With all the news regarding birds and fireworks at the Oregon Coast, I though I would address this issue with regards to the South Waterfront Osprey and our local birds. As background, 4th of July fireworks were cancelled this year in Depoe Bay after the Fish and Wildlife Service documented significant disturbance behavior and nest failure at a nearby Brants Cormorant Colony due to the 2011 4th of July celebration. The South Waterfront osprey should certainly have a spectacular view of the fireworks over downtown Portland this evening and we have had a variety of questions regarding how our local birds might fare.
The reality is that loud noise can definitely impact locally nesting birds. Think about how out pet cats and dogs react to 4th of July fireworks and then think abiut how wild animals that are much more sensitive to threats might react. Fireworks can spook young that are not ready to fly into leaving the nest prematurely. They can cause parents to leave the nest temporarily exposing eggs or young to predation as well as overheating and cooling. They can also disupt feeding behaviors.
Certain species are more vulnerable to disturbance than others. There are also variations among individual birds within a species--some individuals have higher tolerance than others. So for example an osprey that nests in an urban environment with a high level of ongoing surrounding activity and noise may have a much higher tolerance than an osprey that nests in a remote wilderness lake. The same exact disturbance might have no impact on the urban birds but cause the remote birds to abandon a site forever.
We deal with this issue all the time with peregrines. People assume that because they nest on urban bridges with cars and trucks and all kinds of other activity, that peregrines that nest on remote cliffs can also tolerate lots of activity--say for example the introduction of climbing on the cliff or a new hiking trail right near the nest. In fact what you need to do is consider the baseline of disturbance that the individual pair is used to experiencing. Regardless of the environment, we tend to be concerned about activities that are introduced into the nesting area after nesting that has begun that are either competely new to the birds or existing activities that increase significantly in intensity.
Which brings us back to fireworks. Huge explosions at the neighborhood scale as well as the big municipal fireworks displays certainly constitute potential disturbance for nesting birds. It represents a huge and sudden increase in both intensity and volume from the baseline that these birds are used to even on an urban landscape. With the exception of owls, most of our birds are hunkered down at night and most will just stay still and ride it out. However, the risk factor is absolutely real.
We tend to worry the most about either imperiled species or species that nest in large colonies where significant numbers of birds could be simultaneously impacted. We also tend to be more concerned when these displays are in close proximity to willdife refuges and other areas that have been specifically set aside for birds. In Depoe Bay the fireworks were in close proximity to a Brandt's cormorant colony within the Oregon Island's National Wildlife Refuge.
odds are that the South Waterfront osprey as well as the nesting robins in your backyard will ride it out...but I am also not at all surprised by the reports that we get at Audubon on July 5th about bird nests that have suddenly failed or of nestlings too young to fly that are suddenly found stranded on the ground.