Field Journal 7: Reproductive Ecology and Evolution

Date - April 23, 2021
Start time - 12:00
End time - 13:30
Location - Intervale and Riverwalk
Weather - Sunny, 50 degrees, moderate wind
Habitat(s) - Deciduous, floodplain forest, Agriculture, River

I noticed behavior related to reproduction throughout the day. It is clear that birds are in the processes of mate selection, territory establishment, nest building, and egg laying. First, I saw an American Robin on nest. The nest was about 10 feet up in the crotch of a thin deciduous tree (see figure 1: https://docs.google.com/document/d/1ISR4lDfVUAxZtw_siz1_ohjNSSAL2CImqDzYR-pQ2BQ/edit?usp=sharing). The nest was about 5 inches in diameter and deeper than I expected it to be. It was made from thin twigs and even some thin strips of plastic. This nest was located very close to the walking trail and close to the trailhead with people and cars often passing underneath. I was surprised to see a nest so close to all of this commotion. I think this goes to show how comfortable a species like the American Robin has gotten to our human presence and built environment. I wonder if all of the better nesting locations further into the woods were taken, and that's why this robin had to build a nest in a less desirable place.

Further along into the Intervale trail I noticed one particular area where there were a lot of birds singing. Specifically, I noticed a male and female pair of Ruby-crowned Kinglets that were communicating back and forth, singing loudly and frequently in this area, and were using the space. Other birds seemed to often come into this area but would only pass through and wouldn't stay long. It seemed to me that the two Ruby-crowned Kinglets were defending this territory. The area they were defending seemed to have good resources. It had trees of varying size, some with fruit on them and plenty of roosting spots. This suggests that the two birds have good fitness and are able to effectively defend these resources. Birds tend to defend resources when there is an intermediate amount: too many resources, and there is little benefit in defending a territory, but too few resources and a territory that yielded sufficient resources would be too large to defend. There was also a pair of song sparrows that were occupying a jumbled area of twigs and downed trees on the outskirts of the Ruby-crowned Kinglets territory. The kinglet territory is more suited to their habitat preferences as the downed trees and twigs is more suited to the Song Sparrows.

The Sound Map activity was very productive and allowed me to notice a lot of nuance in how the birds in the area are interacting (See figure 2: https://docs.google.com/document/d/1ISR4lDfVUAxZtw_siz1_ohjNSSAL2CImqDzYR-pQ2BQ/edit?usp=sharing)

Publicado el abril 24, 2021 08:59 TARDE por gthiggins