Private and commercial wind turbines should not have a significant impact on bird populations in the town of Aquinnah as long as suitable regulations are in place, said Matt Pelikan, Islands program director for The Nature Conservancy, in a public forum held Wednesday night.

The forum was part of a series sponsored by the Aquinnah planning board on a new draft bylaw to regulate wind turbine use in town.

Mr. Pelikan was invited on Wednesday to discuss possible effects of wind turbine use on Island birds. “Any kind of development, whether it’s for energy or otherwise, has impact,” Mr. Pelikan began. He went on to give an overview of bird populations on the Island, followed by examples of the ways in which turbines might affect bird mortality rates.

He said rural Aquinnah is home to a large and diverse populations of birds, and he noted its location in the migratory flyway. “Migration is a notoriously fluky and variable event,” Mr. Pelikan said, making it difficult to predict with any certainty the number of birds that will come through the town in any given year.

He identified both direct and indirect impacts of turbines on birds. Direct impacts include birds colliding with turbines. Plate glass windows and housecats provide more threat to bird populations than such collisions, Mr. Pelikan said. He suggested that turbines be located in areas where birds will be less likely to become disoriented due to factors such as fog.

Indirect impacts include habitat change or fragmentation resulting from building the turbines. This is more damaging, Mr. Pelikan said. He suggested placing turbines in areas less likely to contain undisturbed habitats, such as areas already cleared for other purposes.

Predictably, studies show that large groups of turbines lead to higher bird mortality rates than single-standing structures, and that smaller turbines of up to 100 feet have less of an impact than those approaching 300 feet. One specific problem with taller turbines is the fact that many require illumination for aviation safety. Birds are often attracted to the lights, and will zero in and circle the towers. There are documented instances of a single lighted tower killing thousands of birds in one night, but it is a rare phenomenon.

“In general, the mortality that turbines cause among birds is quite low,” said Mr. Pelikan. But “even relatively small increases in the mortality rate are not a good thing,” he added.

He recommended that the town establish no-build zones for turbines along shorelines and in other areas that attract large number of birds. He also suggested that the town cap the number of turbines allowed and make spacing requirements for those that are allowed.

Mr. Pelikan also suggested minimal lighting on taller structures that can be turned off during challenging weather conditions for birds. Finally, he recommended that the town develop some kind of monitoring system to get a better idea of what kind of mortality rates the turbines are causing.

“My feeling about wind is . . . any kind of energy development is going to have impacts. It’s just the way of the world,” said Mr. Pelikan. He continued: “I am very concerned about global climate change . . . Maybe what Aquinnah needs is not just a wind power bylaw but an energy bylaw.” He said his greatest concern is that the development of new energy resources will lead to increased energy use, having an equal or greater impact on the environment.

Ms. Rose said the draft wind energy bylaw in Aquinnah is still a work in progress; she said information from Mr. Pelikan’s talk would be presented for consideration when the bylaw comes before voters at a special town meeting slated to take place in October. “There hasn’t really been a dialogue on the Island concerning this,” she said. “Nothing is set in stone.”