Spring Migration

Meteorological spring starts Sunday, and we are already starting to hear the calls of early migratory birds, heading north from southern wintering grounds, working to establish territory their among the best nesting sites available. 

Some birds, including red-winged blackbirds, Agelaius phoeniceus, get their cue to start spring migration as temperatures get warmer.  These species head to prairies, forests, and wetlands to claim a location they can protect, call for a mate, and establish a nesting site with good protection and food sources.  Other birds, including many warbler species, return in spring when daylight hours lengthen.  Generally flying at night, they use star positions and the Earth’s magnet field to guide them.  If nights are stormy or heavily overcast, early morning may find hundreds of them waiting in fields for clear skies.  Birds may also stop for a day or two in areas located on the southern shores of any large body of water to rest and feed before crossing.

Bird species around the world generally follow established flyways, established routes over specific locations between their southern and northern territories.  Many migration routes do not follow a straight path.  Some species have historical stopover or feeding locations that provide a rest point along the way.  Other species may not be able to cross a mountain range; or a large body of water can act as a barrier for land birds, but may be a required food source for wetland birds.

Long distance migration routes are most common for birds wintering in subtropical and tropical areas and breeding in the northern hemisphere.  Long migrations in the southern hemisphere are far less common because there is less land near the South Pole to support breeding activities.  The record holder for migration distance is the Arctic tern, Sterna paradisaea, overwintering in Antarctica and breeding in Arctic locations, a round trip between 30,000 and 55,000 miles.  Some shorter migrations are between upper and lower altitudes in mountainous regions.

Most birds migrate in flocks, which reduces the energy needed to fly long distances and provides added protection against predators.  Penguins migrate without flying.  Most penguin species swim between locations, covering up to 1,000 miles round trip.  A few species cover long distances on foot, including dusky grouse, Dendragapus obscurus, in the Rocky Mountains which walk from lower to higher elevations.  However, a flock may encounter unfavorable weather or flying conditions that causes a large number of birds to stall in one location, introducing other risks including depleted food sources and predation by land-based animals.

At the Jurica-Suchy Nature Museum, we host a nature walk every other week to observe changes in our campus including the birds that are moving through the area.  There are many birding groups worldwide that provide opportunities to observe and learn about migratory birds in every location.  Consider joining a group, or take your own bird walk as we have clear days and warming temperatures and see who’s on the move in your area.