Archivos de diario de abril 2019

08 de abril de 2019

Spring Migration

I went to a few different locations for this assignment. One around my house and in Centennial Woods where I saw red-winged blackbirds and American Robins (4/6/19). One in Shelburne Bay where I saw a turkey vulture eating a dead fish (4/7/19). The last was incidental on my way to Camel's Hump for a ski trip but at the base of the road was an American Kestrel which I thought was a neat find (4/7/19).

The spring is heating up and migrants are slowly trickling in back to Vermont for the summer. Our winter residents such as black-capped chickadees, tufted titmouse, american crow, barred owl, and common goldeneye stick around because they are adapted to deal with the cold temperatures that often occur in winter. They forego migration because they are able to find sufficient food in wintertime. Black-capped chickadees can survive facultative hypothermia and allow their body temperature to drop far below normal levels. Ducks have warm and waterproof feathers that allow them to stay warm in cold water. Their feet also can be much colder than the rest of their body thanks to countercurrent exchange. Gathering together in large flocks for warmth is a behavioral adaptation many birds such as crows use to survive cold nights.

Turkey vultures are coming back to Vermont right now and are likely a short distance migrant. They are not able to survive the coldest parts of the winter in Vermont so they travel south a little to survive. There also may not be enough food (carrion) for vultures to find in winter due to lowered biodiversity levels in winter. Fewer animals are around and as a result there will be less dead ones. Red-winged blackbirds are also coming in droves in order to establish territory for the breeding season. The days are growing longer which is signaling to the birds that migration is just around the corner. Temperatures are becoming warmer and the snow is beginning to melt. These are just a few things that are changing in the environment but are crucial for signaling to birds to migrate.

Turkey Vultures only have migrated 175 miles from their northernmost wintering area in Connecticut.
Red-winged blackbirds may have migrated as much as 780miles or more from the southern US.

I found that American Robins are short distance migrants but many overwinter as far south as Mexico. The map lists them as a year-round species in Vermont.

The majority of American Kestrels spend their winters in the Southern US, and if they are coming back to Vermont from there that would be a distance of around 800miles.

Red winged blackbirds are short distance migrants, and some may migrate less than 100 miles according to Cornell Lab All About Birds maps.

Ingresado el 08 de abril de 2019 por michaelmcg michaelmcg | 4 observaciones | 0 comentarios | Deja un comentario