Sunday, 21 December 2014

Good vibrations!

The Pheasant - perhaps more clued into their surroundings than we might sometimes think!
I was interested to hear that US scientists tracking Golden-winged warblers, found that they "evacuated" their nesting site one day before a massive tornado arrived. Back in April this year, the scientists, who were using tiny geolocators to monitor the bird’s movements, showed that they left the Appalachians and flew 700km (400 miles) south to the Gulf of Mexico. Remarkably, the warblers had completed their seasonal migration just days earlier, settling down to nest after a 5,000km (3,100 mile) journey from Colombia.

The next day, devastating storms swept across the south and central US causing widespread destruction.

Working with colleagues from the Universities of Tennessee and Minnesota, Dr Streby tagged 20 golden-winged warblers in May 2013, in the Cumberland Mountains of north-eastern Tennessee. The birds nest and breed in this region every summer, and can be spotted around the Great Lakes and the Appalachian Mountains.

After the storm had blown over, the team recaptured five of the warblers and removed the geolocators. These are tiny devices weighing about half a gram, which measure light levels. Based on the timing and length of the days they record, these gadgets allow scientists to calculate and track the approximate location of migratory birds.

In this case, all five indicated that the birds had taken unprecedented evasive action, beginning one to two days ahead of the storm's arrival. They escaped just south of the tornadoes' path - and then went straight home again.

The scientists believe that the birds were “tipped-off” by the deep rumble that tornadoes produce, well below what humans can hear. Noise in this "infra-sound" range travels thousands of kilometres, and may serve as something of an early warning system for animals that can pick it up.

This amazing story reminded me of my own little tale related to sound carrying over big distances.

On the morning of the 11th December 2005, I was awoken by what seemed like every cock Pheasant in my neighbourhood “crowing” furiously. I always sleep with the windows wide open and so the noise was really loud, and what was so unusual this time is that they all kept going on and on. Often something will trigger cock pheasants off, sonic booms or thunder for instance, but within a few seconds they have fallen silent again.

But on this particular morning they seemed to be really upset by whatever had disturbed their slumbers. I looked at the clock which read a minute past 6am, so I got up to make a cup of tea and thought no more about this unusual pre-dawn chorus.

It was not until later in the day that I turned on the news to find out that people across Hertfordshire were awoken that morning by a huge explosion, described by Hertfordshire's Chief Fire Officer as "the largest incident of its kind in peace time Europe". The Fire Brigade and other emergency services were called to attend Buncefield Oil Depot in Hemel Hempstead following reports of a number of huge explosions as 20 large tanks blew up.  

The British Geological Survey measured the first and largest explosion which occurred at 06:01 at 2.4 on the Richter scale. So, that was what had set my local, mid Hampshire Pheasants off on their early morning raucous outburst!

Just out of interest I looked up how far away Hemel Hempstead is from my house as the crow (or Pheasant) flies – approximately 63 miles away. Doesn't quite match the antics of the Golden-winged warblers – but still pretty fascinating don’t you think!   

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