Not much is more charismatic than a chickadee landing on a perch, turning majestically to the camera, and proudly displaying its food trophy. For birds, food is an incredibly important factor for raising a success nest.
It's been estimated that during the nestling period, adult chickadees need to find over 7,500 food items to feed their offspring while the nest is active. What type of food probably matters for birds too. A single large, juicy caterpillar may feed more young than a small beetle.
However, finding enough caterpillars to feed growing nestlings may be more or less difficult, depending on whether the chickadee is searching on an exotic Ginkgo or a native Oak tree.
One part of the Nestwatch Food Web project I've been involved with is filming adult Carolina Chickadees as they provision their offspring. From this, we can see what types of food, as well as at what rate, the nestlings are being fed over a 6-hour period.
It is also a great opportunity for participants to be able to directly see some of the wildlife activity going on in their yards. Some of the Nestwatch home owners were surprised to learn just how many caterpillars the birds were actually finding in their backyards. Other folks were happy to hear that the chickadees were taking care of the insect control on their plants so they didn't have to.
The first part of this data collection involves making a temporary perch so that the chickadees will stop and display for the camera. Although some initially respond with some harsh scolding to the new obstruction, they eventually decide it isn't so bad to have someone show up and build you a front porch, and go about their day as usual.
We film the nests for about 6 hours twice during the nestling period, once when the birds are 4-6 days old and once when they are older, between 9-11 days old. From these videos, we've seen birds bring all kinds of food items: mostly caterpillars, but also spiders, moths, leafhoppers and scale insects to name a few. This year we've video-taped 22 nests which is over 240 hours of chickadee feeding to go through! Fortunately, fast forward buttons help make the transcription process quicker and it doesn't hurt that chickadees are enjoyable to watch too.
After filming, we band three nestlings and take a few measurements (i.e. tarsus (leg bone), feather length, weight). We do this twice so that we can see how fast the nestlings are growing and compare it to
- the food items that were fed to them
- what trees are in the area and
- whether those trees were native or exotic.
We complete our measurements quickly and return the birds to their nests before the adults even know they are gone. The nestlings grow very fast; by time they are nine days old they already start to look like chickadees because their black caps and white cheeks feathers are starting to come in. Soon after, about day 14, the nestling chickadees are fully developed and ready to leave the nest.
Here is some sample video (courtesy D. Narango) from one of our video-taped nests.