Electronic Equipment

One of the crucial aspects of the environmental protection is continuous monitoring of environment. Specific aspect is estimation of the bird species population. It is particularly important for bird species being in danger of extinction. Avian monitoring programs are time and money consuming actions which usually base on terrain expeditions. Certain remedy for this can be automatic acoustical avian monitoring system, described in the paper. Main components of the designed system are: digital audio recorder for bird voices acquisition, computer program automatically recognizing bird species by its signals emitted (voices or others) and object-relational database accessed via the Internet. Optional system components can be: digital camera and camcorder, bird attracting device, wireless data transmission module, power supply with solar panel, portable weather station. The system records bird voices and sends the recordings to the database. Recorded bird voices can be also provoked by the attracting device. Application of wireless data transmission module and power supply with solar panel allows long term operation of digital sound recorder in a hard accessible terrain. Recorded bird voices are analysed by the computer program and labelled with the automatically recognized bird species. Recognition accuracy of the program can be optionally enhanced by an expert system. Besides of labelled sound recordings, database can store also many other information like: photos and films accompanying recorded bird voices/ sounds, information about localization of observation/ recordings (GPS position, description of a place of the observation), information about bird features and behaviour, meteorological information, etc. Database on the base of geographical/ geological digital maps can generate actual maps of bird population (presence, number of individuals of each species). Moreover database can trigger alerts in case of rapidly decreasing bird population. It is also possible to obtain new knowledge about bird species with data mining methods. The paper presents collected data on observed bird species (audio recordings, photos and films) as well as results of experiments testing particular components of the automatic acoustical avian monitoring system.

– Ultrasonic components of bird voices are rarely analyzed in bioacoustical papers. The main reason behind this situation is an equipment used for digital recording of bird voices in which: 1) sampling frequencies do not usually exceed 48 kHz and 2) microphones that limits bandwidth of recorded bird voices are also commonly used. The experiments described in this paper were carried out with 96 kHz sampling frequency and high quality broadband microphones. Moreover, because the commonly used 1-bit sigma-delta A/D converters introduce some distortion to the signal – they particularly affect its high frequency components. In the research we propose using the SAR converter instead. Preliminary automatic recognition research comparing performance of SAR and 1-bit sigma-delta A/D is also presented in the paper. Investigation concerned analysis of several voices of passerine birds e.g. Parus major, Passer montanus in ultrasonic range which unveiled existence of strong ultrasonic tonal frequency components and formants in the analyzed bird voices. Methodology that allowed us to record bird voices in an ultrasound range was described. Additionally, the general conclusion outlining the best bird voices recording strategy has been drawn. Biological meaning of the ultrasound components in bird voices still remains an open research question.