Sunday, December 08, 2013

A Tale of Two "Swallows" (b) Dusky Woodswallow

        The second encounter took place a couple of weeks later and less than a kilometre from the Welcome Swallow photo opp. mentioned below. I have taken a little, some might say a large, liberty with suggesting they are both "swallows", because they are not related. They are both summer migrants to Tasmania. As might be suggested by the bill colour, woodswallows are more closely related to Butcherbirds amd Magpies. They are a  little longer than Welcome Swallows, but weigh in at around 35 gram, over 3 times heavier, a solid, often pugnacious, bird. They are usually found in open woodland and often nest in small colonies of a few pairs. Their nests consist of twigs and grass, often placed in the fork of a gum and, in my experience, are among the easiest nests to find.
         Like swallows, they feed on flying insects, making forays from chosen vantage points. They will also forage for food on the ground among the leaf litter, particularly on cool mornings. On warm summer days they can be seen soaring often to great heights chasing flying insects, sometimes in flocks numbering over a hundred. They seem somewhat drab birds, but in the hand, the subtle smokey pink brown body and dark blue grey wings are particularly beautiful--my shots, taken on a dull, overcast day, do not do them justice.
          I was returning from a brief visit to Goat Bluff, on a showery, windy day that had few bright spots save for a fleeting, but exhilarating view of a Peregrine Falcon as it "rushed" by. As I turned off the highway, I noticed a bird in the middle of the road which I couldn't initially ID, and pulled off to the side to use my binoculars on it. It turned out to be a Dusky Woodswallow, but what was it doing in the middle of the road?
               In these situations I invariably take a photograph or two and identify the prey on my PC later, which I did here. My first thoughts were that it had a chrysalis that it was trying to 'unravel'. It was hammering away at whatever it was, raising itself  to its' full height and 'crashing' down forcibly onto the prey. A passing car caused it to fly off  briefly, returning to the road some distance away. Later, on the PC, I could see that the prey was a moderate size beetle, somewhere around the size of a Dung Beetle. Obviously the road made a suitable 'anvil' to hammer the beetle against.
           Woodswallows are in my experience surprisingly resourceful. On a warm late summer day, I stopped to watch a flock of Yellow-rumped Thornbills feeding on the edge of the road. I couldn't make out what they were feeding on, but assumed it was probably seeds. While standing there, I noted, sitting on the power lines some 100 metres or more away, several Dusky Woodswallows. My thoughts drifted back to the Yellowrumps as I tried to work out if I could get close enough to photograph them, but a passing car put paid to that and they flew off. However looking down the road I could see the woodswallows were now flying at speed back and forth along the road, obviously catching some unseen prey. I moved closer. Another passing car and a repeat of the previous excursion from the power line by the woodswallows. Then the penny dropped! The woodswallows were waiting for the passing cars to stir up clouds of very small 'midges' from the roadside and they were taking full toll of them as they were briefly disturbed. I sat and watched for some time, mesmerised by their actions. As I said, surprisingly resourceful.


Sonja said...

That's interesting about them taking advantage of the insects flushed by cars. I guess it's a similar but more effective strategy to Grey Fantails keeping close to walkers for the same reason.

Carole M. said...

interesting find; I love the woodswallow species too