Reproductive Ecology and Evolution
Date - 4/24/21
Start Time - 9:05am
End Time - 10:30
Location - University of Vermont Redstone Campus
Temperature - 54 deg F
Wind 10mph S/SE
~100% cloud cover
Zero precipitation
Habitat was mostly very suburban, with numerous buildings populating open, grassy areas, and sparse trees. Spent some time around a swampy-pond area within the residential areas.
The main behaviors related to territory/nest/mate selection were defensive strategies against other birds both of the same and different species. An American Crow chased a Red-tailed Hawk between the trees to defend its territory. Two male American Robins stood near each other outside one of the Redstone dorms, either getting ready to fight or having just gotten out of one and probably trying to defend nesting territory and/or mates. These interactions took place near trees and shrubs next to tall buildings - aka places that nests likely reside. Crows typically build their nests in tree crotches or on branches, while Robins make their nests among shrubby bushes and conifers and can be found in residential areas! Generally, early nesting birds like the Robin as well as Northern Cardinals and Chipping Sparrows use conifers and shrubs as their nesting sites to gain the most cover, and which are also near sources of food like seeds and fruit. As demonstrated, Robins can be very territorial, and they only make about one nest per bush. Other species similarly need cover when choosing their nesting sites, and which must be closer to their own respective sources of food. Red-winged Blackbirds build their nests 1-1.5ft above areas of water amongst dense vegetation like cattails - close to the water surface so they can feed on insects, frogs, and snails, with no real need to go out to the trees. Similarly, Canada Geese make their nests right near the water in order to feed on fish, insects, and the vegetation on the banks.
We found a Red-bellied Woodpecker singing very loudly on a tall tree right outside of a house. It was the only one of its species there. In one sense it might not be defending very good territory, because there are not as many sources of food around the house as there might be within woods (there was really only one or two trees on the property). Depending on the species, human interference might also pose a real survival problem. Additionally, the lack of other birds around the property could be a sign that the territory is not the most desired and fruitful. However, in another sense the house and other materials on the property might provide plenty of cover for the Woodpecker, and the tall tree the Woodpecker was on might itself be enough of a source of food and cover just for that bird. Some people may also have bird-feeders on their property as well. Furthermore, perhaps human presence is a good deterrent to rival species of birds that are not as well-adapted to human activities. Overall I’d say the Red-bellied Woodpecker seemed pretty well off for itself and was defending fairly good territory compared to other members of its species, indicating that that bird had high fitness compared to those other members as well.
The main nests that we observed were the nests of American Robins, made of dead twigs, grasses, hairs, and even some mud and dirt. The bottoms were very solid. Generally, the coarser materials were on the outside of the nest while the finer, more valuable materials made up the center, making it easy for the birds to rebuild their nests if the outside was destroyed. The bird would have to carefully scout the ground for twigs, grasses, and hairs. Much of their materials would probably be concentrated on the ground around forests, near trees and vegetation. Most of the nests we saw were also made in the center of shrubs where most of the deader branches reside, making it quite easy for birds to acquire those materials in the same spot they intend to make their nests! Some of the materials like hairs might also be found closer to residential areas rather than forests, and of course, human-planted shrubs and trees also conveniently exist on those properties as well.
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