeditions – a Birdlife International “Birdlife Species Champion” – has uncovered hitherto undiscovered breeding locations on the Chukotka coast of Far East Russia. Read more on the BirdLife International site »

Let’s begin by meeting the bark foraging specialists: they are the Varied Sitellas, the Tree Creepers and the Shrike-tits.

Varied Sitellas

Varied Sitella of the nominate race "chrysoptera". Image © 2006 Nevil Lazarus

The Varied Sitella Daphoenositta chrysoptera is a very small, highly active bark foraging bird which, as its name implies, comes in a great variety of colour and pattern combinations according to the part of the continent where they live. There’s at least 5 races of this species, every one of which has obvious yellow bare parts (bill, feet and eye rings). They are regularly seen in large, extended family groups and there have been frequent suggestions of cooperative breeding among these birds.

White-throated Treecreeper

White-throated Treecreeper. Image © 2008 Julian Robinson.

Treecreepers are medium-small passerines that spend their lives working up the trunks of trees taking invertebrates from on and beneath their bark. Unlike the woodpeckers found on other continents and which use stiffened tail feathers as props to lean on, treecreepers appear to get their ability to stay propped out from branches and trunks from their long hallux, or rear toe, nail. There are six species of treecreepers found across the continent, with some showing more commitment to life on tree trunks than others: the Brown Treecreeper Climacteris picumnus, Rufous Treecreeper C rufa and Black-tailed Treecreeper C melanura all spend varying percentages of their day also foraging on the ground. We’ll be looking at the White-browed Treecreeper C leucophaeus here, which lives on the eastern seaboard and is highly dedicated to life on tree trunks.

Crested Shrike-tit

Crested Shrike-tit. Image © 2007 Lindsay Hansch.

The Shrike-tits are a medium-small passerine which, like the sitellas, are highly acrobatic bark foragers. The black and white banding of their heads, erectile crest, radiant golden underbodies and a call which sounds like the artificial “Flipper” the dolphin call from the old 1960′s TV show all make for one of the more charismatic birds that one could hope to meet on a day’s outing in the forests which they frequent. There are three species, with the most widespread being the Crested Shrike-tit Falcunculus frontatus, which is found over much of the South East Coast of Australia and a good way inland. Crested Shrike-tits spend much of the year in pairs, with the remainder of the year raising their two or three young.

Resource-sharing strategies

ALL THREE of these species have, to varying degrees, adopted a social strategy called “intraspecific resource partitioning”. This is a system where each sex forages practically side by side but in a slightly different manner or for slightly different prey, so that they enjoy the benefits of each other’s companionship but without directly competing with each other. In the case of the bark foragers, the males tend to forage on the trunks and main branches of the tree and the females tend to forage on the outer branches and sometimes the leaves. Of course, opportunism rules, so either sex may occasionally forage on the other’s turf. There are certain times of year when this strategy is more strictly followed, but as a general rule, each sex tends to play by the rule. Generally we see that the males are the enforcers in this strategy: That if the female strays from the leaves and outer branches and forages on the trunk, the male will frequently chase her back onto the outer branches.

Why this is so may be a mechanism for pairs or social groups to spend less time in vigilance protecting larger territories. It could be so that more of their kind can be crammed into smaller patches or territories, or it could be that it is not very profitable to make a living foraging purely on bark unless certain sharing strategies are adopted to reduce competition. It could be all of the above. I think that when we examine the presence and absence of these species in remnant woodlands we find much to suggest that it is the latter of the three which is the main driving factor.

A male (left) and a female (right) Crested Shrike-tit, collected in the 1930's from Sydney's Northern Beaches for the Australian Museum. Note the very different bill sizes which reflects their different uses.

IT’S OF INTEREST that each of our bark foraging species exhibit varying degrees of meticulousness when it comes to resource partitioning: the Crested Shrike-tit tends to be very strict for most of the year – so much so that the male and female have remarkably different bill sizes and structures; the White-throated Treecreeper tends to be fairly strict for a good part of the year and; the Varied Sitella tends to be not so strict all year. Also of interest is that in remnant forests, as the patches get smaller the species begin to disappear. i.e. in very small patches we don’t ever get bark foragers, in slightly larger patches we may get Varied Sitellas, in larger patches again we get White-throated Treecreepers and Varied Sitellas and in still larger patches we begin to get all three species. It appears that there is a correlation between the presence or absence of these species, the strictness to which they adhere to resource partitioning or require its practice and the size of remnant forests or patches where they are found.

Lessons for environmental management

To me, this suggests that bark foraging is not very profitable and this is the reason for this social strategy. It also tells us that there are important management principles required if we want to have functional urban bushland remnants which support all the species required to keep them humming along in a viable and sustainable manner. The first of these is to keep urban bushland remnant plots as large as possible. Failing this, linking remnant plots with appropriately structured bush corridors (more on structure in a future post) is the next best strategy as this effectively turns small patches into large ones, enabling species which require larger patches a better chance of holding on. Bush corridors also permit the movement of individuals which in turn permits “gene flow”, the spread of more individuals’ genes which keeps species’ genetic diversity high and therefore more robust.

IT ALL ADDS UP to understanding the needs of our environment and being aware of the indicators to help us respond to those needs. The outcome is not only sustainable remnant forests where diversity is maintained, but happier communities of humans who enjoy the benefits of investment in the care of our natural world. Humans are naturally drawn to nature, because we are intimately connected to it in many ways and dysfunctional when we live lives where we are disconnected. Just watch property values plummet in any locality where there are fewer well managed bush reserves and therefore fewer birds and mammals and reptiles and amphibians and butterflies and cicadas present. Have a chat to the Real Estate Agents around Avalon, on Sydney’s Northern Beaches, who are offering a bounty for anybody who can confirm the presence of Koalas in the locality.

The morphology, behaviour and social structures of these birds have much to tell us about the environment and the strategies that birds use to carve a niche for themselves in their respective habitats and I’ll be visiting the bark foragers frequently in these notes to share, explore and celebrate their diverse and wonderful ways.

Until next time . . . happy birding!

WYONG Local Government Area takes in a range of beautiful wetlands, both coastal and inland, several of which support rare, Threatened and iconic species from several Classes. Of course, those wetlands also support surrounding habitats and contribute to the quality of life that humans who rely on those habitats also enjoy.

It was great to catch up with or meet up with seasoned presenters and enthusiasts for wetlands, including the team from WetlandCare Australia, bird aficionado Alan Morris and Council’s Estuary Management Education Officer Suzy Tsaprounis. Of course, it was also great to be met by so many large turnouts of locals, eager to soak up the story of wetlands, celebrate the wonders of nature, share their love of nature and learn more about the parts they can play to preserve these important habitats.

Share the love

WHAT IS REQUIRED now is for people on the Central Coast to continue to share their passion for wetlands and spread that contagion for nature. More studies which help us to understand how these places work and of the lives of the residents of these wonderful habitats are required. Politicians at all levels need to be encouraged in the understanding that large sections of the community want these places retained, restored and managed appropriately and that there is a strong necessity for science to be listened to and acted upon as part of this process.

Who gets the bill?

Here in Australia, we are fortunate in that there are still opportunities to preserve much of our natural world and that with wise, informed management we can have our cake and eat it too. Our leaders need to know that the bill for all human activity should not always be handed to the world of nature. Every one of us has a role to play in a process of realignment which our society will have to go through if we hope to achieve sustainability. Surely education will be a big part of this process.

Until next time . . . happy birding!

NEWS & NOTES