April 18, 2023- UVM Bioresearch Complex

Date - 04/18/2023
Start time- 9:30 am
End time- 10:30 am
Location- UVM Bioresearch Complex, Burlington Country Club
Weather- 45°F, overcast, low wind, no precipitation
Habitats- open fields, shrublands, deciduous forest

While in the UVM Bioresearch Complex field, I noticed behaviors that indicated that the breeding season has commenced. I heard an increasing prevalence of song, observed species building nests, and male and female birds in pairs.

The first song I heard was that of the Brown-headed Cowbird. This song was produced by a male in an effort to attract a mate. Brown-headed Cowbirds are parasitic nesters, meaning they lay their eggs in the nests of other birds who will rear their young. This is harmful to the other fledglings in the nest, as they receive less food, but beneficial to the mother cowbird, who can exert the significant energy it would take to care for her young elsewhere.

I observed a pair of Canada Geese traveling around the field together. They were likely foraging in the grassy patch, as they typically build their nests within 150 feet of water. Both geese were circling the area and honking loudly. This indicated that they were defending the area. There was a wide variety of vegetation in this area, so it was presumably high-quality foraging grounds for the two geese. If so, that would indicate high fitness in the geese, as they would have the means to defend the area from competitors. Canada Geese are monogamous and often mate for life.

Another typically monogamous bird I observed was the Osprey. I saw a total of 4 Ospreys during my time in the field, which were presumably 2 breeding pairs. I watched one Osprey carrying a stick to add to its nest which was perched atop a tall manmade nesting structure. This is valuable habitat for Ospreys, as it mimics their natural habitat atop tall trees. High-up areas like these allow the Ospreys to maintain an unobstructed view of the area surrounding their nest as well as protect their eggs from terrestrial predators. Their nesting structures were adjacent to a large golf course pond, where fish are an easily accessible food source. In addition to maintaining the same partner for life, Ospreys tend to use the same nest year after year. The Osprey I viewed carrying a stick to its nest was likely adding to the collection it has accumulated over several years. There are many wooded areas around the fields and golf course, so the Osprey does not have to travel far to gather materials.

In addition to the Brown-headed Cowbird, 2 Canada Geese, and 4 Ospreys, I also observed 4 American Goldfinch, 9 American Robins, 8 Red-winged Blackbirds, and 1 Downy Woodpecker.

Posted on April 24, 2023 10:38 PM by lhaigh