Wednesday, 17 July 2013

American-style bathouse

Having to potentially do a pipistrelle exclusion this summer, I thought I'd have a go at making and installing an American style bathouse on the building just to see if it worked. I used some modified plans from the Bat Conservation International (BCI) publication 'The bat house builder's handbook' to construct it. I had to adapt the plans slightly for the metric measurements so used a quarter sheet of 9mm ply and another of 12mm ply. I also used exterior grade plywood for the sides as this would make it more long-lasting I figured. This means you will need a little extra ply for this and luckily I had some scraps laying around. I also left out the ventilation holes as it's cooler in the UK, and added a bottom as well.

The total construction cost was around £70 but if you make them in bulk with four boxes to a full sheet of 9mm and 12mm ply, it should come down. I also added a roofing felt cap over the top to keep the rain off longer.

This is the ply all marked out ready for cutting.

This is the timber all cut out and ready for assembly.

The assembled and painted bat house with a 30cm ruler for scale.

View with the bottom door open at the four internal chambers.

Total construction time was about three hours, excluding painting.

Tuesday, 9 July 2013

D500x firmware upgrade

The new D500x firmware version 2.2.2 has been released. The trigger sensitivity option now allows for better rejection of noise events and there is a new timer option that can start and stop the detector relative to sunrise and sunset when you put in your latitude and longitude. Both are very welcome additions.

One of the most useful features I've found though is that the log file created during recording events shows the battery voltage through time. This really helps in choosing the right batteries for the duration the detector is used. I trialled it with an external battery case with four NiMh 'C' cells which gave out 4 x 1.2v = 4.8 V. You could see the voltage change through time until the detector got to 4.2 V when the detector stopped working. I'm sure with four alkaline C cells at a total of 4 x 1.5v = 6 V it would have been fine.

While we all want to be responsible and use rechargeables, it often just does not work with devices like this when you need them to be reliable and are not checking on the batteries all the time. Most of my NiMh AA cells are unusable after two seasons as they suddenly lose charge. I think the best power source is still a 6V lead-acid battery for long periods in the field.

I've had some lovely long-eared recordings from my D500x from a church recently, plus a load of very varied but wonderful social calls. Long-eard bats are certainly very talkative.