While his experience was extreme, De Biasi called bird strikes "very common" and said their unpredictable nature makes them more dangerous than ice.
"Birds, well, it depends on your skill and your luck, because you don't even know when you'll be hit," he said.
But bird strikes are of particular concern around New York, where a congested flight path overlaps with the birds' Atlantic flyway.
"There were many birds," Sullenberger told members of the National Transportation Safety Board who gathered last week to hear more about his Jan. 15 emergency landing. "They were very large, and they filled the entire windscreen."
Sullenberger also said warnings pilots get about birds aren't always helpful.
"In my experience, the warnings we get are general in nature and not specific and therefore have limited usefulness," he testified.
After Sullenberger's splash landing in January, people pressed to know how often planes hit birds. At first the Federal Aviation Administration said the information was classified, but later changed its mind, making its database public in late April.
The information released included reports of fewer than 3,000 bird strikes per year for the first several years of reporting from 1990 through 1994. The numbers increase from there, hitting a peak of 9,650 bird strikes in 2007. In total, FAA data indicates there have been more than 73,000 bird strikes in the United States in the past eight years.
Sullenberger's heroic tale may have brought more attention to the issue, but it was actually a "very, very close call" on an airplane in 2003 that prompted New York City to take action, Begier said.
That's when officials started using various tactics to remove geese from the region, such as oiling Canada goose eggs to prevent more geese from hatching and using noisemakers, fireworks and even falcons to scare them away.
"Birds are a hazard," De Biasi said Monday.
"I think every airport should have bird hazard protection plans," he added.
ABC News' Ki Mae Heussner and Sarah Netter contributed to this report.