Habitat Use Profiling

BaTML uses technology in an innovative way through which directional information and activity can be measured accurately. As far as we are aware no one is using our methodology anywhere else in relation to bat studies. We would like to acknowledge the assistance provided by Peter Rigby and David Dodds in helping us acquire the correct specification of equipment.

In total 22 sites between Glasgow and Edinburgh are being covered. The total length of the canal network roughly equals 110 km. Therefore on average we have a study location every 5 km across the Central Belt of Scotland. All sites have been surveyed to obtain basic habitat information, of which some have been looked at in more depth with regards to bank side vegetation.

Standard Survey Model – Pipistrelle and Daubenton’s

We have 2 separate bat surveys running side-by-side commencing 30 minutes after sunset. A survey lasts for 90mins, giving us 180mins of data for each evening (the total of the 2 surveys added together). All the information gathered is then replayed and analysed later before various databases are populated with our results.

 

To survey for Daubenton’s bat we use 4 Heterodyne Bat Detectors linked via cabling to a central 4-track tape recorder. Each detector records on a separate channel and each has its own level indicator. Therefore when a bat flies past a detector its echolocation is recorded and the bat pass can be timed. In other words we know when a bat is on a particular part of the canal. The detectors are set up in sequence allowing us to measure time, speed and most importantly, direction. This directional information allows us to narrow down the likely location of any roosts. In addition to this we are also able to say with a reasonable degree of confidence how many bats are present in terms of minimum numbers. Most Daubenton’s bat passes are confirmed with a visual sighting at the mid point using red torchlight.

To survey for pipistrelle species we use a Time Expansion Detector set up at the mid-point with its own cabling running into a separate recording station. This method allows us to identify which type of pipistrelle bat is present and also gives us a maximum number of bat passes per species. In addition to recording the echolocation of these bats this system also picks up their social calls, as well as the sounds made by any other species of bat that may pass by.

Radio Detector Survey Model

One of the key objectives of BaTML is to understand in much greater detail how the bats that use these canal corridors interact with their habitat. In order to have a healthy and sustainable bat population three basic features need to be present, namely:

• Roosts - a number and choice of suitable places (including Hibernacula) that will be used at different times of the year by different bats depending on species/sex.
• Foraging Areas where there is an abundance of insects for bats to feed upon.
• Commuting Corridors that connect the roost sites to foraging areas, thus allowing bats to navigate around their habitat at night.

With all of this in mind we developed a survey methodology that allowed us to do a number of things, including the following:

• Narrow down the location of roosts.
• Find the main foraging hotspots on the canal system.
• Discover at which points along the canal bats enter and/or leave the system.
• Find the important commuting corridors that connect to the canal habitat.
• Work out how many different populations of bats use the habitat.
  

This methodology allows us to quickly get a snapshot of what is happening in a particular area, from which we can do subsequent surveys to help complete the picture. The number of surveys for each location varies according to what we find, and a number of support methods can be used to help complete the picture.

This aspect of our work is very important as it goes beyond just finding out what our bats are doing and protecting their roosting areas. With the level of detail achieved, potentially we are able to advise landowners, developers and consultants what features need to be retained/enhanced in order to keep a healthy environmental balance with bats playing their vital role in the control of insect populations.