ChiroRivers is the monitoring program of bats in aquatic ecosystems. It was launched experimentally in 2007, and its definitive protocol was established in 2008. It represents a simple monitoring program, adapted from the British Waterway Survey (Bat Conservation Trust, UK) which is the long-term survey that started in mid 1990s. Through the monitoring of bat populations along the rivers, we can detect changes in the ecological quality of water and riparian forests! If is essential to maintain this monitoring for many years in order to infer changes in these bat populations and river courses.

Any non-expert person can do it. Nevertheless, we will organize training sessions to explain the protocol, and we offer the possibility to join more experienced observers in the field, from whom you can get personal advices. Only one sampling per year is performed during June, July or August. The survey always starts 60 minutes after the sunset, and on average it takes approximately two hour. If desired, few replicas during the season can be done.


Who can participate?

Anyone regardless of previous knowledge about bats can do it. During single one-night training you can learn how to do it. If you want to join the monitoring, just contact us. In the Granollers Museum we organize training sessions to explain the protocol, and we offer the possibility to join more experienced observers in the field, from whom you can get personal advice.

Where it can be carried out?

Rivers, ponds and water reservoirs are all perfect candidates for a ChiroRivers monitoring stations. Before starting a specific monitoring, you must sign up for free in monitoring application (, from where you can easily set up your monitoring stations. There you can also see if there is any currently inactive monitoring station and restart it.

What does it consist of?

It consists of counting Daubenton’s bats and pipistrelles from four observing points per sampling station during the evening/night. That’s so simple!

How is it carried out?

At each survey point observer stands on the river bank looking at the river perpendicularly, with the flashlight that allows the observer to see other bank. For 10 minutes light beam is directed towards the water surface, and the observer must count Daubenton’s bats (Myotis daubentonii) that cross the light beam. After that, for following 5 minutes light beam is rised approximately 1 meter above the water surface and passes of pipistrelles (Pipistrellus sp.) are being counted. Same procedure is repeated at four sampling points. And that’s all!

When it should be carried out?

The survey/census should be carried out one evening a year, any evening/night between June, July and August. The survey always starts one hour after the sunset, and it usually lasts around 2 hours, depending on accessibility to the sampling points. Optionally, few replicas can be done during the season.

Which equipment is needed/necessary?

To perform this survey, only a flashlight and a mobile phone are sufficient. ChiroRivers is a visual census, and because of that it is essential to have a flashlight that is strong enough to alow us to see whole width of the river in order to count all the bats that pass. Mobile phone serves to enter the data/counts directly on our website. If you do not have a mobile phone, you can use a field notebook to write down the data and upload it once you are at home. Ultrasound detector can also help us to warn us when the bat is arriving, but it is not essential. Keep in mind that Daubenton’s bats broadcast calls around 42 kHz, and for pipistrelles  farem servir els 50kHz, pel que cal tenir-lo ben sintonitzat si el fem servir.

Sending and checking the results

Through web application you can access to the tools to design and register your transect, you can send us your observations and also see the results of other stations in the network. The results must be submitted before the end of August. The data can be submitted online directly from the field, or it can be written down to field notebook and uploaded after the fieldwork.

If you would like to participate or to join some training session in order to learn more about the monitoring, please do not hesitate to contact us!


Training sessions

Occasionally we organize training sessions in order to disseminate information about the monitoring, to encourage the volunteers and to provide them with the necessary knowledge to be able to carry out this simple protocol, for which previous knowledge about bats is not necessary. An alternative to training sessions is to accompany other researchers during their transects, and to obtain enough experience within one day to be able to carry out the procotol autonomously.


In order to enhance visual and acoustic identification of Daubenton’s bats and pipistrelles (that sometimes can be confused) we provide you with some recordings and video as an example:

  • How to create your transect: We will create some videos here that explain how to create the routes.
  • Visual recognition of flight typesin the ChiroRivers census, we count animals that cross our visual field, and we can see them easily thanks to the flashlight (that is indispensable part of the equipment for this monitoring). It is impossible, even for a bat expert, to distnguish the majority of bat species only based on their flight. Fortunately, Daubenton’s bats are an exception to this rule. They forage over the water bodies and have developed a flight strategy that is completely different from the rest of the species, and it is possible to identify it without capturing.
    • Typical flight behaviour of a pipistrelle. Very erratic, without the maintaining a fixed height, often along the edge of vegetation, where they seek for prey and roosts.:
      Ruta de vol de Pipistrellus
    • Typical flight behaviour of Daubenton’s batThe drawing represents a water course, where animals are “making” long twists, often repeated with insistence, always close to the surface of water, where they find their prey
      Ruta de vol de Myotis daubentonii
    • In the following video video (documentary in English) foraging behaviour of Daubenton’s bats was recorded at one stream in England. You can also hear how their echolocation calls sound with heterodyne detector:
  • The ultrasound calls through the heterodyne detector. Both species broadcast similar signals, but when we compare them, they sound different. Pipistrelles produce a sound that reminds us of applause, and it has very irregular rhythm, Daubenton’s bats emit faster and more dry sounds, with less regular pulse.

    Left: Myotis daubentonii, right: Pipistrellus sp.