A Bat Hunt at Birmingham NEC

After exploring the Bluebell wood and walking round the Birmingham NEC, I had a quick meal at the Crowne Plaza and then came out again in the hope of finding some bats.  The Bat Conservation Trust tells us that "Bat use high frequency calls normally beyond the range of human hearing to build up a sound picture of their surroundings. This echolocation system enables them to wing their way through the dark night hunting the tiniest of insects." I had a "heterodyne" bat detector with me, which makes these calls audible to my much less sensitive human ears. 

View of Pendigo lake from the Crowne Plaza - early morning.

The photo, taken from my hotel room gives an idea of the layout of the area.  The Resorts World hotel and outlet is on the immediate left and the big red building seen to the North of the lake is one of the NEC halls. The trees to the immediate right of the red building are the woodland that I explored earlier in the evening.  The path you can see in the foreground leads round the edge of the lake.

Pendigo lake from the South end of Pendigo lake - about 9pm.

At about 9pm, about half-an-hour after sunset I left the hotel. I turned right and followed the path round the South end of the lake. I had set the bat detector to 45, which is the frequency that our most common bat, the common pipistrelle uses to echo locate its prey in the dark.  While walking, I held the detector up and swept it round. Just a few metres from the hotel I heard some clicks coming from one of the trees at the lake edge. I couldn't see anything and swung round. There were louder clicks coming from a group of trees on a grassy bank between the lake and the car park. As I watched, I could see two and then three bats dancing in the air.

View of Resort World from the South end of the lake - 9:20pm.

They left the trees and flew in the direction of the lake. I watched for a moment then walked to the end of the lake-side path. From here I took nearly an hour to follow the path anti-clockwise round the lake, ending up at the entrance to the wood I had explored earlier.  I detected hunting bats nearly all the way round. The only gaps were in front of the Resort World hotel and the shingle beach at the North West end of the lake. The absence of bats in front of Resort World fits in Bristol University's web page, which tells us:

"Warren et al. (2000) found that when foraging over water, common pipistrelles prefer areas of smooth water surface with trees on both banks. These areas were found to be abundant in flying insects and low in acoustic noise."

Resort World from the North end of the lake - about 10pm.

Just before the end of my walk I encountered two young men who wanted to know what I had in my hand. I explained about the bats and pointed the detector over the lake so they could hear it click. They were exited to hear the bats and told me about the wildlife near their own homes - one had owls nearby and the other had foxes that visited his garden.

Wednesday evening

Sun dipping below the horizon - approx. 8:30pm.

This time I wanted to find out when the bats emerged so, before the sun set, I waited by the trees where they seemed to gather on the previous night. The sun set at approximately 8:30pm and I waited about half-an-hour for the bats to appear.

View from the South end - 8:45 pm

9:04pm - First clicks. One bat appeared and flew round the trees  for about 5 minutes before disappearing over the bank separating the lake from the car parks. A few minutes later it returned.

9:17pm - Second bat appeared and joined the first.

9:22pm - They were joined by a third and then all three went hunting over the lake.The bats are not the only ones hunting the insects that fly over the lake. Every minute or so I hear a plop and see rings spreading out over the water - presumably from hungry fish.

Great-Crested Grebe - 9:09 pm.

Birds were still active too. In the time that I was waiting, a heron flew over the lake into the woodland on the East side. A Great-Crested Grebe glided past and I decided to leave the dark lake to the creatures of the night.