Journal Post #4- 4/7/19

Today I went out behind the golf course to observe birds. There's a pond by the Redstone Lofts where I've seen lots of different species before so I decided to do my bird watching there. I started at 9:30 and went to 10:30. The weather was warm, probably about 40 degrees, but cloudy. It wasn't windy though so overall it was a good day to go. Today I saw quite a few gulls, but I couldn't identify them because they were flying by too fast. I also saw 3 Rock Pigeons on top of one of the buildings. There were a few different small flocks of birds that flew by- I think they were blackbirds but again, they were moving too fast to identify. There were also 2 Canada Geese and a male and female Mallard.

Thinking back to why some species stay through the winter, I would assume that it's because while it's hard to survive a winter in Vermont, it's also extremely hard to migrate- it takes a lot of energy. I think it would be too hard for something the size of a Black-capped Chickadee to migrate hundreds of miles. Because their bodies are so small and their metabolism is high, I think it would be too hard for them to fly for extended periods of time. In the case of the Black-capped Chickadee though, they are pretty well adapted to a winter in Vermont. They are generalist feeders, so they have more resources as options, and they can behaviorally prepare for a very cold they. They can go into facilitated hypothermia, where they allow their body temperature to decrease substantially in order to preserve energy.

Migrating birds try to avoid those cold days by just leaving the area entirely. The Mallards were coming from the southern parts of the US, and probably were travelling to find a suitable place to build a nest for the breeding season. I'm assuming the change in temperature helped facilitate their decision to travel back up, but it also has to do with their internal annual clock. Mallards are obligate migrators, but they may be a little surprised by the mid-April weather in VT. I think that their annual clock just tells them what time to leave where the wintered and to come up to wherever they're breeding, but I think if the climate is changing they can't exactly count on that, their temporal clock is depending on past conditions, so they definitely could be surprised by the cold days we've been having. There's an advantage to leaving earlier, as they get the first choice on territory, but the disadvantage is that it's still cold and they have to wait for females to arrive before they get to mate.

I looked at where Mallards are migrating to and from, and it looks like it's a distance similar to from Kentucky to Montreal. That's about 950 miles. If they were in VT, and it's 100 miles from Burlington to Montreal, that means they had already traveled up to 850 miles!

Posted on 07 de abril de 2019, 08:48 PM by