In praise of dirt
Bushwalking and dirt tracks go hand in hand. Some tracks are built by compressing dirt to form a solid surface, while others are simply the exposed surface of the natural soil profile. Either way, they are a means of getting somewhere rather than an attraction in their own right.
This week challenged that view with dirt tracks featuring large in three wildlife encounters. The first was on a sandy track on the coast near Kurnell. It was a sunny morning, one of those days when the local reptiles start to stir in the warmth. Something small was writhing in the middle of the track. My first thought was a snake shedding its skin, but a closer approach revealed two Cunninghams Water Skinks.
The skinks were grabbing one another’s tails in their mouths and twisting to throw the other to the ground. They seemed oblivious as they battled for supremacy. I crept closer and eventually they disengaged and fled into the undergrowth. I retreated and they returned to the fight. Whether the fight was about territory or mates, the track was clearly the favoured arena.
I dropped into Centennial Park just before sunset. A flock of Fairy Martins was flying low over one of the horse paddocks, concentrated around a shallow pool. The water was only a couple of centimetres deep and had a broad rim of damp earth. I watched several Fairy Martins landing on the wet dirt. Instead of taking a drink they bent to scoop up the sodden soil. They seemed to be after a particular dampness and consistency of mud, trying a few spots before filling their beaks.
Beaks full of mud the martins headed in a straight line across the paddock and over one of the park’s large ponds. Fairy Martins normally wheel around the sky, circling to take advantage of thermals then dashing down to snatch flying insects. These ones flew straight as an arrow with their cargo of mud.
I walked to the edge of the pond and tracked them over the wide expanse of pond. The martins disappeared as they reached the opposite shore. Looking through the camera’s telephoto lens I could see the disappearing act was achieved by ducking into a large storm water drain.
The storm water drain was a couple of metres wide and about a metre high. The floor of the entrance was underwater, however it was possible to see partway inside from the side. Even better, the low angle of the late afternoon sun and reflection off the water combined to light up the first couple of metres of drain. Enough light to see Fairy Martins busily constructing mud nests on the roof.
Only two nests were visible from my position outside the drain. The broad gourd shaped bases were complete and the martins were working on the narrow ‘spouts’ of their nests. The edges were still wet, and as I watched a martin landed on the closest nest, ducked inside, turned around to start painting globs of mud around the rim. After a couple of minutes it flew off. A few minutes later it or its mate returned with another load of mud.
There was a continuous stream of Fairy Martins in and out of the drain. I took off my shoes and braved the dubious looking pond water. Peering into the drain it took my eyes a moment to adjust. When they I could see several dozen nests stretching far down the drain.
I retreated and sat to dry my feet. A tree near the entrance was covered in preening Fairy Martins. Further out across the pond other martins were catching insects in the air and snatching others off the surface of the water. The martins didn’t just dip their beaks, they were crashing into the water in pursuit of their prey.
A damp corner of a horse paddock and a storm water drain are hardly the most glamorous places for watching wildlife. Nonetheless, I couldn’t help feeling satisfied with my detective work, linking mud suckers to nesting colony. It wasn’t a scene I expected in one of the most heavily modified urban parklands in Sydney. A mistake, because the reality is that the site ticked all the boxes for Fairy Martins colonies: a reliable source of mud; a secure nesting site not too far from the mud; and open areas to chase after flying insects.
My final encounter with wildlife on dirt was a close relative of the martins, Welcome Swallows. Normally hyperactive flyers Welcome Swallows do roost when the temperature and insect activity drops. They are partial to roosting on the ground, especially in cold and blustery conditions.
Returning to Centennial Park a few days later the weather was revolting, cold and windy. The park is ringed by a dirt track dedicated to horse riding. The sandy soils and hoof prints produce an undulating surface. Not long after parking, walking towards the Fairy Martin nesting site, I noticed dozens of Welcome Swallows huddled on the ground. The swallows were using the hoof marks as shelter, a tactic I’ve seen used by tiny Red Capped Plovers, although in their case it was human footprints on the beach. Wind strength is lowest just above undulating ground and both species take advantage of this phenomena.
Dirt tracks might be essential for getting close enough to see many species of wildlife, but that exposed dirt is well worth a bit of scrutiny as potential wildlife habitat in its own right.
Odds and sods of the week