Barrington Tops NP: The curious behaviour of tree martins
December 13, 2015
A strange thing happened during our trip to Barrington Tops. We had just set up our tents on the banks of the Barrington River, and were standing under Pete's tarpaulin discussing the possibility of making a cup of tea, when a whole flock of tiny birds settled on the fireplace a couple of metres away, seemingly undisturbed by our presence. I moved back to grab my camera and Laura moved forward to get hers from her tent, but as quickly as they had come the whole flock departed.
"Don't worry", Laura assured me. "They will come back." But they didn't - at least not while I was there.
We watched the flock wheeling and diving high above our heads in pursuit of insects and identified them as fairy martins from the white patch on their rump that distinguishes martins from swallows.
The next day Laura came back from a trip up the slope and said that they seemed to be nesting in the trees in the picnic area, and that she had seen them on the ground near a puddle on the road, 'flipping leaves about'.
And that she thought they were tree martins.
We had seen martins before, often flying near culverts and bridges as we travelled along country roads, but we had never been close enough to take decent photos. We just assumed that they were fairy martins.
The main difference between the two species is in the colour of their heads, which is dark in tree martins and an orange colour in fairy martins. These were clearly tree martins.
They were nesting close together in a group of snow gums in the picnic area that provided suitable hollows. Most pairs had individual nests, although all the trees were in close proximity, but there did seem to be a few pairs nesting together in one hollow branch with two entrances.
In fact, in contrast to other species with established territories, these birds seemed to want to do everything together. If one martin lands near a muddy puddle, more birds will land with each low swoop of the high-flying, whirling flock.
They line their nests with leaves and grass and the "leaf flipping" behaviour may have been part of the selection process in the quest to find suitable leaves.
If one martin lands on a lookout post high up in the top of dead tree, as sure as eggs within a short time others will decide that that is exactly what they want to do too.
Even bathing is a communal activity, and for a short time in the late afternoon sun we watched them diving one after the other into the crystal-clear headwaters of the Barrington River, just below our camp.
But the most surprising behaviour of all was their attraction to old campfire sites. Time after time we would watch as a flock wheeled around above a small patch of ash and cinders, gradually descending until one, or a few birds, landed.
With continued circling above, more and more birds would land until there might be as many as a couple of dozen or more standing around on the site - doing what?
That was what they did when they landed, they simply stood there looking intently down towards the ground.
I have photo after photo showing the birds standing around, just looking down. Without the assistance of a strong telephoto lens and a computer monitor it was impossible to tell what the purpose of the behaviour was.
But looking at the photos at high magnification, later, showed that some of the birds had pieces of grass in their mouths and were even flying off with them.
So it seems that once again the answer is that they were collecting nesting material. Snowgrass is tough and finding the burnt off grass around fire sites must make life a little bit easier for these tiny birds.
But they didn't feel confident on the ground and at the slightest hint of alarm they would suddenly all be airborne again and back to the safety of the sky.
Sometimes a bolder or more determined bird would remain, and then you knew that soon the rest of the flock would come back, wheeling around, getting lower and lower until a couple more had landed again...... and then a few more...........!
And then you would have the chance to take a few more photos.