Write a note on migration in animals?

Migration refers to the regular movement of animals from one location to another, often over long distances. It is a fascinating and complex animal behavior observed in various species across the animal kingdom.

Definition

• Migration is driven by various factors, such as seasonal changes, food availability, breeding opportunities, and environmental conditions.

Types

1. Seasonal Migration

Seasonal migration refers to the cyclical movement of animals between two or more areas in response to changing seasons. It allows animals to access resources and habitats that vary with the time of year.

Example

• The Arctic Tern (Sterna paradisaea) undertakes one of the longest known migrations, flying from its Arctic breeding grounds to the Antarctic and back. This round-trip journey spans over 40,000 kilometers (25,000 miles) each year, allowing the terns to follow the polar summer and access abundant food sources in both hemispheres.

• Altitudinal Migration

Altitudinal migration involves the movement of animals between different elevations within a particular geographic area. Animals may move to higher altitudes during one season and then descend to lower altitudes in another.

Example

• The Alpine Ibex (Capra ibex) demonstrates altitudinal migration. During the summer, these agile goats move to higher elevations in the Alps to find fresh grazing grounds, while in winter, they descend to lower altitudes for milder temperatures and better shelter.

The Alpine Ibex (Capra ibex)

• Reproductive Migration

Reproductive migration, also known as breeding migration, refers to the movement of animals to specific areas for the purpose of reproduction and raising offspring in favourable conditions.

Example

• The Humpback Whale (Megaptera novaeangliae) migrates thousands of kilometers from its feeding grounds in polar regions to warm tropical waters for mating and calving. The warm, sheltered waters offer protection for the newborn calves during their early months.

• Nomadic Migration

Nomadic migration involves the continuous movement of animals without fixed patterns or specific destinations. These migrations are typically driven by the search for food, water, and suitable living conditions.

Example

• The Wildebeest (Connochaetes) undertake nomadic migrations across the African savannah in search of fresh grazing areas and water sources. This massive movement involves millions of individuals, creating one of the most impressive natural spectacles on Earth.

Wildebeest (Connochaetes)

• Latitudinal Migration

Latitudinal migration involves the movement of animals along a north-south or south-north axis, often covering long distances to access resources and adjust to changing environmental conditions.

Example

• The Monarch Butterfly (Danaus plexippus) undertakes a latitudinal migration, with populations from North America traveling thousands of kilometers to overwinter in central Mexico. In the spring, successive generations return northward to the United States and Canada to breed and complete their life cycle.

Migration Rout of Monarch Butterfly (Danaus plexippus)

Mechanism of navigation during migration

The mechanism of navigation during migration is a fascinating and complex process that varies among different animal species. Animals use a combination of sensory cues, innate instincts, and learned behaviors to successfully navigate across vast distances and return to specific locations. Here are some of the key mechanisms of navigation during migration.

1. Magnetic Field Detection

Many migratory animals, such as birds, sea turtles, and certain fish species, possess specialized cells or structures that allow them to sense the Earth’s magnetic field. These cells act like an internal compass, helping the animals determine their direction relative to the Earth’s magnetic poles.

• Celestial Navigation

Animals often rely on celestial cues, such as the position of the sun, stars, and moon, to navigate accurately. They can use the patterns of celestial bodies to maintain a particular course during both day and night.

• Visual Landmarks and Memory

Some migratory species, especially birds, have excellent visual memory and can recognize familiar landmarks along their migration routes. This helps them to follow specific pathways even when they cannot see the stars or landmarks directly.

• Olfactory (Smell) Navigation

Certain animals, like salmon, can detect chemical cues in the water using their sense of smell. They rely on these cues to find their way back to their natal streams or to locate breeding grounds during migration.

• Inherited Genetic Information

Migration is often an innate behavior coded in an animal’s genes. Young animals may inherit migratory routes and destinations from their parents and ancestors. This genetic information guides them during their first migration, even without prior experience or direct instruction.

• Social Learning

In some species, especially mammals and birds, migration can involve social learning. Juvenile animals may follow experienced adults during their first migration, learning the route and other essential navigation skills from the older individuals.

• Environmental Cues

Animals are highly attuned to changes in environmental conditions, such as changes in temperature, wind patterns, and ocean currents. These cues provide valuable information that helps them adjust their course and make necessary adaptations during migration.

Causes of Migration

There are following causes of migration.

1. Seasonal Changes

Many animals migrate in response to changing seasons to escape extreme weather conditions and locate favourable habitats.  

• Food Availability

Scarcity of food resources in one region can drive animals to undertake long journeys in search of more abundant food sources.

• Breeding Opportunities

Some species migrate to specific areas for optimal breeding conditions and to ensure the survival of their offspring.

Challenges & Conservative Measures in Migration

Migration is a critical behavior for many animal species, enabling them to survive, reproduce, and maintain ecological balance. However, migration faces numerous challenges, often exacerbated by human activities and environmental changes. Conservation efforts are essential to safeguard these incredible journeys and preserve the diverse species that undertake them. Below are some of the key challenges and conservation measures, along with suitable examples that highlight the significance of protecting migration:

1. Habitat Loss and Fragmentation

Human activities such as deforestation, urbanization, and infrastructure development can disrupt migration routes and destroy critical habitats.

Example

The migration of the African Elephant (Loxodonta africana) is threatened by habitat loss due to expanding human settlements and agriculture. Their traditional migration paths often intersect with human-dominated landscapes, leading to conflicts and loss of vital habitats.

• Conservation Measure

Establishing protected areas and wildlife corridors that connect essential habitats can help maintain the integrity of migration routes for animals like the African Elephant.

• Climate Change and Altered Weather Patterns

Climate change can impact the timing and availability of resources along migration routes.

Example

The migration of the Arctic Caribou (Rangifer tarandus) in northern regions may be disrupted as warmer temperatures cause changes in vegetation growth and snow cover. This can lead to a mismatch between the caribou’s migration timing and the availability of food resources.

• Conservation Measure

Monitoring climate patterns and adapting conservation strategies to accommodate changing environmental conditions can assist in preserving migration routes for species like the Arctic Caribou.

• Hunting and Poaching

Unsustainable hunting and poaching can have devastating effects on migratory species.

Example

The African wildebeest, a key player in the Serengeti migration, has faced threats from illegal hunting. Poachers often target these animals for their valuable hides and meat, disrupting the delicate balance of the ecosystem.

• Conservation Measure

Implementing strict anti-poaching measures, community-based conservation initiatives, and engaging local communities in wildlife protection can help safeguard species like the African wildebeest.

• Barriers to Migration

Human-made barriers such as dams, fences, and roads can obstruct migratory routes and prevent animals from reaching essential habitats.

Example

The migration of salmon in many rivers is impeded by dams, which hinder their ability to reach spawning grounds.

• Conservation Measure

Employing fish ladders, removing obsolete dams, and designing wildlife-friendly infrastructure can enable species like salmon to overcome migration barriers.

• Pollution and Contamination

Pollution, especially in water bodies, can be harmful to migratory species that rely on clean environments during their journeys.

Example

Marine animals like sea turtles often ingest plastic waste, mistaking it for food, leading to serious health consequences.

• Conservation Measure

Reducing plastic pollution, controlling industrial waste discharge, and promoting sustainable practices can help protect migratory species like sea turtles from pollution-related threats.

Advantages of Migration

There are following advantages of migration

1. Access to abundant food and resources in different habitats.
2. Escape from harsh environmental conditions and extreme weather.
3. Opportunities for successful reproduction and breeding.
4. Reduction of competition for limited resources among different populations.
5. Genetic diversity through mixing of different populations.
6. Restoration and maintenance of ecological balance in different ecosystems.
7. Spread of seeds and pollination for plant species.
8. Migration is a survival strategy for certain species in changing environments.
9. Migration helps control pest populations in agricultural areas.
10. Adaptation to changing environmental conditions and ecological niches.

Disadvantages of Migration

There are following disadvantages of migration.

1. Exposure to new predators, diseases, and unfamiliar environmental hazards.
2. Risk of injury or death during the migration journey.
3. Loss of individuals during migration disrupts population dynamics.
4. Energy expenditure and exhaustion during long-distance journeys.
5. Disruption of natural behaviors due to human interference along migration routes.
6. Separation from familiar territories and social groups.
7. Conflicts with human activities, such as collisions with vehicles or infrastructure.
8. Reduced access to resources or critical habitats due to human encroachment.
9. Decreased reproductive success if migration patterns are disrupted or habitats are degraded.
10. Challenges in adapting to new environments and climate variations during migration.