We had  been told about some White-collared Swifts that had been seen in a cave, behind a waterfall, though they had not been seen for three years.

At dawn one morning we climbed up a mountain,  then down into an arid valley and followed a small stream.  Although it was the dry season the presence of the stream indicated that the waterfall would be there and it was.

We spent some hours searching  in vain for the swifts, they may have been present, hiding in the dark recesses of the cave.   We decided to wait and see if any returned to the cave for the night.

White-collared Swifts breed all the way down from Mexico, through the western side of South America as far as Argentina, so we were at the very southern limit of their distribution.  Three years before, there had only been juveniles seen in the cave, no one had recorded adults.  These swifts being mainly tropical breed in March and April so if they were around now it would indicate year round residency – very important to know.

The sun dropped behind the far mountains, then a blur above us and a flurry of  activity inside the cave: swifts!

It happened so quickly.  We had seen nothing in the sky above us; some swifts had flown into the cave almost unseen.

We  crept around the waterfall, water was dripping everywhere, including on what was now a very wet swift clinging to the wall.  We could make out its white collar and amazingly long wings, but had to retreat out of the drenching water and maintain our vigil outside.

Another hour went by and the same thing happened. This time we just managed to see the swifts coming.  A small tightly bunched group flew low round the distant curve of the valley.  Like black leather-clad racers, they passed us like a lightening flash straight through the curtain of water and disappeared. I didn’t have time to raise my camera – they were gone into the void.

The same thing happened several times.  Small groups appeared as if from nowhere and darted into the cave.  By now we had counted at least 35. As the numbers inside grew so did the noise inside the cave.  Whenever new birds arrived, they were greeted with high pitched screams.  They bunched up together, water pouring over them.

It was getting dark and thunder clouds started to roll over the hills.  Afraid of rain making the return treacherous, we headed home.

We had found what we wanted, a resident population of at least 50 White-collared Swifts, rare birds this far south.

Not only swifts but also a stream fed by a graceful waterfall,  a watery haven for a host of animals.