In those cases where flash causes temporary visual impairment, it's not only the case that the bird is disturbed (as it would be by a range of other activities in the park); the bird's ability to act with its typical effectiveness in response to the disturbance is diminished. This suggests to me that some restrictions on the use of flash in the bird garden would be appropriate, such as a time-of-day restriction that would take into account natural light levels.
An additional comment: I do wish Olivero and Cohen had included citations, as I would like to know how they reached their conclusions.
Saint Louis, Missouri
On May 21, 2010, at 9:19 PM, David Becher wrote: