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The Devil is in the Details
NestWatchers often question the importance of entering data from individual nest checks. "Do I really have to report what was in the nest every time that I visited?" "Isn't it good enough to just know how many birds fledged from all of my nest boxes?" "Why would someone want that much information anyway?" Although it may seem excessive to record and report the contents of nests every few days as the NestWatch protocol requests, this level of detail is necessary to accurately detect changes in nesting success and to determine the causes of these changes. Simple end-of-the-year nest summaries often are not very informative and can be misleading, especially when summarized across nests. For example, a 60% fledging rate for 5 bluebird boxes that each had 5 eggs could mean that only 3 birds fledged from each nest or that all 5 birds fledged from 3 of the nests while no nestlings survived in the other 2. The implications of these two scenarios are quite different. The first suggests that something is causing all of the local bluebirds to have poor nesting success, while the second may mean that two of the boxes are located in poor habitat. Without knowing the stories of each nest, we could never determine appropriate management strategies.
House Wren chicks in a natural cavity. Photo by Mary Roen
If you calculate a simple percentage of success based only on the total number of eggs and fledglings that you observe, you will overestimate the actual nesting success of the entire population. That's because many nests are lost to predators or bad weather early in the nesting period while others are missed all together. To solve these problems, researchers instead use nest observations collected every few days to calculate the likelihood that nests will survive from one day to the next. This daily survival rate is a much better estimate of the reproductive health of birds and allows us to accurately understand how various factors, such as air temperature, influence nesting. For instance, knowing that half the young in a nest died during a hot summer may point to the heat as the culprit, but by comparing actual daily temperatures to daily survival rates we can pinpoint the critical temperature at which nestlings perish. This would enable us to design nest boxes that keep the nest temperature below this lethal level. So, while it does take a bit more work to collect and enter detailed nest checking data, the benefits of doing so are well worth the time.
Bombaci (rear, in tan cap) enjoys sharing his discoveries along the Prothonotary trail.
Featured NestWatcher: Charles Bombaci, Protector of the Prothonotaries
Growing up only a few miles from Roger Tory Peterson's house, Charles Bombaci was destined from a young age to make a mark in the world of bird conservation. As a boy, he was always interested in nature and often explored the woods and wetlands of his parents' property in Connecticut. Soon after college, Charles moved to central Ohio where he became very involved in the local birding community. He has participated in Audubon Christmas Bird Counts since the late 1970s, spent 6 years collecting data for the Second Ohio Breeding Bird Survey, and is currently a member of the Cornell Lab of Ornithology, the Nature Conservancy, the Ohio Ornithological Society, and the advisory council of the Hoover Nature Preserve in Franklin and Delaware Counties (OH).
Prothonotary Warbler photo by Charles Bombaci
It is in the Hoover Nature Preserve that Charles's true passion resides. In 1988, Charles and a graduate student from The Ohio State University installed 12 Prothonotary Warbler nest boxes. These boxes successfully provided nesting habitat for the warblers, which are listed as a Species of Concern in Ohio. The student eventually moved on, but for the past 25 years Charles has continued to expand the Hoover Nature Preserve's Prothonotary Warbler nest box program. There currently are 250 boxes distributed throughout the area's swamp forest, resulting in Prothonotary Warblers nesting in most suitable habitat throughout the site. Charles does most of the monitoring and nest box maintenance himself, which is no small feat, but he is always happy to share the joys of his Prothonotary trail with others. Charles has been submitting his nest-monitoring data to NestWatch since 2002 and has entered the 7th highest total number of nesting attempts into our database (1,289)! Thank you, Charles, for all that you do and for showing us that one person can make a difference!
Thank you for your participation in NestWatch to help science and the birds!
Jason Martin NestWatch and NestCams project leader Cornell Lab of Ornithology 159 Sapsucker Woods Rd Ithaca, NY 14850
The Cornell Lab of Ornithology is a membership institution dedicated to interpreting and conserving the earth's biological diversity through research, education, and citizen science focused on birds. Visit the Cornell Lab's website at http://www.birds.cornell.edu.
Cornell Lab of Ornithology 159 Sapsucker Woods Rd, Ithaca NY 14850 Questions or Comments?
Barn Owl "Wing" is still roosting in the box she used to raise two offspring in Italy, Texas.
Thank you to all of our viewers and camera hosts for another awesome season! While we're waiting patiently for next year, check out the NestCams archives. Also, our female Barn Owl in Italy, Texas, has been roosting in front of the camera so we will continue to broadcast from there throughout the winter.
At the beginning of each month, NestWatch randomly selects one participant to receive a copy of the NestWatch Common Nesting Birds of North America poster. This month's lucky winner is Ruth Mattes. Congratulations, Ruth!
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