American Robin

American Robin
American Robin
Turdus migratorius
Courtesy US FWS, images.fws.gov
Dr. Thomas G. Barnes, Photographer
 

Robin with Chicks in NestAmerican Robin
Turdus migratorius
Courtesy US FWS, images.fws.gov
Lee Karney, Photographer
 

Robin with Chicks in NestRobin with Chicks in Nest
Courtesy US FWS, images.fws.gov
James C. Leopold, Photographer

The American robin with its abundance, red breast, and loud song is one of the most recognizable backyard birds in North America. For many of us the robin – or Turdus migratorius – is also thought of as a herald of spring. So why is it that we still occasionally see them in our wintry Utah backyards?

Seasonal bird migration can be triggered by a number of things, but the two main drivers are food supply and nesting habitat. In spring and summer the birds move northward to take advantage of insect hatches, budding plants, and the plethora of nesting sites. Then, as food sources dwindle in fall, the birds move southward to areas where the necessary resources are still plentiful.

The distances birds migrate in order to access these resources can range widely. Therefore, birds are generally categorized as being short-, medium-, or long-distance migrants. Robins are considered short-distance migrants. While their range spans all of Canada and the United States extending down into Mexico, most robins do not travel far from their breeding grounds in winter and may not leave at all. Only the populations that breed and reside on the edges of this range will migrate seasonally.

The robin’s varied diet and behavioral adaptability are the primary reasons these short-migratory or non-migratory patterns are possible. Robins are preferably ground foragers, feasting on insects and earthworms in the spring and summer months. Yet, during the fall and winter, robins eat a fruit-based diet. They track this seasonal food source in flocks, abandoning their summer individualistic and territorial behavior. These flocks – or roosting aggregates – also help them survive the cold winter temperatures. As a result, robins are able to cope with the ground freezing, the disappearance of their preferred food source, and the harsh winter weather.

Returning to our original question: is the American robin truly a sign of spring here in Utah? Is it strange to see this bird in our backyards during the winter months? The simple answer is no. Robins can be found year round almost anywhere south of Canada. While they may migrate nomadically, staying or leaving areas as weather and snow cover affect their food supply, there could be some keeping us company in Utah all winter.

For Wild About Utah, I’m Anna Bengtson.

Credits:
Image: Courtesy US FWS, Lee Karney, James C. Leopold, Photographers
Text: Anna Bengston

Sources & Additional Reading:

American Robin Profile, Utah Birds http://utahbirds.org/birdsofutah/BirdIndex.htm

American Robin, Cornell Lab of Ornithology http://www.allaboutbirds.org/guide/american_robin/id

American Robin, The Birds of North America Online http://bna.birds.cornell.edu/bna/species/462/articles/introduction

Studying Migration, Cornell Lab of Ornithology http://www.birds.cornell.edu/AllAboutBirds/studying/migration/

Migration Patterns, Cornell Lab of Ornithology http://www.birds.cornell.edu/AllAboutBirds/studying/migration/patterns

Where Have all the Robins Gone?, Migration, Cornell Lab of Ornithology http://www.birds.cornell.edu/AllAboutBirds/faq/master_folder/migration/document_view

Snow Depth Survey, The Great Backyard Bird Count http://www.birdsource.org/gbbc/science-stories/past-stories/snow-depth-survey

Winter Robins, The Great Backyard Bird Count http://www.birdsource.org/gbbc/science-stories/past-stories/is-that-winter-flock-of-robins-in-your-yard-unusual

Robins in Winter

American Robin
American Robin
Turdus migratorius
Courtesy US FWS, images.fws.gov
Dr. Thomas G. Barnes, Photographer
 

Robin with Chicks in NestAmerican Robin
Turdus migratorius
Courtesy US FWS, images.fws.gov
Lee Karney, Photographer
 

Robin with Chicks in NestRobin with Chicks in Nest
Courtesy US FWS, images.fws.gov
James C. Leopold, Photographer

The American robin with its abundance, red breast, and loud song is one of the most recognizable backyard birds in North America. For many of us the robin – or Turdus migratorius – is also thought of as a herald of spring. So why is it that we still occasionally see them in our wintry Utah backyards?

Seasonal bird migration can be triggered by a number of things, but the two main drivers are food supply and nesting habitat. In spring and summer the birds move northward to take advantage of insect hatches, budding plants, and the plethora of nesting sites. Then, as food sources dwindle in fall, the birds move southward to areas where the necessary resources are still plentiful.

The distances birds migrate in order to access these resources can range widely. Therefore, birds are generally categorized as being short-, medium-, or long-distance migrants. Robins are considered short-distance migrants. While their range spans all of Canada and the United States extending down into Mexico, most robins do not travel far from their breeding grounds in winter and may not leave at all. Only the populations that breed and reside on the edges of this range will migrate seasonally.

The robin’s varied diet and behavioral adaptability are the primary reasons these short-migratory or non-migratory patterns are possible. Robins are preferably ground foragers, feasting on insects and earthworms in the spring and summer months. Yet, during the fall and winter, robins eat a fruit-based diet. They track this seasonal food source in flocks, abandoning their summer individualistic and territorial behavior. These flocks – or roosting aggregates – also help them survive the cold winter temperatures. As a result, robins are able to cope with the ground freezing, the disappearance of their preferred food source, and the harsh winter weather.

Returning to our original question: is the American robin truly a sign of spring here in Utah? Is it strange to see this bird in our backyards during the winter months? The simple answer is no. Robins can be found year round almost anywhere south of Canada. While they may migrate nomadically, staying or leaving areas as weather and snow cover affect their food supply, there could be some keeping us company in Utah all winter.

For Wild About Utah, I’m Anna Bengtson.

Credits:
Image: Courtesy US FWS, Lee Karney, James C. Leopold, Photographers
Text: Anna Bengston

Sources & Additional Reading:

American Robin Profile, Utah Birds http://utahbirds.org/birdsofutah/BirdIndex.htm

American Robin, Cornell Lab of Ornithology http://www.allaboutbirds.org/guide/american_robin/id

American Robin, The Birds of North America Online http://bna.birds.cornell.edu/bna/species/462/articles/introduction

Studying Migration, Cornell Lab of Ornithology http://www.birds.cornell.edu/AllAboutBirds/studying/migration/

Migration Patterns, Cornell Lab of Ornithology http://www.birds.cornell.edu/AllAboutBirds/studying/migration/patterns

Where Have all the Robins Gone?, Migration, Cornell Lab of Ornithology http://www.birds.cornell.edu/AllAboutBirds/faq/master_folder/migration/document_view

Snow Depth Survey, The Great Backyard Bird Count http://www.birdsource.org/gbbc/science-stories/past-stories/snow-depth-survey

Winter Robins, The Great Backyard Bird Count http://www.birdsource.org/gbbc/science-stories/past-stories/is-that-winter-flock-of-robins-in-your-yard-unusual

Nesting Season

Lark Sparrow Nest, Courtesy & Copyright © Jim Cane, Photographer
Lark Sparrow Nest, June
Courtesy & © Copyright
Jim Cane, Photographer 

While we swelter in summer’s heat, the southward shorebird migration has begun. But some songbirds find this a perfect time to nest. We think of spring as nesting season and for the majority of birds it is. But there are some birds nesting almost year round in Utah.

Living organisms are impelled to maximize the number of successful offspring they produce. Therefore, they tend to reproduce during times of plenty, because the breeding season is strenuous. Males compete for mates and territory and females produce eggs. Both parents may guard the nest from predators and feed the young. Many birds feed nutrient rich insects to their nestlings so nesting season is timed to coincide with the greatest abundance of insects, usually spring in temperate and arctic climes.

American and Lesser Goldfinches are one example of birds who do things differently. (Lesser Goldfinch. Kevin Colver: Songbirds of the Southwest Canyon Country) Instead of insects, they feed their young a regurgitated milky seed pulp. Therefore, they time their nesting for greatest abundance of seeds, especially sunflower and thistle, which is in the summer.

Other birds prefer one type of nut. These include Pinon Jays and crossbills. Abundant pinon nuts trigger Pinon Jay nesting. (Pinon Jay. Kevin Colver: Songbirds of the Southwest Canyon Country) If they have enough nuts cached from the previous season, they will nest in late winter, even while snow blankets the landscape. In years with a bumper crop of pinon nuts, they will also breed in late summer to take advantage of the plentiful food. Good conifer cone crops determine when and where crossbills nest, which can be almost any time.

Great-horned Owls are one of the first to nest each year. (Great-horned Owl. Kevin Colver: Songbirds of the Southwest Canyon Country) You can hear courting pairs hoot back and forth in midwinter. They may incubate their eggs while covered in snow, and if the temperature is too frigid, the eggs freeze and the young die. Many predatory birds nest early, perhaps to insure that the young learn how to proficiently hunt before winter.

The drive to reproduce is inviolable and birds take advantage of whatever season gives them the greatest chance for success. For every nesting bird there is a season.

Thanks to Kevin Colver for the use of his bird recordings.

This is Linda Kervin for Bridgerland Audubon Society and Wild About Utah.

Credits:
Images: Jim Cane, Bridgerland Audubon Society
Audio: Kevin Colver,
Text: Linda Kervin, Bridgerland Audubon Society

Additional Reading:

http://www.allaboutbirds.org/guide/red_crossbill/lifehistory

http://www.birds.cornell.edu/AllAboutBirds/owlp/ghowl

http://birds.audubon.org/birds/american-goldfinch

http://books.simonandschuster.com/Birders-Handbook/Paul-Ehrlich/9780671659899