May 02, 2019

Reproductive Ecology and Evolution

For this observation I was in two different locations, in the morning I went to Centennial Woods and in the afternoon I went to Shelburne Bay. One of the most striking aural mate selection observations I heard was the song of the winter wren which was a very impressive display of a complex song to attract a mate. I played the song back and he came in a little closer, while repeating it back every time I played it. This could be his defense of his territory to let other males know that he is around and has laid stake to it. Winter wrens nest in tree cavities near to the ground or as much as 23 feet up. The habitat I saw this individual in was tall conifers intermixed with deciduous understory. Many of the tall conifers had cavities likely excavated by pileated woodpeckers which would be very suitable for winter wren nesting. The next bird I observed was a pileated woodpecker, which upon call-playback did the same thing and came in for a closer look. These birds are also cavity nesters but they can excavate their own cavities pretty easily. As long as there are tall dead snags and ample trees full of insects they will nest, and this was true for the area in Centennial Woods. The most interesting species I observed from a nesting point of view were two ospreys in Shelburne Bay. They were undergoing the process of building their nest on a platform close to the water's edge. They would bring large sticks to build up the nest in the anticipation of a soon to arrive chick. These species need to be near water as their primary prey source is fish, and one was even eating one as I was watching it.

The mini-activity of the sound map was a very interesting exercise. I heard 5 red-winged blackbirds in various locations around me, two northern cardinals, one belted kingfisher, an eastern phoebe, about 2 american crows, one song sparrow, and a woodpecker drumming. In total I heard 7 species.

Posted on May 02, 2019 17:08 by michaelmcg michaelmcg | 8 observations | 0 comments | Leave a comment

April 08, 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.

Posted on April 08, 2019 17:15 by michaelmcg michaelmcg | 4 observations | 0 comments | Leave a comment

March 25, 2019

Social Behavior and Phenology

Observations for this field journal were between 5:00 and 7:00pm at Woodside Park. I had the chance to observe a flock of crows which are incredibly social species and quite interesting to watch. They constantly do their “caw-caw” call to communicate with one another. They feed together in groups and have individuals looking out for any threats. They will sound an alarm if anything spooks them and then they all will fly away in unison. Individual crows also may fly around and scout areas for potential food and notify the flock that they have found something.

I also observed a red winged blackbird and a few white-breasted nuthatches. Red winged blackbirds have distinct red shoulder patches to attract mates and will puff them out to catch the eye of a female. White-breasted nuthatches on the other hand are a little more drab in coloration which may help in camouflage and likely makes it harder to see them hopping along on trees. Birds will develop different coloration depending on the pressures they face, in the case of red-winged blackbirds it may be sexual selective pressures and by comparison, white breasted nuthatches may have more pressure of predation.

There was also a group of european starlings sitting high up in the trees. They were all resting which fits into the context of their circadian rhythm with getting ready for the sun to go down and to sleep. Birds like starlings are generally more active in the morning so it was not surprising to see them all resting in the trees.

I did not come across any chickadees this time but I have done “pishing” to try and attract them before. This sound may be so enticing to small birds because the noise emits a very wide range of frequencies. Some think it could be related to it sounding like an alarm call and often birds exhibit a mobbing behavior to drive way predators which may be why they are attracted to the sound.

Posted on March 25, 2019 15:33 by michaelmcg michaelmcg | 2 observations | 0 comments | Leave a comment

March 08, 2019

Winter Bird Physiology

Chickadees are wonderfully cold adapted and can drop their body temperature quite a lot through regulated hypothermia during the night. They spend most of the day foraging for food to keep their high metabolism satisfied and to gain enough calories to be able to burn throughout a cold night. Most often they go for foods high in fat content but will ravenously eat just about anything during winter months. Since they are expending much more energy during winter months in comparison to summer they need to maintain a high caloric intake and as such diets shift.
Bird feet contain very little soft tissue and thus can be kept quite cold in relation to the rest of their body. The warm blood from their body keeps their feet just above the temperature of getting frostbitten. This system is called counter-current heat exchange. Birds also fluff their feathers to trap air in between them which warms the air and thus warms the bird too. Birds may also gather together in roosts, such as the crows of downtown Burlington to huddle together for warmth during the night.
In Red Rocks Park where I observed a peregrine falcon, some chickadees, and heard a pileated woodpecker many species may overnight in dense thickets far from the water. This ensures that the birds are far from the cold winds coming off the lake at night. Some species may nest in cavities as well to stay warm.
There were a decent amount of snags at Red Rocks and cavities within them. Many large pileated woodpecker created holes that an eastern screech owl might inhabit, as well as some smaller holes perhaps created by other species such as northern flicker. Snags provide many homes for numerous birds and other wildlife. Tree swallows and wood ducks utilize them during the spring breeding season and mammals such as squirrels or raccoons may also inhabit them.

Posted on March 08, 2019 00:07 by michaelmcg michaelmcg | 2 observations | 0 comments | Leave a comment

February 14, 2019

Flight Physiology Observation

I had the chance to observe a red-tailed hawk, some gulls, a bald eagle, and a few goldeneyes at Shelburne Farms. The red-tailed hawk was really utilizing the strong winds this day and soaring with it’s head pointed into the wind. It stabilized itself and remained motionless being held up solely by the wind blowing directly at it. They have passive soaring wings with low aspect ratios which allow them to ride currents and not spend much energy flapping. They have slotted primary feathers they move independently to make minor adjustments in flight. Their flaps are slow compared to other birds and infrequent. The gulls on the other hand actually have a similar flight technique but a very different wing shape. Long and tapered and used for active soaring the gulls require wind currents to sustain their flight without flapping. They fly more erratically than a hawk and much faster with the right wind. Without adequate wind however, I know from previous observation that they flap much more often than a hawk would due to their lack of a broad wing surface. A hawk is an open area aerial predator and as such they need to glide slowly and with minimal effort to scan fields for prey. Gulls on the other hand are seabirds and soar on coastal wind currents and munching on anything they can find along the shore. Each has a distinct flight style and wing shape based on their particular habitat niche. Using flight pattern to identify is a very useful thing. If you see a bird flying high in the distance soaring on thermals you will be able to narrow it down to a hawk or eagle. A bird soaring low and fast or flapping about near the shore of a lake or ocean would be easy to narrow down to a gull strictly based on flight pattern. Potentially a big reason why I did not find many birds this day was because of the wind along the lake. I was focused on trying to find ducks but the waves were likely too turbulent for them and many may have relocated to calmer waters. Additionally I went around sunset when most birds are heading back to their nighttime sleeping spots. Additionally, since it is winter many species are simply not around yet as we have fairly few winter residents compared to summer. To have better luck I would ideally get up at sunrise and look around when the birds are most active and explore within the woodlands instead of on major paths and roads.

Posted on February 14, 2019 02:43 by michaelmcg michaelmcg | 3 observations | 0 comments | Leave a comment

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