At ECS, we constantly evolve and move toward the future and new capabilities in our industry. Welcome back to our series about bats with Project Manager and Wildlife Biologist Vance Nepomuceno within our environmental group from our Richmond, VA office, where we learn more about bat surveys, options available for surveys and project requirements for a survey.
Q: What is a Preliminary Roost Assessment? How is it different from a Bat Activity Survey?
A: A Preliminary Roost Assessment (PRA) is a survey to identify potential bat roosts in a project area. The purpose of a PRA is to provide a preliminary assessment of the presence, location and type of bat roosts within the survey area and to identify the potential impacts of a proposed project on these roosts.
A PRA typically involves visually inspecting structures, such as buildings or trees, which bats may use as roosting sites. Surveyors will look for evidence of bats, such as droppings, staining, or odors, as well as physical features of the structure that may provide a suitable roosting habitat. The survey may also involve an assessment of the surrounding habitat and foraging areas, as well as an evaluation of potential risks to roosts, such as disturbance, destruction or lighting.
On the other hand, a Bat Activity Survey is a type of survey conducted to assess the activity levels of bats in a project area. The purpose of a Bat Activity Survey is to provide information on the presence, abundance and behavior of bats within the survey area and to identify the potential impacts of a proposed project on these bats.
A Bat Activity Survey typically involves using acoustic or mist-netting surveys to detect and identify bat species within the survey area. The survey may also involve an assessment of the surrounding habitat and foraging areas and potential risks to bat populations, such as habitat destruction or fragmentation, loss of foraging habitat, or disturbance.
Q: What projects typically require bat surveys? At what part of a project lifecycle should a bat survey be performed?
A: Projects involving construction, alteration, demolition of structures or land use changes that may impact bat habitats or roosting sites (i.e., tree clearing) may require bat surveys. Depending on the specifics of a project, a survey could be required by state or federal regulators. Examples of projects that may require bat surveys include wind energy projects, mining operations, commercial and residential development and road and bridge construction.
Generally, a bat survey should be performed during a project’s planning phase before any construction or land use changes are typically made. This allows developers to identify areas where bats are present and determine the best ways to minimize the project’s impact on bat populations. The exact timing and duration of the survey will depend on several factors, including the project’s location, the season and the species of bats which may be present. In some cases, multiple surveys may be required to gather sufficient data.
Q: What are mist-net and acoustic surveys? Are those the types of tests you perform for Bat Activity Surveys?
A: Mist-net and acoustic surveys are two standard methods used for bat surveys and they can be part of a bat activity survey to evaluate the presence of a protected bat species.
Mist-net surveys help determine the presence and relative abundance of bats in an area, as well as gather data on their behavior and ecology. Mist-net surveys involve setting up fine nylon nets across areas where bats are known to fly. The nets are usually set up at night when bats are active and are monitored by trained surveyors. When a bat flies into the net, it becomes entangled. The surveyor can safely extract the bat, identify the species and record other data such as age, sex and reproductive status.
Acoustic surveys, on the other hand, involve using specialized equipment to record the echolocation calls bats use to navigate and locate prey. These calls are usually at frequencies too high for humans to hear, so specialized equipment is needed to detect them. By analyzing the characteristics of the calls, surveyors can identify the species of bats present and determine their activity levels. Acoustic surveys are often combined with mist-net surveys to gather more complete data on bat populations.
Both mist-net and acoustic surveys can be part of a bat activity survey, which is a type of survey that is used to assess the presence and behavior of bats in a particular area. Bat activity surveys are typically conducted before starting a construction or development project to determine the potential impact on bat populations and to inform mitigation measures to minimize that impact.
Q: How long does it take to complete a bat survey?
A: Bat survey length is dependent on the size of the area. Preliminary Roost Assessments can be conducted in the time it takes for a thorough walk through of the site.
Acoustic and mist-net surveys, however, take much longer. For most acoustic surveys, the detectors must be deployed for several days to a month and that data can take some time to go through after the survey has concluded. Mist-net surveys can be as short as three days or up to a month for larger projects.
Survey time is also weather dependent; cold or windy nights are not surveyable nights.
Q: What do reports look like for a bat survey? What information do you typically need to deliver?
A: The exact format and content of a bat survey report can vary depending on the project’s specific requirements, the jurisdiction in which the project is located and the type of survey conducted. However, a typical bat survey report will include the following components:
Executive Summary, Introduction, Site Description, Results, Discussion, Conclusions and Recommendations and References.
In general, a bat survey report should provide a comprehensive and accurate assessment of the potential impact of a project on bat populations. The report should include all relevant data and analysis and clear and actionable recommendations for mitigating almost any potential impacts to satisfy regulators that are involved on the project.
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