Six weeks into a Sydney lockdown.  Everyone confined to their homes with occasional outings for food and exercise no more than a few ks away.  I feel super lucky that this bit of Dyarrubbin still falls within the 10 k radius I’m allowed to stray from my house. Berowra Creek, at the end of my street, is super quiet at the moment, the houseboats rocking empty at their moorings, jet-skis banished – only the locals heading out in ones or twos for some fresh air.

It seems fitting that the “feature wildlife” of my escape to the river last weekend was also a local – Sydney’s only endemic bird, origma solitaria, the rockwarbler.

Sydney’s only endemic bird – the rock warbler

These little birds are only found within 250 km of Sydney, hopping around mostly on Hawkesbury sandstone, though I’ve hear they also pop up on the limestone and granite, where it is to be found.  Their range on the coast extends from Mollymook  to Raymond Terrace, and they can be found as far west as Orange and in the north can be found up in the beautiful Coolah Tops National Park, according to the CSIRO Australian bird guide favouring “exposed, dissected rock outcrops…from coast (including sea cliffs) to high plateaus  of the ranges” (2017, 340).

Rockwarbler on a mossy rock

Rockwarblers are not uncommon – despite their restricted range they’re flagged as of least concern, conservation-wise – though they don’t appear to inhabit cities like Newcastle, Sydney or even Wollongong or Nowra.  On my noodling 12 k paddle last weekend I spotted one pair busily feeding and nestbuilding on rocks by the waterside, and then, having tuned my ear to their high pitched calls, spotted another pair doing much the same, on the return journey.

I don’t see them on every trip out but I’ve observed them behind golden beaches on Cowan Water and in rocky bays near Dangar Island, and even in one of the spots  at Berowra Creek with the most foot traffic, at Washpool Creek where the Great North Walk meets the estuary.

The rockwarbler is an unremarkable looking little bird – “a small, plump, dark brown-grey bird with a cinnamon-tinged face and forehead, a dull white throat speckled black, reddish-brown underparts”, almost the definition of the LBB – but has some interesting habits.  It makes pendulous domed nests that hang in darkened overhangs and caves in the rocky terrain it prefers – apparently its common name used to be “hanging dick”.  Who says all folk wisdom  needs to be kept alive, eh?

I spotted my first rockwarbler for the day collecting what looked like nest material – roots and possibly spider webs  in the exposed root system of toppled trees on the shoreline. She flew off intermittently into a group of boulders behind some casuarina trees – I couldn’t get a clear shot of the crevice she seemed to be returning to, so no photo of a hanging dick, for which you might well be grateful.

Despite all this, I’d like to get a glimpse of a nest – the description in Birdlife’s online site have a hard core goth appeal:

Made from grasses and plant fibres and coated with spider webs, [the nest] is attached to a rocky overhang or roof of a cave by spider webs, which the bird hammers into place with its bill. They are then covered with saliva to hold them in place

You can see in these pictures that the spot I saw my first pair of rockwarblers has been a important place for humans as well as non-human animals for thousands of years.  The soil here is thick with oystershells, left by the custodians of this country over the centuries, and now woven into the earth in scores of places right along the shores of Berowra Creek.  Everywhere you look around here there’s a midden.

Rockwarblers look a little bit like northern hemisphere robins and seem to have a similar outgoing personality – “confiding” in the words of the CSIRO blue bird book.  This bird and its mate, that soon arrived on the scene, didn’t seem particularly disturbed by a kayaker loitering nearby with a camera, and I managed to drift quite close while they scoured the rocky shore for largely invisible food.

I’ve read that rockwarblers are primarily insect eaters although Carol Probert has reported seeing nectar drinking in some she watched in the Blue Mountains. No evidence of this here but there seemed to be plenty to eat.  This pair traversed the rocks briskly, picking mysterious things from amongst the moss, and even dipping beaks into the little bowls comprised of previously-opened mollusc shells on the rocks.  I’m not sure  if the rockwarblers were scrounging for critters that had found a home in these tiny rockpools.

A second pair of rock warblers looking for food together

There were plenty of insects about in the lee of the rocks, but i didn’t see any of the birds I watched that morning snatching a snack from the air, despite the temptation.

What I did see – once with each pair of birds – was what I think were nuptial gifts – one bird feeding the other snack, perhaps with romantic intentions.  I stress I did not witness any subsequent feathered intimacies but with birds you blink and you’ll miss it, so that doesn’t necessarily mean a lot!

Here’s pair number one, coming beak to beak.

And the second pair

I think I can see a insect leg sticking out from the crumb in the beak of the bird with the tuft of feathers on its back.  I guess these scenes could have been adults feeding juveniles, which look similar to the grown-up rock warblers, only paler in colour, but I didn’t hear any pitiful calls from the recipients and given the time of year – roundabout the beginning of breeding season for many birds – a romantic gesture seems a bit more likely.

Rockwarbler happily feeding

The rockwarblers were pretty friendly to me but also to the other little birds hopping around the nest area, particularly a family of variegated fairywrens that seemed to follow them as they hopped about round the edge of the water.  The warblers kept their feet mostly on rock, the wrens mostly flitting from twig to twig in undergrowth nearby. If there’s dietary competition between these little birds, it’s a very friendly one.

In fact, I suspect this was more like the mixed-flock foraging that have been noticed in many parts of the world in wintertime, when different species of small insectivous birds move around feeding as a group.  Maybe the rockwarblers’ hopping stirred up some flying insects for the wrens to eat?  Some researchers have found that variegated wrens, sometimes hang out with “friends” from other species whose territory overlaps with their own, sharing the defense of that territory, travelling and foraging together. This benefited the wrens a lot – they “spent more time foraging, were less vigilant [and] had greater first-nest fledging success” (Johnson, 2018, 821).  I wonder if the wrens were as friendly as this with my rockwarblers?

Male variegated fairywren

jenny variegated fairywren

silvereye in the casuarinas

The atmos not so friendly amongst the waterbirds feeding nearby.  I watched a whitefaced heron repeatedly asserting dominance over a striated heron on a sequence of estuarine patches, as I trekked back the put-in.  Berowra’s ubiquitous waders are higher up the pecking order than ubiquitous lurkers it seems.

Striated heron irked enough to walk away

Striated heron finally gives up on this patch of shoreline

And then, just as I turned the corner to the marina, high over all, the alpha local of these lands.   A wedgie soaring silently, surveying its domain.

References

Smith, Peter ; Smith, Judy “Re-use of a rockwarbler ‘origma solitaria’ nest over a 13-year period” Australian field ornithology, 2012-06-01, Vol.29 (2), p.77-82