April 22, 2020 Reproductive Ecology and Evolution

On April 19, 2020 from 11:00am to 1:00 pm, I hiked a short segment of the Long Trail (about 2 miles) in Bolton, Vermont with my roommate. The temperature was about 54 degrees F, and the sun was shining for majority of the day. It was also quite windy while we were hiking.

The hike starts out by bringing you up to a small cliff that overlooks the highway and a small valley. I had been here last week and saw multiple Peregrine Falcons in a tall tree near a rock face across the valley, so I wanted to see if they were still here today. Unfortunately, they were not in the trees, but I did see one soar high above us in the sky around 11:20 am. The falcon seemed to be making big circles before I lost sight of it. I think this behavior was either related to hunting for prey or perhaps for territory selection? The falcon was very high up in the sky, so I'm not sure if it would have been able to see prey. There was also a black vulture that passed over head minutes before, and the falcon was following in the same direction. This made me think that the falcon was patrolling its territory and making sure that the vulture wouldn't come near. The rock faces in Bolton are known to have Peregrine Falcon nests as they make for the perfect breeding habitat. I saw signs around the area to steer clear of the cliffs to not disrupt falcons. Not many other birds that I know of nest on rock ledges at high altitudes. I assume they pick these spots because they provide good shelter and allows them to hide from other predators like Eagles and Great Horned Owls. The rock ledges also allow the parents to hunt from them, as they can dive down towards prey that is flying by.

The next bird that I saw around 12:15 pm was a Hermit Thrush on the branch of a tree. It blended in very well, and I only noticed it because I happened to take a water break right then. The Hermit Thrush was not singing or moving, perhaps because I was a bit of a threat to it. The woods around it were pretty open with a lot of conifer trees, beech trees, and other smaller trees that I wasn't able to identify. There were also a lot of smaller shrubs and fallen over trees. While the bird wasn't moving when I was observing it, I imagine that it is trying to gather supplies for its nest since this habitat was perfect for ground nests. There were a lot of leaves and pine needles on the ground, which I think would be good materials for a Hermit Thrush nest, which is typically made on the ground in areas sheltered by shrubs and trees. This is different from other birds that nest in tree cavities, like tree swallows or chickadees. Those birds do not need to collect as many materials, they just need some leaf matter or something of the sorts to line the inside of the cavity. They don't have to form the outside of the nest since they instead make holes in soft wood to lay eggs in.

At around 12:40 pm, I heard some calls that I could not identify. As I stopped and looked through the trees, I saw four Hairy Woodpeckers flying around near each other. There were two males and two females. I had never heard a hairy woodpecker call, and I honestly never really thought that they even had a call besides banging their beaks into trees. The call was a short and sharp "peek" note, and the males seemed to be calling as they left a tree and flew to another. As I watched them for longer, it became more obvious that there were two separate pairs. It seemed as though the male would make a call and fly after the female and attempt to land right next to her on the tree or on a tree nearby. Each pair operated independently, but the pairs stayed in their respective areas. One pair remained to the left of me, and the other was further back to the right. They never overlapped trees or areas despite being so close to each other. I imagine that each pair had its own territory and they were very close to the territory of the other. I think the calls occurred as the pairs were making sure the other did not step over the imaginary territory dividing line. It reminded me of the video we watching in class with David Attenborough knocking on the tree and the woodpecker flying over to investigate and outcompete his knocks. Each territory consisted of the same habitat since they were so close to each other. Both habitat were therefore pretty rich in that they had a variety of living and dead trees with lots of cavities. The dead trees with cavities seemed like the perfect nesting spot for the woodpeckers, although I did not see any evidence of nesting.

I did the sound map activity for the woodpeckers. Each squiggle represents a call made, and the red represents one pair while the blue represents the other pair. I made this note in my phone because I didn't have any paper! Also my apologies for the poor quality photos of the woodpeckers- they were hard to see when they weren't in flight.

Publicado el abril 22, 2020 04:48 TARDE por aneu