A Look into the Breeding Behaviors of the Avifauna of Shelburne Pond Wetlands

I arrived at the UVM Natural Area Wetlands, located just south of Shelburne Pond, at 6:07 in the morning. The temperature was a crisp 35 degrees and the sun had only just begun to spread it’s warming light over the land. Although the marsh was cast in shadows, the clear skies and light morning breeze had every bird in the swamp singing away. The songs of Swamp Sparrows and Red-winged Blackbirds filled the Cattail marsh and brushy thickets of this very special habitat. While most of the Red-winged Blackbirds in the area rose up from the marsh and flew south in a large morning movement, probably to wherever the best food is currently located, there were plenty of males that stayed behind and continued to sing their “Conk-la-reee!” songs all through the morning. The Swamp Sparrows, on the other hand, all seemed to have their respective territories all marked out with invisible borders through the marsh, as each singing bird seemed to be uniformly spread throughout the dead reeds and budding brush. Bisecting the marsh is a large swath of alder/willow thickets (I’m not exactly sure what species of bush). Although this is less than optimal habitat for a Swamp Sparrow, who prefers to nest in solely grassy, reedy vegetation, there were still some males singing away from small patches of reeds within these thickets. The high abundance of Swamp Sparrows in this area has forced some birds to take up residence in less than ideal locations within the swamp and I can only assume that these individuals are weaker and/or younger than their neighbors. From time to time, I would use playback of a Swamp Sparrow song, and the male that owned the territory that I was in would promptly arise from his hiding place deep in the marsh to confront the “intruder” on his territory.

Along my travels, I came across another bird that also frequents marshes, swamps, and ponds, a pair of Wood Ducks. Sitting high in a tree, the male continually made soft whistling calls as he stuck his beautifully patterned head out. Either this bird was on the lookout for possible predators, maybe even watching my approach, or he was showing off his colorful plumage to his relatively relaxed mate. Soon enough, the hen Wood Duck will take to finding a suitable nesting cavity if one has not already been selected. With a brood of potentially 15 to 16 ducklings to raise to adulthood, female Wood Ducks waste no time collecting nesting materials. Instead, they simply pull down feathers from their breast and line the cavity with these warm, soft, cushioning feathers to help protect their eggs. This makes a lot of sense when you think about it. If the Wood Duck ducklings are just going to leap from the nesting cavity one day after they hatch, then why should the mother even bother with creating a real nest infrastructure?

A third species that I witnessed giving territorial displays was a possible pair of American Bitterns. The male bird was heard giving multiple songs from deep within the swamp and another bird was seen flying in the direction of this calling bird shortly after I arrived at the natural area. These medium sized members of the heron family use a low frequency song that travels well through the dense vegetation of the wetland. It actually sounds a little like water dripping into a puddle, only deeper and more emphatic. With probably only 2 or 3 pairs (estimate based on high count of 4 birds being seen at once at this location in 2019 - eBird Data) of American Bittern nesting in the wetland, there probably isn’t too much competition for the relatively uniform habitat. Female American Bitterns are thought to be the ones to construct the nest. Nests are typically a mound of cattails and debris about 4 to 8 inches above the water’s surface (allaboutbirds.org). Nesting material is certainly not difficult to find in this densely vegetated wetland!

By the end of my outing, the sun had bathed the entire marsh in it’s glorious light and I was able to warm my hands. I had observed some 37 species in the 105 minutes that I had spent at the natural area. I also walked a distance of 0.6 miles along Pond Rd. All in all, it was an excellent day of birding!

Posted on April 23, 2020 02:06 AM by jacobcbirds