Field Observation 6: Reproductive Ecology & Evolution
I went to Centennial Woods in Burlington, VT on Tues., April 23, 2019. I arrived at about 5:00 PM and the sun was out and the temperature was ~63 degrees Fahrenheit. The sun was still out but there was a slight sprinkling of rain. This limited the amount of birds observed as most were finding shelter from the rain.
Despite the limited number of actual sightings, I did hear plenty of calls in the distance. Many of the calls I heard were actually birds of the same species calling back and forth to one another, potentially seeking a mate. I heard two chickadees calling back and forth. I also heard two American Robins calling to each other. I was able to actually see two species of birds that were both in pairs. I saw two Pileated Woodpeckers, as I drew closer they began flying away tree to tree together. I also saw two White-breasted Nuthatches that were exploring holes a tree (probably from these Pileated Woodpeckers) and they stayed there for quite awhile and didn't seem to mind me sitting there for about ten minutes and watching. They were grabbing small materials and placing them inside the holes so I believe they were creating nesting beds inside the hollow holes. I don't believe these Nuthatches were a breeding pair though, as female Nuthatches usually build the nests on their own. However, both these females may have thought that this tree in particular was a great nesting place because of the already dug out woodpecker holes.
It was clear that many of the birds in Centennial were preparing for breeding season by either calling for mates, creating nests, or scavenging for food with their mates. The nesting process specifically will look quite different depending on the bird species. Pileated Woodpeckers usually nest in standing dead trees, or snags. So they would probably be located in more of the old growth patches that have lots of snags available. White-breasted Nuthatches probably will end up nesting nearby the Pileated Woodpecker nests as they use smaller holes dug out by the woodpeckers for their nests and also mainly eat insects for their diet. Chickadees also prefer to nest in abandoned woodpecker holes but often choose those made by Downy Woodpeckers as they are smaller. However Chickadees' diets are about half plant matter and half insects so they may want to choose a nesting site that is near small-seed and/or berry producing vegetation. Contrastingly, American Robins do not nest in tree cavities, but rather build nests on horizontal tree branches. They choose branches that usually have dense cover above them so that there is some insulation/protection. Their diets consist of a lot of worms, but they also eat fruits. So, their besting sites will likely be in a tree with a dense crown, and by soft soils rich in worms.
Mini Activity: I sat in the meadow-like opening that is located by the large parking lot side entrance to Centennial. Here I was able to hear a few birds but I probably would have had more luck deeper in the woods as it was slightly raining so birds would be under denser coverage areas. I heard a Hermit Thrush singing alone. I also heard an even-toned call that at first I was not able to identify until I looked it up later. It turned out to be the trill of a Dark-eyed Junco. I heard a couple more Black-capped Chickadees and American Robins along the forest edges. I saw three Mallards, and two Ring-billed Gulls fly overhead as I was in a clearing and was able to have a clear view of the sky. This activity really allowed me to be patient and critically analyze distant calls which is something I need practice with. So this activity really challenged me in a good way.
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