Sam Christopher, Field Observation 3: Social Behavior and Phenology

I went birding on March 14, 2019, from 8:20 to 10 am. The starting temperature was 42 °F with a cloud cover of 40 % and the ending temperature was 47 °F with a cloud cover of 20%. This birding walk took place in Joe Palaia Park in Monmouth, New Jersey. The habitat in this location consisted of both denser forested trails and open park area with minimal trees and large fields.
Right at the beginning of the walk I encountered a large mixed species flock made up of Mourning Doves, American Robins, House Finches, Dark-eyed Juncos, and Blue Jays. Although there were multiple species within this flock, the species tended to stay segregated from one another. The Dark-eyed Juncos grouped together on the ground to forage, the Mourning Doves sat on a telephone wire, and the House Finches, Blue Jays, and American Robins occupied different trees. It is interesting to think why these species would come together to this patch of trees together. Possibly it has an abundance of resources that allows all of them to coexist together. Another thought is that having a larger flock is beneficial to decrease predation risk, decrease energy spent on vigilance, and increase the amount of time spent foraging. The interactions amongst these species allows for every individual to gain an advantage.
The communication varied between species. The Dark-eyed Juncos, American Robins, and House Finches seemed to constantly chatter as they foraged on the ground while the Mourning Doves remained relatively silent. The constant chatter between these species could be an information exchange between individuals to share information about food resources or just to identify individuals within the species. It was interesting to listen to the Blue Jays who had a very different pattern of calls. In opposite trees, one Blue Jay would do its “jeer” call and a different Blue Jay in the other tree would make its “gurgle” call. These two individuals did this back and forth for a few minutes while I was observing this group of birds. Possibly this call could be mating or courtship behavior used to communicate between potential mates. Another idea is that this call and response is more competitive or territorial. Possibly one of these individuals was in the others’ territory.
Continuing on my walk I headed into a denser area of trees that had a much smaller presence of birds compared to the mixed flock found out in the open. Possibly this is due to less sunlight or resources. There was a male and female pair of Northern Cardinals within the trees. The male has bright red plumage with a few black markings around the face while the female’s plumage is almost a light brown with a few red highlights through the wings and black markings around the beak. The male’s bright coloring might aid in courtship if females prefer brightly colored males. This red color may indicate good genes or good health that the females would want to utilize for her own young. This bright red may also draw attention away from the drab female and nest if a predator is nearby. Dark-eyed Juncos have a much less colorful plumage. These birds have a darker head with a lighter shade underneath their body. These birds might be following a different tactic. Instead of attempting to stand out to find mates, Dark-eyed Juncos seem to be more inclined to blend in to increase their chance of survival. Their countershading allows them to camouflage. The lighter underside makes them less detectable from the ground if seen from below due to the usually sunlight background or bright sky above. The darker dorsal part of their body makes them less detectable if viewed from top down with a dark background. Plumage may indicate different strategies that species undertake to be successful.
One particular bird observed for a while was a Cooper’s Hawk. This individual flew and landed on a telephone pole around 40 meters away from the mixed flock described earlier. It remained facing the direction of the flock for about 10 minutes until my movement possibly scared it back into a nearby group of trees. This individual was possibly in the process of foraging if it was interested in the flock of birds nearby as a food source. The Cooper’s Hawk also could have been just resting in the sun to decrease the amount of energy it would have to expend on thermoregulation. Both of these are examples of an activity that would fit into its circadian rhythm.

Mini Activity:
During my time birding I was successful at drawing some House Finches out of their trees when I emitted some “pish” calls. Two emerged from the thicker branches and perched on the tips to look at me. At first I thought that this technique to draw out birds works since these birds may just be curious about the noise and want to see where the call is coming from. With some research, I understand that there are also theories that “pish” calls sound like an alarm call made by small birds. If a bird hears this alarm call they may want to investigate who the intruder is and whether or not they deem the intruder a threat. Hearing the “pish” instigates individuals to come towards you to investigate and allows the birder to get a better observation of the birds present.

Publicado el marzo 22, 2019 09:59 TARDE por sgchrist