Ever wonder why some birds migrate, and others don’t during the spring or the fall seasons? For instance, why do some birds migrate and other birds, like cardinals, stay all year round? This question has puzzled several bird watchers, scientists, and ornithologists.
Several birds make their way south to their wintering grounds. However, only some birds migrate, and others don’t. Some birds, like robins, choose to stay in the north during the harsh cold winter months. Around 40 percent of all bird species are migratory. Thus, more than half of all bird species do not migrate and stay in the same region.
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According to experts, when birds migrate from one place to another, it is mainly about the bird’s food source and not always about the temperature. Several birds are able to survive in extremely cold temperatures only if they are able to find sufficient food. Birds that mostly consume fruits or insects need to migrate towards the south during winter in order to find enough food to survive. For example, hummingbirds and orioles need to migrate as they feed on fruits and flower nectar.
Birds that consume seeds are able to find lots of food during the harsh winter months to survive. Berry and seed-eating birds like cardinals, finches, chickadees, and robins usually do not migrate as they find their food all year round. Some birds that consume spiders and other insects under tree bark do not migrate as well. They use their food and convert it into body heat to survive in the cold.
According to research and analyses, seasonal regions have a higher number of migratory birds- they migrate to the closest regions they can find that best meets their needs. In order to find sufficient food sources, birds make different kinds of migrations. Some birds travel very short distances, such as from a higher elevation to a lower elevation. While some birds travel very long distances, crossing countries and even continents- Central to South America or from Asia to Europe. The Arctic tern migrates the longest distance than any other bird in the world- they can fly more than 49,700 miles in a year.
Some birds migrate to other regions to find a better climate. For example, several birds migrate from their Arctic breeding grounds to more warm or more suitable temperature regions to avoid the harsh winter months in the Arctic. Some birds travel from the warmest tropical regions to more harsh climates to raise and nurture their young. Today, due to climate change and global warming, several birds will begin to migrate as temperatures and conditions become unsuitable and harsh for them to survive.
Some birds do not migrate to other regions as they choose to save their energy and overwinter in their own territory. Instead of traveling far distances or toward the south, they use their energy to forage, raise and nurture their young, protect themselves from predators, and do other activities during the winter months to survive.
Breeding, Protecting and Nurturing the Young
Several birds migrate in the spring for breeding purposes. Migratory birds can fly hundreds and thousands of kilometers to find the best climatic and ecological conditions and habitats for breeding, feeding, and raising their chicks. However, some birds migrate to help their young survive. It is surprising to know that some bird parents leave their mature chicks and remain with immature chicks to protect and nurture them. Bird parents also remain with inexperienced chicks so that they will be able to travel alone the next time.
Some birds prefer to nurture and stay with their young over migrating to warmer regions during the winter months. The extra care that bird parents give their young helps the chicks to survive inclement weather and helps them become strong and healthy. Few non-migratory birds raise additional broods later in the season. About 25 percent of breeding birds in North America do not migrate.
Running Away from Predators or Defending Territory
Regions having abundant food sources throughout the year invite several predators. Some birds migrate to different regions to avoid the threats of predators. The habitats or areas where predators do not get access include steep coastal cliffs and rocky offshore islands. Thus, birds wanting to escape predators travel to these locations or others.
Some birds do not choose to migrate to other areas as they want to defend their territory. Most territorial birds do not migrate to warmer locations in the harsh winter. Some of the non-migratory territorial birds include black-capped chickadees, common ravens, pileated woodpeckers, black vultures, and more. These territorial birds stay put in their territory to protect themselves from other migrating birds in the spring.
Preventing Diseases or Living in the Tropics
Several birds travel to different locations to avoid diseases and parasites. Sometimes, a new and unknown disease can destroy or disrupt a whole breeding colony. Thus, birds move from one region to another to keep themselves and their young safe. They need to migrate for their survival.
Usually, birds living in tropical regions do not migrate to other regions. They do not migrate as they are already living in warm temperatures. The winter in tropical areas is not harsh. Thus, allowing birds to stay there throughout the years. Some tropical states in the United States include California, Hawaii, Florida, and Texas. Birds in these areas may not experience four seasons.
Dr. Emily Greenfield is a highly accomplished environmentalist with over 30 years of experience in writing, reviewing, and publishing content on various environmental topics. Hailing from the United States, she has dedicated her career to raising awareness about environmental issues and promoting sustainable practices.