The Smithsonian Migratory Bird Center isn't just about the migratory birds that spend the winter in the tropics. We're also interested in the birds that spend the year in your backyards too! I'm a University of Delaware Student who is working within the Washington, D.C. Dr. Pete Marra and Dr. Doug Tallamy to study the familiar (and arguably, most feisty) backyard bird, the Carolina Chickadee. I focus on the chickadee as a model insectivorous bird to investigate how urbanization and exotic plants affect food resources for breeding birds.
During the breeding season most birds, especially chickadees, feed their young almost exclusively insects. Caterpillars in particular are an important and abundant food source in forest systems. However, caterpillars are sensitive to the chemical compounds of individual plant species, so some types of trees may not support as many caterpillars as others. Dr. Tallamy's research on insects has shown that exotic plants support fewer caterpillars and insects than native alternatives and that caterpillars feeding on exotic plants do not grow as large. My research will expand on these findings to determine whether these patterns have consequences for individual breeding birds in urban/ suburban areas, where exotic plants can be abundant.
In >100 participating backyards throughout the DC metropolitan area, I set up PVC-pipe tubes to attract Carolina Chickadees to nest in. This tube design was chosen because chickadees prefer nesting in tubes that more closely resemble the cavities found in natural trees. They are also easy to make and all the supplies can be found at your local hardware store. If you're interested in making one for yourself, you can find the directions here. We use 3 cm entrance holes to keep out predators and house sparrows but entrance holes can be made bigger to attract large cavity nesters like Eastern Bluebirds or Tree Swallows.
This is the second year of my research and the birds have kept us very busy. Chickadees nest synchronously, meaning many birds have their nests at the nearly the same time. The trees in DC began to flower later than they had last year, likely because of the late snow and cold temperatures. The benefit of being a resident bird that stays here year round is that they can respond very quickly to changes in the phenology (‘timing') of the environment. As soon as the cherries and maples began to grow leaves, my birds were busy pairing up and gathering moss to build their nests. This flexibility in nest timing allows birds to feed their nestlings when insects should be most abundant on young, palatable tree leaves.
Because I have so many sites, participant volunteers are helping me monitor nest tubes in their backyard to let me know where and when I have active pairs. One day I had eight people email me the same day to report birds with nest material! When birds build their nests at the same time, they're also hatching at the same time, meaning a burst of fun and lots of data collection for me and my technicians. With help from volunteer landowners and friendly neighbors we've collected data on 55 chickadee territories this season.
In this region, Carolina chickadees nest from the beginning of April until about Mid-June. Now that the season is slowing down, we can take a breather and let you know more about some of the data that we are collecting. Following individual color-banded chickadees within the suburban environment has been both challenging and exciting. Some of the data we collect includes observing the tree species chickadees are foraging in, identifying the insects we find on certain species of trees, surveying the other bird species breeding in the area, measuring nestlings, and using video to determine which insects chickadees are bringing their young. Stay tuned for more blog entries to share some of the interesting things we've found so far.