[CT Birds] Night Migration talk tonight - Menunkatuck Audubon Society

Robert DeCandido PhD rdcny at earthlink.net
Wed Jan 13 13:26:28 EST 2010

Tonight at 7:30pm in Guilford, the Menunkatuck Audubon Society will 
host a talk on the Night Migration of Birds as seen from the Empire 
State Building in NYC. The sub-title and theme of the talk is: "Are 
Skyscrapers Killing Our Birds?"

In my talk I will detail the history of night migrating birds and 
their (occasional) collisions with NYC buildings such as the Statue 
of Liberty (beginning in 1888), and the Empire State Building 
(beginning in the 1930s). Occasionally, up to 1500 birds have 
collided with these illuminated structures at night. However, all is 
not gloom and doom...For example, it is because birds collided with 
the Statue of Liberty that the newly formed Museum of Natural History 
was able to augment their collection (particularly with less common 
species such as Bicknell's Thrush). And it is precisely because birds 
collided with the Statue that scientists had concrete evidence that 
most birds migrate at night. So by collecting dead birds at the 
Statue, along with previous studies by J.A. Allen of the American 
Museum at lighthouses in North America), scientists learned much 
about the timing and magnitude of night migration - and that most 
birds migrate at night.

Simultaneously to the early bird migration studies in our area, there 
was an outcry in magazine editorials about the needless destruction 
of birds at night at buildings. Electricity was "invented" in the 
1880s and was first installed at the Statue of Liberty in late 1887. 
By the spring of 1888, birds were colliding (mostly) with the base of 
the Statue. Magazines such as Harper's Weekly ran editorials about 
this needless loss of life. And similar accounts came in from other 
cities such as Milwaukee (by Kumlien), etc. So right from the 
beginning, conservationists recognized the hazards that light posed 
to some night migrating birds. (A greater threat to birds at the time 
came from the millinery trade - using feathers, and indeed sometimes 
entire birds - to adorn hats.)

Fast forward the time machine: The Empire State Building is erected 
in the 1930s, and low and behold, birds occasionally collide with it 
- mostly on nights with light northwest winds, and overcast (foggy) 
conditions. On 11 September 1948, the largest kill occurs - about 750 
birds) and reports of this appear in Time Magazine, the New York 
Times and elsewhere. The future founder of the Nature Conservancy 
(Richard Pough) also writes an editorial on the matter.

In the next decade (1950s) reports occasionally come in about dead 
birds found at the Empire State Building. Curiously, on at least one 
occasion, most of the bird collisions happen after midnight, when the 
lights of the building are turned off! Yes, collisions occurred after 
the lights were turned off on the Empire State Building.

Since about 1980 no large kills (greater than 100) of birds are 
reported from the Empire State Building. And in our study in 
2004-2005, though we counted more than 30,000 migrants, less than ten 
birds collided with the Empire State Building - that we know of. What 
happened? Why the changes?

In this slide presentation, I'll talk about what we know about the 
history of birds colliding with buildings at night in our area. I'll 
talk a bit about the differences in lighting (halogen vs. 
fluorescent, eg.) and the importance of weather (particularly wind). 
And I will talk a lot about the amazing experience of watching birds 
migrating at night including important scientific discoveries from 
our research done right in the middle of an urban area. All is not 
gloom and doom...And I will suggest strategies for making skyscrapers 
even safer for night migrants. Much remains to be learned, and much 
can be discovered by anyone with an interest in sitting atop a tall 
building at night in our area. This is a new frontier of study and 
people in cities from our area to Chicago to Kuala Lumpur can 
contribute significant information. It is truly amazing seeing those 
tiny birds (weighing less than an ounce in some cases) winging their 
way south at night. I've counted more than a thousand in hour on 
certain nights (about one migrant every three seconds). Much remains 
to be seen, learned and discovered.

One last note: the problems facing night migrants should not be 
confused with birds colliding with glass during the day (but I will 
talk the latter too); nor should one take my research and apply it to 
the issue of wind turbines and night migrant birds. These are all 
separate and distinct issues that require their own studies. There is 
some overlap, but they are not to be lumped into any one category. 
And I'll conclude with this: there are many more positive things 
happening in our skies at night - worthy of the attention of anyone 
with an interest in night migration. You might even begin to wonder 
about why it is most small birds migrate at night (though finches and 
Cedar Waxwings are largely an exception to this...)?

Hope to see you tonight, Wednesday, at 7:30pm.


More information about the CTBirds mailing list