Top Five Migrations in Maryland and DC

Nature on the Move

Each year, seasonal migrations sees nature in motion as animals fly, swim, run, and crawl to their summer or winter homes and breeding grounds.  Celebrate this pageant of nature with our list of Top Five Migrations in Maryland and DC.

Blue Crab (Callinectus sapidus)

When people "migrate" to the beach for their summer vacations, a crab feast is often on the agenda.  but did you know the crabs of the Chesapeake Bay also make their own migration?

The journey begins when pregnant females (called "Jennys") travel down to the southern tip of the Chesapeake Bay to release their eggs.  In their first life stage, crabs are helpless larvae that float along with the current between the Bay and the Atlantic Ocean.  After 45 days they begin to earn their scientific name Callinectus sapidus ("beautiful swimmers") by molting into their mobile crab stage and swimming higher into the Chesapeake Bay.

For a year and a half they feed along the shores and tributaries of the upper Bay before the migration process starts all over again.  The adult crabs mate, and the Jennys swim back down to the mouth of the Chesapeake to release their eggs.

The adult male crabs (called "Jimmies") do their own migration - a vertical one.  When winter comes they dig down into the  mud where temperatures are more stable, and await the siren song of warmer temperatures and swimming Jennys to emerge.

The Nature Conservancy is working to conserve blue crabs by protecting the forests that filter water going into the Chesapeake Bay, finding solutions to reduce run off from stormwater and agriculture, and restoring oyster reefs the provide nurseries and habitat.

Baltimore Oriole (Icterus galbula)

Neotropical migratory songbirds herald the arrival of spring in Maryland and across North America, raising young and spending their summers here.  In the fall, massive flocks hurtle into the night skies as they depart for their winter homes in Mexico, Central America, South America, or the Caribbean.

Springtime also means baseball's opening day.  Maryland has a rich baseball heritage, as the birthplace of both Babe Ruth and thousands of Baltimore orioles - Maryland's state bird and Baltimore's Major League Baseball mascot.

Much of Maryland lies within the southern rage of the Baltimore orioles' summer breeding grounds, with nests found along the edges of forests.  Preserves where Baltimore orioles can be found during the summer include Nanjemoy Creek and Third Haven Woods


Abundant food around the mouth of the Chesapeake Bay helps attract two of Maryland's most majestic migratory animals.  During the winter, humpback (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) feed along the Maryland coast as they head south to mate and calve in tropical waters.  Humpbacks grow to 50 feet long.  Their songs and spectacular leaps from the ocean thrill seafarers of all ages.  Fin whales grow even longer; in fact, these powerful swimmers are the second-largest animal on Earth after the blue whale.

From late December through mid March, the Assateague Island National Seashore provides a viewing point from the beach.  The Virginia Aquarium and Marine Science Center offers whale watching trips departing from Virginia Beach.

Great Blue Heron (Ardea herodias)

These largest members of the heron family are nicknamed the "love birds" because around Valentine's Day each year these tall, stately birds woo a mate and settle down to nest.  Hundreds of great blue heron nests can be found together in rookeries around the Chesapeake Bay and its tributaries.

The raucous calls of the nestlings, squabbling between adults, and low swooping flights of the parents give these rookeries a near-prehistoric feel.  In the summer the nestlings fly off, and the herons look to migrate south in the fall to ply the waters off the Carolinas, Georgia, and Florida for fish, crabs, and frogs.

You can see great blue herons many places in Maryland, but you are almost guaranteed to see one if you visit Blackwater National Wildlife Refuge in the summer.

American Shad (Alosa sapidissima)

A spring run of this "founding fish" was said to have saved General Washington's Continental Army from starvation in 1778 at Valley Forge, along the Schuylkill River in Pennsylvania.

American shad spend the majority of their lives in the Atlantic Ocean.  But with the coming of spring, the fish are cued by changes in water temperatures and salinity to move up the freshwater tributaries of the Chesapeake Bay to mate and lay eggs.  Like a clock, the seasonal flows of these rivers tell the shad when to migrate.

The Susquehanna River is the largest tributary of the Chesapeake Bay, and The Nature Conservancy is working with the Federal government to improve conditions for migrating shad along the Susquehanna's four dams.