Right, I've now given up with NiMH batteries, you think you've got a good charged set, and then you look away and they've faded. Having got fed up with checking the D500x and finding out that it recorded only two nights out of the four as the batteries died, I've gone back to environmentally unfriendly alkalines. Having done that, I've managed to get seven nights of recording from one set of four batteries (3 second files at 500 kHz) of 2500 files and still had the batteries at 4.7 V, so probably fine for another night or two. I've got an external battery box that will take four C cells, so I would imagine that with good quality alkalines in those I should get up to two weeks recording. I shall check that when we get to August.

D500x settings

When setting up the D500x, the settings that might cause some confusion are the gain, trigger level, interval and trigger sensitivity. The gain is how much the signal is amplified, so set it low if the bats are near and loud, or high if they're far and quiet. The trigger level is level at which the signal will trigger the device. The interval is the time between recordings in seconds  - this is to avoid recording the same bat over and over again (unless you want to of course). The one that's got me scratching my head is the tigger sensitivity, which seems to be how long the signal has to remain over the trigger level to start the device. The options are very high, high, medium, low and very low. I guess the idea is to have a setting that will not tigger the device over short signals, rain perhaps.
When setting it up, the device gives a handy indication of when it will be triggered, so you can jangle keys or loose change and make sure it will trigger but that it's also not going all the time.
For the purposes of testing it in my garden, I've got gain and tigger level set to 30, interval at 0 and tigger sensitivity at low.

D500x - it's arrived

After a slightly delayed trip from Sweden via several courier depots and my neighbour, my D500x has arrived. First impressions are that it's small and well built. The menu is quite user friendly, and it's pretty easy to set up. Unlike the older versions with the previous firmwear, this one just needs Windows FAT32 formatted CF cards in it, not the specially formatted ones that the D1000x needs.
As the device is not totally weatherproof, and looks rather high-tech and appealing dangling from a tree, I set about maiking an enclosure to keep the weather off, and make it more discrete.
I started off with an plastic electronics enclosure box and cut a hole for the microphone. I then used that cut-off section as a shield above the microphone. The external power lead annoyingly comes out the front of the device which means you have to bend the lead back in to the battery pack.
For batteries I made a pack up from a 6xAA holder I got from Maplins. That should give about 7.2 V at 2500 mAH. The device only needs about 4 V to work, but six batteries should give some margin if a battery or two fails, which seems to be quite common for NiMH batteries, for me anyway.

The D500x with a 6 AA battery pack wired into the external power socket.

Packed inside the box, the external power cable has to come out and then be net back around again.

All done up inside the box and sprayed a nice drab olive colour.

The microphone is shielded from rain by the cut-out section which has been bolted to the lid.

Deployed for testing in my garden.

Went out newt hunting with Richard Roe, one of my ex students who now runs Kingdom Ecology. We looked at a development site in Cheshire with four ponds to do and set bottle traps at all of them. The morning revealed a good haul of great crested newts as well as a lot of smooth newts, nine in one bottle trap. Torching at night was interesting as we found a fair number of great crested newts that were very light, almost an olive colour which made separation from smooth newts something of a challenge when seen briefly.

I've been looking into getting a remote monitoring system for bat echolocation. I ruled out the EcoObs batcorder due to cost, so it was between the Wildlife Acoustics SM2+ and the Pettersson D500x. It was not an easy decision, but after weighing up cost, recording quality, expandability and integration into Batsound I went with the D500x. This is to deploy at a couple of sites this summer to be used in conjunction with transects so it's likely to be out in the field for a few months. Needless to say, I'll be testing it in the garden first, let's see if I can get further than the usual species list of P. pipistrellus.

Just got back from running a two day course on sound analysis in the New Forest. It was a good opportunity to review the literature on automated logging of bat passes and automatic recognition of bat calls. There are some very interesting statistical techniques being used, but I have to say, not with a great deal of success, mostly with separating some Myotis species and especially with the separation of serotine from Leisler's. There is also considerable confusion between Plecotus and Barbastellus. Close but no cigar.

Ran the BCT 'Bat Ecology and Conservation' introductory course yesterday at Juniper Hall near Dorking.Went very well, I may alter a little bit of it to include some more of the recent findings around bat phylogeny and the fossil record. We had a fantastic display of live bats courtesy of Jenny Clarke from the Sussex bat hospital, with serotines, Leisler's, Natterer's and all three UK pipistrelles in the same hand (see below) left to right: Soprano, Common and Nathusius'.