FJ4: Social Behavior & Phenology

Time: 2:20pm - 4:00pm
Date: 03/22/2020
Weather: 35 degrees, partly sunny
Habitat: farmstead with open pasture, a pond, and mixed deciduous and conifer stands in the backyard

I visited my friend’s farm in Craftsbury this weekend. He lives in a pretty remote part of Vermont, and his house is at least a few miles from any other structure in any direction. He wanted to work on his car and replace the hood and pull out the carpets, and I decided it would be a perfect opportunity for me to explore his property and look for birds! At first, it was hard to find anything besides American Crows and one pesky Hairy Woodpecker that’s been eating away at the side of their barn for the past several weeks. I could hear many other species of birds while I was near his house, I just couldn’t see them. But, once I walked about a mile or two into the forest, I started to hear and see so much!

Birds are constantly interacting using posture, plumage, and vocal message. I immediately noticed that there was this one relatively large American Crow perched pretty low on a branch and raising its feathers and screeching at any bird that flew above it, regardless of the species. When a bird came too close to his branch, tree or the compost pile, he issued a series of warning calls, fluffed his feathers, and immediately went into aerial attack. Then I noticed that he was in the perfect position to pick vegetable and fruit seeds out of the large compost pile next to the barn. I started wondering if he set up shop in that same spot every day to get the best food scraps? He did seem much meatier than other American Crows, and maybe this extra source of food helped him through the winter and the extra weight gave him an advantage over other males when breeding season comes along.

Contrasting to this American Crow’s agonistic behavior towards other birds, I walked down to one of the ponds on my friend’s property and there were 3 mated pairs of Common Mergansers that were clearly enjoying one of the first sunny days in a while. The females have really funny tufts of brown feathers on their heads that make them look like they’ve just woken up with some major bedhead, and it always makes me chuckle. Each pair was allopreening, and when one of the males got too close to one of the females that was not his mate, you could see a reaction from the male where his posture completely changed and he would swim over and push his mate away while making small warning quacks at the intruding male. Most male birds I’ve seen (those that travel with their mate) are quite aggressive towards other males coming into their space, which we can probably connect to human behavior as well. Common Merganser males use countershading (white belly with black and other melanin’s on the back and the head) to avoid predation but they also have pretty bold colorations with iridescent greenish-blue on their face and some repeating patterns along their wings. These patterns help males when advertising for females and can also send warning signals to other males.

The patterns on Mergansers are very different than the ones on Eastern Phoebe’s and House Sparrows, which appear mostly to be used for camouflage, helping them blend in with the trees and greenery in the background of their habitat and protect themselves from predators like hawks and falcons. I watched a group of House Sparrows resting and chirping in a bush on the edge of the forest habitat. Right now, many birds are migrating back to Vermont from warmer places down South. As this event is occurring, the length of each day is growing and soon we will see many species arriving at breeding grounds and beginning nesting behavior and ovulation. The length of daylight is an essential environmental cue that triggers sex hormones and increases the size of gonads. Males proclaim their territories with songs and sometimes fights, pair bonds are established or reaffirmed, and mating takes place. One particular house sparrow was sleeping with its head scrunched down into its feathers. This was towards the end of my walk when it was getting to be around 4:00 pm, and the sun wasn’t as strong and the birds seemed less active.

I attempted to solicit "pish" calls while I was around the group of House Sparrows and experimented doing it quietly and then loudly at different volumes and timbres. They were not having it, and almost completely ignored me, with some retreating even farther into the brambles. Alas, I will have to work on my spishing skills and try them out on some other foraging species. All together I had a great experience and saw a lot of activity!

Publicado el marzo 25, 2020 06:24 TARDE por olivialiu