Night Migration Tracking

A Project of the Bedford Audubon Education & Science Committee

Ornithologists tell us that the vast majority of birds migrate at night. Using internal navigational systems yet to be fully understood by humans, birds travel vast distances at night using the darkness to safely avoid predators. As dawn breaks migratory birds will find suitable habitat to feed, rest, and then proceed on to their nesting or wintering grounds.

For those of us interested in understanding the full cycle of migration in our area, Bedford Audubon’s early morning bird walks look at just one piece of the puzzle. Although they are visually pleasing, spring and fall morning walks will only identify a small number of species that actually stop in our area. Since most species of birds migrate during the night in large numbers, they cannot be visually recorded in the same way as those seen in daytime bird walks.

Recently, ornithologists have begun using two types of technology to enhance their ability to track migratory bird patterns; one is the use of NEXRAD radar and the other is through the recording and deciphering of the birds’ night flight calls.

Ornithologists have actually discovered a way to understand which bands in the NEXRAD radar that you and I see on a regular televised weather report are rain clouds and which are “clouds” of migratory birds headed for Central Park in New York City, the Great Swamp in Patterson, or Bylane Farm in Katonah. This data can be used to alert teams of volunteers to be ready to get out on the mornings when migratory groups are passing through our area and can pinpoint the locales to send them to.

And to identify those species that don’t stop to rest in our area, the technology wizards have created a low cost, but incredibly powerful tool that almost anyone with a relatively new computer can use. Using a very simple microphone to record the birds’ calls as they fly overhead, our tech friends have developed software that sorts the “spectrogram” the noise produces and then actually tells the user what bird it is. This astonishing capacity allows us to marry it with the enhanced visual tracking NEXRAD provides so we can get the most robust data possible for bird migration in our area.

Collection of this type of data for our chapter’s geographical area, and for the greater Hudson Valley, is vital right now. Due to the enormous pressure to develop land in our area, the lower Hudson Valley is one of the most fragile links in the Atlantic migratory flyway. For that reason, Bedford Audubon’s Education & Science Committee has decided to embark on this project that will unite old and new methods of tracking bird migration in an attempt to provide ornithologists and land use decision makers with the necessary data to ensure they can make the best choices when deciding to preserve and protect land for habitat and migratory purposes.

The idea of Bedford Audubon becoming involved in a major migratory tracking project sprung from our attendance at the Spring 2004 Birds of the Hudson River Estuary Conference held in New York City. There, during a presentation, Paul Kerlinger, an expert on bird migration, mentioned that there had been very little empirical data compiled on migratory paths in the Hudson Valley. That got some of us thinking about how we could use this challenge to institute a multi-Audubon chapter project to gather the data needed by the scientific community.

Bedford Audubon reached out to several local chapters which had also expressed interest in the project and Bedford Audubon agreed to pilot the project and do some of the initial research needed to get it up and running.

The project’s objectives are over time, and with sound science and research, to:

• Compile significant data on migratory patterns over New York City and the Hudson Valley that will assist scientists and land use planners in their decision making processes;

• Get more people involved in citizen science;

• Increase the pool of birders able to conduct sound science-based censuses and counts;

• Increase the general public's awareness of the migratory process through New York City, the Hudson Valley, and Long Island Sound Region

• Increase the public’s awareness of NYC Audubon’s Project Safe Flight Project, and add to the project's knowledge of migration patterns in the New York City metropolitan area.

Making Bedford Audubon's Bylane Farm headquarters the pilot sight for this project made total sense to all involved. For years many BAS members have marveled at how many bird species can be heard migrating over our Bylane Farm headquarters. Not that this is a unique phenomenon. Many of the same species fly right over New York City; it is just that the tranquility of a semi-rural setting at Bylane provides the opportunity to hear and identify many more. So while we are in the testing period for software capacity among other things, we decided that this location with the lowest level of background noise would be the best.

Due to the never ending generosity of our supporters Bedford Audubon was able to afford a very robust, new computer which will be used to record and detect all the night calls occurring over Bylane Farm. Several staff members from the Cornell Lab of Ornithology have been instrumental in helping us build our microphone, identify and understand the several bird call identification software programs that are available, and how to scope out the overall project. We expect to provide both the Lab and our colleagues at Audubon NY, working on the international Important Bird Area program, with our data so they can utilize it in the vast array of conservation projects they administer.

The next steps for us are to begin testing and collecting data. As we enter the fall 2004 migration period we are reviewing the most cost effective ways to attain and decipher NEXRAD radar images. We are beginning to test the several types of bird call identification software to understand fully the capabilities of each. Naturally, we are starting with the free materials and slowly moving to ones that cost money as the need arises. We are currently looking for an intern who wants to take this on as a thesis or full semester project. This person would participate in the project’s scoping, supervise volunteer data collection, and then write the reports for each migratory period tracked.

As we move forward please return to this page as we will be posting links to the data we collect. Please contact us by email if you wish to learn more or volunteer for this project. If you want to learn more about the science behind our methods, how to build a recording device for your own home tracking, or any more info on this topic we have provided some articles and links to websites below. Much of this information is available at the Bedford Audubon Resource Library located at Bylane Farm, or may be available at your local library. Please feel free to contact us for more information.

“Birds on the Move, How weather will change the way you look at birds;” Paul Kerlinger; Birder’s World; February2004
Bill Evans's nocturnal flight call monitoring website, http://www.oldbird.org
Cornell’s link to bioacoustics research, http://www.birds.cornell.edu/brp

Copyright © 2004-2005 Bedford Audubon Society
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