Last weekend (6th August) I visited Booderee National Park, one of the most beautiful and unspoilt parts of the NSW south coast. Long straight flower spikes had shot up like spears from the grass-trees (Xanthorrhoea sp.) and tiny star-like flowers were opening to form a delicate white mantle on their surface. These flowers are highly attractive to nectar-feeding birds and insects; on this occasion it was mostly Yellow-faced Honeyeaters and Silvereyes converging on them.
I waited quietly near a particularly productive flower spike to try for photos of the nectar-feeding birds. To my surprise, it was a White-throated Treecreeper that landed next at the base of the flowering spike. Treecreepers normally work their way up the trunks and branches of trees to feed on insects (including ants) and spiders they find on and under the bark. This one worked its way up and around the spike as if it were a skinny tree, probing its bill into each little flower in turn. After climbing most of the way up, it did something I’ve never seen a treecreeper do: it reversed quickly down, backwards…to start again at the bottom.
It’s hard to be sure whether a bird is feeding on nectar or tiny insects attracted to it, but the treecreeper’s behaviour suggested it was after the nectar. And none of the photos show any insects in the bird’s bill.
Nectar produced by flowers is an important food resource for many Australian birds — most notably honeyeaters, lorikeets and Swift Parrots. In addition, Silvereyes, woodswallows and chats have a brush-like tongue similar to honeyeaters and can also take nectar. But it’s surprising how many other birds take advantage of a rich nectar flow when they have the opportunity. For example, normally insectivorous Brown Thornbills will feed at banksia flowers when they’re full of nectar. I’ve seen a Rockwarbler do the same thing.
Rosellas and cockatoos don’t have a pointed bill or a brush-like tongue so they obtain nectar by chewing the flowers to pieces. Banksia wheels — those neat circular slices of flower-head scattered under a banksia — are a sign that cockies have been getting a sugar fix (as opposed to their more usual habit of demolishing the woody fruit to snack on the seeds).
I’ve also seen a cunning Pied Currawong watch a Red Wattlebird feeding at a banksia before attempting to copy its technique. The currawong’s heavier bill and shorter tongue would have ensured its efforts were less successful.
A treecreeper’s bill is remarkably similar to a honeyeater’s — longish and slightly down-curved, though its tongue isn’t brush-tipped like those of the more specialist nectar-feeders. Nevertheless, White-throated Treecreepers are known to occasionally feed on banksia nectar, for example see this post from 2006 on my old website.
On a related note, last summer I photographed a Brown Treecreeper (below) which seemed to be tasting the sap flowing from a eucalyptus trunk in the Capertee Valley. The only other birds I’ve seen feeding on eucalypt sap are honeyeaters — always when it’s freshly exuded and still flowing. (The sticky red sap or kino that oozes from damaged eucalypt trunks is the reason they’re commonly called ‘gum trees’. Within a few hours it hardens into an amber-like substance.)
You could say that treecreepers feeding on nectar and sap ‘haven’t read the books’ to know what they’re supposed to be doing. Then again, it might just be ‘the books’ that are wrong.
For those who like to be formally introduced
Australian Treecreepers: family Climacteridae
White-throated Treecreeper: Cormobates leucophaea
Brown Treecreeper: Climacteris picumnus