Autonomous Recording Units (ARUs)

Overview

Autonomous recording units (ARUs) are pieces of equipment used to conduct acoustic surveys in the field. These units are left unattended and programmed to record on a set schedule. The use of ARUs has increased in the past few years within the field of avian research. Similar to point counts, ARUs can provide a snapshot of bird species and their activity at a given location and time interval. In contrast to point counts, a permanent record is collected which can be used to reduce observer bias, assess detection probability, etc. 

ARUs are deployed into the field by field technicians, taking only a few minutes to set up or take down. The ARU is programmed prior to going into the field, the programming defines when the unit will turn on to record audio.

Types of ARU Data

Given the flexibility and adaptability of ARUs, they can be used to collect a variety of data types. For example, they can be programmed to detect when birds arrive at a site. They can also be used to collect nocturnal data (e.g., night flight), ultrasonic bat data, amphibian data, community based monitoring data, and the list goes on. The type of data being collected affects how the unit is programmed prior to going into the field.

The key differences in the type of ARU data being collected relates to factors such as whether the unit is set to turn on if triggered, or at a set hours in the day, how long the unit records for each time it turns on, what frequency the unit is triggered at, etc. There are a variety of variables that alter the data collection method.

How and Where to Access These Data

Over the years, and given the increase in use of ARUs’ various data tools, platforms and archives have been created to support acoustic data. Significant efforts have been undertaken in order to facilitate data discovery and accessibility of acoustic data. Such platforms and tools include:

WildTrax

WildTrax is an online platform for storing, managing, processing, and sharing data collected by environmental sensors for wildlife monitoring.

NatureCounts

The NatureCounts platform contains avian occurrence data, including data collected with ARUs, gathered by a network of volunteers and scientists in dozens of partnership programs. Data from ARUs that is tagged or validated by people in the WildTrax platform is sent to NatureCounts. This ensures that all available data on birds are centralized. The raw audio data and spectrograms are available at WildTrax.