Rob,

I understand the history of the 1893 hurricane, but I'm not so sure that a 
storm has to travel 2000 miles to pick up large numbers of birds. I believe 
that the vast majority of the birds get picked up as the storm pushes 
through the more inshore waters of the Caribbean and Gulf Stream. Looking at 
the birds that are brought into shore, these are birds that are expected in 
the gulf stream waters, but not birds that seem to be far out of place. Most 
of the range maps in Harrison's shore birds of the world show most of the 
pelagics of the north Atlantic to be birds of the new world islands, there 
really aren't many depicted as occurring in the eastern part of the Atlantic 
north of the equator.

Again, I believe that what happens is the birds that are caught up on the 
northeast side of the storm as it progresses north and west are trying to 
flee the system by riding the counter-clockwise winds when they get caught 
up by land and are drawn into the eye. The birds would otherwise ride the 
storm around to the 'calmer' southwest side and move away from the course of 
the storm, escaping to calmer conditions. Remember, a bird moving in a 100 
MPH wind is still moving through the air at the same velocity as it would in 
calm winds. It's only the speed at which it's moving in regards to the 
stationary land or sea that it's measured against. The turbulence in the 
fast moving wind currents will cause it distress due to frequent shear, but 
unless it tries to land to get out of the system or gets caught in a 
tornado, I don't believe that it's in any major danger from the circulating 
winds. The danger arises when the birds ride the winds over land and they 
encounter stationary objects. Of course, the higher the wind speed, the more 
unlikely that the birds will have an easy escape from the system. The higher 
velocities force the birds to remain in the air and they are carried farther 
inland than in a weaker storm, where the bird's have the ability to drop out 
sooner and flee back out to sea once the worst of the conditions pass.

I believe that the birds that we see that drop out over the mainland are the 
birds picked up close (with-in 100 miles) to shore. The large numbers of 
birds that show up when the storms make landfall in North Carolina are a 
prime example of this. With the Gulf Stream relatively close to shore here, 
the birds don't have time to escape when they get squeezed by their 
encounter with land and that is why they tend to get large numbers of 
pterodroma petrels there while other states with much more open water 
between the gulf stream and the coast do not. I have no documentation or 
study data to back up my assertions, but I believe that the circumstantial 
evidence supports this hypothesis.

Anyway, regardless of what we do or do not believe, each time one of these 
storms makes landfall there seems to be a difference in patterns to the 
species delivered and where they fall out of the storm. Hopefully this one 
will provide the region with some great viewing opportunities without the 
damage and loss of life that can come with a major storm.

Ed Boyd
Westminster, MD
----- Original Message ----- 
From: "Rob Hilton" <>
To: <>
Sent: Tuesday, September 02, 2008 1:43 PM
Subject: Re: [MDOSPREY] Hurricane Hannah and historical precedents


Ed,

The 1893 hurricane traveled almost all the way across the Atlantic, spending 
more than 12 days over open water. Hanna will not have done that. The last 
4.5 days of the 1893 hurricane's path, which was a steady, straight line, 
were as a major hurricane. Hanna has been slowly meandering (almost crawling 
at times) as a tropical storm and briefly as a hurricane in a much smaller 
part of the ocean. You can see the 1893 storm track and intensity here: 
http://weather.unisys.com/hurricane/atlantic/1893/index.html.

I believe that storms of Hanna's ilk don't normally bring the full 
complement of seabirds that a more powerful storm such as Isabel, to places 
as far from the landfall point as Washington, DC. Isabel (a large storm that 
had once been a category 5 hurricane over the open ocean) brought 
storm-petrels into DC, Hunting Creek in nearby Virginia, and Charles County, 
etc.; Ernesto (briefly a hurricane days before North Carolina landfall and a 
strong tropical storm hitting North Carolina) brought Sooty Terns and two 
jaegers into DC and Montgomery County, etc.

I should have been specific in my first post. I am not expecting 
storm-petrels far inland, near DC, from Hanna, because this storm does not 
look to be another Sea Islands Hurricane. But every storm is different, and 
I will be down along the Potomac if the current track prediction pans out.

Best,

Rob